OffsetClipRgn: 移動剪切區域; PtVisible: 判斷點是否在剪切區域中.
本例效果圖:
代碼文件:
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 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);
procedure FormPaint(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
var
bit: TBITMAP;
f: Boolean;
x1,y1: Integer;
cvs: TCanvas;
procedure TForm1.FormCreate(Sender: TObject);
var
Rgn: HRGN;
begin
bit := TBitmap.Create;
bit.LoadFromFile('c:\temp\Test.bmp');
ClIEntWidth := bit.Width;
ClIEntHeight := bit.Height;
cvs := TCanvas.Create;
cvs.Handle := GetDC(Handle);
Rgn := CreateEllipticRgn(30,30,140,140);
SelectClipRgn(cvs.Handle, Rgn);
DeleteObject(Rgn);
end;
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
if PtVisible(cvs.Handle, X, Y) then
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;
OffsetClipRgn(cvs.Handle, X-x1, Y-Y1);
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
cvs.Draw(0,0,bit);
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
bit.Free;
cvs.Free;
end;
end.
窗體文件:
object Form1: TForm1
Left = 402
Top = 230
Caption = 'Form1'
ClIEntHeight = 206
ClIEntWidth = 339
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'Tahoma'
Font.Style = []
OldCreateOrder = False
Position = poDesigned
OnCreate = FormCreate
OnDestroy = FormDestroy
OnMouseDown = FormMouseDown
OnMouseMove = FormMouseMove
OnMouseUp = FormMouseUp
OnPaint = FormPaint
PixelsPerInch = 96
TextHeight = 13
end