QPixmap(3qt)QPixmap(3qt)NAMEQPixmap - Off-screen, pixel-based paint device
SYNOPSIS
#include <qpixmap.h>
Inherits QPaintDevice and Qt.
Inherited by QBitmap and QCanvasPixmap.
Public Members
enum ColorMode { Auto, Color, Mono }
enum Optimization { DefaultOptim, NoOptim, MemoryOptim = NoOptim,
NormalOptim, BestOptim }
QPixmap ()
QPixmap ( const QImage & image )
QPixmap ( int w, int h, int depth = -1, Optimization optimization =
DefaultOptim )
QPixmap ( const QSize & size, int depth = -1, Optimization optimization
= DefaultOptim )
QPixmap ( const QString & fileName, const char * format = 0, ColorMode
mode = Auto )
QPixmap ( const QString & fileName, const char * format, int
conversion_flags )
QPixmap ( const char * xpm[] )
QPixmap ( const QByteArray & img_data )
QPixmap ( const QPixmap & pixmap )
~QPixmap ()
QPixmap & operator= ( const QPixmap & pixmap )
QPixmap & operator= ( const QImage & image )
bool isNull () const
int width () const
int height () const
QSize size () const
QRect rect () const
int depth () const
void fill ( const QColor & fillColor = Qt::white )
void fill ( const QWidget * widget, int xofs, int yofs )
void fill ( const QWidget * widget, const QPoint & ofs )
void resize ( int w, int h )
void resize ( const QSize & size )
const QBitmap * mask () const
void setMask ( const QBitmap & newmask )
bool selfMask () const
bool hasAlpha () const
bool hasAlphaChannel () const
QBitmap createHeuristicMask ( bool clipTight = TRUE ) const
QPixmap xForm ( const QWMatrix & matrix ) const
QImage convertToImage () const
bool convertFromImage ( const QImage & image, ColorMode mode = Auto )
bool convertFromImage ( const QImage & img, int conversion_flags )
bool load ( const QString & fileName, const char * format = 0,
ColorMode mode = Auto )
bool load ( const QString & fileName, const char * format, int
conversion_flags )
bool loadFromData ( const uchar * buf, uint len, const char * format =
0, ColorMode mode = Auto )
bool loadFromData ( const uchar * buf, uint len, const char * format,
int conversion_flags )
bool loadFromData ( const QByteArray & buf, const char * format = 0,
int conversion_flags = 0 )
bool save ( const QString & fileName, const char * format, int quality
= -1 ) const
bool save ( QIODevice * device, const char * format, int quality = -1 )
const
int serialNumber () const
Optimization optimization () const
void setOptimization ( Optimization optimization )
virtual void detach ()
bool isQBitmap () const
Static Public Members
int defaultDepth ()
QPixmap fromMimeSource ( const QString & abs_name )
QPixmap grabWindow ( WId window, int x = 0, int y = 0, int w = -1, int
h = -1 )
QPixmap grabWidget ( QWidget * widget, int x = 0, int y = 0, int w =
-1, int h = -1 )
QWMatrix trueMatrix ( const QWMatrix & matrix, int w, int h )
const char * imageFormat ( const QString & fileName )
Optimization defaultOptimization ()
void setDefaultOptimization ( Optimization optimization )
Protected Members
QPixmap ( int w, int h, const uchar * bits, bool isXbitmap )
virtual int metric ( int m ) const
RELATED FUNCTION DOCUMENTATION
QDataStream & operator<< ( QDataStream & s, const QPixmap & pixmap )
QDataStream & operator>> ( QDataStream & s, QPixmap & pixmap )
void copyBlt ( QPixmap * dst, int dx, int dy, const QPixmap * src, int
sx, int sy, int sw, int sh )
DESCRIPTION
The QPixmap class is an off-screen, pixel-based paint device.
QPixmap is one of the two classes Qt provides for dealing with images;
the other is QImage. QPixmap is designed and optimized for drawing;
QImage is designed and optimized for I/O and for direct pixel
access/manipulation. There are (slow) functions to convert between
QImage and QPixmap: convertToImage() and convertFromImage().
One common use of the QPixmap class is to enable smooth updating of
widgets. Whenever something complex needs to be drawn, you can use a
pixmap to obtain flicker-free drawing, like this:
<ol type=1>
1 Create a pixmap with the same size as the widget.
2 Fill the pixmap with the widget background color.
3 Paint the pixmap.
4 bitBlt() the pixmap contents onto the widget.
