Question

我有这样的形象:

[![此处插入图像说明](https://i.stack.imgur.com/st2qY.png)](https://i.stack.imgur.com/st2qY.png)/ <<<<>>

我有一套改良产品(paintEvent()。

在我的形象之上,我想用一个或一个以上试金包 spare。有了四舍五入的玉米和适当的反恐怖。

可在 QPainter:CompositionMode 。但情况如何? 可否将超支引向QImage? 无意中?

油漆:net 我在第二层中选取了一条直径,然后用魔.挑选内部,删除。我不知道如何与QPainter打交道。

Answer 1

与组成模式合作是可能的,但需要完全了解他们的行为(奇怪的是,我从来没有能够把自己的头包起来)。

此外,在绘制地图时,它常常需要进一步的步骤,即把一个层推到一个临时的“ffer”(另一个QPixmap或QImage)。

As long as the "masking" is simple, it doesn t involve alpha blending of multiple images, and the image is opaque (no transparency at all), we could just follow a simpler path, which is painting over and eventually "clear" the required areas by clipping the contents.

The procedure is actually easy:

draw the pixmap;

fill the whole area with the "shaded" color;

create a QPainterPath() and add all areas we need to be "clear";

use setClipPath() on the QPainter (with the Antialiasing render hint set);
draw again the pixmap;

我不能在C++中写字,但以下简单的例子就足够清楚:

from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *

class ClipTest(QWidget):
    def __init__(self):
        super().__init__()
        # This is the original image used in the question
        self.pixmap = QPixmap( baseimage.png )
        self.setFixedSize(self.pixmap.size())

    def paintEvent(self, event):
        qp = QPainter(self)

        # draw the source image
        qp.drawPixmap(0, 0, self.pixmap)

        # draw the darker "shade" on the whole widget
        qp.fillRect(self.rect(), QColor(32, 32, 32, 127))

        path = QPainterPath()
        # add a couple of rounded rects, which are also colliding
        path.addRoundedRect(250, 110, 140, 140, 20, 20)
        path.addRoundedRect(380, 110, 140, 140, 20, 20)

        # to fill all enclosed regions, including those of colliding
        # sub paths that may be otherwise be unpainted
        path.setFillRule(Qt.WindingFill)

        # clip the painting on the path above
        qp.setClipPath(path)

        # for proper antialiased clipping
        qp.setRenderHint(qp.Antialiasing)

        # redraw the pixmap again
        qp.drawPixmap(0, 0, self.pixmap)


app = QApplication([])
win = Test()
win.show()
app.exec()

其结果如下:

友情链接