How to Convert a BMP file into a gif
lazarus / 39-Graphics

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Possum · 2019-10-27 02:38

Hi

I really though I knew how to do this. I may have years ago in
Delphi..


I need to convert a BMP file into a gif file

Why does this not work

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i   procedure
ConvertBMP2GIF;var  bmp: TBitmap;  gif: TGIFImage;begin  gif :=
TGifImage.Create;  try    bmp := TBitmap.Create;    try     
bmp.LoadFromFile('MyBitmap.BMP');      gif.Assign(bmp);    finally   
 bmp.Free;    end;    gif.SaveToFile('MyBitmap.GIF');  finally   
gif.Free;  end;end;
I get an exception at the savetofile command but that is due to no
file being created..

Any help appreciated..

I want to convert back and forth from gif to bmp and bmp to gif..

Thank You..

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wp · 2019-10-27 10:03

fcl-image does not provide writing support for gif -- look in folder
(fpc)/packages/fcl-image/src: there is a file fpreadgif, but no
fpwritegif.

I don't know of any Lazarus package which addes gif writing support.
You probably must port Anders Melander's/Finn Tolderlund's TGifImage
(http://www.tolderlund.eu/delphi/). Or use one of the big imaging
libraries such as Vampyre Imaging (http://imaginglib.sourceforge.net/
- works with Laz out of the box) or FreeImage
(http://freeimage.sourceforge.net/ - not sure if it works directly
with Lazarus)

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lainz · 2019-10-27 13:32

BGRABitmap supports saving gif, see this example code:

https://forum.lazarus.freepascal.org/index.php/topic,47062.msg336312.h
tml#msg336312

In this case is an animated gif, but I suppose just adding a single
frame is enough.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i var  gif :
TBGRAAnimatedGif;  bmp: TBGRABitmap;begin  bmp :=
TBGRABitmap.Create(100,100,BGRAWhite);  bmp.FontHeight := 30; 
bmp.TextRect(Rect(0,0,100,100), 'Hello', taCenter, tlCenter,
BGRABlack);   gif := TBGRAAnimatedGif.Create;  gif.SetSize(100,100); 
gif.LoopCount:=100;  gif.AddFullFrame(bmp, 500);  
bmp.Fill(BGRAWhite);  bmp.TextRect(Rect(0,0,100,100), 'World',
taCenter, tlCenter, BGRABlack);   gif.AddFullFrame(bmp, 500); 
gif.SaveToFile('image.gif');  gif.Free;   bmp.Free;

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Possum · 2019-10-27 23:36

I didn't know PNG's have a transparent color. So I will use them.

Thx Everyone.

Maybe I should have asked how to I find out as much as I can about
Lazarus and PNG files..

Cheers..

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winni · 2019-10-28 00:00

Hi

There is also animation support for png files called APNG.

APNG files are shown by Firefox and Chrome.

More about APNG here:

http://littlesvr.ca/apng/

Winni