com.trolltech.qt.gui
Class QImage

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.gui.QImage
All Implemented Interfaces:
QPaintDeviceInterface, QtJambiInterface, java.lang.Cloneable

public class QImage
extends QtJambiObject
implements QPaintDeviceInterface, java.lang.Cloneable

The QImage class provides a hardware-independent image representation that allows direct access to the pixel data, and can be used as a paint device. Qt provides four classes for handling image data: QImage, QPixmap, QBitmap and QPicture. QImage is designed and optimized for I/O, and for direct pixel access and manipulation, while QPixmap is designed and optimized for showing images on screen. QBitmap is only a convenience class that inherits QPixmap, ensuring a depth of 1. Finally, the QPicture class is a paint device that records and replays QPainter commands.

Because QImage is a QPaintDevice subclass, QPainter can be used to draw directly onto images. When using QPainter on a QImage, the painting can be performed in another thread than the current GUI thread.

The QImage class supports several image formats described by the Format enum. These include monochrome, 8-bit, 32-bit and alpha-blended images which are available in all versions of Qt 4.x.

QImage provides a collection of functions that can be used to obtain a variety of information about the image. There are also several functions that enables transformation of the image.

QImage objects can be passed around by value since the QImage class uses implicit data sharing. QImage objects can also be streamed and compared.

Note: If you would like to load QImage objects in a static build of Qt, refer to the Plugin HowTo.

Reading and Writing Image Files

QImage provides several ways of loading an image file: The file can be loaded when constructing the QImage object, or by using the
load() or loadFromData() functions later on. QImage also provides the static fromData() function, constructing a QImage from the given data. When loading an image, the file name can either refer to an actual file on disk or to one of the application's embedded resources. See The Qt Resource System overview for details on how to embed images and other resource files in the application's executable.

Simply call the save() function to save a QImage object.

The complete list of supported file formats are available through the QImageReader::supportedImageFormats() and QImageWriter::supportedImageFormats() functions. New file formats can be added as plugins. By default, Qt supports the following formats:

Format
Description
Qt's support
BMP Windows Bitmap Read/write
GIF Graphic Interchange Format (optional) Read
JPG Joint Photographic Experts Group Read/write
JPEG Joint Photographic Experts Group Read/write
PNG Portable Network Graphics Read/write
PBM Portable Bitmap Read
PGM Portable Graymap Read
PPM Portable Pixmap Read/write
TIFF Tagged Image File Format Read/write
XBM X11 Bitmap Read/write
XPM X11 Pixmap Read/write

Image Information

QImage provides a collection of functions that can be used to obtain a variety of information about the image:
Available Functions
Geometry The size(), width(), height(), dotsPerMeterX(), and dotsPerMeterY() functions provide information about the image size and aspect ratio.

The rect() function returns the image's enclosing rectangle. The valid() function tells if a given pair of coordinates is within this rectangle. The offset() function returns the number of pixels by which the image is intended to be offset by when positioned relative to other images, which also can be manipulated using the setOffset() function.

Colors The color of a pixel can be retrieved by passing its coordinates to the pixel() function. The pixel() function returns the color as a QRgb value indepedent of the image's format.

In case of monochrome and 8-bit images, the numColors() and colorTable() functions provide information about the color components used to store the image data: The colorTable() function returns the image's entire color table. To obtain a single entry, use the pixelIndex() function to retrieve the pixel index for a given pair of coordinates, then use the color() function to retrieve the color. Note that if you create an 8-bit image manually, you have to set a valid color table on the image as well.

The hasAlphaChannel() function tells if the image's format respects the alpha channel, or not. The allGray() and isGrayscale() functions tell whether an image's colors are all shades of gray.

See also the Pixel Manipulation and Image Transformations sections.

Text The text() function returns the image text associated with the given text key. An image's text keys can be retrieved using the textKeys() function. Use the setText() function to alter an image's text.
Low-level information The depth() function returns the depth of the image. The supported depths are 1 (monochrome), 8 and 32 (for more information see the Image Formats section).

The format(), bytesPerLine(), and numBytes() functions provide low-level information about the data stored in the image.

The cacheKey() function returns a number that uniquely identifies the contents of this QImage object.

Pixel Manipulation

The functions used to manipulate an image's pixels depend on the image format. The reason is that monochrome and 8-bit images are index-based and use a color lookup table, while 32-bit images store ARGB values directly. For more information on image formats, see the Image Formats section.

In case of a 32-bit image, the setPixel() function can be used to alter the color of the pixel at the given coordinates to any other color specified as an ARGB quadruplet. To make a suitable QRgb value, use the qRgb() (adding a default alpha component to the given RGB values, i.e. creating an opaque color) or qRgba() function. For example:



        QImage image = new QImage(3, 3, QImage.Format.Format_RGB32);
        int value;

        value = new QColor(189, 149, 39).rgb(); // 0xffbd9527
        image.setPixel(1, 1, value);

        value = new QColor(122, 163, 39).rgb(); // 0xff7aa327
        image.setPixel(0, 1, value);
        image.setPixel(1, 0, value);

        value = new QColor(237, 187, 51).rgb(); // 0xffedba31
        image.setPixel(2, 1, value);
32-bit
In case of a 8-bit and monchrome images, the pixel value is only an index from the image's color table. So the setPixel() function can only be used to alter the color of the pixel at the given coordinates to a predefined color from the image's color table, i.e. it can only change the pixel's index value. To alter or add a color to an image's color table, use the setColor() function.

An entry in the color table is an ARGB quadruplet encoded as an QRgb value. Use the qRgb() and qRgba() functions to make a suitable QRgb value for use with the setColor() function. For example:



        QImage image = new QImage(3, 3, QImage.Format.Format_Indexed8);
        int value;

        value = new QColor(122, 163, 39).rgb(); // 0xff7aa327
        image.setColor(0, value);

        value = new QColor(237, 187, 51).rgb(); // 0xffedba31
        image.setColor(1, value);

        value = new QColor(189, 149, 39).rgb(); // 0xffbd9527
        image.setColor(2, value);

        image.setPixel(0, 1, 0);
        image.setPixel(1, 0, 0);
        image.setPixel(1, 1, 2);
        image.setPixel(2, 1, 1);
8-bit
QImage also provide the scanLine() function which returns a pointer to the pixel data at the scanline with the given index, and the bits() function which returns a pointer to the first pixel data (this is equivalent to scanLine(0)).

Image Formats

Each pixel stored in a QImage is represented by an integer. The size of the integer varies depending on the format. QImage supports several image formats described by the
Format enum. The monochrome (1-bit), 8-bit and 32-bit images are available in all versions of Qt. In addition Qt for Embedded Linux also supports 2-bit, 4-bit, and 16-bit images. For more information about the Qt Extended specific formats, see the documentation of the Format enum.

Monochrome images are stored using 1-bit indexes into a color table with at most two colors. There are two different types of monochrome images: big endian (MSB first) or little endian (LSB first) bit order.

