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QImage Class Reference
^{[QtGui module]}

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. More...

Inherits QPaintDevice.

Types

• enum Format { Format_Invalid, Format_Mono, Format_MonoLSB, Format_Indexed8, ..., Format_ARGB4444_Premultiplied }
• enum InvertMode { InvertRgb, InvertRgba }

Methods

• __init__ (self)
• __init__ (self, QSize size, Format format)
• __init__ (self, int width, int height, Format format)
• __init__ (self, str data, int width, int height, Format format)
• __init__ (self, sip.voidptr data, int width, int height, Format format)
• __init__ (self, str data, int width, int height, int bytesPerLine, Format format)
• __init__ (self, sip.voidptr data, int width, int height, int bytesPerLine, Format format)
• __init__ (self, list-of-str xpm)
• __init__ (self, QString fileName, str format = None)
• __init__ (self, QImage)
• __init__ (self, QVariant variant)
• bool allGray (self)
• QImage alphaChannel (self)
• int bitPlaneCount (self)
• sip.voidptr bits (self)
• int byteCount (self)
• int bytesPerLine (self)
• int cacheKey (self)
• int color (self, int i)
• int colorCount (self)
• list-of-int colorTable (self)
• QImage convertToFormat (self, Format format, Qt.ImageConversionFlags flags = Qt.AutoColor)
• QImage convertToFormat (self, Format format, list-of-int colorTable, Qt.ImageConversionFlags flags = Qt.AutoColor)
• QImage copy (self, QRect rect = QRect())
• QImage copy (self, int x, int y, int w, int h)
• QImage createAlphaMask (self, Qt.ImageConversionFlags flags = Qt.AutoColor)
• QImage createHeuristicMask (self, bool clipTight = True)
• QImage createMaskFromColor (self, int color, Qt.MaskMode mode = Qt.MaskInColor)
• int depth (self)
• detach (self)
• int devType (self)
• int dotsPerMeterX (self)
• int dotsPerMeterY (self)
• fill (self, Qt.GlobalColor color)
• fill (self, QColor color)
• fill (self, int pixel)
• Format format (self)
• bool hasAlphaChannel (self)
• int height (self)
• invertPixels (self, InvertMode mode = QImage.InvertRgb)
• bool isDetached (self)
• bool isGrayscale (self)
• bool isNull (self)
• bool load (self, QIODevice device, str format)
• bool load (self, QString fileName, str format = None)
• bool loadFromData (self, str data, str format = None)
• bool loadFromData (self, QByteArray data, str format = None)
• int metric (self, QPaintDevice.PaintDeviceMetric metric)
• QImage mirrored (self, bool horizontal = False, bool vertical = True)
• int numBytes (self)
• int numColors (self)
• QPoint offset (self)
• QPaintEngine paintEngine (self)
• int pixel (self, QPoint pt)
• int pixel (self, int x, int y)
• int pixelIndex (self, QPoint pt)
• int pixelIndex (self, int x, int y)
• QRect rect (self)
• QImage rgbSwapped (self)
• bool save (self, QString fileName, str format = None, int quality = -1)
• bool save (self, QIODevice device, str format = None, int quality = -1)
• QImage scaled (self, int width, int height, Qt.AspectRatioMode aspectRatioMode = Qt.IgnoreAspectRatio, Qt.TransformationMode transformMode = Qt.FastTransformation)
• QImage scaled (self, QSize size, Qt.AspectRatioMode aspectRatioMode = Qt.IgnoreAspectRatio, Qt.TransformationMode transformMode = Qt.FastTransformation)
• QImage scaledToHeight (self, int height, Qt.TransformationMode mode = Qt.FastTransformation)
• QImage scaledToWidth (self, int width, Qt.TransformationMode mode = Qt.FastTransformation)
• sip.voidptr scanLine (self, int)
• int serialNumber (self)
• setAlphaChannel (self, QImage alphaChannel)
• setColor (self, int i, int c)
• setColorCount (self, int)
• setColorTable (self, list-of-int colors)
• setDotsPerMeterX (self, int)
• setDotsPerMeterY (self, int)
• setNumColors (self, int)
• setOffset (self, QPoint)
• setPixel (self, QPoint pt, int index_or_rgb)
• setPixel (self, int x, int y, int index_or_rgb)
• setText (self, QString key, QString value)
• QSize size (self)
• swap (self, QImage other)
• QString text (self, QString key = QString())
• QStringList textKeys (self)
• QImage transformed (self, QMatrix matrix, Qt.TransformationMode mode = Qt.FastTransformation)
• QImage transformed (self, QTransform matrix, Qt.TransformationMode mode = Qt.FastTransformation)
• bool valid (self, QPoint pt)
• bool valid (self, int x, int y)
• int width (self)

Static Methods

• QImage fromData (str data, str format = None)
• QImage fromData (QByteArray data, str format = None)
• QMatrix trueMatrix (QMatrix, int w, int h)
• QTransform trueMatrix (QTransform, int w, int h)

Special Methods

• bool __eq__ (self, QImage)
• bool __ne__ (self, QImage)

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.

