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Storing image useing hDC

Posted on 1998-11-17
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Last Modified: 2010-04-04
 How to use hDC(and what is hDC) to store big image?
I'm doing graphics editor.
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Question by:jack_p50
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4 Comments
 
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Expert Comment

by:Thaddy
ID: 1347110
hDC means 'Handle' to a 'Device Context'
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BoRiS earned 30 total points
ID: 1347111
jack_p50

Thaddy is totally right on the meaning and here is an example on how to use it this does a simple screen capture and dumps it on to the forms canvas..

unit scrcap;

interface

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

type
  TForm1 = class(TForm)
    Image1: TImage;
    SpeedButton1: TSpeedButton;
    procedure SpeedButton1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.SpeedButton1Click(Sender: TObject);
var
  ScreenDC : HDC;
begin
  ScreenDC:=CreateDC('DISPLAY',nil,nil,nil);
  BitBlt(Image1.Canvas.Handle, 0,0, Image1.Width, Image1.Height,
  ScreenDC, 0,0, SRCCOPY);
  Image1.Refresh;
  DeleteDC(ScreenDC);
end;

end.

Later
BoRiS
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LVL 4

Author Comment

by:jack_p50
ID: 1347112
Please give me syntax of all hDC-related funtions and procs (i.e. createDC).
Btw, I don't want to use TImage or TBitmap. I need ability to get memory and access
any byte of it.
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LVL 4

Expert Comment

by:BoRiS
ID: 1347113
jack_p50

I would give you all the syntax etc that go with HDC but we will be here forever, the best thing to do is open the win32.hlp (API help file) and search for CreateDC it will explain the whole thing to you, as well as give you the procedures that go with CreateDC etc...

Later
BoRiS
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