In Koordinatensystem auf Punkt "zuzoomen"

[Bummi]

und wenn Du die Zeichenroutinen/Berechnungen unangetastet lässt und nur das Rendering anpasst?

Delphi-Quellcode:

unit ExCanvasTools;
// 20100915 by Thomas Wassermann
interface
uses
  Windows, SysUtils,  Classes, Graphics;

  Function Grad2Rad(w:Double):Double;
  Procedure PaintGraphic(ACanvas:TCanvas;x,y:Integer;AGraphic:TGraphic;Faktor,Winkel:Double;PosIsCenter:Boolean=false);
  Procedure PaintText(ACanvas:TCanvas;Const s:String;x,y:Integer;Faktor,Winkel:Double;PosIsCenter:Boolean=false);
  Procedure ResetCanvas(ACanvas:TCanvas);
  procedure SetCanvasZoomAndRotation(ACanvas: TCanvas;Zoom:Double;Angle:Double;CenterpointX,CenterpointY:Double);

implementation

Function Grad2Rad(w:Double):Double;
  begin
     Result := w  / 360 * PI *2;
  end;

Procedure PaintText(ACanvas:TCanvas;Const s:String;x,y:Integer;Faktor,Winkel:Double;PosIsCenter:Boolean=false);
var
  px,py:Integer;
begin
     SetCanvasZoomAndRotation(ACanvas , Faktor, Winkel, x,y);
     if PosIsCenter then
        begin
          px := Round( ACanvas.TextWidth(s) / 2 );
          py := Round( ACanvas.TextHeight(s) / 2 );
        end
     else
        begin
          px := 0;
          py := 0;
        end;

     ACanvas.TextOut(-px ,-py ,s);
     ResetCanvas(ACanvas);
end;




Procedure PaintGraphic(ACanvas:TCanvas;x,y:Integer;AGraphic:TGraphic;Faktor,Winkel:Double;PosIsCenter:Boolean=false);
var
  px,py:Integer;
begin
     if PosIsCenter then
        begin
          px := Round( AGraphic.Width / 2 );
          py := Round( AGraphic.Height / 2 );
        end
     else
        begin
          px := 0;
          py := 0;
        end;
     SetCanvasZoomAndRotation(ACanvas , Faktor, Winkel, x , y  );
     ACanvas.Draw(-px ,-py ,AGraphic);
     ResetCanvas(ACanvas);
end;





Procedure ResetCanvas(ACanvas:TCanvas);
begin
   SetCanvasZoomAndRotation(ACanvas , 1, 0, 0,0);
end;

Procedure SetCanvasZoomAndRotation(ACanvas:TCanvas;Zoom:Double;Angle:Double;CenterpointX,CenterpointY:Double);
var
    form : tagXFORM;
    Winkel:Double;

begin
      Winkel := Grad2Rad(Angle);
      SetGraphicsMode(ACanvas.Handle, GM_ADVANCED);
      SetMapMode(ACanvas.Handle,MM_ANISOTROPIC);
      form.eM11 := Zoom * cos( Winkel);
      form.eM12 := Zoom *Sin( Winkel)  ;
      form.eM21 := Zoom * (-sin( Winkel));
      form.eM22 := Zoom * cos( Winkel) ;
      form.eDx := CenterpointX;
      form.eDy := CenterpointY;
      SetWorldTransform(ACanvas.Handle,form);
end;

end.