再学 GDI+[12] 准备工作 - 矩形命中

 

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    procedure FormPaint(Sender: TObject);
    procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure FormMouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
uses
  GDIPOBJ,GDIPAPI;
var
  PtArr:array of TRect;
  x1,y1,x2,y2:Integer;
  flag:Boolean;
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  flag:=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 flag then
  begin
    Canvas.DrawFocusRect(Rect(x1,y1,x2,y2));
    x2:=x;
    y2:=y;
    Canvas.DrawFocusRect(Rect(x1,y1,x2,y2));
  end
  else
  begin
    Text:='';
  end;
    for i := Low(PtArr) to High(PtArr) do
      if PtInRect(ptarr[i], Point(X,Y)) then
        Text := Format('在第 %d 个矩形中', [i+1]);
end;

procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  if not flag then
  Exit;
  SetLength(PtArr,Length(PtArr)+1);
  PtArr[High(PtArr)]:=Rect(x1,y1,x2,y2);
  flag:=False;
  Repaint;
end;

procedure TForm1.FormPaint(Sender: TObject);
var
  g:TGPGraphics;
  p:TGPPen;
  i:Integer;
begin
  g:=TGPGraphics.Create(Canvas.Handle);
  g.Clear(aclWhite);
  p:=TGPPen.Create(aclRed,2);

  for I := Low(PtArr) to High(PtArr) do
  begin
    g.DrawRectangle(p,MakeRect(ptarr[i]));
  end;
  p.Free;
  g.Free;

end;

end.