Warning: Painting on a QImage with the format QImage.Format_Indexed8 is not supported.

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:

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:

32-bit
	QImage image(3, 3, QImage.Format_RGB32); QRgb value; value = qRgb(189, 149, 39); // 0xffbd9527 image.setPixel(1, 1, value); value = qRgb(122, 163, 39); // 0xff7aa327 image.setPixel(0, 1, value); image.setPixel(1, 0, value); value = qRgb(237, 187, 51); // 0xffedba31 image.setPixel(2, 1, value);

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:

8-bit
	QImage image(3, 3, QImage.Format_Indexed8); QRgb value; value = qRgb(122, 163, 39); // 0xff7aa327 image.setColor(0, value); value = qRgb(237, 187, 51); // 0xffedba31 image.setColor(1, value); value = qRgb(189, 149, 39); // 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);

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)).

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.

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.

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, and the rgbSwapped() function constructs a BGR image from a RGB image.

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:

For smooth scaling, the transformed() functions use code based on smooth scaling algorithm by Daniel M. Duley.

Type Documentation

QImage.Format

The following image formats are available in Qt. Values greater than QImage.Format_RGB16 were added in Qt 4.4. See the notes after the table.

Note: Drawing into a QImage with QImage.Format_Indexed8 is not supported.

Note: Do not render into ARGB32 images using QPainter. Using QImage.Format_ARGB32_Premultiplied is significantly faster.

See also format() and convertToFormat().

QImage.InvertMode

This enum type is used to describe how pixel values should be inverted in the invertPixels() function.

See also invertPixels().

Method Documentation

QImage.__init__ (self)

Constructs a null image.

See also isNull().

QImage.__init__ (self, QSize size, Format format)

Constructs an image with the given size and format.

A null image is returned if memory cannot be allocated.

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.__init__ (self, int width, int height, Format format)

Constructs an image with the given width, height and format.

A null image will be returned if memory cannot be allocated.

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.__init__ (self, str data, int width, int height, 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, data must be 32-bit aligned, and each scanline of data in the image must also be 32-bit aligned.

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 setColorCount() or setColorTable() before the image is used.

QImage.__init__ (self, sip.voidptr data, int width, int height, Format format)

Constructs an image with the given width, height and format, that uses an existing read-only memory buffer, data. The width and height must be specified in pixels, data must be 32-bit aligned, and each scanline of data in the image must also be 32-bit aligned.

The buffer must remain valid throughout the life of the QImage and all copies that have not been modified or otherwise detached from the original buffer. 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 setColorCount() or setColorTable() before the image is used.

Unlike the similar QImage constructor that takes a non-const data buffer, this version will never alter the contents of the buffer. For example, calling QImage.bits() will return a deep copy of the image, rather than the buffer passed to the constructor. This allows for the efficiency of constructing a QImage from raw data, without the possibility of the raw data being changed.

QImage.__init__ (self, str data, int width, int height, int bytesPerLine, 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 setColorCount() or setColorTable() before the image is used.

QImage.__init__ (self, sip.voidptr data, int width, int height, int bytesPerLine, 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 setColorCount() or setColorTable() before the image is used.

Unlike the similar QImage constructor that takes a non-const data buffer, this version will never alter the contents of the buffer. For example, calling QImage.bits() will return a deep copy of the image, rather than the buffer passed to the constructor. This allows for the efficiency of constructing a QImage from raw data, without the possibility of the raw data being changed.

QImage.__init__ (self, list-of-str xpm)

Constructs an image from the given xpm image.

 static const char * const start_xpm[] = {
     "16 15 8 1",
     "a c #cec6bd",
 ....

QImage.__init__ (self, QString fileName, str format = None)

Constructs an image and tries to load the image from the file with the given fileName.

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

See also isNull() and Reading and Writing Image Files.

QImage.__init__ (self, QImage)

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 Resource System overview for details on how to embed images and other resource files in the application's executable.

You can disable this constructor by defining QT_NO_CAST_FROM_ASCII when you compile your applications. This can be useful, for example, if you want to ensure that all user-visible strings go through QObject.tr().

See also QString.fromAscii(), isNull(), and Reading and Writing Image Files.

QImage.__init__ (self, QVariant variant)

Constructs a shallow copy of the given image.

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

See also copy().

bool QImage.allGray (self)

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

See also isGrayscale().

QImage QImage.alphaChannel (self)

int QImage.bitPlaneCount (self)

Returns the number of bit planes in the image.

