QPixmap¶

PyQt6.QtGui.QPixmap

Inherited by QBitmap.

Description¶

The QPixmap class is an off-screen image representation that 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. The isQBitmap() function returns true if a QPixmap object is really a bitmap, otherwise returns false. Finally, the QPicture class is a paint device that records and replays QPainter commands.

A QPixmap can easily be displayed on the screen using QLabel or one of QAbstractButton’s subclasses (such as QPushButton and QToolButton). QLabel has a pixmap property, whereas QAbstractButton has an icon property.

QPixmap objects can be passed around by value since the QPixmap class uses implicit data sharing. For more information, see the Implicit Data Sharing documentation. QPixmap objects can also be streamed.

Note that the pixel data in a pixmap is internal and is managed by the underlying window system. Because QPixmap is a QPaintDevice subclass, QPainter can be used to draw directly onto pixmaps. Pixels can only be accessed through QPainter functions or by converting the QPixmap to a QImage. However, the fill() function is available for initializing the entire pixmap with a given color.

There are functions to convert between QImage and QPixmap. Typically, the QImage class is used to load an image file, optionally manipulating the image data, before the QImage object is converted into a QPixmap to be shown on screen. Alternatively, if no manipulation is desired, the image file can be loaded directly into a QPixmap.

QPixmap provides a collection of functions that can be used to obtain a variety of information about the pixmap. In addition, there are several functions that enables transformation of the pixmap.

Reading and Writing Image Files¶

QPixmap provides several ways of reading an image file: The file can be loaded when constructing the QPixmap object, or by using the load() or loadFromData() functions later on. 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 QPixmap object.

The complete list of supported file formats are available through the supportedImageFormats() and 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
XBM	X11 Bitmap	Read/write
XPM	X11 Pixmap	Read/write

Pixmap Information¶

QPixmap provides a collection of functions that can be used to obtain a variety of information about the pixmap:

Available Functions

Geometry

The size(), width() and height() functions provide information about the pixmap’s size. The rect() function returns the image’s enclosing rectangle.

Alpha component

The hasAlphaChannel() returns true if the pixmap has a format that respects the alpha channel, otherwise returns false. The hasAlpha(), setMask() and mask() functions are legacy and should not be used. They are potentially very slow.

The createHeuristicMask() function creates and returns a 1-bpp heuristic mask (i.e. a QBitmap) for this pixmap. It works by selecting a color from one of the corners and then chipping away pixels of that color, starting at all the edges. The createMaskFromColor() function creates and returns a mask (i.e. a QBitmap) for the pixmap based on a given color.

Low-level information

The depth() function returns the depth of the pixmap. The defaultDepth() function returns the default depth, i.e. the depth used by the application on the given screen.

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

Pixmap Conversion¶

A QPixmap object can be converted into a QImage using the toImage() function. Likewise, a QImage can be converted into a QPixmap using the fromImage(). If this is too expensive an operation, you can use fromImage() instead.

To convert a QPixmap to and from HICON you can use the toHICON() and fromHICON() functions respectively (after converting the QPixmap to a QImage, as explained above).

Pixmap Transformations¶

QPixmap supports a number of functions for creating a new pixmap that is a transformed version of the original:

The scaled(), scaledToWidth() and scaledToHeight() functions return scaled copies of the pixmap, while the copy() function creates a QPixmap that is a plain copy of the original one.

The transformed() function returns a copy of the pixmap 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 pixmap containing all transformed points of the original pixmap. The static trueMatrix() function returns the actual matrix used for transforming the pixmap.

Methods¶

__init__(): Constructs a null pixmap.

See also

isNull().

__init__(QSize)

This is an overloaded function.

Constructs a pixmap of the given size.

Warning: This will create a QPixmap with uninitialized data. Call fill() to fill the pixmap with an appropriate color before drawing onto it with QPainter.

__init__(list[str]): TODO

__init__(QPixmap): Constructs a pixmap that is a copy of the given pixmap.

See also

copy().

__init__(Any): TODO

__init__(int, int)

Constructs a pixmap with the given width and height. If either width or height is zero, a null pixmap is constructed.

Warning: This will create a QPixmap with uninitialized data. Call fill() to fill the pixmap with an appropriate color before drawing onto it with QPainter.

See also

isNull().

__init__(Optional[str], format: str = None, flags: ImageConversionFlag = AutoColor)

Constructs a pixmap from the file with the given fileName. If the file does not exist or is of an unknown format, the pixmap becomes a null pixmap.