Pixel data in a pixmap is internal and is managed by the underlying
window system. Pixels can be accessed only through QPainter functions,
through bitBlt(), and by converting the QPixmap to a QImage.
You can easily display a QPixmap on the screen using
QLabel::setPixmap(). For example, all the QButton subclasses support
pixmap use.
The QPixmap class uses copy-on-write, so it is practical to pass
QPixmap objects by value.
You can retrieve the width(), height(), depth() and size() of a pixmap.
The enclosing rectangle is given by rect(). Pixmaps can be filled with
fill() and resized with resize(). You can create and set a mask with
createHeuristicMask() and setMask(). Use selfMask() to see if the
pixmap is identical to its mask.
In addition to loading a pixmap from file using load() you can also
loadFromData(). You can control optimization with setOptimization() and
obtain a transformed version of the pixmap using xForm()
Note regarding Windows 95 and 98: on Windows 9x the system crashes if
you create more than about 1000 pixmaps, independent of the size of the
pixmaps or installed RAM. Windows NT-systems (including 2000, XP and
following versions) do not have the same limitation, but depending on
the graphics equipment the system will fail to allocate pixmap objects
at some point (due to system running out of GDI resources).
Qt tries to work around the resource limitation. If you set the pixmap
optimization to QPixmap::MemoryOptim and the width of your pixmap is
less than or equal to 128 pixels, Qt stores the pixmap in a way that is
very memory-efficient when there are many pixmaps.
If your application uses dozens or hundreds of pixmaps (for example on
tool bar buttons and in popup menus), and you plan to run it on Windows
95 or Windows 98, we recommend using code like this:
QPixmap::setDefaultOptimization( QPixmap::MemoryOptim );
while ( ... ) {
// load tool bar pixmaps etc.
QPixmap *pixmap = new QPixmap(fileName);
}
QPixmap::setDefaultOptimization( QPixmap::NormalOptim );
In general it is recommended to make as much use of QPixmap's implicit
sharing and the QPixmapCache as possible.
See also QBitmap, QImage, QImageIO, Shared Classes, Graphics Classes,
Image Processing Classes, and Implicitly and Explicitly Shared Classes.
Member Type Documentation
QPixmap::ColorMode
This enum type defines the color modes that exist for converting QImage
objects to QPixmap.
QPixmap::Auto - Select Color or Mono on a case-by-case basis.
QPixmap::Color - Always create colored pixmaps.
QPixmap::Mono - Always create bitmaps.
QPixmap::OptimizationQPixmap has the choice of optimizing for speed or memory in a few
places; the best choice varies from pixmap to pixmap but can generally
be derived heuristically. This enum type defines a number of
optimization modes that you can set for any pixmap to tweak the
speed/memory tradeoffs:
QPixmap::DefaultOptim - Whatever QPixmap::defaultOptimization()
returns. A pixmap with this optimization will have whatever the current
default optimization is. If the default optimization is changed using
setDefaultOptimization(), then this will not effect any pixmaps that
have already been created.
QPixmap::NoOptim - No optimization (currently the same as MemoryOptim).
QPixmap::MemoryOptim - Optimize for minimal memory use on Windows 9x
and X11 systems.
QPixmap::NormalOptim - Optimize for typical usage. Often uses more
memory than MemoryOptim, and is often faster.
QPixmap::BestOptim - Optimize for pixmaps that are drawn very often and
where performance is critical. Generally uses more memory than
NormalOptim and may provide a little more speed.
We recommend using DefaultOptim.
MEMBER FUNCTION DOCUMENTATIONQPixmap::QPixmap ()
Constructs a null pixmap.
See also isNull().
QPixmap::QPixmap ( const QImage & image )
Constructs a pixmap from the QImage image.
See also convertFromImage().
QPixmap::QPixmap ( int w, int h, int depth = -1, Optimization optimization =
DefaultOptim )
Constructs a pixmap with w width, h height and depth bits per pixel.
The pixmap is optimized in accordance with the optimization value.
The contents of the pixmap is uninitialized.
The depth can be either 1 (monochrome) or the depth of the current
video mode. If depth is negative, then the hardware depth of the
current video mode will be used.
If either w or h is zero, a null pixmap is constructed.
See also isNull() and QPixmap::Optimization.
QPixmap::QPixmap ( const QSize & size, int depth = -1, Optimization
optimization = DefaultOptim )
This is an overloaded member function, provided for convenience. It
behaves essentially like the above function.
