[delphi]WinAPI: PtInRegion、OffsetRgn绘图移动

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所属分类:[开发技巧]


--------------------------------------------------------------------------
unit Unit1;

interface

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

type
TForm1 = class(TForm)
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure FormPaint(Sender: TObject);
procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
procedure FormMouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

var
Rgn: HRGN;
f: Boolean;
x1,y1: Integer;

procedure TForm1.FormCreate(Sender: TObject);
begin
Rgn := CreateEllipticRgn(11, 11, 111, 66);
end;

procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if PtInRegion(Rgn, X, Y) then {判断鼠标当前点是否在区域内}
begin
f := True;
x1 := X;
y1 := y;
end;
end;

procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
begin
if not f then Exit;
OffsetRgn(Rgn, X-x1, Y-y1); {移动区域}
Repaint;
x1 := X;
y1 := y;
end;

procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
f := False;
end;

procedure TForm1.FormPaint(Sender: TObject);
begin
Canvas.Brush.Color := clSilver;
Canvas.Brush.Style := bsCross;
FillRgn(Canvas.Handle, Rgn, Canvas.Brush.Handle);

Canvas.Brush.Color := clRed;
Canvas.Brush.Style := bsSolid;
FrameRgn(Canvas.Handle, Rgn, Canvas.Brush.Handle, 2, 2);
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
DeleteObject(Rgn);
end;

end.

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