Image1.Canvas画图笔刷

 

如何背景透明

 

 

 

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.ExtCtrls;

type
  TForm1 = class(TForm)
    Image1: TImage;
     procedure Image1MouseMove(Sender: TObject; Shift: TShiftState; X,
      Y: Integer);
     procedure Image1MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
     procedure Image1MouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
     procedure FormCreate(Sender: TObject);
   private
     { Private declarations }
   public
     { Public declarations }
   end;

var
  Form1: TForm1;

  pt:tpoint;
  Move:integer ;
implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
   with Image1.Canvas do
   begin
     Pen.Width := 10;
     Pen.Color :=clRed;
     brush.Style :=bsCross;


      //透明
   end;
end;

procedure TForm1.Image1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  move := 1;
  pt.x :=x;
  pt.Y :=y;
end;

procedure TForm1.Image1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
   if move <> 0 then
   begin
    Image1.Canvas.MoveTo(pt.X,pt.Y);
    Image1.Canvas.LineTo(x,y);
    pt.X :=x;
    pt.Y :=y;
   end;
end;

procedure TForm1.Image1MouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
    Move := 0;
end;

end.

来自为知笔记(Wiz)