BitmapData.draw with different shape

is it possible to change the Rectangle I use as fifth parameter of draw Bitma开发者_开发问答pData class?

bitmapData.draw(image,null,null,null,rect,false);

I'm trying to draw and save a different shape (with the shape of a particular MovieClip).

If you look at the definition for the BitmapData's copyPixels method (adobe documentation), you'll see:

"If you include the alphaBitmap and alphaPoint parameters, you can use a secondary image as an alpha source for the source image. If the source image has alpha data, both sets of alpha data are used to composite pixels from the source image to the destination image. The alphaPoint parameter is the point in the alpha image that corresponds to the upper-left corner of the source rectangle. Any pixels outside the intersection of the source image and alpha image are not copied to the destination image."

You can probably get this to do what you want.