fixes around isOpaque and dithering
- copyTo() now preserves isOpaqueness, and BitmapCopyTest tests it
- bitmap shader doesn't claim to have shadespan16 if dithering is on, since its
sampler doesn't auto-dither (note that gradients do auto-dither in their
16bit sampler)
- blitter setup just relies on the shader to report if its 16bit sampler can be
called (allowing gradients to say yes regardless of dither, but bitmaps to say
no if dithering is on)
git-svn-id: http://skia.googlecode.com/svn/trunk@331 2bbb7eff-a529-9590-31e7-b0007b416f81
8 files changed