Constructs a pixmap of size size, depth bits per pixel, optimized in
accordance with the optimization value.
QPixmap::QPixmap ( const QString & fileName, const char * format = 0,
ColorMode mode = Auto )
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 fileName, format and mode parameters are passed on to load(). This
means that the data in fileName is not compiled into the binary. If
fileName contains a relative path (e.g. the filename only) the relevant
file must be found relative to the runtime working directory.
See also QPixmap::ColorMode, isNull(), load(), loadFromData(), save(),
and imageFormat().
QPixmap::QPixmap ( const QString & fileName, const char * format, int
conversion_flags )
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 fileName, format and conversion_flags parameters are passed on to
load(). This means that the data in fileName is not compiled into the
binary. If fileName contains a relative path (e.g. the filename only)
the relevant file must be found relative to the runtime working
directory.
If the image needs to be modified to fit in a lower-resolution result
(e.g. converting from 32-bit to 8-bit), use the conversion_flags to
specify how you'd prefer this to happen.
See also Qt::ImageConversionFlags, isNull(), load(), loadFromData(),
save(), and imageFormat().
QPixmap::QPixmap ( const char * xpm[] )
Constructs a pixmap from xpm, which must be a valid XPM image.
Errors are silently ignored.
Note that it's possible to squeeze the XPM variable a little bit by
using an unusual declaration:
static const char * const start_xpm[]={
"16 15 8 1",
"a c #cec6bd",
....
The extra const makes the entire definition read-only, which is
slightly more efficient (for example, when the code is in a shared
library) and ROMable when the application is to be stored in ROM.
In order to use that sort of declaration you must cast the variable
back to const char ** when you create the QPixmap.
QPixmap::QPixmap ( const QByteArray & img_data )
Constructs a pixmaps by loading from img_data. The data can be in any
image format supported by Qt.
See also loadFromData().
QPixmap::QPixmap ( const QPixmap & pixmap )
Constructs a pixmap that is a copy of pixmap.
QPixmap::QPixmap ( int w, int h, const uchar * bits, bool isXbitmap )
[protected]
Constructs a monochrome pixmap, with width w and height h, that is
initialized with the data in bits. The isXbitmap indicates whether the
data is an X bitmap and defaults to FALSE. This constructor is
protected and used by the QBitmap class.
QPixmap::~QPixmap ()
Destroys the pixmap.
bool QPixmap::convertFromImage ( const QImage & img, int conversion_flags )
Converts image img and sets this pixmap. Returns TRUE if successful;
otherwise returns FALSE.
The conversion_flags argument is a bitwise-OR of the
Qt::ImageConversionFlags. Passing 0 for conversion_flags sets all the
default options.
Note that even though a QPixmap with depth 1 behaves much like a
QBitmap, isQBitmap() returns FALSE.
If a pixmap with depth 1 is painted with color0 and color1 and
converted to an image, the pixels painted with color0 will produce
pixel index 0 in the image and those painted with color1 will produce
pixel index 1.
See also convertToImage(), isQBitmap(), QImage::convertDepth(),
defaultDepth(), and QImage::hasAlphaBuffer().
Examples:
bool QPixmap::convertFromImage ( const QImage & image, ColorMode mode = Auto )
This is an overloaded member function, provided for convenience. It
behaves essentially like the above function.
Converts image and sets this pixmap using color mode mode. Returns TRUE
if successful; otherwise returns FALSE.
See also QPixmap::ColorMode.
QImage QPixmap::convertToImage () const
Converts the pixmap to a QImage. Returns a null image if it fails.
If the pixmap has 1-bit depth, the returned image will also be 1 bit
deep. If the pixmap has 2- to 8-bit depth, the returned image has 8-bit
depth. If the pixmap has greater than 8-bit depth, the returned image
has 32-bit depth.
Note that for the moment, alpha masks on monochrome images are ignored.
See also convertFromImage().
Example: qmag/qmag.cpp.
QBitmap QPixmap::createHeuristicMask ( bool clipTight = TRUE ) const
Creates and returns a heuristic mask for this pixmap. It works by
selecting a color from one of the corners and then chipping away pixels
of that color, starting at all the edges.
The mask may not be perfect but it should be reasonable, so you can do
things such as the following:
pm->setMask( pm->createHeuristicMask() );
This function is slow because it involves transformation to a QImage,
non-trivial computations and a transformation back to a QBitmap.