8-bit images are stored using 8-bit indexes into a color table, i.e. they have a single byte per pixel. The color table is a QVector<QRgb>, and the QRgb typedef is equivalent to an unsigned int containing an ARGB quadruplet on the format 0xAARRGGBB.

32-bit images have no color table; instead, each pixel contains an QRgb value. There are three different types of 32-bit images storing RGB (i.e. 0xffRRGGBB), ARGB and premultiplied ARGB values respectively. In the premultiplied format the red, green, and blue channels are multiplied by the alpha component divided by 255.

An image's format can be retrieved using the format() function. Use the convertToFormat() functions to convert an image into another format. The allGray() and isGrayscale() functions tell whether a color image can safely be converted to a grayscale image.

Image Transformations

QImage supports a number of functions for creating a new image that is a transformed version of the original: The createAlphaMask() function builds and returns a 1-bpp mask from the alpha buffer in this image, and the createHeuristicMask() function creates and returns a 1-bpp heuristic mask for this image. The latter function works by selecting a color from one of the corners, then chipping away pixels of that color starting at all the edges.

The mirrored() function returns a mirror of the image in the desired direction, the scaled() returns a copy of the image scaled to a rectangle of the desired measures, the rgbSwapped() function constructs a BGR image from a RGB image, and the alphaChannel() function constructs an image from this image's alpha channel.

The scaledToWidth() and scaledToHeight() functions return scaled copies of the image.

The transformed() function returns a copy of the image that is transformed with the given transformation matrix and transformation mode: Internally, the transformation matrix is adjusted to compensate for unwanted translation, i.e. transformed() returns the smallest image containing all transformed points of the original image. The static trueMatrix() function returns the actual matrix used for transforming the image.

There are also functions for changing attributes of an image in-place:

Function
Description
setAlphaChannel() Sets the alpha channel of the image.
setDotsPerMeterX() Defines the aspect ratio by setting the number of pixels that fit horizontally in a physical meter.
setDotsPerMeterY() Defines the aspect ratio by setting the number of pixels that fit vertically in a physical meter.
fill() Fills the entire image with the given pixel value.
invertPixels() Inverts all pixel values in the image using the given InvertMode value.
setColorTable() Sets the color table used to translate color indexes. Only monochrome and 8-bit formats.
setNumColors() Resizes the color table. Only monochrome and 8-bit formats.

Legal Information

For smooth scaling, the
transformed() functions use code based on smooth scaling algorithm by Daniel M. Duley.Copyright (C) 2004, 2005 Daniel M. DuleyRedistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

See also:
QImageReader, QImageWriter, QPixmap, QSvgRenderer, Image Composition Example, Image Viewer Example, Scribble Example, and Pixelator Example.


Nested Class Summary
static class QImage.Format
          The following image formats are available in all versions of Qt.
static class QImage.InvertMode
          This enum type is used to describe how pixel values should be inverted in the invertPixels() function.
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QImage()
          Constructs a null image.
QImage(byte[] data, int width, int height, QImage.Format format)
          Constructs an image with the given width, height, depth, bytesPerLine, colortable, numColors and bitOrder, that uses an existing memory buffer, data.
QImage(int width, int height, QImage.Format format)
          Constructs an image with the given width, height and format.
QImage(QImage arg__1)
          Constructs a shallow copy of the given image.
QImage(QNativePointer data, int width, int height, int bytesPerLine, QImage.Format format)
          Constructs an image with the given width, height and format, that uses an existing memory buffer, data.
QImage(QSize size, QImage.Format format)
          Constructs an image with the given size and format.
QImage(java.lang.String fileName)
          Constructs an image from the given xpm image.
QImage(java.lang.String[] xpm)
           
QImage(java.lang.String fileName, java.lang.String format)
          Constructs an image and tries to load the image from the file with the given fileName.
 
Method Summary
 boolean allGray()
          Returns true if all the colors in the image are shades of gray (i.
 QImage alphaChannel()
          Returns the alpha channel of the image as a new grayscale QImage in which each pixel's red, green, and blue values are given the alpha value of the original image.
 QNativePointer bits()
          Returns a pointer to the first pixel data.
 int bytesPerLine()
          Returns the number of bytes per image scanline.
 long cacheKey()
          Returns a number that identifies the contents of this QImage object.
 QImage clone()
          This method is reimplemented for internal reasons
 int color(int i)
          Returns the color in the color table at index i.
 java.util.List colorTable()
          Returns a list of the colors contained in the image's color table, or an empty list if the image does not have a color table
 QImage convertToFormat(QImage.Format f)
          Returns a copy of the image in the given format.
 QImage convertToFormat(QImage.Format f, java.util.List colorTable)
          Returns a copy of the image in the given format.
 QImage convertToFormat(QImage.Format f, java.util.List colorTable, Qt.ImageConversionFlag[] flags)
           
 QImage convertToFormat(QImage.Format f, java.util.List colorTable, Qt.ImageConversionFlags flags)
          Returns a copy of the image in the given format.
 QImage convertToFormat(QImage.Format f, Qt.ImageConversionFlag[] flags)
           
 QImage convertToFormat(QImage.Format f, Qt.ImageConversionFlags flags)
          Returns a copy of the image in the given format.
 QImage copy()
          Returns a sub-area of the image as a new image.
 QImage copy(int x, int y, int w, int h)
          This is an overloaded member function, provided for convenience.
 QImage copy(QRect rect)
          Returns a sub-area of the image as a new image.
 byte[] copyOfBytes()
          Returns a copy of the image data.
 QImage createAlphaMask()
          Builds and returns a 1-bpp mask from the alpha buffer in this image.
 QImage createAlphaMask(Qt.ImageConversionFlag[] flags)
           
