asked on

CombineRgn function

I wish to display a triangle in a picture (Image1 ) filled with Image2 .

How can I use CombineRgn to do that ?

I have , until now , this test code :

unit Unit1;

interface

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

type
TForm1 = class(TForm)
Image1: TImage;
Image2: TImage;
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
var bmp:TBitmap;
begin
bmp:=TBitmap.Create;
bmp.Height:=70;
bmp.Width:=70;

combineRgn(bmp.Handle,Image2.Canvas.Handle,Image1.Canvas.Handle,RGN_AND);
Image1.Canvas.Draw(0,0,bmp);
Application.ProcessMessages;
end;

end.

ASKER CERTIFIED SOLUTION

Lischke

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ginsonic

ASKER

Can U send me a project file with this ?
I will increase the points to 150 .
My e-mail is nick@radioterra.ro
Thanks in advance.

doncov

See example;
unit Unit1;

{The transparent form effect is done with Regions.
First create a region that encompasses the entire form.
Then, find the client area of the form (Client vs. non-Client) and
combine with the full region with RGN_DIFF to make the borders
and title bar visible. Then create a region for each of the
controls and combine them with the original (FullRgn) region.}

{From various posts in the newsgroups - based on some famous
author I'm sure, but I first saw the post by Kerstin Thaler...}

interface

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

type
TForm1 = class(TForm)
Button1: TButton;
Panel1: TPanel;
Button2: TButton;
procedure FormDestroy(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure FormResize(Sender: TObject);
private
{ Private declarations }
procedure DoVisible;
procedure DoInvisible;
public
{ Public declarations }
end;

var
Form1: TForm1;
FullRgn, ClientRgn, CtlRgn : THandle;

implementation

{$R *.DFM}

procedure TForm1.DoInvisible;
var
AControl : TControl;
A, Margin, X, Y, CtlX, CtlY : Integer;
begin
Margin := ( Width - ClientWidth ) div 2;
//First, get form region
FullRgn := CreateRectRgn(0, 0, Width, Height);
//Find client area region
X := Margin;
Y := Height - ClientHeight - Margin;
ClientRgn := CreateRectRgn( X, Y, X + ClientWidth, Y + ClientHeight );
//'Mask' out all but non-client areas
CombineRgn( FullRgn, FullRgn, ClientRgn, RGN_DIFF );

//Now, walk through all the controls on the form and 'OR' them
// into the existing Full region.
for A := 0 to ControlCount - 1 do begin
AControl := Controls[A];
if ( AControl is TWinControl ) or ( AControl is TGraphicControl )
then with AControl do begin
if Visible then begin
CtlX := X + Left;
CtlY := Y + Top;
CtlRgn := CreateRectRgn( CtlX, CtlY, CtlX + Width, CtlY + Height );
CombineRgn( FullRgn, FullRgn, CtlRgn, RGN_OR );
end;
end;
end;
//When the region is all ready, put it into effect:
SetWindowRgn(Handle, FullRgn, TRUE);
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
//Clean up the regions we created
DeleteObject(ClientRgn);
DeleteObject(FullRgn);
DeleteObject(CtlRgn);
end;

procedure TForm1.DoVisible;
begin
//To restore complete visibility:
FullRgn := CreateRectRgn(0, 0, Width, Height);
CombineRgn(FullRgn, FullRgn, FullRgn, RGN_COPY);
SetWindowRgn(Handle, FullRgn, TRUE);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
//We start out as a transparent form....
DoInvisible;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
//This button just toggles between transparent and not trans..
if Button1.Caption = 'Show Form' then begin
DoVisible;
Button1.Caption := 'Hide Form';
end
else begin
DoInvisible;
Button1.Caption := 'Show Form';
end;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
Application.Terminate;
end;

procedure TForm1.FormResize(Sender: TObject);
begin
//Need to address the transparency if the form gets re-sized.
//Also, note that Form1 scroll bars are set to VISIBLE/FALSE.
//I did that to save a little coding here....
if Button1.Caption = 'Show Form' then
DoInvisible
else
DoVisible;
end;

end.

Lischke

doncov, this is much better than the other question ;-) (you know, the one with the OEM cursor). I have no example ready for Nick so he will surely welcome your contribution.

Ciao, Mike

ginsonic

ASKER

I have this sample .
But I don't understand how work .
Can you help me with a sample for my case ?

Regards,
Nick

ginsonic

ASKER

Help me ~75% .
But I had a start point .

Thanks,
Nick

Lischke

Thank you Nick. The B grading is totally correct. I din't expect to get any point here since doncov provided an example. Doncov would you like to share the points then tell me and I post a dummy question for you?

Ciao, Mike

ginsonic

ASKER

The doncov's example don't help me .
I have this sample from UNDU . But :(

I use only this

Rgn := CreateRectRgnIndirect(R);
SelectClipRgn(bmp.Canvas.Handle,Rgn);
DeleteObject(Rgn);

from your code , Lischke .
But if you wish to share is your choice , your points . :)

Thanks again

Lischke

Aha, well, thank you Nick, good to know...

Ciao, Mike