Andreas Raab skrev:
> karl wrote:
>> Images with alpha translucency will now keep the translucency in 8 
>> and 16 bit screen resolution. (Rotated forms will not, that has to do 
>> with WarpBlt internals I don't really understand yet.) It would be 
>> nice if people could play with this enhancement and report any issues.
> The way to fix that is by either converting the input form into 
> pre-multiplied form first (as shown in the above) the cost of which is 
> the obvious memory hit or by writing other custom BitBlt methods just 
> like for rule 34 (only for using the regular Form>>blend operator).
Here is a version which pre-multiply the forms and results with colors 
are much better :-)

In the first version I  was testing using a black circle which blurred 
to transparent so I did not catch obvious color errors.

I have also added a enhancement to preserve translucency when a morph is 
rotated, this works only in 32 bit screen resolution for the time being.

Karl
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'From OLPC2.0 of ''24 October 2006'' [latest update: #1141] on 17 December 2006 at 11:42:34 pm'!
"Change Set:		FormTranslucency
Date:			17 December 2006
Author:			Karl Ramberg

Project to make translucency work in different screen resolutions and with rotated morphs "!


!Canvas methodsFor: 'drawing-images' stamp: 'kfr 12/17/2006 23:35'!
translucentImage: aForm at: aPoint sourceRect: sourceRect
	"Draw a translucent image using the best available way of representing translucency.
	Note: This will be fixed in the future."
	| multipliedForm |
	self shadowColor ifNotNil:[
		^self stencil: aForm at: aPoint sourceRect: sourceRect color: self shadowColor].
	((self depth < 32 and:[aForm depth = 32]) and:[self depth > 4])
		ifTrue:[ 
    "Convert aForm to pre-multiplied"
    multipliedForm := Form extent: aForm extent depth: 32.
    aForm displayOn: multipliedForm at: 0 at 0 rule: Form blend.
    ^self image: multipliedForm at: aPoint sourceRect: sourceRect rule: 34].
	(self depth < 32 or:[aForm isTranslucent not]) 
		ifTrue:[^self paintImage: aForm at: aPoint sourceRect: sourceRect].
	self image: aForm
		at: aPoint
		sourceRect: sourceRect
		rule: Form blend! !


!FormCanvas methodsFor: 'drawing-support' stamp: 'kfr 12/17/2006 23:39'!
transformBy: aDisplayTransform clippingTo: aClipRect during: aBlock	 smoothing: cellSize 

	"Note: This method has been originally copied from TransformationMorph."
	| innerRect patchRect sourceQuad warp start subCanvas |
	(aDisplayTransform isPureTranslation) ifTrue:[
		^aBlock value: (self copyOffset: aDisplayTransform offset negated truncated
							clipRect: aClipRect)
	].
	"Prepare an appropriate warp from patch to innerRect"
	innerRect _ aClipRect.
	patchRect _ (aDisplayTransform globalBoundsToLocal: innerRect) truncated.
	sourceQuad _ (aDisplayTransform sourceQuadFor: innerRect)
					collect: [:p | p - patchRect topLeft].
	warp _ self warpFrom: sourceQuad toRect: innerRect.
	warp cellSize: cellSize.

	"Render the submorphs visible in the clipping rectangle, as patchForm"
	start _ (self depth = 1 and: [self isShadowDrawing not])
		"If this is true B&W, then we need a first pass for erasure."
		ifTrue: [1] ifFalse: [2].
	start to: 2 do:
		[:i | "If i=1 we first make a shadow and erase it for opaque whites in B&W"
		subCanvas _ self class extent: patchRect extent depth: self depth.
		i=1	ifTrue: [subCanvas shadowColor: Color black.
					warp combinationRule: Form erase]
			ifFalse: [self isShadowDrawing ifTrue:
					[subCanvas shadowColor: self shadowColor].
					(self depth = 32) ifTrue:[warp combinationRule: 34]
					ifFalse:[warp combinationRule: Form paint]].
		subCanvas translateBy: patchRect topLeft negated
			during:[:offsetCanvas| aBlock value: offsetCanvas].
		warp sourceForm: subCanvas form; warpBits.
		warp sourceForm: nil.  subCanvas _ nil "release space for next loop"]
! !