Not only because pdf and flash have 2 different coordinates system and because the gradient matrix is applied in 2 different ways, but also if you want to convert gradient with transparent colors inside.
Let me say that I’ve encountered the same issue Mario posted here, even if I made a little modification to his solution: GradientMatrix.as
This is the swf example. Click on the sprite to start the animation. It will rotate and translate both the sprite and its gradient matrix, then click again to stop the animation and create the pdf file at that frame.
In order to create the correct gradient matrix with the right position and rotation in purePDF I’ve used the PdfShading.complexAxial static method in this way:
var cb_shading: PdfShading = PdfShading.complexAxial( writer, top_left.x, top_left.y, top_right.x, top_right.y, cb_colors, cb_ratios, true, true );
then for the alpha masking I’ve created a PdfTransparencyGroup applied to the alpha mask.
You can see my solution (which probably is not the best one, but it’s the one I discovered for now) in the code below.