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 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 ()
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 QPixmap::Optimization.
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; see QPixmap::Optimization.
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 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 )
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 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 )
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 bitmap becomes a null
bitmap.
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().
This file is part of the Qt toolkit.
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