See also depth(), format(), and Image Formats.

sip.voidptr QImage.bits (self)

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(), byteCount(), and constBits().

int QImage.byteCount (self)

Returns the number of bytes occupied by the image data.

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

int QImage.bytesPerLine (self)

Returns the number of bytes per image scanline.

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

See also scanLine().

int QImage.cacheKey (self)

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.

int QImage.color (self, 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.

int QImage.colorCount (self)

Returns the size of the color table for the image.

See also setColorCount() and Image Information.

list-of-int QImage.colorTable (self)

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(), colorCount(), and color().

QImage QImage.convertToFormat (self, Format format, Qt.ImageConversionFlags flags = Qt.AutoColor)

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.

QImage QImage.convertToFormat (self, Format format, list-of-int colorTable, Qt.ImageConversionFlags flags = Qt.AutoColor)

This is an overloaded function.

Returns a copy of the image converted to the given format, using the specified colorTable.

Conversion from 32 bit to 8 bit indexed is a slow operation and will use a straightforward nearest color approach, with no dithering.

QImage QImage.copy (self, QRect rect = QRect())

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().

QImage QImage.copy (self, int x, int y, int w, int h)

QImage QImage.createAlphaMask (self, Qt.ImageConversionFlags flags = Qt.AutoColor)

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.

QImage QImage.createHeuristicMask (self, bool clipTight = True)

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.

QImage QImage.createMaskFromColor (self, int color, Qt.MaskMode mode = Qt.MaskInColor)

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().

int QImage.depth (self)

Returns the depth of the image.

See also bitPlaneCount(), convertToFormat(), Image Formats, and Image Information.

QImage.detach (self)

int QImage.devType (self)

int QImage.dotsPerMeterX (self)

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.

int QImage.dotsPerMeterY (self)

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.

QImage.fill (self, Qt.GlobalColor color)

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.

QImage.fill (self, QColor color)

This is an overloaded function.

Fills the image with the given color, described as a standard global color.

This function was introduced in Qt 4.8.

QImage.fill (self, int pixel)

This is an overloaded function.

If the depth of the image is 1, the image will be filled with 1 if color equals Qt.color1; it will otherwise be filled with 0.

If the depth of the image is 8, the image will be filled with the index corresponding the color in the color table if present; it will otherwise be filled with 0.

This function was introduced in Qt 4.8.

Format QImage.format (self)

Returns the format of the image.

See also Image Formats.

QImage QImage.fromData (str data, str format = None)

Constructs a QImage from the first size bytes of the given binary data. The loader attempts to read the image using the specified format. If format is not specified (which is the default), the loader probes the file for a header to guess the file format. binary data. The loader attempts to read the image, either using the optional image format specified or by determining the image format from the data.

If format is not specified (which is the default), the loader probes the file for a header to determine the file format. If format is specified, it must be one of the values returned by QImageReader.supportedImageFormats().

If the loading of the image fails, the image returned will be a null image.

See also load(), save(), and Reading and Writing Image Files.

QImage QImage.fromData (QByteArray data, str format = None)

This is an overloaded function.

Loads an image from the given QByteArray data.

bool QImage.hasAlphaChannel (self)

Returns true if the image has a format that respects the alpha channel, otherwise returns false.

See also Image Information.

int QImage.height (self)

Returns the height of the image.

See also Image Information.

QImage.invertPixels (self, InvertMode mode = QImage.InvertRgb)

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.

bool QImage.isDetached (self)

bool QImage.isGrayscale (self)

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.

bool QImage.isNull (self)

Returns true if it is a null image, otherwise returns false.

bool QImage.load (self, QIODevice device, str 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, e.g., PNG or JPG. If format is not specified (which is the default), 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 Resource System overview for details on how to embed images and other resource files in the application's executable.

See also Reading and Writing Image Files.

bool QImage.load (self, QString fileName, str format = None)

This is an overloaded function.

This function reads a QImage from the given device. This can, for example, be used to load an image directly into a QByteArray.

bool QImage.loadFromData (self, str data, str format = None)

Loads an image from the first len bytes of the given binary data. Returns true if the image was successfully loaded; otherwise returns false.

See also Reading and Writing Image Files.

bool QImage.loadFromData (self, QByteArray data, str format = None)

This is an overloaded function.

Loads an image from the given QByteArray data.

int QImage.metric (self, QPaintDevice.PaintDeviceMetric metric)

QImage QImage.mirrored (self, bool horizontal = False, bool vertical = True)

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.

int QImage.numBytes (self)

int QImage.numColors (self)

QPoint QImage.offset (self)

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.

QPaintEngine QImage.paintEngine (self)

int QImage.pixel (self, QPoint pt)

Returns the color of the pixel at the given position.