If clipTight is TRUE the mask is just large enough to cover the pixels;
otherwise, the mask is larger than the data pixels.
See also QImage::createHeuristicMask().
int QPixmap::defaultDepth () [static]
Returns the default pixmap depth, i.e. the depth a pixmap gets if -1 is
specified.
See also depth().
Optimization QPixmap::defaultOptimization () [static]
Returns the default pixmap optimization setting.
See also setDefaultOptimization(), setOptimization(), and
optimization().
int QPixmap::depth () const
Returns the depth of the pixmap.
The pixmap depth is also called bits per pixel (bpp) or bit planes of a
pixmap. A null pixmap has depth 0.
See also defaultDepth(), isNull(), and QImage::convertDepth().
void QPixmap::detach () [virtual]
This is a special-purpose function that detaches the pixmap from shared
pixmap data.
A pixmap is automatically detached by Qt whenever its contents is about
to change. This is done in all QPixmap member functions that modify the
pixmap (fill(), resize(), convertFromImage(), load(), etc.), in
bitBlt() for the destination pixmap and in QPainter::begin() on a
pixmap.
It is possible to modify a pixmap without letting Qt know. You can
first obtain the system-dependent handle() and then call system-
specific functions (for instance, BitBlt under Windows) that modify the
pixmap contents. In such cases, you can call detach() to cut the pixmap
loose from other pixmaps that share data with this one.
detach() returns immediately if there is just a single reference or if
the pixmap has not been initialized yet.
void QPixmap::fill ( const QColor & fillColor = Qt::white )
Fills the pixmap with the color fillColor.
Examples:
void QPixmap::fill ( const QWidget * widget, int xofs, int yofs )
This is an overloaded member function, provided for convenience. It
behaves essentially like the above function.
Fills the pixmap with the widget's background color or pixmap. If the
background is empty, nothing is done. xofs, yofs is an offset in the
widget.
void QPixmap::fill ( const QWidget * widget, const QPoint & ofs )
This is an overloaded member function, provided for convenience. It
behaves essentially like the above function.
Fills the pixmap with the widget's background color or pixmap. If the
background is empty, nothing is done.
The ofs point is an offset in the widget.
The point ofs is a point in the widget's coordinate system. The
pixmap's top-left pixel will be mapped to the point ofs in the widget.
This is significant if the widget has a background pixmap; otherwise
the pixmap will simply be filled with the background color of the
widget.
Example:
void CuteWidget::paintEvent( QPaintEvent *e )
{
QRect ur = e->rect(); // rectangle to update
QPixmap pix( ur.size() ); // Pixmap for double-buffering
pix.fill( this, ur.topLeft() ); // fill with widget background
QPainter p( &pix );
p.translate( -ur.x(), -ur.y() ); // use widget coordinate system
// when drawing on pixmap
// ... draw on pixmap ...
p.end();
bitBlt( this, ur.topLeft(), &pix );
}
QPixmap QPixmap::fromMimeSource ( const QString & abs_name ) [static]
Convenience function. Gets the data associated with the absolute name
abs_name from the default mime source factory and decodes it to a
pixmap.
See also QMimeSourceFactory, QImage::fromMimeSource(), and
QImageDrag::decode().
Example: textedit/textedit.cpp.
QPixmap QPixmap::grabWidget ( QWidget * widget, int x = 0, int y = 0, int w =
-1, int h = -1 ) [static]
Creates a pixmap and paints widget in it.
If the widget has any children, then they are also painted in the
appropriate positions.
If you specify x, y, w or h, only the rectangle you specify is painted.
The defaults are 0, 0 (top-left corner) and -1,-1 (which means the
entire widget).
(If w is negative, the function copies everything to the right border
of the window. If h is negative, the function copies everything to the
bottom of the window.)
If widget is 0, or if the rectangle defined by x, y, the modified w and
the modified h does not overlap the widget->rect(), this function will
return a null QPixmap.
This function actually asks widget to paint itself (and its children to
paint themselves). QPixmap::grabWindow() grabs pixels off the screen,
which is a bit faster and picks up exactly what's on-screen. This
function works by calling paintEvent() with painter redirection turned
on. If there are overlaying windows, grabWindow() will see them, but
not this function.
If there is overlap, it returns a pixmap of the size you want,
containing a rendering of widget. If the rectangle you ask for is a
superset of widget, the areas outside widget are covered with the
widget's background.