The loader attempts to read the pixmap 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.

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.

If the image needs to be modified to fit in a lower-resolution result (e.g. converting from 32-bit to 8-bit), use the flags to control the conversion.

The fileName, format and flags parameters are passed on to load(). This means that the data in fileName is not compiled into the binary. If fileName contains a relative path (e.g. the filename only) the relevant file must be found relative to the runtime working directory.

See also

Reading and Writing Image Files.

cacheKey() → int

Returns a number that identifies this QPixmap. Distinct QPixmap objects can only have the same cache key if they refer to the same contents.

The cacheKey() will change when the pixmap is altered.

convertFromImage(QImage, flags: ImageConversionFlag = AutoColor) → bool: Replaces this pixmap’s data with the given image using the specified flags to control the conversion. The flags argument is a bitwise-OR of the Qt::ImageConversionFlags. Passing 0 for flags sets all the default options. Returns true if the result is that this pixmap is not null.

See also

fromImage().

copy(rect: QRect = QRect()) → QPixmap

Returns a deep copy of the subset of the pixmap that is specified by the given rectangle. For more information on deep copies, see the Implicit Data Sharing documentation.

If the given rectangle is empty, the whole image is copied.

See also

operator=(), QPixmap, Pixmap Transformations.

copy(int, int, int, int) → QPixmap

This is an overloaded function.

Returns a deep copy of the subset of the pixmap that is specified by the rectangle QRect( x, y, width, height).

createHeuristicMask(clipTight: bool = True) → QBitmap

Creates and returns a heuristic mask for this pixmap.

The function works by selecting a color from one of the corners and then chipping away pixels of that color, starting at all the edges. 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.

The mask may not be perfect but it should be reasonable, so you can do things such as the following:

# QPixmap myPixmap;
# myPixmap.setMask(myPixmap.createHeuristicMask());

This function is slow because it involves converting to/from a QImage, and non-trivial computations.

createMaskFromColor(Union[QColor, GlobalColor, int], mode: MaskMode = MaskInColor) → QBitmap

Creates and returns a mask for this pixmap based on the given maskColor. If the mode is MaskInColor, all pixels matching the maskColor will be transparent. If mode is MaskOutColor, all pixels matching the maskColor will be opaque.

This function is slow because it involves converting to/from a QImage.

See also

createHeuristicMask().

@staticmethod defaultDepth() → int

Returns the default pixmap depth used by the application.

On all platforms the depth of the primary screen will be returned.

Note: QGuiApplication must be created before calling this function.

See also

depth(), QColormap::depth(), Pixmap Information.

depth() → int

Returns the depth of the pixmap.

The pixmap depth is also called bits per pixel (bpp) or bit planes of a pixmap. A null pixmap has depth 0.

See also

defaultDepth(), Pixmap Information.

detach()

Detaches the pixmap from shared pixmap data.

A pixmap is automatically detached by Qt whenever its contents are about to change. This is done in almost all QPixmap member functions that modify the pixmap (fill(), fromImage(), load(), etc.), and in begin() on a pixmap.

There are two exceptions in which detach() must be called explicitly, that is when calling the handle() or the x11PictureHandle() function (only available on X11). Otherwise, any modifications done using system calls, will be performed on the shared data.

The detach() function returns immediately if there is just a single reference or if the pixmap has not been initialized yet.

deviceIndependentSize() → QSizeF

Returns the size of the pixmap in device independent pixels.

This value should be used when using the pixmap size in user interface size calculations.

The return value is equivalent to pixmap.size() / pixmap.devicePixelRatio(),

devicePixelRatio() → float

Returns the device pixel ratio for the pixmap. This is the ratio between device pixels and device independent pixels.

Use this function when calculating layout geometry based on the pixmap size: QSize layoutSize = image.size() / image.

The default value is 1.0.

See also

setDevicePixelRatio(), QImageReader.

devType() → int: TODO

fill(color: Union[QColor, GlobalColor, int] = white)

Fills the pixmap with the given color.

The effect of this function is undefined when the pixmap is being painted on.

See also

Pixmap Transformations.

@staticmethod fromImage(QImage, flags: ImageConversionFlag = AutoColor) → QPixmap

Converts the given image to a pixmap using the specified flags to control the conversion. The flags argument is a bitwise-OR of the Qt::ImageConversionFlags. Passing 0 for flags sets all the default options.