 QImage createAlphaMask(Qt.ImageConversionFlags flags)
          Builds and returns a 1-bpp mask from the alpha buffer in this image.
 QImage createHeuristicMask()
          Creates and returns a 1-bpp heuristic mask for this image.
 QImage createHeuristicMask(boolean clipTight)
          Creates and returns a 1-bpp heuristic mask for this image.
 QImage createMaskFromColor(int color)
          Creates and returns a mask for this image based on the given color value.
 QImage createMaskFromColor(int color, Qt.MaskMode mode)
          Creates and returns a mask for this image based on the given color value.
 int depth()
          Returns the bit depth (number of bit planes) of the paint device.
 int dotsPerMeterX()
          Returns the number of pixels that fit horizontally in a physical meter.
 int dotsPerMeterY()
          Returns the number of pixels that fit vertically in a physical meter.
 void fill(int pixel)
          Fills the entire image with the given pixelValue.
 QImage.Format format()
          Returns the format of the image.
static QImage fromData(QByteArray data)
          This is an overloaded method provided for convenience.
static QImage fromData(QByteArray data, java.lang.String format)
          This is an overloaded method provided for convenience.
 boolean hasAlphaChannel()
          Returns true if the image has a format that respects the alpha channel, otherwise returns false.
 int height()
          Returns the height of the paint device in default coordinate system units (e.
 int heightMM()
          Returns the height of the paint device in millimeters.
 void invertPixels()
          Inverts all pixel values in the image.
 void invertPixels(QImage.InvertMode arg__1)
          Inverts all pixel values in the image.
 boolean isGrayscale()
          For 32-bit images, this function is equivalent to allGray().
 boolean isNull()
          Returns true if it is a null image, otherwise returns false.
 boolean load(QIODevice device)
          This is an overloaded method provided for convenience.
 boolean load(QIODevice device, java.lang.String format)
          This is an overloaded function provided for convenience.
 boolean load(java.lang.String fileName)
          This is an overloaded method provided for convenience.
 boolean load(java.lang.String fileName, java.lang.String format)
          Loads an image from the file with the given fileName.
 boolean loadFromData(byte[] data)
          Loads an image from the given QByteArraydata.
 boolean loadFromData(byte[] data, java.lang.String format)
          Loads an image from the given QByteArraydata.
 boolean loadFromData(QByteArray data)
          This is an overloaded method provided for convenience.
 boolean loadFromData(QByteArray data, java.lang.String format)
          This is an overloaded method provided for convenience.
 int logicalDpiX()
          Returns the horizontal resolution of the device in dots per inch, which is used when computing font sizes.
 int logicalDpiY()
          Returns the vertical resolution of the device in dots per inch, which is used when computing font sizes.
 int metric(QPaintDevice.PaintDeviceMetric metric)
          Returns the metric information for the given paint device metric.
 QImage mirrored()
          Returns a mirror of the image, mirrored in the horizontal and/or the vertical direction depending on whether horizontal and vertical are set to true or false.
 QImage mirrored(boolean horizontally)
          Returns a mirror of the image, mirrored in the horizontal and/or the vertical direction depending on whether horizontal and vertical are set to true or false.
 QImage mirrored(boolean horizontally, boolean vertically)
          Returns a mirror of the image, mirrored in the horizontal and/or the vertical direction depending on whether horizontal and vertical are set to true or false.
 int numBytes()
          Returns the number of bytes occupied by the image data.
 int numColors()
          Returns the number of different colors available for the paint device.
 QPoint offset()
          Returns the number of pixels by which the image is intended to be offset by when positioning relative to other images.
 QPaintEngine paintEngine()
          Returns a pointer to the paint engine used for drawing on the device.
 boolean paintingActive()
          Returns true if the device is currently being painted on, i.
 int physicalDpiX()
          Returns the horizontal resolution of the device in dots per inch.
 int physicalDpiY()
          Returns the horizontal resolution of the device in dots per inch.
 int pixel(int x, int y)
          This is an overloaded member function, provided for convenience.
 int pixel(QPoint pt)
          Returns the color of the pixel at the given position.
 int pixelIndex(int x, int y)
          This is an overloaded member function, provided for convenience.
 int pixelIndex(QPoint pt)
          Returns the pixel index at the given position.
 void readFrom(QDataStream arg__1)
          Reads a QImage
 QRect rect()
          Returns the enclosing rectangle (0, 0, width(), height()) of the image.
 QImage rgbSwapped()
          Returns a QImage in which the values of the red and blue components of all pixels have been swapped, effectively converting an RGB image to an BGR image.
 boolean save(QIODevice dev)
          This is an overloaded function provided for convenience.
 boolean save(QIODevice dev, java.lang.String format)
          This is an overloaded method provided for convenience.
 boolean save(QIODevice dev, java.lang.String format, int quality)
          This is an overloaded method provided for convenience.
 boolean save(java.lang.String fileName)
          This is an overloaded method provided for convenience.
 boolean save(java.lang.String fileName, java.lang.String format)
          This is an overloaded method provided for convenience.
 boolean save(java.lang.String fileName, java.lang.String format, int quality)
          Saves the image to the file with the given fileName, using the given image file format and quality factor.
 QImage scaled(int w, int h)
          This is an overloaded member function, provided for convenience.
 QImage scaled(int w, int h, Qt.AspectRatioMode aspectMode)
          This is an overloaded member function, provided for convenience.
 QImage scaled(int w, int h, Qt.AspectRatioMode aspectMode, Qt.TransformationMode mode)
          This is an overloaded member function, provided for convenience.
 QImage scaled(QSize s)
          Returns a copy of the image scaled to a rectangle defined by the given size according to the given aspectRatioMode and transformMode.
 QImage scaled(QSize s, Qt.AspectRatioMode aspectMode)
          Returns a copy of the image scaled to a rectangle defined by the given size according to the given aspectRatioMode and transformMode.
 QImage scaled(QSize s, Qt.AspectRatioMode aspectMode, Qt.TransformationMode mode)
          Returns a copy of the image scaled to a rectangle defined by the given size according to the given aspectRatioMode and transformMode.
 QImage scaledToHeight(int h)
          Returns a scaled copy of the image.
 QImage scaledToHeight(int h, Qt.TransformationMode mode)
          Returns a scaled copy of the image.
 QImage scaledToWidth(int w)
          Returns a scaled copy of the image.
 QImage scaledToWidth(int w, Qt.TransformationMode mode)
          Returns a scaled copy of the image.
 QNativePointer scanLine(int arg__1)
          Returns a pointer to the pixel data at the scanline with index i.
 void setAlphaChannel(QImage alphaChannel)
          Sets the alpha channel of this image to the given alphaChannel.
 void setColor(int i, int c)
          Sets the color at the given index in the color table, to the given to colorValue.
 void setColorTable(java.util.List colors)
          Sets the color table used to translate color indexes to QRgb values, to the specified colors.
 void setDotsPerMeterX(int arg__1)
          Sets the number of pixels that fit horizontally in a physical meter, to x.
 void setDotsPerMeterY(int arg__1)
          Sets the number of pixels that fit vertically in a physical meter, to y.
 void setNumColors(int arg__1)
          Resizes the color table to contain numColors entries.
 void setOffset(QPoint arg__1)
          Sets the the number of pixels by which the image is intended to be offset by when positioning relative to other images, to offset.
 void setPixel(int x, int y, int index_or_rgb)
          This is an overloaded member function, provided for convenience.
 void setPixel(QPoint pt, int index_or_rgb)
          Sets the pixel index or color at the given position to index_or_rgb.
 void setText(java.lang.String key, java.lang.String value)
          Sets the image text to the given text and associate it with the given key.
 QSize size()
          Returns the size of the image, i.
 java.lang.String text()
          Returns the image text associated with the given key.
 java.lang.String text(java.lang.String key)
          Returns the image text associated with the given key.
 java.util.List textKeys()
          Returns the text keys for this image.
 QImage transformed(QMatrix matrix)
          Returns a copy of the image that is transformed using the given transformation matrix and transformation mode.
 QImage transformed(QMatrix matrix, Qt.TransformationMode mode)
          Returns a copy of the image that is transformed using the given transformation matrix and transformation mode.
 QImage transformed(QTransform matrix)
          Returns a copy of the image that is transformed using the given transformation matrix and transformation mode.
 QImage transformed(QTransform matrix, Qt.TransformationMode mode)
          Returns a copy of the image that is transformed using the given transformation matrix and transformation mode.
static QMatrix trueMatrix(QMatrix arg__1, int w, int h)
          Returns the actual matrix used for transforming an image with the given width, height and matrix.
static QTransform trueMatrix(QTransform arg__1, int w, int h)
          Returns the actual matrix used for transforming an image with the given width, height and matrix.
 boolean valid(int x, int y)
          This is an overloaded member function, provided for convenience.
 boolean valid(QPoint pt)
          Returns true if pos is a valid coordinate pair within the image; otherwise returns false.
 int width()
          Returns the width of the paint device in default coordinate system units (e.
 int widthMM()
          Returns the width of the paint device in millimeters.
 void writeTo(QDataStream arg__1)
          Writes thisQImage
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QImage

