Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

Making Bitmap Palette Darker

Posted on 2000-03-25
5
Medium Priority
?
383 Views
Last Modified: 2010-05-18
Hi.
I want to make a bitmap darker.
Lets say R := R div 2, G := G div 2, B := B div 2.

Does anyone have an example of how to get the bitmap palette, change it and put it back.

Thanks in advance.
0
Comment
Question by:TheSwine
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
5 Comments
 
LVL 17

Expert Comment

by:inthe
ID: 2657286
Hi
maybe you find something here at the graphics info and links section:

http://www.efg2.com/lab/library/delphi/Default.htm
0
 
LVL 9

Expert Comment

by:ITugay
ID: 2658211
Hi TheSwine,

I write a procedure to manipulate with colors in TBitmap.
//
procedure MixScanLine( P : PByteArray; Trans,Len : word; R,G,B : byte);
//
where
   P : PByteArray - pointer to scanline of bitmap
   Trans - (1..99) transparency
   R,G,B - (0..255) colors to mixup, if all of color =0, then Bitmap becam darker, 255 - lighter. How lighter or darker depend from Trans parameter.

You may play with parameters to see what happen. The sample of using this procedure is bellow.

-----------------
procedure TForm1.SpeedButton2Click(Sender: TObject);
var P : PByteArray;
    Y : integer;
begin
   for Y:=0 to Image1.Picture.Bitmap.Height-1 do
   begin
      P:=Image1.Picture.Bitmap.ScanLine[Y];
      MixScanLine(P,40,Image1.Picture.Bitmap.Width-1,128,0,128);
   end;
   Image1.Invalidate;
end;
------------------

procedure MixScanLine( P : PByteArray; Trans,Len : word; R,G,B : byte);
begin
   asm
      push esi
      push edi
      push ebx
      push edx

      mov  esi,P
      mov  edi,esi
      mov  bl,100
      mov  cx,Len
      mov  dx,Trans

    @0:
      lodsb
      mul   dl
      div   bl
      add   al,byte ptr B
      stosb

      lodsb
      mul   dl
      div   bl
      add   al,byte ptr G
      stosb

      lodsb
      mul   dl
      div   bl
      add   al,byte ptr R
      stosb


      dec   cx
      jnz   @0

      pop  edx
      pop  ebx
      pop  edi
      pop  esi
   end;
end;


I hope, you like it.

Cheers,
Igor.
0
 
LVL 10

Accepted Solution

by:
Lischke earned 300 total points
ID: 2660043
Hi,

here's how to manipulate the palette (not all the bitmap bits):

procedure OffsetPalette(Bitmap: TBitmap; dR, dG, dB: ShortInt);

var
  Pal: TMaxLogPalette;
  I: Integer;

begin
  GetPaletteEntries(Bitmap.Palette, 0, 256, Pal);
  for I := 0 to 255 do
  begin
    Pal.palPalEntry[I].peRed := Pal.palPalEntry[I].peRed + dR;
    Pal.palPalEntry[I].peGreen := Pal.palPalEntry[I].peGreen + dG;
    Pal.palPalEntry[I].peBlue := Pal.palPalEntry[I].peBlue + dB;
  end;
  Pal.palVersion := $300;
  Pal.palNumEntries := 256;
  Bitmap.Palette := CreatePalette(PLogPalette(@Pal)^);
end;

You need to make sure there's no overflow (< 0 or > 255 when applying the differences).

Ciao, Mike
0
 
LVL 1

Author Comment

by:TheSwine
ID: 2660494
That's works but still there are some problems:
When I load bitmap file to an image component and try this it works, but if I copy the bitmap from other bitmap (Screen e.g.) that doesn't work. when I check the palette value after copying is return 0, is there any way of creating the bitmap i copy to an independable HPalette?

I tried some things but nothing worked so source would be nice.

Here is my source:

procedure TForm2.FormShow(Sender: TObject);
var
  DeskTopDC: HDc;
  DeskTopCanvas: TCanvas;
  DeskTopRect: TRect;
begin

  DeskTopDC := GetWindowDC(GetDeskTopWindow);
  DeskTopCanvas := TCanvas.Create;
  DeskTopCanvas.Handle := DeskTopDC;
  DeskTopRect := Rect(Left, Top, Left+Width, Top + Height);

  Bg.Picture.Bitmap.Width := Width;
  Bg.Picture.Bitmap.Height := Height;
  Bg.Picture.Bitmap.Canvas.CopyRect(Rect(0,0,Width,Height),DeskTopCanvas,DeskTopRect);

  ReleaseDC(GetDeskTopWindow,DeskTopDC);

  Fade;

end;

procedure TForm2.Fade;
var
  Pal: TMaxLogPalette;
  I: Integer;
begin
  if Bg.Picture.Bitmap.Palette = 0 then ShowMessage('Not Good');

  GetPaletteEntries(Bg.Picture.Bitmap.Palette, 0, 256, Pal);
  for I := 0 to 255 do
  begin
    Pal.palPalEntry[I].peRed := Pal.palPalEntry[I].peRed div 3;
    Pal.palPalEntry[I].peGreen := Pal.palPalEntry[I].peGreen div 3;
    Pal.palPalEntry[I].peBlue := Pal.palPalEntry[I].peBlue div 3;
  end;
  Pal.palVersion := $300;
  Pal.palNumEntries := 256;
  Bg.Picture.Bitmap.Palette := CreatePalette(PLogPalette(@Pal)^);
end;

Notes :
*
Form2 is shown whenever I press button on form 1.
*
Bg is TImage component on Form2.
If I load any bitmap into it, The Fade procedure will work.
If it's empty... it's not working.

Thanks in advance.
0
 
LVL 10

Expert Comment

by:Lischke
ID: 2660677
You can of course only the palette of images which have actually a palette. Otherwise you need to manipulate the bitmap bits. There is no exception.

You can convert any image to one with palette by decreasing its color depth to at most 8 bit per pixel (set TBitmap.PixelFormat := pf8Bit before you do CopyRect).

Ciao, Mike
0

Featured Post

New feature and membership benefit!

New feature! Upgrade and increase expert visibility of your issues with Priority Questions.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction The parallel port is a very commonly known port, it was widely used to connect a printer to the PC, if you look at the back of your computer, for those who don't have newer computers, there will be a port with 25 pins and a small print…
Have you ever had your Delphi form/application just hanging while waiting for data to load? This is the article to read if you want to learn some things about adding threads for data loading in the background. First, I'll setup a general applica…
In this video you will find out how to export Office 365 mailboxes using the built in eDiscovery tool. Bear in mind that although this method might be useful in some cases, using PST files as Office 365 backup is troublesome in a long run (more on t…
We’ve all felt that sense of false security before—locking down external access to a database or component and feeling like we’ve done all we need to do to secure company data. But that feeling is fleeting. Attacks these days can happen in many w…
Suggested Courses

715 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question