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 程式師世界 >> 編程語言 >> 更多編程語言 >> Delphi >> 學GDI+[14]: DrawBeziers - 繪制一組貝塞爾線

學GDI+[14]: DrawBeziers - 繪制一組貝塞爾線

編輯:Delphi

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 FormPaint(Sender: TObject);
  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 FormCreate(Sender: TObject);
 end;
var
 Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ,GDIPAPI;
var
 pts: array of TGPPoint;
 ptn: Integer = -1;
 f: Boolean;
procedure TForm1.FormCreate(Sender: TObject);
begin
 Text := '按住 Ctrl 鍵可添加點';
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);
 g.DrawBezIErs(p, PGPPoint(pts), Length(pts));
 p.SetColor(aclBlue);
 for i := Low(pts) to High(pts) do
  g.DrawRectangle(p, MakeRect(Rect(pts[i].X-2, pts[i].Y-2, pts[i].X+2, pts [i].Y+2)));
 g.Free;
 p.Free;
end;
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
 Shift: TShiftState; X, Y: Integer);
begin
 f := True;
end;
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
 Y: Integer);
var
 R: TRect;
 i: Integer;
begin
 if f then
 begin
  if ptn = -1 then Exit;
  pts[ptn].X := X;
  pts[ptn].Y := Y;
  Repaint;
 end else begin
  ptn := -1;
  Cursor := crDefault;
  for i := Low(pts) to High(pts) do
  begin
   R := Rect(pts[i].X-2, pts[i].Y-2, pts[i].X+2, pts[i].Y+2);
   if PtInRect(R, Point(X, Y)) then
   begin
    ptn := i;
    Cursor := crHandPoint;
   end;
  end;
 end;
end;
procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
 Shift: TShiftState; X, Y: Integer);
begin
 f := False;
 if ssCtrl in Shift then
 begin
  SetLength(pts, Length(pts)+1);
  pts[High(pts)].X := X;
  pts[High(pts)].Y := Y;
  Canvas.Pen.Color := clBlue;
  Canvas.Rectangle(X-2, Y-2, X+2, Y+2);
  {當點數是 3*n+1 時再繪制}
  if Length(pts) mod 3 = 1 then Repaint;
 end;
end;
end.

窗體文件:object Form1: TForm1
 Left = 0
 Top = 0
 Caption = 'Form1'
 ClIEntHeight = 188
 ClIEntWidth = 254
 Color = clBtnFace
 Font.Charset = DEFAULT_CHARSET
 Font.Color = clWindowText
 Font.Height = -11
 Font.Name = 'Tahoma'
 Font.Style = []
 OldCreateOrder = False
 Position = poDesktopCenter
 OnCreate = FormCreate
 OnMouseDown = FormMouseDown
 OnMouseMove = FormMouseMove
 OnMouseUp = FormMouseUp
 OnPaint = FormPaint
 PixelsPerInch = 96
 TextHeight = 13
end

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