TGraphicControl and child controls
lazarus / 39-Graphics

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Dibo · 2011-04-24 11:12

Hi,

I', writting component which using BGRABitmap for drawing theme. I
inherit from TGraphicControl. Drawing works fine but I can't drop
child controls (like TPanel do). So I switch parent class from
TGraphicControl to TCustomControl with ControlStyle := ControlStyle +
[csAcceptsControls, csOpaque]. Now I can drop childs but transparency
has stopped working. It seems that TCustomControl draw first some
standard background with parent color. I am lock now.

Regards

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lainz · 2011-04-24 15:03

Quote from: Dibo on April 24, 2011, 01:12:33 pmHi,

I', writting component which using BGRABitmap for drawing theme. I
inherit from TGraphicControl. Drawing works fine but I can't drop
child controls (like TPanel do). So I switch parent class from
TGraphicControl to TCustomControl with ControlStyle := ControlStyle +
[csAcceptsControls, csOpaque]. Now I can drop childs but transparency
has stopped working. It seems that TCustomControl draw first some
standard background with parent color. I am lock now.

Regards

Go to the bugtracker.

See this, they fixed my report: added transparency in controls with
controls inside:
http://bugs.freepascal.org/view.php?id=18172

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Dibo · 2011-04-25 10:11

I updated lazarus svn version but still this same problem. TToolbar
have no transparency too. I have linux GTK2

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Zoran · 2011-05-04 10:23

Quote from: Dibo on April 25, 2011, 12:11:14 pmI updated lazarus svn
version but still this same problem. TToolbar have no transparency
too. I have linux GTK2

The solved bug that lainz points to is for win widgetset only.

For Gtk2, there is separate entry in bugtracker:
http://bugs.freepascal.org/view.php?id=18168
This one is not solved yet.

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camauri · 2011-05-12 22:22

Quote from: Dibo on April 24, 2011, 01:12:33 pmNow I can drop childs
but transparency has stopped working. It seems that TCustomControl
draw first some standard background with parent color. I am lock now.

Hi Dibo,
on Windows systems TCustomControl descendant aren't transparent by
default.
This is a correct behaviour in the LCL as in the VCL.
In Mac OS X controls are native fully transparent (tested on my Mac
with Lazarus ver. 0.9.28). See also here
http://www.lazarus.freepascal.org/index.php?topic=9963.0.
Same for GTK and QT.

For transparent controls on Windows can be used the old Delphi trick.

Declare TBGRAButton = class(TCustomControl)Add Messages unitAdd the
following protected declarations:
Code: [Select]{$IFDEF LCLwin32}
procedure CreateParams(var params: TCreateParams); override;
procedure WMEraseBkGnd(var msg: TWMEraseBkGnd); message WM_ERASEBKGND;
{$ENDIF}

Code: [Select]{$IFDEF LCLwin32}
procedure TBGRAButton.CreateParams(var params: TCreateParams);
begin
  inherited CreateParams(params);
  params.ExStyle := params.ExStyle or WS_EX_TRANSPARENT;
end;

procedure TBGRAButton.WMEraseBkGnd(var msg: TWMEraseBkGnd);
begin
  SetBkMode (msg.DC, TRANSPARENT);
  msg.result := 1;
end;
{$ENDIF}


That's all, the component is now working on Windows as transparent
TCustomControl descendant.
For the other platform I will try asap.

Bye.
Camauri

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Dibo · 2011-05-14 10:37

Hm, this trick doesn't work on GTK :/

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camauri · 2011-05-14 16:38

Quote from: Dibo on May 14, 2011, 12:37:28 pmHm, this trick doesn't
work on GTK :/

I know, this trick is for Windows only.
But now BRGAControls on Windows can have the same behavior as in GTK,
QT and Carbon/Cocoa.
Now I'm installing Lazarus on latest Ubuntu distro to try some
solutions for GTK.
Next I will try on Snow Leopard.
Bye.
Camauri