以下成员源于类 QPixmap 已过时。 提供它们是为使旧源代码能继续工作。强烈建议不要在新代码中使用它们。
(obsolete)
QPixmap
|
alphaChannel () const |
(obsolete)
int
|
serialNumber () const |
(obsolete)
void
|
setAlphaChannel (const QPixmap & alphaChannel ) |
Returns the alpha channel of the pixmap as a new grayscale QPixmap in which each pixel's red, green, and blue values are given the alpha value of the original pixmap. The color depth of the returned pixmap is the system depth on X11 and 8-bit on Windows and Mac OS X.
You can use this function while debugging to get a visible image of the alpha channel. If the pixmap doesn't have an alpha channel, i.e., the alpha channel's value for all pixels equals 0xff), a null pixmap is returned. You can check this with the
isNull()
函数。
举例说明：
pixmap = QPixmap(100, 100);
pixmap.fill(Qt::transparent);
QRadialGradient gradient(50, 50, 50, 50, 50);
gradient.setColorAt(0, QColor::fromRgbF(1, 0, 0, 1));
gradient.setColorAt(1, QColor::fromRgbF(0, 0, 0, 0));
QPainter painter(&pixmap);
painter.fillRect(0, 0, 100, 100, gradient);
channelImage = pixmap.alphaChannel();
update();
警告： This is an expensive operation. The alpha channel of the pixmap is extracted dynamically from the pixeldata. Most usecases of this function are covered by QPainter and compositionModes which will normally execute faster.
另请参阅 setAlphaChannel () 和 像素图信息 .
返回的数字标识内容对于此 QPixmap 对象。截然不同的 QPixmap objects can only have the same serial number if they refer to the same contents (but they don't have to).
使用 cacheKey () 代替。
警告： The serial number doesn't necessarily change when the pixmap is altered. This means that it may be dangerous to use it as a cache key. For caching pixmaps, we recommend using the QPixmapCache class whenever possible.
Sets the alpha channel of this pixmap to the given alphaChannel by converting the alphaChannel into 32 bit and using the intensity of the RGB pixel values.
此函数的效果未定义，当描绘像素图时。
警告： This is potentially an expensive operation. Most usecases for this function are covered by QPainter and compositionModes which will normally execute faster.
另请参阅 alphaChannel () 和 像素图变换 .