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再学GDI+[12]: 准备工作 - 矩形命中

时间:2012-05-05 | 栏目:Delphi教程 | 点击:

本例效果图:

代码文件:unit Unit1;
interface
uses
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 Dialogs;
type
 TForm1 = class(TForm)
  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}
uses GDIPOBJ, GDIPAPI;
var
 f: Boolean;
 x1,y1,x2,y2: Integer;
 RectArr: array of TRect;
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
 Shift: TShiftState; X, Y: Integer);
begin
 f := True;
 x1 := X;
 y1 := Y;
 x2 := X;
 y2 := Y;
end;
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
 Y: Integer);
var
 i: Integer;
begin
 if f then
 begin
  Canvas.DrawFocusRect(Rect(x1,y1,x2,y2));
  x2 := X;
  y2 := Y;
  Canvas.DrawFocusRect(Rect(x1,y1,x2,y2));
 end else begin
  Text := '';
  for i := Low(RectArr) to High(RectArr) do
   if PtInRect(RectArr[i], Point(X,Y)) then
    Text := Format('在第 %d 个矩形中', [i+1]);
 end;
end;
procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
 Shift: TShiftState; X, Y: Integer);
begin
 if not f then Exit;
 SetLength(RectArr, Length(RectArr)+1);
 RectArr[High(RectArr)] := Rect(x1,y1,x2,y2);
 f := False;
 Repaint;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
 g: TGPGraphics;
 p: TGPPen;
 i: Integer;
begin
 g := TGPGraphics.Create(Canvas.Handle);
 p := TGPPen.Create(aclRed, 1);
 g.Clear(aclWhite);
 for i := Low(RectArr) to High(RectArr) do
  g.DrawRectangle(p, MakeRect(RectArr[i]));
 g.Free;
 p.Free;
end;
end.

窗体文件:object Form1: TForm1
 Left = 0
 Top = 0
 Caption = 'Form1'
 ClientHeight = 179
 ClientWidth = 277
 Color = clBtnFace
 Font.Charset = DEFAULT_CHARSET
 Font.Color = clWindowText
 Font.Height = -11
 Font.Name = 'Tahoma'
 Font.Style = []
 OldCreateOrder = False
 Position = poDesktopCenter
 OnMouseDown = FormMouseDown
 OnMouseMove = FormMouseMove
 OnMouseUp = FormMouseUp
 OnPaint = FormPaint
 PixelsPerInch = 96
 TextHeight = 13
end

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