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 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 個矩形中', [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.
窗體文件: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
