[Zope] Create Image w PIL and save to OFS.Image.Image subclass instance

[Max M]

Hans wrote:

>want to create a grafik w PIL and store into my instance which is
>subclassed from OFS.Image.Image.
>
Here is an example that works.

The only caveat I found was that you must use the same id for the images 
id in the objectmanager and as the id in the image. Well this is perhaps 
logical, but it bit me once.

so that is like:

imageID = 'myImage'
self._setObject(imageID, OFS.Image.Image(imageID,'Laerings graf',''))

Then it can be called like:

<dtml-var myImage>

regards Max M

    def _drawTriangle(self, a, b, c):

        im = 
PIL.Image.open("C:/root/pythonScripts/PILTest/laeringstilGraf_2.gif")

        """
        Coordinate system:
          d | a
        --------
          c | b
        """

        # a is a sequence of 4 values.
        maxValue = max(a)                   # what value is it
        biggestIndex = a.index(maxValue)    # Where is it?

        if biggestIndex == 0:       # Then draw in a
            dirX, dirY = 1,1
            bX, bY = 200, 300
            cX, cY = 300, 200
        elif biggestIndex == 1:     # Then draw in b
            dirX, dirY = 1,0
            bX, bY = 200, 100
            cX, cY = 300, 200
        elif biggestIndex == 2:     # Then draw in c
            dirX, dirY = 0,0
            bX, bY = 200, 100
            cX, cY = 100, 200
        elif biggestIndex == 3:     # then draw in d
            dirX, dirY = 0,1
            bX, bY = 200, 300
            cX, cY = 100, 200

        tr1 = transformer(200, 200, 4, dirX, dirY)
        sideLength = sqrt(pow(maxValue,2)/2.0) # Pythagoras
        cord1 = tr1.transform(sideLength, sideLength)

        tr2 = transformer(bX, bY, 6, dirX, dirY)
        coord2 = tr2.transform(0,b)

        tr3 = transformer(cX, cY, 1, dirX, dirY)
        coord3 = tr3.transform(c,0)

        draw = PIL.ImageDraw.Draw(im)
        darkBlue  = 2
        draw.polygon([cord1, coord2, coord3], outline=darkBlue, 
fill=darkBlue)
        del draw
        outf = StringIO()
        im.save(outf, 'GIF') # Save it to a temp file
        del im
        data = outf.getvalue()
        outf.close()
        return data


    def updateGraph(self):
        "Updates the graph if it is changed since last view"
        #self.imageLastChanged = 0
        imageID = 'laeringsGraf'
        if self.imageLastChanged == self.lastChanged:   # Image is in sync
            pass
        else:                                           # doesn't exist, 
so render it
            # all stuff happens in the next line
            #data = self._drawTriangle([60, 0, 0, 0], 11, 60)
            data = self._drawTriangle(self._getQ1Result(), 
self._getQ2Result(), self._getQ3Result())
            if not hasattr(self, imageID): # add to objectmanager
                self._setObject(imageID, 
OFS.Image.Image(imageID,'Laerings graf',''))
            self._getOb(imageID).update_data(data)
            self.imageLastChanged = self.lastChanged