pythonpyqtpyqt5qpixmapqpainterpath

How to crop an image using QPainterPath without saving rest of image


I have a QPainterPath and I want to crop an image which is QPixmap. This code worked for me but I want to use PyQt5 builtin functionality like mask without numpy

# 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")

Solution

  • One possible way to replace mask is to use the setClipPath() method of QPainter:

    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')