public QImage()
Constructs a null image.

See also:
isNull().


QImage

public QImage(QImage arg__1)
Constructs a shallow copy of the given image.

For more information about shallow copies, see the Implicit Data Sharing documentation.

See also:
copy().


QImage

public QImage(QSize size,
              QImage.Format format)
Constructs an image with the given size and format.

Warning: This will create a QImage with uninitialized data. Call fill() to fill the image with an appropriate pixel value before drawing onto it with QPainter.


QImage

public QImage(int width,
              int height,
              QImage.Format format)
Constructs an image with the given width, height and format.

Warning: This will create a QImage with uninitialized data. Call fill() to fill the image with an appropriate pixel value before drawing onto it with QPainter.


QImage

public QImage(QNativePointer data,
              int width,
              int height,
              int bytesPerLine,
              QImage.Format format)
Constructs an image with the given width, height and format, that uses an existing memory buffer, data. The width and height must be specified in pixels. bytesPerLine specifies the number of bytes per line (stride).

The buffer must remain valid throughout the life of the QImage. The image does not delete the buffer at destruction.

If format is an indexed color format, the image color table is initially empty and must be sufficiently expanded with setNumColors() or setColorTable() before the image is used.


QImage

public QImage(java.lang.String[] xpm)

QImage

public QImage(byte[] data,
              int width,
              int height,
              QImage.Format format)
Constructs an image with the given width, height, depth, bytesPerLine, colortable, numColors and bitOrder, that uses an existing memory buffer, data. The image does not delete the buffer at destruction.

Warning: This constructor is only available in Qt for Embedded Linux.

The data has to be 32-bit aligned, and each scanline of data in the image must also be 32-bit aligned, so it's no longer possible to specify a custom bytesPerLine value.


QImage

public QImage(java.lang.String fileName,
              java.lang.String format)
Constructs an image and tries to load the image from the file with the given fileName.

The loader attempts to read the image using the specified format. If the format is not specified (which is the default), the loader probes the file for a header to guess the file format.

If the loading of the image failed, this object is a null image.

The file name can either refer to an actual file on disk or to one of the application's embedded resources. See the \l{resources.html}{Resource System} overview for details on how to embed images and other resource files in the application's executable.


QImage

public QImage(java.lang.String fileName)
Constructs an image from the given xpm image.

Make sure that the image is a valid XPM image. Errors are silently ignored.

Note that it's possible to squeeze the XPM variable a little bit by using an unusual declaration:

        String start_xpm[] = {
            "16 15 8 1",
            "a c #cec6bd",
            .... };
The extra const makes the entire definition read-only, which is slightly more efficient (e.g., when the code is in a shared library) and able to be stored in ROM with the application.

Method Detail

allGray

public final boolean allGray()
Returns true if all the colors in the image are shades of gray (i. . their red, green and blue components are equal); otherwise false.

Note that this function is slow for images without color table.

See also:
isGrayscale().


alphaChannel

public final QImage alphaChannel()
Returns the alpha channel of the image as a new grayscale QImage in which each pixel's red, green, and blue values are given the alpha value of the original image. The color depth of the returned image is 8-bit.

You can see an example of use of this function in QPixmap's alphaChannel(), which works in the same way as this function on QPixmaps.

See also:
setAlphaChannel(), hasAlphaChannel(), Pixmap, and Image Transformations.


bits

public final QNativePointer bits()
Returns a pointer to the first pixel data. This is equivalent to scanLine(0).

Note that QImage uses implicit data sharing. This function performs a deep copy of the shared pixel data, thus ensuring that this QImage is the only one using the current return value.

See also:
scanLine(), and numBytes().


bytesPerLine

public final int bytesPerLine()
Returns the number of bytes per image scanline.

This is equivalent to numBytes()/ height().

See also:
scanLine().


cacheKey

public final long cacheKey()
Returns a number that identifies the contents of this QImage object. Distinct QImage objects can only have the same key if they refer to the same contents.

The key will change when the image is altered.


color

public final int color(int i)
Returns the color in the color table at index i. The first color is at index 0.

The colors in an image's color table are specified as ARGB quadruplets (QRgb). Use the qAlpha(), qRed(), qGreen(), and qBlue() functions to get the color value components.

See also:
setColor(), pixelIndex(), and Pixel Manipulation.


colorTable

public final java.util.List colorTable()
Returns a list of the colors contained in the image's color table, or an empty list if the image does not have a color table

See also.
setColorTable(), numColors(), and color().


convertToFormat

public final QImage convertToFormat(QImage.Format f,
                                    Qt.ImageConversionFlag[] flags)

convertToFormat

public final QImage convertToFormat(QImage.Format f)
Returns a copy of the image in the given format.

The specified image conversion flags control how the image data is handled during the conversion process.

See also:
Image Format.


convertToFormat

public final QImage convertToFormat(QImage.Format f,
                                    Qt.ImageConversionFlags flags)
Returns a copy of the image in the given format.

The specified image conversion flags control how the image data is handled during the conversion process.

See also:
Image Format.


convertToFormat

public final QImage convertToFormat(QImage.Format f,
                                    java.util.List colorTable,
                                    Qt.ImageConversionFlag[] flags)

convertToFormat

public final QImage convertToFormat(QImage.Format f,
                                    java.util.List colorTable)
Returns a copy of the image in the given format.

The specified image conversion flags control how the image data is handled during the conversion process.

See also:
Image Format.


convertToFormat

public final QImage convertToFormat(QImage.Format f,
                                    java.util.List colorTable,
                                    Qt.ImageConversionFlags flags)
Returns a copy of the image in the given format.

The specified image conversion flags control how the image data is handled during the conversion process.

See also:
Image Format.


copy

public final QImage copy()
Returns a sub-area of the image as a new image.

