PNG with Alphachannel

infratec · **Posted:** Fri Dec 02, 2011 11:29 pm

Hi,

I have no Mac... but I want to make my programming running on a Mac!

I have only a few points which aren't working.
One of them:

I have an ImageGadget() on the window. The window is red.
The image is a 4 color PNG with alphachannel.
I use CatchImage() to load it.

Result:
The background of the image is not transparent. It is white.

On windows it is working.

Is there a 'special' trick for Mac?

I think I also tried a 24bit colour with alphachannel. Same effect.

Bernd

J. Baker · **Posted:** Fri Dec 02, 2011 11:33 pm

I thought png only did 32bit w/alpha and 8bit w/alpha?

jesperbrannmark · **Posted:** Fri Dec 02, 2011 11:43 pm

I know this is very sensitive on the mac. even if i screwed up the image slightly on windows - it didnt display or showed up as wrong. on mac my program crashed.
So bottom line - be careful and put in extra checks (which you should do doing good practice). use if isimage(XXX) for... well... everything.

infratec · **Posted:** Fri Dec 02, 2011 11:55 pm

Hi,

here is a code snippet for testing:

Code:

UsePNGImageDecoder()

OpenWindow(0, 0, 0, 300, 250, "Test", #PB_Window_SystemMenu|#PB_Window_ScreenCentered)
SetWindowColor(0, $0000CC)

CatchImage(0, ?Logo)
ImageGadget(0, 50, 50, 195, 150, ImageID(0))

Repeat
Until WaitWindowEvent() = #PB_Event_CloseWindow

DataSection
  Logo: IncludeBinary "GuzziForumLogo.png"
EndDataSection

And here is the picture (save it as GuzziForumLogo.png):

And yes, it is 24bit with alphachannel. And it works in windows.
But not in Linux and not on Mac. :cry:

Bernd

jesperbrannmark · **Posted:** Fri Dec 02, 2011 11:58 pm

Works fine with me. Pb 4.6, lion, macbook air.
but that red color is ugly

jesperbrannmark · **Posted:** Sat Dec 03, 2011 12:01 am

Sorry. thoght it was a bug.
here is working transparent :

Code:

UsePNGImageDecoder()

OpenWindow(0, 0, 0, 300, 250, "Test", #PB_Window_SystemMenu|#PB_Window_ScreenCentered)
SetWindowColor(0, $0000CC)

CatchImage(0, ?Logo)
CreateImage(1,ImageWidth(0),ImageHeight(0))
StartDrawing(ImageOutput(1))
Box(0,0,ImageWidth(0),ImageHeight(0),$0000cc)
DrawAlphaImage(ImageID(0),0,0,254)
StopDrawing()
FreeImage(0)
ImageGadget(0, 50, 50, 195, 150, ImageID(1))


Repeat
Until WaitWindowEvent() = #PB_Event_CloseWindow

DataSection
  Logo: IncludeBinary "Gussi.png"
EndDataSection

infratec · **Posted:** Sat Dec 03, 2011 12:13 am

Hi,

but when I set the colour of the box, than I don't need a transparent picture :!:

In windows it looks like this:

That was the reason for transparency.
It is in the lower right corner and overlaps the statusbar.

Bernd

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PNG with Alphachannel

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