WinAPI: MoveToEx 与 LineTo - 绘制直线

//声明:

MoveToEx(

  DC: HDC;         {设备环境句柄}

  p2, p3: Integer; {坐标}

  p4: PPoint       {用于保存 p2、p3 值的 TPoint 结构的指针}

): BOOL;



LineTo(

  DC: HDC;      {设备环境句柄}

  X, Y: Integer {直线终点坐标}

): BOOL;


 
   




//举例:

unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls;



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);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



var

  flag: Boolean;



procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;

  Shift: TShiftState; X, Y: Integer);

begin

  MoveToEx(Canvas.Handle, X, Y, nil);

  flag := True;

end;



procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,

  Y: Integer);

begin

  if flag then LineTo(Canvas.Handle, X, Y);

end;



procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;

  Shift: TShiftState; X, Y: Integer);

begin

  flag := False;

end;



end.


 
   




//效果图:

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