The returned image is copied from the position (rectangle.x(), rectangle.y()) in this image, and will always have the size of the given rectangle.

In areas beyond this image, pixels are set to 0. For 32-bit RGB images, this means black; for 32-bit ARGB images, this means transparent black; for 8-bit images, this means the color with index 0 in the color table which can be anything; for 1-bit images, this means Qt::color0 .

If the given rectangle is a null rectangle the entire image is copied.

See also:
QImage().


copy

public final QImage copy(QRect rect)
Returns a sub-area of the image as a new image.

The returned image is copied from the position (rectangle.x(), rectangle.y()) in this image, and will always have the size of the given rectangle.

In areas beyond this image, pixels are set to 0. For 32-bit RGB images, this means black; for 32-bit ARGB images, this means transparent black; for 8-bit images, this means the color with index 0 in the color table which can be anything; for 1-bit images, this means Qt::color0 .

If the given rectangle is a null rectangle the entire image is copied.

See also:
QImage().


copy

public final QImage copy(int x,
                         int y,
                         int w,
                         int h)
This is an overloaded member function, provided for convenience.

The returned image is copied from the position (x, y) in this image, and will always have the given width and height. In areas beyond this image, pixels are set to 0.


createAlphaMask

public final QImage createAlphaMask(Qt.ImageConversionFlag[] flags)

createAlphaMask

public final QImage createAlphaMask()
Builds and returns a 1-bpp mask from the alpha buffer in this image. Returns a null image if the image's format is QImage::Format_RGB32 .

The flags argument is a bitwise-OR of the Qt::ImageConversionFlags, and controls the conversion process. Passing 0 for flags sets all the default options.

The returned image has little-endian bit order (i.e. the image's format is QImage::Format_MonoLSB ), which you can convert to big-endian (QImage::Format_Mono ) using the convertToFormat() function.

See also:
createHeuristicMask(), and Image Transformations.


createAlphaMask

public final QImage createAlphaMask(Qt.ImageConversionFlags flags)
Builds and returns a 1-bpp mask from the alpha buffer in this image. Returns a null image if the image's format is QImage::Format_RGB32 .

The flags argument is a bitwise-OR of the Qt::ImageConversionFlags, and controls the conversion process. Passing 0 for flags sets all the default options.

The returned image has little-endian bit order (i.e. the image's format is QImage::Format_MonoLSB ), which you can convert to big-endian (QImage::Format_Mono ) using the convertToFormat() function.

See also:
createHeuristicMask(), and Image Transformations.


createHeuristicMask

public final QImage createHeuristicMask()
Creates and returns a 1-bpp heuristic mask for this image.

The function works by selecting a color from one of the corners, then chipping away pixels of that color starting at all the edges. The four corners vote for which color is to be masked away. In case of a draw (this generally means that this function is not applicable to the image), the result is arbitrary.

The returned image has little-endian bit order (i.e. the image's format is QImage::Format_MonoLSB ), which you can convert to big-endian (QImage::Format_Mono ) using the convertToFormat() function.

If clipTight is true (the default) the mask is just large enough to cover the pixels; otherwise, the mask is larger than the data pixels.

Note that this function disregards the alpha buffer.

See also:
createAlphaMask(), and Image Transformations.


createHeuristicMask

public final QImage createHeuristicMask(boolean clipTight)
Creates and returns a 1-bpp heuristic mask for this image.

The function works by selecting a color from one of the corners, then chipping away pixels of that color starting at all the edges. The four corners vote for which color is to be masked away. In case of a draw (this generally means that this function is not applicable to the image), the result is arbitrary.

The returned image has little-endian bit order (i.e. the image's format is QImage::Format_MonoLSB ), which you can convert to big-endian (QImage::Format_Mono ) using the convertToFormat() function.

If clipTight is true (the default) the mask is just large enough to cover the pixels; otherwise, the mask is larger than the data pixels.

Note that this function disregards the alpha buffer.

See also:
createAlphaMask(), and Image Transformations.


createMaskFromColor

public final QImage createMaskFromColor(int color)
Creates and returns a mask for this image based on the given color value. If the mode is MaskInColor (the default value), all pixels matching color will be opaque pixels in the mask. If mode is MaskOutColor, all pixels matching the given color will be transparent.

See also:
createAlphaMask(), and createHeuristicMask().


createMaskFromColor

public final QImage createMaskFromColor(int color,
                                        Qt.MaskMode mode)
Creates and returns a mask for this image based on the given color value. If the mode is MaskInColor (the default value), all pixels matching color will be opaque pixels in the mask. If mode is MaskOutColor, all pixels matching the given color will be transparent.

See also:
createAlphaMask(), and createHeuristicMask().


depth

public final int depth()
Returns the bit depth (number of bit planes) of the paint device.

Specified by:
depth in interface QPaintDeviceInterface

dotsPerMeterX

public final int dotsPerMeterX()
Returns the number of pixels that fit horizontally in a physical meter. Together with dotsPerMeterY(), this number defines the intended scale and aspect ratio of the image.

See also:
setDotsPerMeterX(), and Image Information.


dotsPerMeterY

public final int dotsPerMeterY()
Returns the number of pixels that fit vertically in a physical meter. Together with dotsPerMeterX(), this number defines the intended scale and aspect ratio of the image.

See also:
setDotsPerMeterY(), and Image Information.


fill

public final void fill(int pixel)
Fills the entire image with the given pixelValue.

If the depth of this image is 1, only the lowest bit is used. If you say fill(0), fill(2), etc., the image is filled with 0s. If you say fill(1), fill(3), etc., the image is filled with 1s. If the depth is 8, the lowest 8 bits are used and if the depth is 16 the lowest 16 bits are used.

Note: QImage::pixel() returns the color of the pixel at the given coordinates while QColor::pixel() returns the pixel value of the underlying window system (essentially an index value), so normally you will want to use QImage::pixel() to use a color from an existing image or QColor::rgb() to use a specific color.

See also:
depth(), and Image Transformations.


format

public final QImage.Format format()
Returns the format of the image.

See also:
Image Formats.


hasAlphaChannel

public final boolean hasAlphaChannel()
Returns true if the image has a format that respects the alpha channel, otherwise returns false.

See also:
alphaChannel(), and Image Information.


height

public final int height()
Returns the height of the paint device in default coordinate system units (e. . pixels for QPixmap and QWidget).

See also:
heightMM().

Specified by:
height in interface QPaintDeviceInterface

heightMM

public final int heightMM()
Returns the height of the paint device in millimeters. Due to platform limitations it may not be possible to use this function to determine the actual physical size of a widget on the screen.

See also:
height().

Specified by:
heightMM in interface QPaintDeviceInterface

invertPixels

public final void invertPixels()
Inverts all pixel values in the image.

The given invert mode only have a meaning when the image's depth is 32. The default mode is InvertRgb , which leaves the alpha channel unchanged. If the mode is InvertRgba , the alpha bits are also inverted.

