jpg to bitmap?

[jbpelletier]

hi

im loading a bmp fileinto a tbitmap then i do some canvas manipulation like this :
//filename is 'file1.bmp';

my_bitmap:=Tbitmap.create;
my_bitmap.LoadFromFile(filename);
//canvas manipulation
my_bitmap.free;

i would like to be able to do the canvas manipulation
either if the file is a jpg or a bmp.

any idea on how i could load the jpg as a bitmap? or easily convert it to bmp.

tanx
jb

 

[Stretchwickster]

A quick google search using the terms: delphi "jpg to bmp" returned the following website which may be of use to you:

http://www.efg2.com/Lab/Graphics/BMPJPG.htm

Clive
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"To err is human, but to really foul things up you need a computer."
Paul Ehrlich
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To get the best answers from this forum see: faq102-5096

 

[jbpelletier]

i will try that code asp.

previously
i should have mention that my real problem is not to assign a jpeg into a tbimap, but to have acces to the canvas once its done. The canvas still empty! when the bitmap isn't.

tanx
jb

 

[bobbie100]

Could you clarify what you mean by "the canvas is still empty" and what sort of "canvas manipulation" you are attempting?

The canvas is a drawing surface that provides the ability to draw onto the bitmap image. It is not the image itself.

Bob

 

[jbpelletier]

hi,
all my canvas manipulation are either "canvas.copyrect" with various "option". ex: using and OR, XOR etc..
or canvas.draw.

my problem is that, if i assign a jpg image in a Tbipmap..
i have acces to each of the piture proprieties as width,height etc..
but i dont have an acess to the canvas..
ex: a copyrect will provide no result if i use the Tbitmap as source.

jb

 

[bobbie100]

I can use the bitmap canvas in a CopyRect using the following code. Just open Delphi and add a button and a TImage to the form, then insert this code in Unit1. You will need to insert a file path to a .jpg on your hard disk.

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Image1: TImage;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses
  JPEG;

procedure TForm1.Button1Click(Sender: TObject);
var
  Jpg: TJPEGImage;
  Bmp: TBitmap;
  R: TRect;
begin
  Jpg := TJPEGImage.Create;
  try
    Jpg.LoadFromFile('???');   //Insert path to a .jpg file
    Bmp := TBitmap.Create;
    try
      Bmp.Assign(Jpg);
      R := Rect(0, 0, Bmp.Width, Bmp.Height);
      Image1.Canvas.CopyRect(R, Bmp.Canvas, R);
    finally
      Bmp.Free;
    end;
  finally
    Jpg.Free;
  end;
end;

end.

Have you by any chance been trying to use the following or something similar?

Image1.Picture.Bitmap.Canvas.CopyRect(R, Bmp.Canvas, R);

This produces the effects you describe. Instead you must access the TImage canvas directly (see code in Unit1 above).

Bob

 

[jbpelletier]

yes
i figured that if i load a jpg at design time delphi "convert it" to a "bitmap" .. well at least i can use the canvas.. but at design time.. i can't

so far the only way i found is to save the jpg as a bmp in the c:\temp directory then reload it as a bmp.. and delete de temp file..

but im trying to avoid that...

jb

 

[bobbie100]

jb

Could you include some of the code you have tried that does not work. It is much easier to understand and solve the problems if real code is included.

Bob

 

[lespaul]

you may also want to describe what kind of manipulation you are trying to do? change the image? are you trying to include some kind of image editor?

Leslie