Рисование линий, Как в Paint

Материал из DRKB


unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Image1: TImage;
    procedure FormCreate(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 }
    StartX: Integer;
    StartY: Integer;
    EndX: Integer;
    EndY: Integer;
    isMousePressed: Boolean;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  isMousePressed := False;
  Image1.Picture.Bitmap := TBitmap.create();
  Image1.Picture.Bitmap.Width := Image1.Width;
  Image1.Picture.Bitmap.Height := Image1.Height
end;

procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  StartX := X;
  StartY := Y;
  EndX := StartX;
  EndY := StartY;
  isMousePressed := True
end;

procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  isMousePressed := False;
  Image1.Picture.Bitmap.Canvas.Pen.Mode := pmNOT;
  Image1.Picture.Bitmap.Canvas.moveTo(StartX, StartY);
  Image1.Picture.Bitmap.Canvas.lineTo(EndX, EndY);
  Image1.Picture.Bitmap.Canvas.Pen.Mode := pmCopy;
  EndX := X;
  EndY := Y;
  Image1.Picture.Bitmap.Canvas.MoveTo(StartX, StartY);
  Image1.Picture.Bitmap.Canvas.LineTo(EndX, EndY)
end;

procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
begin
  if isMousePressed then
  begin
    Image1.Picture.Bitmap.Canvas.Pen.Mode := pmNOT;
    Image1.Picture.Bitmap.Canvas.MoveTo(StartX, StartY);
    Image1.Picture.Bitmap.Canvas.LineTo(EndX, EndY);
    EndX := X;
    EndY := Y;
    Image1.Picture.Bitmap.Canvas.MoveTo(StartX, StartY);
    Image1.Picture.Bitmap.Canvas.LineTo(EndX, EndY);
    Image1.Picture.Bitmap.Canvas.Pen.Mode := pmCopy
  end
end;

end.


Более развернутую демку можно найти в папке {$DELPHI7}/Demos/Doc/Graphex


Author: Mischka
Source: http://forum.sources.ru
ID: 03825