Inverting an 8-bit image means to replace all pixels using color index i with a pixel using color index 255 minus i. The same is the case for a 1-bit image. Note that the color table is not changed.

See also:
Image Transformations.


invertPixels

public final void invertPixels(QImage.InvertMode arg__1)
Inverts all pixel values in the image.

The given invert mode only have a meaning when the image's depth is 32. The default mode is InvertRgb , which leaves the alpha channel unchanged. If the mode is InvertRgba , the alpha bits are also inverted.

Inverting an 8-bit image means to replace all pixels using color index i with a pixel using color index 255 minus i. The same is the case for a 1-bit image. Note that the color table is not changed.

See also:
Image Transformations.


isGrayscale

public final boolean isGrayscale()
For 32-bit images, this function is equivalent to allGray().

For 8-bpp images, this function returns true if color(i) is QRgb(i, i, i) for all indexes of the color table; otherwise returns false.

See also:
allGray(), and Image Formats.


isNull

public final boolean isNull()
Returns true if it is a null image, otherwise returns false.

A null image has all parameters set to zero and no allocated data.


logicalDpiX

public final int logicalDpiX()
Returns the horizontal resolution of the device in dots per inch, which is used when computing font sizes. For X11, this is usually the same as could be computed from widthMM().

Note that if the logicalDpiX() doesn't equal the physicalDpiX(), the corresponding QPaintEngine must handle the resolution mapping.

See also:
logicalDpiY(), and physicalDpiX().

Specified by:
logicalDpiX in interface QPaintDeviceInterface

logicalDpiY

public final int logicalDpiY()
Returns the vertical resolution of the device in dots per inch, which is used when computing font sizes. For X11, this is usually the same as could be computed from heightMM().

Note that if the logicalDpiY() doesn't equal the physicalDpiY(), the corresponding QPaintEngine must handle the resolution mapping.

See also:
logicalDpiX(), and physicalDpiY().

Specified by:
logicalDpiY in interface QPaintDeviceInterface

mirrored

public final QImage mirrored(boolean horizontally)
Returns a mirror of the image, mirrored in the horizontal and/or the vertical direction depending on whether horizontal and vertical are set to true or false.

Note that the original image is not changed.

See also:
Image Transformations.


mirrored

public final QImage mirrored()
Returns a mirror of the image, mirrored in the horizontal and/or the vertical direction depending on whether horizontal and vertical are set to true or false.

Note that the original image is not changed.

See also:
Image Transformations.


mirrored

public final QImage mirrored(boolean horizontally,
                             boolean vertically)
Returns a mirror of the image, mirrored in the horizontal and/or the vertical direction depending on whether horizontal and vertical are set to true or false.

Note that the original image is not changed.

See also:
Image Transformations.


numBytes

public final int numBytes()
Returns the number of bytes occupied by the image data.

See also:
bytesPerLine(), bits(), and Image Information.


numColors

public final int numColors()
Returns the number of different colors available for the paint device. Since this value is an int, it will not be sufficient to represent the number of colors on 32 bit displays, in this case INT_MAX is returned instead.

Specified by:
numColors in interface QPaintDeviceInterface

offset

public final QPoint offset()
Returns the number of pixels by which the image is intended to be offset by when positioning relative to other images.

See also:
setOffset(), and Image Information.


writeTo

public final void writeTo(QDataStream arg__1)
Writes thisQImage


readFrom

public final void readFrom(QDataStream arg__1)
Reads a QImage


paintingActive

public final boolean paintingActive()
Returns true if the device is currently being painted on, i. . someone has called QPainter::begin() but not yet called QPainter::end() for this device; otherwise returns false.

See also:
QPainter::isActive().

Specified by:
paintingActive in interface QPaintDeviceInterface

physicalDpiX

public final int physicalDpiX()
Returns the horizontal resolution of the device in dots per inch. For example, when printing, this resolution refers to the physical printer's resolution. The logical DPI on the other hand, refers to the resolution used by the actual paint engine.

Note that if the physicalDpiX() doesn't equal the logicalDpiX(), the corresponding QPaintEngine must handle the resolution mapping.

See also:
physicalDpiY(), and logicalDpiX().

Specified by:
physicalDpiX in interface QPaintDeviceInterface

physicalDpiY

public final int physicalDpiY()
Returns the horizontal resolution of the device in dots per inch. For example, when printing, this resolution refers to the physical printer's resolution. The logical DPI on the other hand, refers to the resolution used by the actual paint engine.

Note that if the physicalDpiY() doesn't equal the logicalDpiY(), the corresponding QPaintEngine must handle the resolution mapping.

See also:
physicalDpiX(), and logicalDpiY().

Specified by:
physicalDpiY in interface QPaintDeviceInterface

pixel

public final int pixel(QPoint pt)
Returns the color of the pixel at the given position.

If the position is not valid, the results are undefined.

See also:
setPixel(), valid(), and Pixel Manipulation.


pixel

public final int pixel(int x,
                       int y)
This is an overloaded member function, provided for convenience.

Returns the color of the pixel at coordinates (x, y).


pixelIndex

public final int pixelIndex(QPoint pt)
Returns the pixel index at the given position.

If position is not valid, or if the image is not a paletted image (depth() > 8), the results are undefined.

See also:
valid(), depth(), and Pixel Manipulation.


pixelIndex

public final int pixelIndex(int x,
                            int y)
This is an overloaded member function, provided for convenience.

Returns the pixel index at (x, y).


rect

public final QRect rect()
Returns the enclosing rectangle (0, 0, width(), height()) of the image.

See also:
Image Information.


rgbSwapped

public final QImage rgbSwapped()
Returns a QImage in which the values of the red and blue components of all pixels have been swapped, effectively converting an RGB image to an BGR image.

The original QImage is not changed.

See also:
Image Transformations.


scaled

public final QImage scaled(QSize s,
                           Qt.AspectRatioMode aspectMode)
Returns a copy of the image scaled to a rectangle defined by the given size according to the given aspectRatioMode and transformMode.

If the given size is empty, this function returns a null image.

See also:
isNull(), and Image Transformations.


scaled

public final QImage scaled(QSize s)
Returns a copy of the image scaled to a rectangle defined by the given size according to the given aspectRatioMode and transformMode.

If the given size is empty, this function returns a null image.

See also:
isNull(), and Image Transformations.


scaled

public final QImage scaled(QSize s,
                           Qt.AspectRatioMode aspectMode,
                           Qt.TransformationMode mode)
Returns a copy of the image scaled to a rectangle defined by the given size according to the given aspectRatioMode and transformMode.

If the given size is empty, this function returns a null image.

See also:
isNull(), and Image Transformations.


scaled

public final QImage scaled(int w,
                           int h,
                           Qt.AspectRatioMode aspectMode)
This is an overloaded member function, provided for convenience.