If an error occurs when trying to grab the widget, such as the size of
the widget being too large to fit in memory, an isNull() pixmap is
returned.
See also grabWindow(), QPainter::redirect(), and QWidget::paintEvent().
QPixmap QPixmap::grabWindow ( WId window, int x = 0, int y = 0, int w = -1,
int h = -1 ) [static]
Grabs the contents of the window window and makes a pixmap out of it.
Returns the pixmap.
The arguments (x, y) specify the offset in the window, whereas (w, h)
specify the width and height of the area to be copied.
If w is negative, the function copies everything to the right border of
the window. If h is negative, the function copies everything to the
bottom of the window.
Note that grabWindow() grabs pixels from the screen, not from the
window. If there is another window partially or entirely over the one
you grab, you get pixels from the overlying window, too.
Note also that the mouse cursor is generally not grabbed.
The reason we use a window identifier and not a QWidget is to enable
grabbing of windows that are not part of the application, window system
frames, and so on.
Warning: Grabbing an area outside the screen is not safe in general.
This depends on the underlying window system.
Warning: X11 only: If window is not the same depth as the root window
and another window partially or entirely obscures the one you grab, you
will not get pixels from the overlying window. The contests of the
obscured areas in the pixmap are undefined and uninitialized.
See also grabWidget().
Example: qmag/qmag.cpp.
bool QPixmap::hasAlpha () const
Returns TRUE this pixmap has an alpha channel or a mask.
See also hasAlphaChannel() and mask().
bool QPixmap::hasAlphaChannel () const
Returns TRUE if the pixmap has an alpha channel; otherwise it returns
FALSE.
NOTE: If the pixmap has a mask but not alpha channel, this function
returns FALSE.
See also hasAlpha() and mask().
int QPixmap::height () const
Returns the height of the pixmap.
See also width(), size(), and rect().
Examples:
const char * QPixmap::imageFormat ( const QString & fileName ) [static]
Returns a string that specifies the image format of the file fileName,
or 0 if the file cannot be read or if the format cannot be recognized.
The QImageIO documentation lists the supported image formats.
See also load() and save().
bool QPixmap::isNull () const
Returns TRUE if this is a null pixmap; otherwise returns FALSE.
A null pixmap has zero width, zero height and no contents. You cannot
draw in a null pixmap or bitBlt() anything to it.
Resizing an existing pixmap to (0, 0) makes a pixmap into a null
pixmap.
See also resize().
Examples:
bool QPixmap::isQBitmap () const
Returns TRUE if this is a QBitmap; otherwise returns FALSE.
bool QPixmap::load ( const QString & fileName, const char * format, int
conversion_flags )
Loads a pixmap from the file fileName at runtime. Returns TRUE if
successful; otherwise returns FALSE.
If format is specified, the loader attempts to read the pixmap using
the specified format. If format is not specified (default), the loader
reads a few bytes from the header to guess the file's format.
See the convertFromImage() documentation for a description of the
conversion_flags argument.
The QImageIO documentation lists the supported image formats and
explains how to add extra formats.
See also loadFromData(), save(), imageFormat(), QImage::load(), and
QImageIO.
Examples:
bool QPixmap::load ( const QString & fileName, const char * format = 0,
ColorMode mode = Auto )
This is an overloaded member function, provided for convenience. It
behaves essentially like the above function.
Loads a pixmap from the file fileName at runtime.
If format is specified, the loader attempts to read the pixmap using
the specified format. If format is not specified (default), the loader
reads a few bytes from the header to guess the file's format.
The mode is used to specify the color mode of the pixmap.
See also QPixmap::ColorMode.
bool QPixmap::loadFromData ( const uchar * buf, uint len, const char * format,
int conversion_flags )
Loads a pixmap from the binary data in buf (len bytes). Returns TRUE if
successful; otherwise returns FALSE.
If format is specified, the loader attempts to read the pixmap using
the specified format. If format is not specified (default), the loader
reads a few bytes from the header to guess the file's format.
See the convertFromImage() documentation for a description of the
conversion_flags argument.
The QImageIO documentation lists the supported image formats and
explains how to add extra formats.
See also load(), save(), imageFormat(), QImage::loadFromData(), and
QImageIO.
bool QPixmap::loadFromData ( const uchar * buf, uint len, const char * format
= 0, ColorMode mode = Auto )
This is an overloaded member function, provided for convenience. It
behaves essentially like the above function.