In case of monochrome and 8-bit images, the image is first converted to a 32-bit pixmap and then filled with the colors in the color table. If this is too expensive an operation, you can use fromImage() instead.

See also

fromImageReader(), toImage(), Pixmap Conversion.

@staticmethod fromImageReader(QImageReader, flags: ImageConversionFlag = AutoColor) → QPixmap

Create a QPixmap from an image read directly from an imageReader. The flags argument is a bitwise-OR of the Qt::ImageConversionFlags. Passing 0 for flags sets all the default options.

On some systems, reading an image directly to QPixmap can use less memory than reading a QImage to convert it to QPixmap.

See also

fromImage(), toImage(), Pixmap Conversion.

hasAlpha() → bool: Returns true if this pixmap has an alpha channel, or has a mask, otherwise returns false.

See also

hasAlphaChannel(), mask().

hasAlphaChannel() → bool: Returns true if the pixmap has a format that respects the alpha channel, otherwise returns false.

See also

hasAlpha().

height() → int: Returns the height of the pixmap.

See also

size(), Pixmap Information.

isNull() → bool

Returns true if this is a null pixmap; otherwise returns false.

A null pixmap has zero width, zero height and no contents. You cannot draw in a null pixmap.

isQBitmap() → bool: Returns true if this is a QBitmap; otherwise returns false.

load(Optional[str], format: str = None, flags: ImageConversionFlag = AutoColor) → bool

Loads a pixmap from the file with the given fileName. Returns true if the pixmap was successfully loaded; otherwise invalidates the pixmap and returns false.

The loader attempts to read the pixmap 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.

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 pixmaps and other resource files in the application’s executable.

If the data needs to be modified to fit in a lower-resolution result (e.g. converting from 32-bit to 8-bit), use the flags to control the conversion.

Note that QPixmaps are automatically added to the QPixmapCache when loaded from a file in main thread; the key used is internal and cannot be acquired.

See also

loadFromData(), Reading and Writing Image Files.

loadFromData(bytes, format: str = None, flags: ImageConversionFlag = AutoColor) → bool

Loads a pixmap from the len first bytes of the given binary data. Returns true if the pixmap was loaded successfully; otherwise invalidates the pixmap and returns false.

The loader attempts to read the pixmap 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 data needs to be modified to fit in a lower-resolution result (e.g. converting from 32-bit to 8-bit), use the flags to control the conversion.

See also

load(), Reading and Writing Image Files.

loadFromData(Union[QByteArray, bytes, bytearray, memoryview], format: str = None, flags: ImageConversionFlag = AutoColor) → bool

This is an overloaded function.

Loads a pixmap from the binary data using the specified format and conversion flags.

mask() → QBitmap

Extracts a bitmap mask from the pixmap’s alpha channel.

Warning: This is potentially an expensive operation. The mask of the pixmap is extracted dynamically from the pixeldata.

See also

setMask(), Pixmap Information.

metric(PaintDeviceMetric) → int: TODO

paintEngine() → QPaintEngine: TODO

rect() → QRect: Returns the pixmap’s enclosing rectangle.

See also

Pixmap Information.

save(Optional[str], format: str = None, quality: int = -1) → bool

Saves the pixmap to the file with the given fileName using the specified image file format and quality factor. Returns true if successful; otherwise returns false.

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

If format is nullptr, an image format will be chosen from fileName’s suffix.

See also

Reading and Writing Image Files.

save(QIODevice, format: str = None, quality: int = -1) → bool

This is an overloaded function.

This function writes a QPixmap to the given device using the specified image file format and quality factor. This can be used, for example, to save a pixmap directly into a QByteArray:

# QPixmap pixmap;
# QByteArray bytes;
# QBuffer buffer(&bytes);
# buffer.open(QIODevice::WriteOnly);
# pixmap.save(&buffer, "PNG"); // writes pixmap into bytes in PNG format

scaled(QSize, aspectRatioMode: AspectRatioMode = IgnoreAspectRatio, transformMode: TransformationMode = FastTransformation) → QPixmap

Scales the pixmap to the given size, using the aspect ratio and transformation modes specified by aspectRatioMode and transformMode.

If aspectRatioMode is IgnoreAspectRatio, the pixmap is scaled to size.
If aspectRatioMode is KeepAspectRatio, the pixmap is scaled to a rectangle as large as possible inside size, preserving the aspect ratio.
If aspectRatioMode is KeepAspectRatioByExpanding, the pixmap 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 pixmap.