Returns a copy of the image scaled to a rectangle with the given width and height according to the given aspectRatioMode and transformMode.

If either the width or the height is zero or negative, this function returns a null image.


scaled

public final QImage scaled(int w,
                           int h)
This is an overloaded member function, provided for convenience.

Returns a copy of the image scaled to a rectangle with the given width and height according to the given aspectRatioMode and transformMode.

If either the width or the height is zero or negative, this function returns a null image.


scaled

public final QImage scaled(int w,
                           int h,
                           Qt.AspectRatioMode aspectMode,
                           Qt.TransformationMode mode)
This is an overloaded member function, provided for convenience.

Returns a copy of the image scaled to a rectangle with the given width and height according to the given aspectRatioMode and transformMode.

If either the width or the height is zero or negative, this function returns a null image.


scaledToHeight

public final QImage scaledToHeight(int h)
Returns a scaled copy of the image. The returned image is scaled to the given height using the specified transformation mode.

This function automatically calculates the width of the image so that the ratio of the image is preserved.

If the given height is 0 or negative, a null image is returned.

See also:
Image Transformations.


scaledToHeight

public final QImage scaledToHeight(int h,
                                   Qt.TransformationMode mode)
Returns a scaled copy of the image. The returned image is scaled to the given height using the specified transformation mode.

This function automatically calculates the width of the image so that the ratio of the image is preserved.

If the given height is 0 or negative, a null image is returned.

See also:
Image Transformations.


scaledToWidth

public final QImage scaledToWidth(int w)
Returns a scaled copy of the image. The returned image is scaled to the given width using the specified transformation mode.

This function automatically calculates the height of the image so that its aspect ratio is preserved.

If the given width is 0 or negative, a null image is returned.

See also:
Image Transformations.


scaledToWidth

public final QImage scaledToWidth(int w,
                                  Qt.TransformationMode mode)
Returns a scaled copy of the image. The returned image is scaled to the given width using the specified transformation mode.

This function automatically calculates the height of the image so that its aspect ratio is preserved.

If the given width is 0 or negative, a null image is returned.

See also:
Image Transformations.


scanLine

public final QNativePointer scanLine(int arg__1)
Returns a pointer to the pixel data at the scanline with index i. The first scanline is at index 0.

The scanline data is aligned on a 32-bit boundary.

Warning: If you are accessing 32-bpp image data, cast the returned pointer to QRgb* (QRgb has a 32-bit size) and use it to read/write the pixel value. You cannot use the uchar* pointer directly, because the pixel format depends on the byte order on the underlying platform. Use qRed(), qGreen(), qBlue(), and qAlpha() to access the pixels.

See also:
bytesPerLine(), bits(), and Pixel Manipulation.


setAlphaChannel

public final void setAlphaChannel(QImage alphaChannel)
Sets the alpha channel of this image to the given alphaChannel.

If alphaChannel is an 8 bit grayscale image, the intensity values are written into this buffer directly. Otherwise, alphaChannel is converted to 32 bit and the intensity of the RGB pixel values is used.

Note that the image will be converted to the Format_ARGB32_Premultiplied format if the function succeeds.

Use one of the composition mods in QPainter::CompositionMode instead.

See also:
alphaChannel(), Image Transformations, and Image Formats.


setColor

public final void setColor(int i,
                           int c)
Sets the color at the given index in the color table, to the given to colorValue. The color value is an ARGB quadruplet.

If index is outside the current size of the color table, it is expanded with setNumColors().

See also:
color(), numColors(), setColorTable(), and Pixel Manipulation.


setColorTable

public final void setColorTable(java.util.List colors)
Sets the color table used to translate color indexes to QRgb values, to the specified colors.

When the image is used, the color table must be large enough to have entries for all the pixel/index values present in the image, otherwise the results are undefined.

See also:
colorTable(), setColor(), and Image Transformations.


setDotsPerMeterX

public final void setDotsPerMeterX(int arg__1)
Sets the number of pixels that fit horizontally in a physical meter, to x.

Together with dotsPerMeterY(), this number defines the intended scale and aspect ratio of the image.

See also:
dotsPerMeterX(), and Image Information.


setDotsPerMeterY

public final void setDotsPerMeterY(int arg__1)
Sets the number of pixels that fit vertically in a physical meter, to y.

Together with dotsPerMeterX(), this number defines the intended scale and aspect ratio of the image.

See also:
dotsPerMeterY(), and Image Information.


setNumColors

public final void setNumColors(int arg__1)
Resizes the color table to contain numColors entries.

If the color table is expanded, all the extra colors will be set to transparent (i.e qRgba(0, 0, 0, 0)).

When the image is used, the color table must be large enough to have entries for all the pixel/index values present in the image, otherwise the results are undefined.

See also:
numColors(), colorTable(), setColor(), and Image Transformations.


setOffset

public final void setOffset(QPoint arg__1)
Sets the the number of pixels by which the image is intended to be offset by when positioning relative to other images, to offset.

See also:
offset(), and Image Information.


setPixel

public final void setPixel(QPoint pt,
                           int index_or_rgb)
Sets the pixel index or color at the given position to index_or_rgb.

If the image's format is either monochrome or 8-bit, the given index_or_rgb value must be an index in the image's color table, otherwise the parameter must be a QRgb value.

If position is not a valid coordinate pair in the image, or if index_or_rgb >= numColors() in the case of monochrome and 8-bit images, the result is undefined.

Warning: This function is expensive due to the call of the internal detach() function called within; if performance is a concern, we recommend the use of scanLine() to access pixel data directly.

See also:
pixel(), and Pixel Manipulation.


setPixel

public final void setPixel(int x,
                           int y,
                           int index_or_rgb)
This is an overloaded member function, provided for convenience.

Sets the pixel index or color at (x, y) to index_or_rgb.


setText

public final void setText(java.lang.String key,
                          java.lang.String value)
Sets the image text to the given text and associate it with the given key.

If you just want to store a single text block (i.e., a "comment" or just a description), you can either pass an empty key, or use a generic key like "Description".

The image text is embedded into the image data when you call save() or QImageWriter::write().

Not all image formats support embedded text. You can find out if a specific image or format supports embedding text by using QImageWriter::supportsOption(). We give an example:

    QImageWriter writer;
    writer.setFormat("png");
    if (writer.supportsOption(QImageIOHandler::Description))
        qDebug() << "Png supports embedded text";
You can use QImageWriter::supportedImageFormats() to find out which image formats are available to you.

See also:
text(), and textKeys().


size

public final QSize size()
Returns the size of the image, i. . its width() and height().

See also:
Image Information.


text

public final java.lang.String text()
Returns the image text associated with the given key. If the specified key is an empty string, the whole image text is returned, with each key-text pair separated by a newline.

See also:
setText(), and textKeys().


text

public final java.lang.String text(java.lang.String key)
Returns the image text associated with the given key. If the specified key is an empty string, the whole image text is returned, with each key-text pair separated by a newline.

