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Date Posted: 20:31:30 09/16/03 Tue
Author: Michel
Subject: Re: Resource to Bitmap to Icon
In reply to: glup 's message, "Resource to Bitmap to Icon" on 11:52:30 09/16/03 Tue

Hi Glup,

There are two things here. Loading the bitmap and converting to icon.

What is the exception you get with:

wStream := TResourceStream.Create(HInstance, aResId, RT_BITMAP);
wBmp.LoadFromStream( wStream );

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

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;
IconSizeX, IconSizeY : integer;
IconInfo: TIconInfo;
IconBitmap, MaskBitmap: TBitmap;
x, y: Integer;
TransparentColor: TColor;
IconSizeX := GetSystemMetrics(SM_CXICON);
IconSizeY := GetSystemMetrics(SM_CYICON);
IconBitmap := nil;
MaskBitmap := nil;
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;
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);

So I would recommend loading with,

wBmp := TBitmap.Create;
wBmp.LoadFromResourceID(HInstance, aResId);

then use BitmapToIcon above.

Best regards,


>I need to display a bitmap 16x16px with 16 colors
>loaded from an resource as a form icon with correkt
>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,
>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;
> wIco.Assign( wBmp );
> self.Icon := wIco;
> FreeAndNil(wIco);
>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 );
> wIcon: THandle;
> wIconInfo: TIconInfo;
> 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;
>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 );
> wHelp: TBitmap;
> wBmp: TBitmap;
> 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;
>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

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