QPixmap Class Reference
Detailed Description
The QPixmap class is an off-screen image representation that can be used as a paint device.Qt provides four classes for handling image data: QImage, QPixmap, QBitmap and QPicture. QImage is designed and optimized for I/O, and for direct pixel access and manipulation, while QPixmap is designed and optimized for showing images on screen. QBitmap is only a convenience class that inherits QPixmap, ensuring a depth of 1. The isQBitmap() function returns true if a QPixmap object is really a bitmap, otherwise returns false. Finally, the QPicture class is a paint device that records and replays QPainter commands.
A QPixmap can easily be displayed on the screen using QLabel or one of QAbstractButton's subclasses (such as QPushButton and QToolButton). QLabel has a pixmap property, whereas QAbstractButton has an icon property. And because QPixmap is a QPaintDevice subclass, QPainter can be used to draw directly onto pixmaps.
In addition to the ordinary constructors, a QPixmap can be constructed using the static grabWidget() and grabWindow() functions which creates a QPixmap and paints the given widget, or window, in it.
Note that the pixel data in a pixmap is internal and is managed by the underlying window system. Pixels can only be accessed through QPainter functions or by converting the QPixmap to a QImage. Depending on the system, QPixmap is stored using a RGB32 or a premultiplied alpha format. If the image has an alpha channel, and if the system allows, the preferred format is premultiplied alpha. Note also that QPixmap, unlike QImage, may be hardware dependent. On X11 and Mac, a QPixmap is stored on the server side while a QImage is stored on the client side (on Windows, these two classes have an equivalent internal representation, i.e. both QImage and QPixmap are stored on the client side and don't use any GDI resources).
There are functions to convert between QImage and QPixmap. Typically, the QImage class is used to load an image file, optionally manipulating the image data, before the QImage object is converted into a QPixmap to be shown on screen. Alternatively, if no manipulation is desired, the image file can be loaded directly into a QPixmap. On Windows, the QPixmap class also supports conversion between HBITMAP and QPixmap.
QPixmap provides a collection of functions that can be used to obtain a variety of information about the pixmap. In addition, there are several functions that enables transformation of the pixmap.
QPixmap objects can be passed around by value since the QPixmap class uses implicit data sharing. For more information, see the {Implicit Data Sharing} documentation. QPixmap objects can also be streamed.
Definition at line 60 of file qpixmap.h.
Public Types | |
| typedef QPixmapData * | DataPtr |
| enum | PaintDeviceMetric { PdmWidth = 1, PdmHeight, PdmWidthMM, PdmHeightMM, PdmNumColors, PdmDepth, PdmDpiX, PdmDpiY, PdmPhysicalDpiX, PdmPhysicalDpiY } |
Public Member Functions | |
| QPixmap | alphaChannel () const |
| qint64 | cacheKey () const |
| QPixmap | copy (const QRect &rect=QRect()) const |
| QPixmap | copy (int x, int y, int width, int height) const |
| QBitmap | createHeuristicMask (bool clipTight=true) const |
| QBitmap | createMaskFromColor (const QColor &maskColor, Qt::MaskMode mode) const |
| QBitmap | createMaskFromColor (const QColor &maskColor) const |
| DataPtr & | data_ptr () |
| int | depth () const |
| void | detach () |
| int | devType () const |
| void | fill (const QWidget *widget, int xofs, int yofs) |
| void | fill (const QWidget *widget, const QPoint &ofs) |
| void | fill (const QColor &fillColor=Qt::white) |
| bool | hasAlpha () const |
| bool | hasAlphaChannel () const |
| int | height () const |
| int | heightMM () const |
| bool | isDetached () const |
| bool | isNull () const |
| bool | isQBitmap () const |
| bool | load (const QString &fileName, const char *format=0, Qt::ImageConversionFlags flags=Qt::AutoColor) |
| bool | loadFromData (const QByteArray &data, const char *format=0, Qt::ImageConversionFlags flags=Qt::AutoColor) |
