Zooming QtQuick Painted item using contents size

contents_scale_test.py

#!/usr/bin/env python3

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

class Item(QQuickPaintedItem):
	def __init__(self, useBoundRect, parent=None):
		super().__init__(parent)
		self._ubr = useBoundRect
	
	def getBoundRect(self):
		if self._ubr:
			return self.contentsBoundingRect()
		else:
			return QRectF(0, 0, self.width(), self.height())
	
	def paint(self, painter):
		br = self.getBoundRect()
		font = painter.font()
		painter.drawText(br, Qt.TextWordWrap | Qt.AlignCenter, 'Hello, cruel world!')

class Window(QMainWindow):
	def __init__(self, parent=None):
		super().__init__(parent)
		self._win = QQuickWindow()
		self._cont = QWidget.createWindowContainer(self._win)
		self._items = []
		self.setCentralWidget(self._cont)
		self.resize(420, 400)

	def add_item(self, useBoundRect, x, y, w, h, ss, cw, ch, cs, col):
		root = self._win.contentItem()
		it = Item(useBoundRect, root)
		it.setX(x)
		it.setY(y)
		it.setScale(ss)
		it.setWidth(w)
		it.setHeight(h)
		it.setContentsScale(cs)
		it.setContentsSize(QSize(cw, ch))
		it.setFillColor(col)
		self._items.append(it)
		return it

if __name__ == '__main__':
	import sys
	app = QApplication(sys.argv)
	win = Window()
	win.show()
	# First and second rows: painting uses contentsBoundingRect()
	# First row: just use item's scale. Content is low-res, but scaled
	#           BoRect,   x    y    w   h  scale cw  ch  cscale, color
	win.add_item(True,   10,  10, 100, 50,   1,   -1, -1,   1, Qt.green)
	win.add_item(True,  150,  20, 100, 50, 1.5,   -1, -1,   1, Qt.yellow)
	win.add_item(True,  275,  10, 100, 50, 0.5,   -1, -1,   1, Qt.yellow)
	# Second row: scale the contents instead of the item
	#           BoRect,   x    y    w   h  scale cw  ch  cscale, color
	win.add_item(True,  10,  100,   1,  1,   1,  100, 50,   1, Qt.red)
	win.add_item(True,  125, 100,   1,  1,   1,  100, 50, 1.5, Qt.magenta)
	win.add_item(True,  300, 100,   1,  1,   1,   50, 25, 0.5, Qt.magenta)

	# Third and fourth rows: painting uses width() and height()
	# Third row: scale the item, same result as before
	win.add_item(False,  10, 210, 100, 50,   1,   -1, -1,   1, Qt.darkGreen)
	win.add_item(False, 150, 220, 100, 50, 1.5,   -1, -1,   1, Qt.darkYellow)
	win.add_item(False, 275, 220, 100, 50, 0.5,   -1, -1,   1, Qt.darkYellow)
	# Fourth row: scale the content
	win.add_item(False,  10, 300, 100, 50,   1,  100, 50,   1, Qt.darkRed)
	win.add_item(False, 125, 300, 100, 50,   1,  100, 50, 1.5, Qt.darkMagenta)
	win.add_item(False, 300, 300, 100, 50,   1,   50, 25, 0.5, Qt.darkMagenta)
	#           BoRect,   x    y    w   h  scale cw  ch  cscale, color

	sys.exit(app.exec_())

Screenshot of 3rd revision:
https://drive.google.com/file/d/0B3kFbLpbTB6aZ0FWdjBBdEZKWE0/view?usp=sharing

Revision 4 fixes a little bug for the 0.5 scales on rows 62 and 72 (contents size was wrong).