The Inbox: Graphics-mt.158.mcz

A new version of Graphics was added to project The Inbox:
http://source.squeak.org/inbox/Graphics-mt.158.mcz

==================== Summary ====================

Name: Graphics-mt.158
Author: mt
Time: 16 November 2010, 8:35:03.184 pm
UUID: 347b600f-3afe-ac4c-acc6-4703d7a3c0bc
Ancestors: Graphics-mt.157

- nicer version of fix for font rendering with translucent colors (thanks to Juan Vuletich)
-> subpixel rendering will be disabled in that case
- minor code clean-up (using Form-constants instead of magic numbers)

=============== Diff against Graphics-mt.157 ===============

Item was changed:
  ----- Method: BitBlt>>installStrikeFont:foregroundColor:backgroundColor: (in category 'private') -----
  installStrikeFont: aStrikeFont foregroundColor: foregroundColor backgroundColor: backgroundColor
  | lastSourceDepth targetColor |
  sourceForm ifNotNil:[lastSourceDepth := sourceForm depth].
  sourceForm := aStrikeFont glyphs.
 
  "Ignore any halftone pattern since we use a color map approach here"
  halftoneForm := nil.
  sourceY := 0.
  height := aStrikeFont height.
 
  sourceForm depth = 1 ifTrue: [
  self combinationRule: Form paint.
  (colorMap notNil and:[lastSourceDepth = sourceForm depth]) ifFalse: [
  "Set up color map for a different source depth (color font)"
  "Uses caching for reasonable efficiency"
  colorMap := self cachedFontColormapFrom: sourceForm depth to: destForm depth.
  colorMap at: 1 put: (destForm pixelValueFor: backgroundColor)].
  colorMap at: 2 put: (destForm pixelValueFor: foregroundColor).
  ]
  ifFalse: [
+ (Preferences subPixelRenderFonts and: [ foregroundColor = Color black
+ "Only use rgbMul with opaque colors as alpha values get lost for translucent colors."
+ or: [ Preferences subPixelRenderColorFonts and: [foregroundColor isOpaque] ]]) ifTrue: [
- (Preferences subPixelRenderFonts and: [ foregroundColor = Color black or: [ Preferences subPixelRenderColorFonts ]]) ifTrue: [
  destForm depth > 8 ifTrue: [
+ "rgbMul is equivalent to component alpha blend if text is black (only faster, hehe)"
+ self combinationRule: Form rgbMul.
- "Only choose #rgbMul if color is not translucent for better result quality. Alpha values are ignored with #rgbMul."
- foregroundColor isTranslucent
- ifTrue: [self combinationRule: Form blend]
- ifFalse: [self combinationRule: Form rgbMul].
  colorMap := (destForm depth = 32 or: [ (foregroundColor = Color black) not ]) ifTrue: [
  "rgbMul / rgbAdd IS component alpha blend for any color of text (neat trick, eh!!)"
  "This colorMap is to be used on the second pass with rule 20 (rgbAdd)
  See #displayString:from:to:at:strikeFont:kern:"
  "Note: In 32bpp we always need the second pass, as the source could have transparent pixels, and we need to add to the alpha channel"
  self colorConvertingMap: foregroundColor from: sourceForm depth to: destForm depth keepSubPixelAA: true]]
  ifFalse: [
+ self combinationRule: Form paint.
- self combinationRule: 25. "Paint"
  targetColor := foregroundColor = Color black ifFalse: [ foregroundColor ].
  colorMap := self colorConvertingMap: targetColor from: sourceForm depth to: destForm depth keepSubPixelAA: true]
  ]
  ifFalse: [
  "Do not use rule 34 for 16bpp display. TTCFont uses it, but it builds a glyphs cache for each color used!!"
+ self combinationRule: (destForm depth = 32 ifTrue: [Form blendAlphaScaled] ifFalse: [Form paint]).
- self combinationRule: (destForm depth = 32 ifTrue: [34 "alphaBlendScaled"] ifFalse: [25 "Paint"]).
  colorMap := self colorConvertingMap: foregroundColor from: sourceForm depth to: destForm depth keepSubPixelAA: false
  ]
  ].!

Item was added:
+ ----- Method: Form class>>blendAlphaScaled (in category 'mode constants') -----
+ blendAlphaScaled
+ "Answer the integer denoting BitBlt's blend-with-alpha-scaled rule."
+
+ ^ 34!