代码文件:
unit Unit1;interfaceuses 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 = 13end