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# QBitmap Class Reference

The QBitmap class provides monochrome (1-bit depth) pixmaps. More...

`#include <qbitmap.h>`

Inherits QPixmap.

List of all member functions.

## Public Members

- QBitmap ()
- QBitmap ( int w, int h, bool clear = FALSE, QPixmap::Optimization optimization = QPixmap::DefaultOptim )
- QBitmap ( const QSize & size, bool clear = FALSE, QPixmap::Optimization optimization = QPixmap::DefaultOptim )
- QBitmap ( int w, int h, const uchar * bits, bool isXbitmap = FALSE )
- QBitmap ( const QSize & size, const uchar * bits, bool isXbitmap = FALSE )
- QBitmap ( const QBitmap & bitmap )
- QBitmap ( const QString & fileName, const char * format = 0 )
- QBitmap & operator= ( const QBitmap & bitmap )
- QBitmap & operator= ( const QPixmap & pixmap )
- QBitmap & operator= ( const QImage & image )
- QBitmap xForm ( const QWMatrix & matrix ) const

## Detailed Description

The QBitmap class provides monochrome (1-bit depth) pixmaps.

The QBitmap class is a monochrome off-screen paint device used mainly for creating custom QCursor and QBrush objects, in QPixmap::setMask() and for QRegion.

A QBitmap is a QPixmap with a QPixmap::depth() of 1. If a pixmap with a depth greater than 1 is assigned to a bitmap, the bitmap will be dithered automatically. A QBitmap is guaranteed to always have the depth 1, unless it is QPixmap::isNull() which has depth 0.

When drawing in a QBitmap (or QPixmap with depth 1), we recommend using the QColor objects `Qt::color0` and `Qt::color1`. Painting with `color0` sets the bitmap bits to 0, and painting with `color1` sets the bits to 1. For a bitmap, 0-bits indicate background (or white) and 1-bits indicate foreground (or black). Using the `black` and `white` QColor objects make no sense because the QColor::pixel() value is not necessarily 0 for black and 1 for white.

The QBitmap can be transformed (translated, scaled, sheared or rotated) using xForm().

Just like the QPixmap class, QBitmap is optimized by the use of implicit sharing, so it is very efficient to pass QBitmap objects as arguments.

See also QPixmap, QPainter::drawPixmap(), bitBlt(), Shared Classes, Graphics Classes, Image Processing Classes and Implicitly and Explicitly Shared Classes.

## Member Function Documentation

### QBitmap::QBitmap ()

Constructs a null bitmap.

See also QPixmap::isNull().

### QBitmap::QBitmap ( int w, int h, bool clear = FALSE, QPixmap::Optimization optimization = QPixmap::DefaultOptim )

Constructs a bitmap with width w and height h.

The contents of the bitmap is uninitialized if clear is FALSE; otherwise it is filled with pixel value 0 (the QColor `Qt::color0`).

The optional optimization argument specifies the optimization setting for the bitmap. The default optimization should be used in most cases. Games and other pixmap-intensive applications may benefit from setting this argument.

See also QPixmap::setOptimization() and QPixmap::setDefaultOptimization().

### QBitmap::QBitmap ( const QSize & size, bool clear = FALSE, QPixmap::Optimization optimization = QPixmap::DefaultOptim )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Constructs a bitmap with the size size.

The contents of the bitmap is uninitialized if clear is FALSE; otherwise it is filled with pixel value 0 (the QColor `Qt::color0`).

The optional optimization argument specifies the optimization setting for the bitmap. The default optimization should be used in most cases. Games and other pixmap-intensive applications may benefit from setting this argument.

### QBitmap::QBitmap ( int w, int h, const uchar * bits, bool isXbitmap = FALSE )

Constructs a bitmap with width w and height h and sets the contents to bits.

The isXbitmap should be TRUE if bits was generated by the X11 bitmap program. The X bitmap bit order is little endian. The QImage documentation discusses bit order of monochrome images.

Example (creates an arrow bitmap):

        uchar arrow_bits[] = { 0x3f, 0x1f, 0x0f, 0x1f, 0x3b, 0x71, 0xe0, 0xc0 };
        QBitmap bm( 8, 8, arrow_bits, TRUE );

### QBitmap::QBitmap ( const QSize & size, const uchar * bits, bool isXbitmap = FALSE )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Constructs a bitmap with the size size and sets the contents to bits.

The isXbitmap should be TRUE if bits was generated by the X11 bitmap program. The X bitmap bit order is little endian. The QImage documentation discusses bit order of monochrome images.

### QBitmap::QBitmap ( const QBitmap & bitmap )

Constructs a bitmap that is a copy of bitmap.

### QBitmap::QBitmap ( const QString & fileName, const char * format = 0 )

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

The parameters fileName and format are passed on to QPixmap::load(). Dithering will be performed if the file format uses more than 1 bit per pixel.

See also QPixmap::isNull(), QPixmap::load(), QPixmap::loadFromData(), QPixmap::save() and QPixmap::imageFormat().

### QBitmap & QBitmap::operator= ( const QBitmap & bitmap )

Assigns the bitmap bitmap to this bitmap and returns a reference to this bitmap.

### QBitmap & QBitmap::operator= ( const QPixmap & pixmap )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Assigns the pixmap pixmap to this bitmap and returns a reference to this bitmap.

Dithering will be performed if the pixmap has a QPixmap::depth() greater than 1.

### QBitmap & QBitmap::operator= ( const QImage & image )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Converts the image image to a bitmap and assigns the result to this bitmap. Returns a reference to the bitmap.

Dithering will be performed if the image has a QImage::depth() greater than 1.

### QBitmap QBitmap::xForm ( const QWMatrix & matrix ) const

Returns a transformed copy of this bitmap by using matrix.

This function does exactly the same as QPixmap::xForm(), except that it returns a QBitmap instead of a QPixmap.

See also QPixmap::xForm().

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