[lazarus] Bitmap transparency?

Micha Nelissen M.Nelissen at student.tue.nl
Sat Nov 8 10:47:35 EST 2003

Mattias Gaertner wrote:

> On Sat, 08 Nov 2003 15:34:48 +0100
> Micha Nelissen <M.Nelissen at student.tue.nl> wrote:
>>How does bitmap transparency work in the lcl? 
> First of all: it is not completely implemented. (Same with palettes).
>>I noticed that recently 
>>most of the buttons in the IDE aren't transparent anymore on win32. Some 
>>have a black background, some gray (these look transparent) and others 
>>are white.
> See bitmap.inc ReadStream.
> The IDE icons are in xpm format, so they are converted to handles with
> CreatePixmapIndirect
> The returned handle is up to the interface. For the gtk-interface it is an
> internal GDI object, which stores the image, the mask and some other info.

Big *sigh*. Turns out that StretchBlt is implemented with transparency 
support in gtk. Really, these extensions need to be documented in 
TInterfaceObject. How else can we EVER expect to get other (like qt) 
interfaces working? The win32 api is at least documented in msdn.

So transparency has never worked for win32, but it just seemed that way 
because the pictures had gray background some weeks ago?


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