Nicolas Cellier wrote:
This code seems to work: PNGReadWriter putForm: ((TextStyle defaultFont characterFormAt: $T) magnifyBy: 16) onFileNamed: 'T1.png'.
This one produces a fully transparent image (at least in mac finder and firefox renderers): PNGReadWriter putForm: ((TextStyle defaultFont characterFormAt: $T) magnifyBy: 16) asMorph imageForm onFileNamed: 'T2.png'.
Though a FileList is able to display a preview of the image for both files, importing with: Form openImageInWindow: (FileDirectory default / 'T2.png') fullName. just leave a transparent image in upper corner...
While Form openImageInWindow: (FileDirectory default / 'T1.png') fullName. works as expected...
Any clue ?
Nicolas
Hi Nicolas,
It is a bug in BitBlt. For instance:
| f f2 blt sourceDepth | sourceDepth := 16. f := Form extent: 16@16 depth: sourceDepth. f fillWhite. f2 := Form extent: 16@16 depth: 32. f2 fillColor: Color blue. blt := BitBlt new. blt setDestForm: f2 sourceForm: f fillColor: nil combinationRule: Form paint destOrigin: 0@0 sourceOrigin: 0@0 extent: 16@16 clipRect: f boundingBox. blt copyBits. f2 colorAt: 0@0
prints 'Color transparent' if sourceDepth = 16, but 'Color white' if sourceDepth = 32.
The problem seems to be in BitBltSimulation>>#rgbMapPixel:flags:, if I replace the last line with
val :=val bitOr: ((255) bitShift: (24)). ^val
and call #copyBitsSimulated (with VMMaker loaded) It seems to work ok. This is just a hack for testing, as it doesn't take into account actual source and destination depths...
Cheers, Juan Vuletich