Hi, Andreas,
First - not that important - why does the compiled generator show up Motion vertical scaled by -100% and in FCP as expected?
This looks like a bug in the plug-in. The plug-in should look at the origin of the output image, and adjust its rendering based on whether the origin is at kFxImageOrigin_BOTTOM_LEFT (FCP) or kFxImageOrigin_TOP_LEFT (Motion). It should probably create its rendering CGContext as "flipped" in the TOP_LEFT case.
Second - also not that important - why does the half-height fields display double height before rendering and normal after rendering in FCP?
I believe that when creating render files, FCP will ask generators to create two progressive frames at each field sample, and then construct interlaced frames from that. This takes longer but produces higher quality.
The "correct for half-height fields" checkbox ensures that the plug-in generates fields correctly. Since FCP is asking the generator for progressive frames during render, the checkbox has no effect.
Third and this is where I stuck - how to get rid of the white background i.e. to make it (semi-)transparent both for simple text and RTF files.
The plug-in clears the image to white before drawing the string. If you'd like a different background color, change this line:
// clear to the background color before we change the context's transformation
[[NSColor whiteColor] set];
NSRectFill (NSMakeRect (0, 0, [outputImage width], [outputImage height]));
You can set a background color with a transparent or semi-transparent alpha if you want. The easiest thing is probably to just use [NSColor clearColor] to get the text drawn on a fully transparent background.
- Paul