python - 如何使用 QPainterPath 裁剪图像而不保存图像的其余部分

Question

我有一个 QPainterPath，我想裁剪一个 QPixmap 图像。这段代码对我有用，但我想使用 PyQt5 内置功能，如没有 numpy 的掩码

# read image as RGB and add alpha (transparency)
im = Image.open("frontal_1.jpg").convert("RGBA")

# convert to numpy (for convenience)
imArray = numpy.asarray(im)

# create mask
polygon = [(444, 203), (623, 243), (691, 177), (581, 26), (482, 42)]

maskIm = Image.new('L', (imArray.shape[1], imArray.shape[0]), 0)
ImageDraw.Draw(maskIm).polygon(polygon, outline=1, fill=1)
mask = numpy.array(maskIm)
...
newIm = Image.fromarray(newImArray, "RGBA")
newIm.save("out.png")

Answer 1

替换掩码的一种可能方法是使用 QPainter 的 setClipPath() 方法：

from PyQt5 import QtCore, QtGui

if __name__ == '__main__':
    image = QtGui.QImage('input.png')
    output = QtGui.QImage(image.size(), QtGui.QImage.Format_ARGB32)
    output.fill(QtCore.Qt.transparent)
    painter = QtGui.QPainter(output)

    points = [(444, 203), (623, 243), (691, 177), (581, 26), (482, 42)]
    polygon = QtGui.QPolygonF([QtCore.QPointF(*point) for point in points])

    path = QtGui.QPainterPath()
    path.addPolygon(polygon)
    painter.setClipPath(path)
    painter.drawImage(QtCore.QPoint(), image)
    painter.end()
    output.save('out.png')

Answer 2

在上面的回答之后，我稍微调整了我的代码，现在它看起来像：

    path = lips_contour_path
    image = QImage('frontal_2.jpg')
    output = QImage(image.size(), QImage.Format_ARGB32)
    output.fill(Qt.transparent)
    painter = QPainter(output)
    painter.setClipPath(path)
    painter.drawImage(QPoint(), image)
    painter.end()
    # To avoid useless transparent background you can crop it like that:
    output = output.copy(path.boundingRect().toRect())
    output.save('out.png')