From: "Pablo Pedrocca" <pjpedrocca@onenet.com.ar>
Subject: Re: Quick way to make an image more blue
Date: 09 Aug 1999 00:00:00 GMT
Message-ID: <7omjdj$7ip3@forums.borland.com>
References: <7old09$6ci3@forums.borland.com>
Organization: Another Netscape Collabra Server User
X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3110.3
Newsgroups: borland.public.delphi.graphics

Hi,
    Try this: set the Bitmap to 24 bits, go trough the bitmap using
scanline[x] and a) add a constant to the blue value or b) substract a
constant to the red and green values or c) set the red and green values to
0.

   image3.Bitmap.HandleType:=bmDIB;
   image3.Bitmap.PixelFormat:=pf24Bit;
   Copywidth:=image3.Width;
   CopyHeight:=image3.Height;


   // Process each pixel:

   For Y:=0 to CopyHeight-1 do begin
      P:=image3.Bitmap.ScanLine[Y];
      For X:=0 to (CopyWidth*3)-1 do begin
        P[X]:=0;        ///that's black. The right number is 000000000000000 11111111
   end;



    If your bitmap can't set to 24 bits, you have to work on the palette.
var
  pal: PLogPalette;       ///Buffer Palette
  img2pal: PlogPalette;   ///Palette of image2
  hpal: HPALETTE;         ///Handle to a new palette
  h2pal: HPALETTE;        ///Handle of image2 palette
  i: Integer;
  x: Integer;

begin
  ///Reset variables
  pal := nil;
  img2pal:=nil;
  try
     ///Takes place in memory to the palettes
    GetMem(img2pal,sizeof(TLogPalette) + sizeof(TPaletteEntry) * 255);
    GetMem(pal, sizeof(TLogPalette) + sizeof(TPaletteEntry) * 255);
    pal.palVersion := $300;
    pal.palNumEntries := 256;       ///256 colors
    img2pal.palVersion := $300;
    img2pal.palNumEntries := 256;

    ///Scan the entries of the palette and reset it.
    for i := 0 to 255 do
    begin
      img2pal.palPalEntry[i].peRed := 0;
      img2pal.palPalEntry[i].peGreen := 0;
      img2pal.palPalEntry[i].peBlue := 0;
    end;

    ///read the entries from the image (the buffer image)
    x:=0 ;
    x :=
getpaletteentries(Image2.picture.Bitmap.Palette,0,255,img2pal.palPalEntry);
//\    x := getpaletteentries(Bitmap.Palette,0,255,img2pal.palPalEntry);
    if x=0 then
       begin
       Showmessage('Funcion falla - function fails');
       exit;
       end;

    ///Now, shift the entries by adding 4. You can change this value.
    for i := 0 to 255 do
    begin
         pal.palPalEntry[i].pered :=
img2pal.palPalEntry[i].pered+shiftvalue;
         pal.palPalEntry[i].pegreen := img2pal.palPalEntry[i].pegreen;
///or :=0
         pal.palPalEntry[i].peBlue := img2pal.palPalEntry[i].peblue;
///or :=0
    end;
    ///Create a new palette using pal (the buffer palette).
    hpal := CreatePalette(pal^);
    ///If successful, assign the new palette to the buffer
    if hpal <> 0 then
      image2.Picture.bitmap.Palette := hpal
//\      bitmap.palette := hpal
      else
       Showmessage('Funcion falla');
  finally
    FreeMem(pal);
  end;
end;


William escribió en mensaje <7old09$6ci3@forums.borland.com>...
>Hi
>
>I am using a listbox with owner draw.  To indicate selected items, I want
>them to appear more blue (as they do when you select an item in Windows
>Explorer).  I don't want to just have a blue background, I want to actually
>take the BMP (i have dynamically created from teh originaly file) and give
>it a bluish hue.
>
>So what is a quick way to make a small BMP image turn blue?
>
>Thanks for your help
>
>Regards
>
>William
>the_white_house@usa.net