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Date Posted: 19:50:44 06/19/01 Tue
Author: wto
Subject: Re: How to change the palette of a 256 color TBitmapGraphic?
In reply to: Michel 's message, "Re: How to change the palette of a 256 color TBitmapGraphic?" on 18:17:50 06/19/01 Tue

Yes, I've refreshed it(Invalidate is also tried), but nothing happens.

>
>Hi,
>
>Did you invalidate your display component, for example,
>
>Image.Invalidate or ImageScrollBox.Redraw(True) ?
>
>Best regards,
>
>Michel
>
>>I've tried it under 256 display mode and true-color
>>mode,
>>all have no effect after the change of palette.
>>
>>>Thank you for your answer, but after I apply
>following
>>>code to a TBitmapGraphic, nothing happens:
>>>
>>> for I := 0 to 255 do
>>> begin
>>>
>BitmapGraphic.PalettePtr^.palPalEntry[I].peRed
>>>:= 0;
>>>
>>>BitmapGraphic.PalettePtr^.palPalEntry[I].peGreen
>:=0;
>>>
>BitmapGraphic.PalettePtr^.palPalEntry[I].peBlue
>>> := 0;
>>>
>>>BitmapGraphic.PalettePtr^.palPalEntry[I].peFlags :=
>>>PC_RESERVED;
>>> end;
>>>Why?
>>>
>>>>
>>>>Hi,
>>>>
>>>>Sorry about that, I looked too quickly. Use,
>>>>
>>>>BitmapGraphic.PalettePtr^.palPalEntry[N].peRed := X;
>>>>
>>>>Best regards,
>>>>
>>>>Michel
>>>>>Thank you for your answer, but the property of
>>>>>TDibGraphic.Palette is read only, so when I written
>>>>>code like this:
>>>>> BitmapGraphic.Palette.palPalEntry[N].peRed := X;
>>>>>The Delphi compiler will said "Left side cannot
>>>assign
>>>>>to" .
>>>>>
>>>>>>
>>>>>>Hi,
>>>>>>
>>>>>>The TBitmapGraphic already exposes the palette
>from
>>>>>>the TDibGraphic base class.
>>>>>>
>>>>>>For example, you can change an entry,
>>>>>>
>>>>>>BitmapGraphic.Palette.palPalEntry[N].peRed := X;
>>>>>>
>>>>>>Best regards,
>>>>>>
>>>>>>Michel
>>>>>>
>>>>>>>Hi,
>>>>>>> I'm trying to change the palette of a 256 color
>>>>>>>TBitmapGraphic like this:
>>>>>>>var
>>>>>>> Pal: array[0..255] of TPaletteEntry;
>>>>>>> Image: TImage;
>>>>>>>begin
>>>>>>> Image := TImage.Create;
>>>>>>> Image.Picture.Graphic := TBitmapGraphic.Create;
>>>>>>> for I := 0 to 255 do
>>>>>>> begin
>>>>>>> Pal[i].peFlags:=PC_RESERVED;
>>>>>>> Pal[i].peRed:=Random(255);
>>>>>>> Pal[i].peGreen:=Random(255);
>>>>>>> Pal[i].peBlue:=Random(255);
>>>>>>> end;
>>>>>>> if
>>>>>>>SetPaletteEntries(TBitmapGraphic(image.picture.Gr
>a
>>p
>>>h
>>>>i
>>>>>c
>>>>>>)
>>>>>>>.PaletteHandle, 0, 256, Pal) <> 0 then
>>>>>>>
>>>>>>>RealizePalette(TBitmapGraphic(image.picture.Graph
>i
>>c
>>>)
>>>>.
>>>>>D
>>>>>>C
>>>>>>>);
>>>>>>>
>>>>>>> but the image will not change at all! What is
>>the
>>>>>>>problem?

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