Loads a pixmap from the binary data in buf (len bytes) using color mode
mode. Returns TRUE if successful; otherwise returns FALSE.
If format is specified, the loader attempts to read the pixmap using
the specified format. If format is not specified (default), the loader
reads a few bytes from the header to guess the file's format.
See also QPixmap::ColorMode.
bool QPixmap::loadFromData ( const QByteArray & buf, const char * format = 0,
int conversion_flags = 0 )
This is an overloaded member function, provided for convenience. It
behaves essentially like the above function.
const QBitmap * QPixmap::mask () const
Returns the mask bitmap, or 0 if no mask has been set.
See also setMask(), QBitmap, and hasAlpha().
int QPixmap::metric ( int m ) const [virtual protected]
Internal implementation of the virtual QPaintDevice::metric() function.
Use the QPaintDeviceMetrics class instead.
m is the metric to get.
QPixmap & QPixmap::operator= ( const QPixmap & pixmap )
Assigns the pixmap pixmap to this pixmap and returns a reference to
this pixmap.
QPixmap & QPixmap::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 pixmap that is assigned to this pixmap.
Returns a reference to the pixmap.
See also convertFromImage().
Optimization QPixmap::optimization () const
Returns the optimization setting for this pixmap.
The default optimization setting is QPixmap::NormalOptim. You can
change this setting in two ways:
Call setDefaultOptimization() to set the default optimization for all
new pixmaps.
Call setOptimization() to set the optimization for individual pixmaps.
See also setOptimization(), setDefaultOptimization(), and
defaultOptimization().
QRect QPixmap::rect () const
Returns the enclosing rectangle (0,0,width(),height()) of the pixmap.
See also width(), height(), and size().
void QPixmap::resize ( int w, int h )
Resizes the pixmap to w width and h height. If either w or h is 0, the
pixmap becomes a null pixmap.
If both w and h are greater than 0, a valid pixmap is created. New
pixels will be uninitialized (random) if the pixmap is expanded.
Examples:
void QPixmap::resize ( const QSize & size )
This is an overloaded member function, provided for convenience. It
behaves essentially like the above function.
Resizes the pixmap to size size.
bool QPixmap::save ( const QString & fileName, const char * format, int
quality = -1 ) const
Saves the pixmap to the file fileName using the image file format
format and a quality factor quality. quality must be in the range
[0,100] or -1. Specify 0 to obtain small compressed files, 100 for
large uncompressed files, and -1 to use the default settings. Returns
TRUE if successful; otherwise returns FALSE.
See also load(), loadFromData(), imageFormat(), QImage::save(), and
QImageIO.
Example: qmag/qmag.cpp.
bool QPixmap::save ( QIODevice * device, const char * format, int quality = -1
) const
This is an overloaded member function, provided for convenience. It
behaves essentially like the above function.
This function writes a QPixmap to the QIODevice, device. This can be
used, for example, to save a pixmap directly into a QByteArray:
QPixmap pixmap;
QByteArray ba;
QBuffer buffer( ba );
buffer.open( IO_WriteOnly );
pixmap.save( &buffer, "PNG" ); // writes pixmap into ba in PNG format
bool QPixmap::selfMask () const
Returns TRUE if the pixmap's mask is identical to the pixmap itself;
otherwise returns FALSE.
See also mask().
int QPixmap::serialNumber () const
Returns a number that uniquely identifies the contents of this QPixmap
object. This means that multiple QPixmap objects can have the same
serial number as long as they refer to the same contents.
An example of where this is useful is for caching QPixmaps.
See also QPixmapCache.
void QPixmap::setDefaultOptimization ( Optimization optimization ) [static]
Sets the default pixmap optimization.
All new pixmaps that are created will use this default optimization.
You may also set optimization for individual pixmaps using the
setOptimization() function.
The initial default optimization setting is QPixmap::Normal.
See also defaultOptimization(), setOptimization(), and optimization().
void QPixmap::setMask ( const QBitmap & newmask )
Sets a mask bitmap.
The newmask bitmap defines the clip mask for this pixmap. Every pixel
in newmask corresponds to a pixel in this pixmap. Pixel value 1 means
opaque and pixel value 0 means transparent. The mask must have the same
size as this pixmap.
Warning: Setting the mask on a pixmap will cause any alpha channel data
to be cleared. For example:
QPixmap alpha( "image-with-alpha.png" );
QPixmap alphacopy = alpha;
alphacopy.setMask( *alphacopy.mask() );
Now, alpha and alphacopy are visually different.
