🚀 go-pugleaf

Should nave mentioned, this is with Delphi 5
 

On Jul 16, 11:22 pm, "IB" <i...@ib.com> wrote:
> I create 2 pens, set the canvas pen handle to the first, draw, works ok, the
> the canvas pen handle to the second, draw, works ok, set it back to the
> first again, and the color and width are lost (get pen black and width 1).
> Why is this?
>
> Here's the code:
>
> unit Unit1;
>
> interface
>
> uses
>   Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs;
>
> type
>   TForm1 = class(TForm)
>     procedure FormPaint(Sender: TObject);
>   private
>     procedure Test(P:HPen; Y:integer);
>     { Private declarations }
>   public
>     { Public declarations }
>   end;
>
> var
>   Form1: TForm1;
>
> implementation
>
> {$R *.DFM}
>
> procedure TForm1.Test(P:HPen; Y:integer);
> var
>   R:TRect;
> begin
>   R.Left:=300;
>   R.Right:=350;
>   R.Top:=Y+10;
>   R.Bottom:=Y+50;
>
>   Canvas.Pen.Handle:=P;
>
>   Canvas.MoveTo(10,Y+10);
>   Canvas.LineTo(100,Y+10);
>   Canvas.LineTo(120,Y+30);
>
>   Canvas.RoundRect(200, Y+10, 250, Y+50,50,50);
>   Canvas.FillRect(R);
>
> end;
>
> procedure TForm1.FormPaint(Sender: TObject);
> var PH1, PH2: HPEN;
>   Style : cardinal;
>   Brush : TLogBrush;
>   W:integer;
>
> begin
>   Style := PS_GEOMETRIC or PS_SOLID;
>   //Style := Style or PS_ENDCAP_SQUARE or PS_JOIN_MITER;
>   Style := Style or PS_ENDCAP_ROUND or PS_JOIN_ROUND;
>
>   Brush.lbStyle := BS_SOLID;
>   Brush.lbColor := RGB(255,0,0);
>   Brush.lbHatch := 0;
>
>   PH1:= ExtCreatePen(Style, 10, Brush, 0, nil);
>
>   Brush.lbColor := RGB(255, 128, 0);
>
>   PH2:= ExtCreatePen(Style, 5, Brush, 0, nil);
>
>   //Canvas.Brush.Color:= RGB(255,0,255);
>
>   Test(PH1, 0);
>   Test(PH2, 100);
>
>   //Brush.lbColor := RGB(255,0,0);
>   //PH1:= ExtCreatePen(Style, 10, Brush, 0, nil);
>
>   Test(PH1, 200);
>
> end;
>
> end.

You shouldn't really need to be fiddling with the internal handles of
ANY object. Usually ends up with a headache.

When assigning a value to the pen handle, the TPen class frees the
resource the current handle is pointing to.

Therefore: By assigning PH1, you free the original resource. After
that you assign PH2, you free the PH1's resource.

Have a look the TPen.SetHandle in Graphics.pas, and follow the trail
of funtions TResourceManager.ChangeResource()

I recommend you rather use the TPen class, and assigning its
properties using Canvas.Pen.Assign()

  pen1 := TPen.Create;  //remember to free this later
  pen1.Width := 5;
  pen1.Color := clBlue;
  pen1.Style := etc etc

  pen2 := TPen.Create;  //remember to free this later
  pen2.Width := 15;
  pen2.Color := clLime;
  pen2.Style := etc etc

  Canvas.Pen.Assign(pen1);
  //Do some drawing

  Canvas.Pen.Assign(pen2);
  //Do some drawing

  Canvas.Pen.Assign(pen1);
  //Do some drawing


Does this help?

hello