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

Warning: This function is expensive when used for massive pixel manipulations.

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

int QImage.pixel (self, int x, int y)

This is an overloaded function.

int QImage.pixelIndex (self, 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.

int QImage.pixelIndex (self, int x, int y)

This is an overloaded function.

QRect QImage.rect (self)

Returns the enclosing rectangle (0, 0, width(), height()) of the image.

See also Image Information.

QImage QImage.rgbSwapped (self)

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.

bool QImage.save (self, QString fileName, str format = None, int quality = -1)

Saves the image to the file with the given fileName, using the given image file format and quality factor. If format is 0, 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.

See also Reading and Writing Image Files.

bool QImage.save (self, QIODevice device, str format = None, int quality = -1)

This is an overloaded function.

This function writes a QImage to the given device.

This can, for example, be used to save an image directly into a QByteArray:

         QImage image;
         QByteArray ba;
         QBuffer buffer(&ba);
         buffer.open(QIODevice.WriteOnly);
         image.save(&buffer, "PNG"); // writes image into ba in PNG format

QImage QImage.scaled (self, int width, int height, Qt.AspectRatioMode aspectRatioMode = Qt.IgnoreAspectRatio, Qt.TransformationMode transformMode = Qt.FastTransformation)

Returns a copy of the image scaled to a rectangle defined by the given size according to the given aspectRatioMode and transformMode.

• If aspectRatioMode is Qt.IgnoreAspectRatio, the image is scaled to size.
• If aspectRatioMode is Qt.KeepAspectRatio, the image is scaled to a rectangle as large as possible inside size, preserving the aspect ratio.
• If aspectRatioMode is Qt.KeepAspectRatioByExpanding, the image is scaled to a rectangle as small as possible outside size, preserving the aspect ratio.

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

See also isNull() and Image Transformations.

QImage QImage.scaled (self, QSize size, Qt.AspectRatioMode aspectRatioMode = Qt.IgnoreAspectRatio, Qt.TransformationMode transformMode = Qt.FastTransformation)

This is an overloaded function.

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.

QImage QImage.scaledToHeight (self, int height, Qt.TransformationMode mode = Qt.FastTransformation)

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.

QImage QImage.scaledToWidth (self, int width, Qt.TransformationMode mode = Qt.FastTransformation)

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.

sip.voidptr QImage.scanLine (self, int)

Returns a pointer to the pixel data at the scanline with index i. The first scanline is at index 0.

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(), Pixel Manipulation, and constScanLine().

int QImage.serialNumber (self)

QImage.setAlphaChannel (self, QImage alphaChannel)

QImage.setColor (self, 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 setColorCount().

See also color(), colorCount(), setColorTable(), and Pixel Manipulation.

QImage.setColorCount (self, int)

Resizes the color table to contain colorCount entries.

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

QImage.setColorTable (self, list-of-int 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.

QImage.setDotsPerMeterX (self, int)

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, and determines the scale at which QPainter will draw graphics on the image. It does not change the scale or aspect ratio of the image when it is rendered on other paint devices.

See also dotsPerMeterX() and Image Information.

QImage.setDotsPerMeterY (self, int)

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, and determines the scale at which QPainter will draw graphics on the image. It does not change the scale or aspect ratio of the image when it is rendered on other paint devices.

See also dotsPerMeterY() and Image Information.

QImage.setNumColors (self, int)

QImage.setOffset (self, QPoint)

Sets 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.

QImage.setPixel (self, 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 >= colorCount() 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.

QImage.setPixel (self, int x, int y, int index_or_rgb)

This is an overloaded function.

QImage.setText (self, QString key, QString value)

Sets the image text to the given text and associate it with the given key.

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().

QSize QImage.size (self)

Returns the size of the image, i.e. its width() and height().

See also Image Information.

QImage.swap (self, QImage other)

Swaps image other with this image. This operation is very fast and never fails.

This function was introduced in Qt 4.8.

QString QImage.text (self, QString key = QString())

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().

QStringList QImage.textKeys (self)

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().

QImage QImage.transformed (self, QMatrix matrix, Qt.TransformationMode mode = Qt.FastTransformation)

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.

QImage QImage.transformed (self, QTransform matrix, Qt.TransformationMode mode = Qt.FastTransformation)

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.

QMatrix QImage.trueMatrix (QMatrix, 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.

QTransform QImage.trueMatrix (QTransform, 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.

bool QImage.valid (self, QPoint pt)

Returns true if pos is a valid coordinate pair within the image; otherwise returns false.

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

bool QImage.valid (self, int x, int y)

This is an overloaded function.

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

int QImage.width (self)

Returns the width of the image.

See also Image Information.

bool QImage.__eq__ (self, QImage)

bool QImage.__ne__ (self, QImage)