[PyKDE] PyQt4: Problems with QImage.loadFromData(data)

[Stephan Heuel]

Dear all

I have now a working example, the main point is to correctly convert
the string to PIL and import it into PyQt:

s = im.convert("RGB").tostring("jpeg","RGB")
image.loadFromData(QtCore.QByteArray(s))

A complete working example is attached below.

Cheers
Stephan

--------------------------------------------
# How to use PIL images in PyQt4
#
# PIL:   http://www.pythonware.com/products/pil/
# PyQt4: http://www.riverbankcomputing.com/Downloads/Snapshots/PyQt4/
# 14.03.2006 - 16:40

import os, sys
import Image
from PyQt4 import QtCore, QtGui

class MiniViewer(QtGui.QWidget):
    "this class demonstrates how to use PIL images in PyQt [does not work yet!]"
    def __init__(self, parent = None):
        QtGui.QWidget.__init__(self, parent)
        # initialize QImage
        self.image = QtGui.QImage()

    def open(self,infile):
        # load an image using PIL, first read it
        self.PILimage  = Image.open(infile)

        # now update the QImage according to the PIL image
        self.__PIL2Qt()


    def __PIL2Qt(self, encoder="jpeg", mode="RGB"):
        # I have only tested the jpeg encoder, there are others, see
        # http://mail.python.org/pipermail/image-sig/2004-September/002908.html
        PILstring = self.PILimage.convert(mode).tostring(encoder, mode)
        self.image.loadFromData(QtCore.QByteArray(PILstring))


    def paintEvent(self, Event):
        painter = QtGui.QPainter(self)
        painter.drawImage(0,0,self.image)

    def perspectiveTransform(self):
        # this is just an example to demonstrate that one can do
        # perspective transformations with PIL (something not
        # supported with Qt, it "only" can do affine transformations).
        size = self.PILimage.size
        self.PILimage = self.PILimage.transform(size,
                                                Image.PERSPECTIVE,
                                               
[2,0,0,0,2,0,0.002,0.002,1],Image.BILINEAR)
        self.__PIL2Qt()


if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    viewer = MiniViewer()

    # load your own file, do a PIL transformation and show it off!
    viewer.open("D:/Data/Images/mit.png")
    viewer.perspectiveTransform()
    viewer.show()

    sys.exit(app.exec_())