From 37682242e58b015976561d80ca042457cf58a948 Mon Sep 17 00:00:00 2001 From: Matthew Flatt Date: Thu, 16 Dec 2010 19:35:23 -0700 Subject: [PATCH] docs: clarify effect of mask-bitmap alphas channel in dc<%> draw-bitmap --- collects/scribblings/draw/dc-intf.scrbl | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/collects/scribblings/draw/dc-intf.scrbl b/collects/scribblings/draw/dc-intf.scrbl index c870723184..16f3c928c5 100644 --- a/collects/scribblings/draw/dc-intf.scrbl +++ b/collects/scribblings/draw/dc-intf.scrbl @@ -112,8 +112,10 @@ If the @racket[mask] bitmap is monochrome, drawing occurs in the If the @racket[mask] bitmap is grayscale, then the blackness of each mask pixel controls the opacity of the drawn pixel (i.e., the mask acts as an inverted alpha channel). If the @racket[mask] bitmap is - color, the component values of a given pixel are averaged to arrive - at an @racket[alpha] value for the pixel. + color, the color component values of a given pixel are averaged to arrive + at an @racket[alpha] value for the pixel. If the @racket[mask] bitmap + has an alpha channel, it is combined for masking with the alpha value that is + computed from the color components. The current brush, current pen, and current text for the DC have no effect on how the bitmap is drawn, but the bitmap is scaled if the DC