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Date Posted: 04:22:05 09/17/03 Wed
Author: glup
Subject: Re: Resource to Bitmap to Icon
In reply to: Michel 's message, "Re: Resource to Bitmap to Icon" on 20:31:30 09/16/03 Tue

Hi Michel

>What is the exception you get with:
>
>wStream := TResourceStream.Create(HInstance, aResId,
>RT_BITMAP);
>wBmp.LoadFromStream( wStream );

EGmbError: gmb_read_header_failed.
The exception is raised after gbm_read_header in LoadGraphicWithGbm.

>
>I have not tried it, but LoadFromStream should be
>generic. Maybe the stream needs to be reset with
>Seek(0, soFromBeginning) ?

The Stream is at its begin.

>
>Converting from a bitmap to an icon is not trivial
>because of transparency. Here is some code I found on
>newsgroups that works well but requires a TBitmap:
>
>function BitmapToIcon(Bitmap: TBitmap): TIcon;
>var
> IconSizeX, IconSizeY : integer;
> IconInfo: TIconInfo;
> IconBitmap, MaskBitmap: TBitmap;
> x, y: Integer;
> TransparentColor: TColor;
>begin
> IconSizeX := GetSystemMetrics(SM_CXICON);
> IconSizeY := GetSystemMetrics(SM_CYICON);
> IconBitmap := nil;
> MaskBitmap := nil;
> try
> IconBitmap:= TBitmap.Create;
> IconBitmap.Width:= IconSizeX;
> IconBitmap.Height:= IconSizeY;
> IconBitmap.Canvas.StretchDraw(Classes.Rect(0,
>0, IconSizeX, IconSizeY), Bitmap);
> IconBitmap.TransparentColor:=
>Bitmap.TransparentColor;
> TransparentColor:= IconBitmap.TransparentColor
>and $FFFFFF;
> MaskBitmap:= TBitmap.Create;
> MaskBitmap.Assign(IconBitmap);
> for y:= 0 to IconSizeY - 1 do
> for x:= 0 to IconSizeX - 1 do
> if IconBitmap.Canvas.Pixels[x, y] =
>TransparentColor then
> IconBitmap.Canvas.Pixels[x, y]:= clBlack;
> IconInfo.fIcon:= True;
> IconInfo.hbmMask:= MaskBitmap.MaskHandle;
> IconInfo.hbmColor:= IconBitmap.Handle;
> Result:= TIcon.Create;
> Result.Handle:= CreateIconIndirect(IconInfo);
> finally
> MaskBitmap.Free;
> IconBitmap.Free;
> end;
>end;
>

Mhhh...
First point the size: My graphic size is not system dependent and for the testcase 16x16. Doesn't Delphi do allready the stretching?
Second creating the Mask: TBitmap creates allready a handle for a correct mask when I set Transparent := true. It calls the Graphics internal CopyBitmapAsMask. I have displayed that mask and it looks correct.

>So I would recommend loading with,
>
>wBmp := TBitmap.Create;
>wBmp.LoadFromResourceID(HInstance, aResId);
>
>then use BitmapToIcon above.
>
[...]

But why is TIconGraphic adding this anoying whitspace and does not Stretch as it should?

Rgds

:glup

>
>>I need to display a bitmap 16x16px with 16 colors
>>loaded from an resource as a form icon with correkt
>>tranparency.
>>
>>I want to use Envision Components only, since I will
>>add later transformations and resized TIFFs.
>>
>>The resource-stored bitmap use clFuchsia as the
>>transparent color.
>>
>>
>>First problem is to load the graphic from the
>resource:
>>
>>wBmp := TBitmapGraphic.Create;
>>wStream := TResourceStream.Create(HInstance, aResId,
>>RT_BITMAP);
>>wBmp.LoadFromStream( wStream );
>>
>>does not work - I get an exception.
>>
>>
>>wBmp := TBitmap.Create;
>>wBmp.LoadFromResourceID(HInstance, aResId);
>>
>>works without a Problem.
>>
>>
>>
>>
>>Second issue is to Convert to an icon and set it to a
>>TForm.Icon property:
>>
>>wIco := TIconGraphic.Create;
>>try
>> wIco.Assign( wBmp );
>> self.Icon := wIco;
>>finally
>> FreeAndNil(wIco);
>>end;
>>
>>This icon has on my system (XP, 1600x1200, large font)
>>lots of unwanted whitespace (clWhite). On an old
>>system (Win95, 640x480, small fonts) it does not
>>(possibly since the system icon size is 16x16). Also
>>the transparent color is not recognized.
>>
>>
>>Following I found somewhere:
>>
>>procedure TForm1.BitmapToIcon( const aBmp: TBitmap;
>>const aIcon: TIcon );
>>var
>> wIcon: THandle;
>> wIconInfo: TIconInfo;
>>begin
>> aBmp.TransparentColor := clFuchsia;
>> aBmp.Transparent := true;
>> with wIconInfo do begin
>> fIcon := true;
>> hbmMask := aBmp.MaskHandle;
>> hbmColor := aBmp.Handle;
>> end;
>>
>> wIcon := CreateIconIndirect( wIconInfo );
>> if wIcon = 0 then
>> RaiseLastOsError;
>>
>> aIcon.Handle := wIcon;
>>end;
>>
>>
>>This works better; there is no whitespace, but still
>>the transparency is still not recognized even the Mask
>>seams to be correct; I tested this with
>>
>>procedure TForm1.DrawMask( aBmp: TBitmap );
>>var
>> wHelp: TBitmap;
>> wBmp: TBitmap;
>>begin
>> wHelp := TBitmap.Create;
>> try
>> wHelp.Handle := aBmp.MaskHandle;
>> wHelp.Transparent := false;
>>
>> wBmp := img1.Picture.Bitmap;
>> wBmp.Width := 100;
>> wBmp.Height := 100;
>> wBmp.PixelFormat := pf8bit;
>> wBmp.HandleType := bmDIB;
>>
>> wBmp.Canvas.Draw(20, 20, wHelp);
>> finally
>> FreeAndNil(wHelp);
>> end;
>>end;
>>
>>
>>
>>My questions again and explicit:
>>1. How to load a RT_BITMAP with TBitmapGraphic
>>2. Hot to convert general a TDibGraphic in 16x16 or
>>32x32 and 16 to 256 colors to an Icon without
>>whitespace and with correct transparency. A HICON
>>would be sufficient, since I could just set
>>Form1.Icon.Handle to it.
>>
>>
>>I'm looking for the simplest solution (short and fast
>>code).
>>
>>
>>:-glup

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