QBitmap Class▲

  • Header: QBitmap

  • CMake:

    find_package(Qt6 REQUIRED COMPONENTS Gui)

    target_link_libraries(mytarget PRIVATE Qt6::Gui)

  • qmake: QT += gui

  • Inherits: QPixmap

  • Group: QBitmap is part of Painting Classes, shared

Detailed Description▲

The QBitmap class is a monochrome off-screen paint device used mainly for creating custom QCursor and QBrush objects, constructing QRegion objects, and for setting masks for pixmaps and widgets.

QBitmap is a QPixmap subclass ensuring a depth of 1, except for null objects which have a depth of 0. If a pixmap with a depth greater than 1 is assigned to a bitmap, the bitmap will be dithered automatically.

Use the QColor objects Qt::color0 and Qt::color1 when drawing on a QBitmap object (or a QPixmap object with depth 1).

Painting with Qt::color0 sets the bitmap bits to 0, and painting with Qt::color1 sets the bits to 1. For a bitmap, 0-bits indicate background (or transparent pixels) and 1-bits indicate foreground (or opaque pixels). Use the clear() function to set all the bits to Qt::color0. Note that using the Qt::black and Qt::white colors make no sense because the QColor::pixel() value is not necessarily 0 for black and 1 for white.

The QBitmap class provides the transformed() function returning a transformed copy of the bitmap; use the QTransform argument to translate, scale, shear, and rotate the bitmap. In addition, QBitmap provides the static fromData() function which returns a bitmap constructed from the given uchar data, and the static fromImage() function returning a converted copy of a QImage object.

Just like the QPixmap class, QBitmap is optimized by the use of implicit data sharing. For more information, see the Implicit Data Sharing documentation.

See Also▲

See also QPixmap, QImage, QImageReader, QImageWriter

Member Function Documentation▲

 

QBitmap::QBitmap()▲

Constructs a null bitmap.

See Also▲

See also QPixmap::isNull()

QBitmap::QBitmap(int width, int height)▲

Constructs a bitmap with the given width and height. The pixels inside are uninitialized.

See Also▲

See also clear()

[explicit] QBitmap::QBitmap(const QString &fileName, const char *format = nullptr)▲

Constructs a bitmap from the file specified by the given fileName. If the file does not exist, or has an unknown format, the bitmap becomes a null bitmap.

The fileName and format parameters are passed on to the QPixmap::load() function. If the file format uses more than 1 bit per pixel, the resulting bitmap will be dithered automatically.

See Also▲

See also QPixmap::isNull(),