QBitmap Class Reference

Detailed Description

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 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 transparent) and 1-bits indicate foreground (or opaque). 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 ()

See also QPixmap::isNull().

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

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 QPixmap::Optimization.

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

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

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; see QPixmap::Optimization.

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

The isXbitmap flag 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 )

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

The isXbitmap flag 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 )

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

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 )

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 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::xForm ( const QWMatrix & matrix ) const

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

See also QPixmap::xForm().

This file is part of the Qt toolkit. Copyright © 1995-2003 Trolltech. All Rights Reserved.