GDIPlus Issues?

General
#1

My latest build on Windows, I turned on GDIPlus because of bad drawing issues with canvases on tabpanels.
But I have several new issues

1/ I cannot draw an image with transparency.
Source image is 256 x 256, icon on a white background. Its a PNG file, and has transparency built in.
Works perfectly on a mac.
Adding a mask… still draws with a white background
Set transparency to white… still draws with a white background.

if its significant, the screen is using Rubberviews
any ideas?

And on another part of the program, trying to use a figureshape with 50% fill on a graphics.mask gets me a crash when GDIPlus is turned on, and doesnt when it is not.

Error is :

D:\Builder\QuickstableVS\build\Universal\Simplevector.h\207
Failure Condition: 0

#2

Hi Jeff,

There could be a couple of reasons for losing transparency:

  1. The default settings on Xojo Windows are typically for a Mac. Here are a few suggestions for changing these default settings to Windows:
    a) me.EraseBackground = False
    b) me.DoubleBuffer = True
    c) me.Transparent = True
    d) app.UseGDIPlus = True
  2. When drawing and filling primary shapes (circles, rectangles, etc.) check to see if the alpha channel was used with the fill command, otherwise the default white background will be drawn.

I hope this helps.

#3

[quote=237844:@Eugene Dakin]Hi Jeff,

There could be a couple of reasons for losing transparency:

  1. The default Canvas settings on Xojo Windows are typically for a Mac. Here are a few suggestions for changing these default settings to Windows:
    a) me.EraseBackground = False
    b) me.DoubleBuffer = True
    c) me.Transparent = True
    d) app.UseGDIPlus = True
  2. When drawing and filling primary shapes (circles, rectangles, etc.) check to see if the alpha channel was used with the fill command, otherwise the default white background will be drawn.

I hope this helps.[/quote]

Edit: Added the word Canvas to make it clearer :slight_smile:

#4

Thanks.
All makes sense.
Sadly, none made any difference.
Lots of hmmm.

#5

The loss of transparency is not due to GDI PLus but to double buffer. When used, transparency is not supported.

#6

Hi Jeff,

Sorry, I don’t know what to say. I tried some of the examples in the Canvas book and the transparency for pictures and shapes seem to work with Xojo 2015 r4 on the Windows OS.

#7

yep.
It all makes sense, but…

For now, Im so desperate to get a bug fix release out (the crash I mentioned) that Im going to have to ship with this horrible white background.

#8

Jeff. Have you read my post above ? Just turn off DoubleBuffer.

#9

I did, thank you.
I have tracked it down.
When I was testing the crash in GDIPlus, I turned GDIPlus off.
Then Rubberviews failed to compile due to the new picture constructor that lacks a depth.

So I added a depth. After which RubberCanvas didnt draw properly but ordinary canvas did.
Long story cut short, I have it sorted now. Thanks all for the input, which did help a lot.

And I have a workaround for the crash… dont have time to find the cause…

#10