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Add global composite and alpha functions #6

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Merged
merged 1 commit into from Sep 12, 2014
Merged

Add global composite and alpha functions #6

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49 changes: 49 additions & 0 deletions src/Graphics/Canvas.purs
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Original file line number Diff line number Diff line change
Expand Up @@ -167,6 +167,55 @@ setLineCap Round = setLineCapImpl "round"
setLineCap Square = setLineCapImpl "square"
setLineCap Butt = setLineCapImpl "butt"

data Composite
= SourceOver
| SourceIn
| SourceOut
| SourceAtop
| DestinationOver
| DestinationIn
| DestinationOut
| DestinationAtop
| Lighter
| Copy
| Xor

instance showComposite :: Show Composite where
show SourceOver = "source-over"
show SourceIn = "source-in"
show SourceOut = "source-out"
show SourceAtop = "source-atop"
show DestinationOver = "destination-over"
show DestinationIn = "destination-in"
show DestinationOut = "destination-out"
show DestinationAtop = "destination-atop"
show Lighter = "lighter"
show Copy = "copy"
show Xor = "xor"

foreign import setGlobalCompositeOperationImpl
"function setGlobalCompositeOperationImpl(ctx) {\
\ return function(op) {\
\ return function() {\
\ ctx.globalCompositeOperation = op;\
\ return ctx;\
\ };\
\ };\
\}" :: forall eff. Context2D -> String -> Eff (canvas :: Canvas | eff) Context2D

setGlobalCompositeOperation :: forall eff. Context2D -> Composite -> Eff (canvas :: Canvas | eff) Context2D
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@paf31 paf31 Sep 12, 2014

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It might be a little simpler to implement Composite -> String and then define setGlobalCompositeOperation by composition.

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@ghost ghost Sep 12, 2014

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Added an instance for Show Composite originally this was a new class ToJS (essentially identical to Show here) but I had removed it when I saw the existing pattern for setLineCap above.

setGlobalCompositeOperation ctx composite = setGlobalCompositeOperationImpl ctx (show composite)

foreign import setGlobalAlpha
"function setGlobalAlpha(ctx) {\
\ return function(alpha) {\
\ return function() {\
\ ctx.setGlobalAlpha = alpha;\
\ return ctx;\
\ };\
\ };\
\}" :: forall eff. Context2D -> Number -> Eff (canvas :: Canvas | eff) Context2D

-- |
-- Paths
--
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