Kurt Griffin <[EMAIL PROTECTED]> wrote:
> I'm copying a dupe of the image of a text member into a dupe of the
> image of a png member. Given the fact that both carry alpha images, the
> result is not surprising - the copypixels op pastes the text in, but
> also cuts a rect the size of the text image out of the background image
> (as in, the alpha is getting copied to, as well as the image).
Hi Kurt,
Try this:
on copyText(anAlphaImage, aTextMember, anOffset) ---------------------
-- INPUT: <anAlphaImage> should be a 32-bit image object
-- <aTextMember> should be a text member
-- <anOffset> may be a point
-- ACTION: Copies the text of aTextMember onto anAlphaImage. The
-- alpha channel is made opaque under the text.
--------------------------------------------------------------------
tTextImage = aTextMember.image
tTextRect = aTextMember.rect
-- Use anOffset to position the text image as required
if ilk(anOffset, #point) then
tTargetRect = tTextRect.offset(anOffset.locH, anOffset.locV)
else
tTargetRect = tTextRect
end if
-- Take a copy of the alpha channel before any changes are made
tAlpha = anAlphaImage.extractAlpha()
-- Copy the text into the rgb channel of the target image, with
-- anti-aliasing. This will affect the alpha channel.
anAlphaImage.useAlpha = FALSE
anAlphaImage.copyPixels(tTextImage, tTargetRect, tTextRect)
-- Copy a black image of the text into the alpha channel. This
-- overcomes a couple of quirks:
-- * copying the text image itself into the image's alpha channel
-- will lead to semi-transparent areas where the text is a color
-- other than black
-- * copying the text alpha directly into the image alpha using
-- #darkest ink leads to banding
tBlack = image(tTextRect.width, tTextRect.height, 32, 8)
tBlack.fill(tTextRect, rgb(0, 0, 0))
tBlack.setAlpha(tTextImage.extractAlpha())
-- Copy the text alpha data into the image's original alpha channel
tAlpha.copyPixels(tBlack, tTargetRect, tTextRect)
-- Set the alpha channel of the image to the composite alpha image
anAlphaImage.setAlpha(tAlpha)
anAlphaImage.useAlpha = TRUE
end copyText
Cheers,
James
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