Setting a null mask resets the mask.
See also mask(), createHeuristicMask(), and QBitmap.
void QPixmap::setOptimization ( Optimization optimization )
Sets pixmap drawing optimization for this pixmap.
The optimization setting affects pixmap operations, in particular
drawing of transparent pixmaps (bitBlt() a pixmap with a mask set) and
pixmap transformations (the xForm() function).
Pixmap optimization involves keeping intermediate results in a cache
buffer and using the cache to speed up bitBlt() and xForm(). The cost
is more memory consumption, up to twice as much as an unoptimized
pixmap.
Use the setDefaultOptimization() to change the default optimization for
all new pixmaps.
See also optimization(), setDefaultOptimization(), and
defaultOptimization().
Example: desktop/desktop.cpp.
QSize QPixmap::size () const
Returns the size of the pixmap.
See also width(), height(), and rect().
Example: movies/main.cpp.
QWMatrix QPixmap::trueMatrix ( const QWMatrix & matrix, int w, int h )
[static]
Returns the actual matrix used for transforming a pixmap with w width
and h height and matrix matrix.
When transforming a pixmap with xForm(), the transformation matrix is
internally adjusted to compensate for unwanted translation, i.e.
xForm() returns the smallest pixmap containing all transformed points
of the original pixmap.
This function returns the modified matrix, which maps points correctly
from the original pixmap into the new pixmap.
See also xForm() and QWMatrix.
int QPixmap::width () const
Returns the width of the pixmap.
See also height(), size(), and rect().
Examples:
QPixmap QPixmap::xForm ( const QWMatrix & matrix ) const
Returns a copy of the pixmap that is transformed using matrix. The
original pixmap is not changed.
The transformation matrix is internally adjusted to compensate for
unwanted translation, i.e. xForm() returns the smallest image that
contains all the transformed points of the original image.
This function is slow because it involves transformation to a QImage,
non-trivial computations and a transformation back to a QPixmap.
See also trueMatrix(), QWMatrix, QPainter::setWorldMatrix(), and
QImage::xForm().
Examples:
RELATED FUNCTION DOCUMENTATIONvoid copyBlt ( QPixmap * dst, int dx, int dy, const QPixmap * src, int sx, int
sy, int sw, int sh )
Copies a block of pixels from src to dst. The alpha channel and mask
data (if any) is also copied from src. NOTE: src is not alpha blended
or masked when copied to dst. Use bitBlt() or QPainter::drawPixmap() to
perform alpha blending or masked drawing.
sx, sy is the top-left pixel in src (0, 0 by default), dx, dy is the
top-left position in dst and sw, \sh is the size of the copied block
(all of src by default).
If src, dst, sw or sh is 0 (zero), copyBlt() does nothing. If sw or sh
is negative, copyBlt() copies starting at sx (and respectively, sy) and
ending at the right edge (and respectively, the bottom edge) of src.
copyBlt() does nothing if src and dst have different depths.
QDataStream & operator<;< ( QDataStream & s, const QPixmap & pixmap )
Writes the pixmap pixmap to the stream s as a PNG image.
Note that writing the stream to a file will not produce a valid image
file.
See also QPixmap::save() and Format of the QDataStream operators.
QDataStream & operator>> ( QDataStream & s, QPixmap & pixmap )
Reads a pixmap from the stream s into the pixmap pixmap.
See also QPixmap::load() and Format of the QDataStream operators.
SEE ALSO
http://doc.trolltech.com/qpixmap.html
http://www.trolltech.com/faq/tech.html
COPYRIGHT
Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com. See the
license file included in the distribution for a complete license
statement.
AUTHOR
Generated automatically from the source code.
BUGS
If you find a bug in Qt, please report it as described in
http://doc.trolltech.com/bughowto.html. Good bug reports help us to
help you. Thank you.
The definitive Qt documentation is provided in HTML format; it is
located at $QTDIR/doc/html and can be read using Qt Assistant or with a
web browser. This man page is provided as a convenience for those users
who prefer man pages, although this format is not officially supported
by Trolltech.
If you find errors in this manual page, please report them to qt-
bugs@trolltech.com. Please include the name of the manual page
(qpixmap.3qt) and the Qt version (3.3.8).
Trolltech AS 2 February 2007 QPixmap(3qt)
