[Ok]CreateImage : Does BackColor arg care about alpha?

[Olliv]

Hello,

it seems that :

Code: Select all

CreateImage(0, 16, 16, 32, RGBA(0, 0, 0, alphavalue) )

ignores alpha value on PB 5.50 LTS x64.

[netmaestro]

RGB() is the only documented source for the backcolor parameter. You can use an RGBA() colorref without error but as you discovered, also without effect. Your only option would be to create the image with background colorref = #PB_Image_Transparent and then box the RGBA colorref to it with DrawingMode = #PB_2DDrawing_AllChannels.

[Olliv]

I thank you for telling this option, I tried to replace, but not again for this time.

(to illustrate your help)

Code: Select all

Image = CreateImage(#PB_Any, 16, 16, 32)

If StartDrawing(ImageOutput(Image) )
   ; Reset alpha channel for every pixel
   DrawingMode(#PB_2DDrawing_AllChannels)
   W = OutputWidth()
   H = OutputHeight()
   Box(0, 0, W, H, RGBA(0, 0, 0, 0) )

   ; pattern drawing, especially vector drawing

   StopDrawing()
EndIf

[Olliv]

(I replaced 'obviously' by 'especially' and apologize for my mistakes in the language of Shakespeare)

[chi]

You forgot #PB_Image_Transparent...

Code: Select all

Image1 = CreateImage(#PB_Any, 64, 64, 32, #PB_Image_Transparent)
If StartDrawing(ImageOutput(Image1))
  DrawingMode(#PB_2DDrawing_AllChannels)
  Box(0, 0, OutputWidth()/2, OutputHeight()/2, RGBA(255, 0, 0, 255))
  Box(OutputWidth()/2, OutputHeight()/2, OutputWidth(), OutputHeight(), RGBA(0, 0, 0, 50))
  StopDrawing()
EndIf

Image2 = CreateImage(#PB_Any, 64, 64, 32, #PB_Image_Transparent)
If StartDrawing(ImageOutput(Image2))
  DrawingMode(#PB_2DDrawing_AlphaBlend)
  Box(0, 0, OutputWidth()/2, OutputHeight()/2, RGBA(255, 0, 0, 255))
  Box(0, 0, OutputWidth(), OutputHeight(), RGBA(0, 0, 0, 50))
  StopDrawing()
EndIf

ShowLibraryViewer("Image", Image1)
CallDebugger

[Olliv]

You forgot #PB_Image_Transparent..

It's not me... I forget nothing ! My brain maybe...
Thank you !

@NetMaestro

Thanks to chi, now I understand fully your help.

Code: Select all

Image = CreateImage(#PB_Any, 16, 16, 32, #PB_Image_Transparent) ; full alpha reset is here now
If StartDrawing(ImageOutput(Image) )

    ; pattern drawing, especially vector drawing

    StopDrawing()
EndIf