| bool | loadFromData (const uchar *buf, uint len, const char *format=0, Qt::ImageConversionFlags flags=Qt::AutoColor) |
| int | logicalDpiX () const |
| int | logicalDpiY () const |
| QBitmap | mask () const |
| int | numColors () const |
| operator QVariant () const | |
| bool | operator! () const |
| QPixmap & | operator= (const QPixmap &) |
| QPaintEngine * | paintEngine () const |
| bool | paintingActive () const |
| int | physicalDpiX () const |
| int | physicalDpiY () const |
| QPixmapData * | pixmapData () const |
| QPixmap (const QPixmap &) | |
| QPixmap (const char *const xpm[]) | |
| QPixmap (const QString &fileName, const char *format=0, Qt::ImageConversionFlags flags=Qt::AutoColor) | |
| QPixmap (const QSize &) | |
| QPixmap (int w, int h) | |
| QPixmap (QPixmapData *data) | |
| QPixmap () | |
| QRect | rect () const |
| bool | save (QIODevice *device, const char *format=0, int quality=-1) const |
| bool | save (const QString &fileName, const char *format=0, int quality=-1) const |
| QPixmap | scaled (const QSize &s, Qt::AspectRatioMode aspectMode=Qt::IgnoreAspectRatio, Qt::TransformationMode mode=Qt::FastTransformation) const |
| QPixmap | scaled (int w, int h, Qt::AspectRatioMode aspectMode=Qt::IgnoreAspectRatio, Qt::TransformationMode mode=Qt::FastTransformation) const |
| QPixmap | scaledToHeight (int h, Qt::TransformationMode mode=Qt::FastTransformation) const |
| QPixmap | scaledToWidth (int w, Qt::TransformationMode mode=Qt::FastTransformation) const |
| int | serialNumber () const |
| void | setAlphaChannel (const QPixmap &) |
| void | setMask (const QBitmap &) |
| QSize | size () const |
| QImage | toImage () const |
| QPixmap | transformed (const QTransform &, Qt::TransformationMode mode=Qt::FastTransformation) const |
| QPixmap | transformed (const QMatrix &, Qt::TransformationMode mode=Qt::FastTransformation) const |
| int | width () const |
| int | widthMM () const |
| ~QPixmap () | |
Static Public Member Functions | |
| static int | defaultDepth () |
| static QPixmap | fromImage (const QImage &image, Qt::ImageConversionFlags flags=Qt::AutoColor) |
| static QPixmap | grabWidget (QWidget *widget, int x=0, int y=0, int w=-1, int h=-1) |
| static QPixmap | grabWidget (QWidget *widget, const QRect &rect) |
| static QPixmap | grabWindow (WId, int x=0, int y=0, int w=-1, int h=-1) |
| static QTransform | trueMatrix (const QTransform &m, int w, int h) |
| static QMatrix | trueMatrix (const QMatrix &m, int w, int h) |
Protected Member Functions | |
| int | metric (PaintDeviceMetric) const |
Protected Attributes | |
| ushort | painters |
Private Types | |
| enum | Type { PixmapType, BitmapType } |
Private Member Functions | |
| void | deref () |
| bool | doImageIO (QImageWriter *io, int quality) const |
| void | init (int, int, int) |
| void | init (int, int, Type=PixmapType) |
| QPixmap (const QSize &s, int type) | |
| QPixmap (const QSize &s, Type) | |
Private Attributes | |
| QPixmapData * | data |
Friends | |
| Q_GUI_EXPORT QDataStream & | operator>> (QDataStream &, QPixmap &) |
| class | QBitmap |
| class | QCoreGraphicsPaintEngine |
| class | QDetachedPixmap |
| class | QDirect3DPaintEngine |
| class | QDirect3DPaintEnginePrivate |
| class | QGLWidget |
| class | QMacPixmapData |
| class | QPaintDevice |
| class | QPainter |
| class | QPixmapData |
| class | QRasterBuffer |
| class | QRasterPaintEngine |
| Q_GUI_EXPORT qint64 | qt_pixmap_id (const QPixmap &pixmap) |
| class | QWidgetPrivate |
| class | QX11PaintEngine |
| class | QX11PixmapData |
Related Functions | |
| (Note that these are not member functions.) | |
| QDataStream & | operator<< (QDataStream &stream, const QPixmap &pixmap) |
| const Q_GUI_EXPORT QX11Info * | qt_x11Info (const QPaintDevice *pd) |
The documentation for this class was generated from the following files:
- qt4-x11-4.5.0~rc1/src/gui/image/qpixmap.h
- qt4-x11-4.5.0~rc1/src/gui/image/qpixmap.cpp
- qt4-x11-4.5.0~rc1/src/gui/image/qpixmap_x11.cpp
- qt4-x11-4.5.0~rc1/src/gui/kernel/qwidget.cpp