HomeHome

ClassesAnnotated - TreeFunctionsHomeStructure

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


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 automatically dithered. A QBitmap is guaranteed to always have the depth 1, unless it is QPixmap::isNull() (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.

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() and Shared Classes

Examples: cursor/cursor.cpp


Member Function Documentation

QBitmap::QBitmap ()

Constructs a null bitmap.

See also: QPixmap::isNull().

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 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 ( const QBitmap & bitmap )

Constructs a bitmap which is a copy of bitmap.

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

Constructs a bitmap with w width and h height.

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

Constructs a bitmap with w width and h height 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, bool clear = FALSE, QPixmap::Optimization optimization = QPixmap::DefaultOptim )

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

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

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

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

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::operator= ( const QPixmap & pixmap )

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 QBitmap & bitmap )

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

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

Returns a transformed copy of this bitmap, 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().


Search the documentation, FAQ, qt-interest archive and more (uses www.trolltech.com):


This file is part of the Qt toolkit, copyright © 1995-2000 Trolltech, all rights reserved.


Copyright İ 2000 TrolltechTrademarks
Qt version 2.2.0-beta2