In some cases it can be more beneficial to draw the pixmap to a painter with a scale set rather than scaling the pixmap. This is the case when the painter is for instance based on OpenGL or when the scale factor changes rapidly.

See also

isNull(), Pixmap Transformations.

scaled(int, int, aspectRatioMode: AspectRatioMode = IgnoreAspectRatio, transformMode: TransformationMode = FastTransformation) → QPixmap

This is an overloaded function.

Returns a copy of the pixmap 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 pixmap.

scaledToHeight(int, mode: TransformationMode = FastTransformation) → QPixmap

Returns a scaled copy of the image. The returned image is scaled to the given height using the specified transformation mode. The width of the pixmap is automatically calculated so that the aspect ratio of the pixmap is preserved.

If height is 0 or negative, a null pixmap is returned.

See also

isNull(), Pixmap Transformations.

scaledToWidth(int, mode: TransformationMode = FastTransformation) → QPixmap

Returns a scaled copy of the image. The returned image is scaled to the given width using the specified transformation mode. The height of the pixmap is automatically calculated so that the aspect ratio of the pixmap is preserved.

If width is 0 or negative, a null pixmap is returned.

See also

isNull(), Pixmap Transformations.

scroll(int, int, QRect) → QRegion

Scrolls the area rect of this pixmap by (dx, dy). The exposed region is left unchanged. You can optionally pass a pointer to an empty QRegion to get the region that is exposed by the scroll operation.

# QPixmap pixmap("background.png");
# QRegion exposed;
# pixmap.scroll(10, 10, pixmap.rect(), &exposed);

You cannot scroll while there is an active painter on the pixmap.

See also

QWidget::scroll()QGraphicsItem::scroll().

scroll(int, int, int, int, int, int) → QRegion: This convenience function is equivalent to calling scroll()(dx, dy, QRect(x, y, width, height), exposed).

See also

scroll(), scroll().

setDevicePixelRatio(float)

Sets the device pixel ratio for the pixmap. This is the ratio between image pixels and device-independent pixels.

The default scaleFactor is 1.0. Setting it to something else has two effects:

QPainters that are opened on the pixmap will be scaled. For example, painting on a 200x200 image if with a ratio of 2.0 will result in effective (device-independent) painting bounds of 100x100.

Code paths in Qt that calculate layout geometry based on the pixmap size will take the ratio into account: QSize layoutSize = pixmap.size() / pixmap.devicePixelRatio() The net effect of this is that the pixmap is displayed as high-DPI pixmap rather than a large pixmap (see Drawing High Resolution Versions of Pixmaps and Images).

setMask(QBitmap)

Sets a mask bitmap.

This function merges the mask with the pixmap’s alpha channel. A pixel value of 1 on the mask means the pixmap’s pixel is unchanged; a value of 0 means the pixel is transparent. The mask must have the same size as this pixmap.

Setting a null mask resets the mask, leaving the previously transparent pixels black. The effect of this function is undefined when the pixmap is being painted on.

Warning: This is potentially an expensive operation.

See also

mask(), Pixmap Transformations, QBitmap.

size() → QSize: Returns the size of the pixmap.

See also

width(), height(), Pixmap Information.

swap(QPixmap): Swaps this pixmap with other. This operation is very fast and never fails.

toImage() → QImage

Converts the pixmap to a QImage. Returns a null image if the conversion fails.

If the pixmap has 1-bit depth, the returned image will also be 1 bit deep. Images with more bits will be returned in a format closely represents the underlying system. Usually this will be Format_ARGB32_Premultiplied for pixmaps with an alpha and Format_RGB32 or Format_RGB16 for pixmaps without alpha.

Note that for the moment, alpha masks on monochrome images are ignored.

See also

fromImage(), Image Formats.

transformed(QTransform, mode: TransformationMode = FastTransformation) → QPixmap

Returns a copy of the pixmap that is transformed using the given transformation transform and transformation mode. The original pixmap is not changed.

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

This function is slow because it involves transformation to a QImage, non-trivial computations and a transformation back to a QPixmap.

See also

trueMatrix(), Pixmap Transformations.

@staticmethod trueMatrix(QTransform, int, int) → QTransform

Returns the actual matrix used for transforming a pixmap with the given width, height and matrix.

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

See also

Pixmap Transformations, transformed().

width() → int: Returns the width of the pixmap.

See also

size(), Pixmap Information.