See also:
setText(), and textKeys().


textKeys

public final java.util.List textKeys()
Returns the text keys for this image.

You can use these keys with text() to list the image text for a certain key.

See also:
text().


transformed

public final QImage transformed(QMatrix matrix)
Returns a copy of the image that is transformed using the given transformation matrix and transformation mode.

The transformation matrix is internally adjusted to compensate for unwanted translation; i.e. the image produced is the smallest image that contains all the transformed points of the original image. Use the trueMatrix() function to retrieve the actual matrix used for transforming an image.

See also:
trueMatrix(), and Image Transformations.


transformed

public final QImage transformed(QMatrix matrix,
                                Qt.TransformationMode mode)
Returns a copy of the image that is transformed using the given transformation matrix and transformation mode.

The transformation matrix is internally adjusted to compensate for unwanted translation; i.e. the image produced is the smallest image that contains all the transformed points of the original image. Use the trueMatrix() function to retrieve the actual matrix used for transforming an image.

See also:
trueMatrix(), and Image Transformations.


transformed

public final QImage transformed(QTransform matrix)
Returns a copy of the image that is transformed using the given transformation matrix and transformation mode.

The transformation matrix is internally adjusted to compensate for unwanted translation; i.e. the image produced is the smallest image that contains all the transformed points of the original image. Use the trueMatrix() function to retrieve the actual matrix used for transforming an image.

Unlike the other overload, this function can be used to perform perspective transformations on images.

See also:
trueMatrix(), and Image Transformations.


transformed

public final QImage transformed(QTransform matrix,
                                Qt.TransformationMode mode)
Returns a copy of the image that is transformed using the given transformation matrix and transformation mode.

The transformation matrix is internally adjusted to compensate for unwanted translation; i.e. the image produced is the smallest image that contains all the transformed points of the original image. Use the trueMatrix() function to retrieve the actual matrix used for transforming an image.

Unlike the other overload, this function can be used to perform perspective transformations on images.

See also:
trueMatrix(), and Image Transformations.


valid

public final boolean valid(QPoint pt)
Returns true if pos is a valid coordinate pair within the image; otherwise returns false.

See also:
rect(), and QRect::contains().


valid

public final boolean valid(int x,
                           int y)
This is an overloaded member function, provided for convenience.

Returns true if QPoint(x, y) is a valid coordinate pair within the image; otherwise returns false.


width

public final int width()
Returns the width of the paint device in default coordinate system units (e. . pixels for QPixmap and QWidget).

See also:
widthMM().

Specified by:
width in interface QPaintDeviceInterface

widthMM

public final int widthMM()
Returns the width of the paint device in millimeters. Due to platform limitations it may not be possible to use this function to determine the actual physical size of a widget on the screen.

See also:
width().

Specified by:
widthMM in interface QPaintDeviceInterface

metric

public int metric(QPaintDevice.PaintDeviceMetric metric)
Returns the metric information for the given paint device metric.

See also:
PaintDeviceMetric .

Specified by:
metric in interface QPaintDeviceInterface

paintEngine

public QPaintEngine paintEngine()
Returns a pointer to the paint engine used for drawing on the device.

Specified by:
paintEngine in interface QPaintDeviceInterface

trueMatrix

public static QMatrix trueMatrix(QMatrix arg__1,
                                 int w,
                                 int h)
Returns the actual matrix used for transforming an image with the given width, height and matrix.

When transforming an image using the transformed() function, the transformation matrix is internally adjusted to compensate for unwanted translation, i.e. transformed() returns the smallest image containing all transformed points of the original image. This function returns the modified matrix, which maps points correctly from the original image into the new image.

See also:
transformed(), and Image Transformations.


trueMatrix

public static QTransform trueMatrix(QTransform arg__1,
                                    int w,
                                    int h)
Returns the actual matrix used for transforming an image with the given width, height and matrix.

When transforming an image using the transformed() function, the transformation matrix is internally adjusted to compensate for unwanted translation, i.e. transformed() returns the smallest image containing all transformed points of the original image. This function returns the modified matrix, which maps points correctly from the original image into the new image.

Unlike the other overload, this function creates transformation matrices that can be used to perform perspective transformations on images.

See also:
transformed(), and Image Transformations.


copyOfBytes

public final byte[] copyOfBytes()
Returns a copy of the image data.

Returns:

save

public final boolean save(java.lang.String fileName,
                          java.lang.String format,
                          int quality)
Saves the image to the file with the given fileName, using the given image file format and quality factor. If format is null, QImage will attempt to guess the format by looking at fileName's suffix.

The quality factor must be in the range 0 to 100 or -1. Specify 0 to obtain small compressed files, 100 for large uncompressed files, and -1 (the default) to use the default settings.

Returns true if the image was successfully saved; otherwise returns false.


save

public final boolean save(java.lang.String fileName,
                          java.lang.String format)
This is an overloaded method provided for convenience.


save

public final boolean save(java.lang.String fileName)
This is an overloaded method provided for convenience.


save

public final boolean save(QIODevice dev,
                          java.lang.String format,
                          int quality)
This is an overloaded method provided for convenience.


save

public final boolean save(QIODevice dev,
                          java.lang.String format)
This is an overloaded method provided for convenience.


save

public final boolean save(QIODevice dev)
This is an overloaded function provided for convenience.


load

public final boolean load(java.lang.String fileName,
                          java.lang.String format)
Loads an image from the file with the given fileName. Returns true if the image was successfully loaded; otherwise returns false.

The loader attempts to read the image using the specified format. If the format is null, the loader probes the file for a header to guess the file format.

The file name can either refer to an actual file on disk or to one of the application's embedded resources. See the \l{resources.html}{Resource System} overview for details on how to embed images and other resource files in the application's executable.


load

public final boolean load(java.lang.String fileName)
This is an overloaded method provided for convenience.


load

public final boolean load(QIODevice device,
                          java.lang.String format)
This is an overloaded function provided for convenience.


load

public final boolean load(QIODevice device)
This is an overloaded method provided for convenience.


loadFromData

public final boolean loadFromData(byte[] data,
                                  java.lang.String format)
Loads an image from the given QByteArraydata.


loadFromData

public final boolean loadFromData(byte[] data)
Loads an image from the given QByteArraydata.


loadFromData

public final boolean loadFromData(QByteArray data,
                                  java.lang.String format)
This is an overloaded method provided for convenience.


loadFromData

public final boolean loadFromData(QByteArray data)
This is an overloaded method provided for convenience.


fromData

public static QImage fromData(QByteArray data,
                              java.lang.String format)
This is an overloaded method provided for convenience.

Loads an image from the given QByteArray data.


fromData

public static QImage fromData(QByteArray data)
This is an overloaded method provided for convenience.

Loads an image from the given QByteArray data.


clone

public QImage clone()
This method is reimplemented for internal reasons

Overrides:
clone in class java.lang.Object