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 程式師世界 >> 編程語言 >> 更多編程語言 >> Delphi >> 再學GDI+[83]: TGPImage(3) - 平行四邊形變換

再學GDI+[83]: TGPImage(3) - 平行四邊形變換

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 FormCreate(Sender: TObject);
  procedure FormDestroy(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);
 end;
var
 Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
var
 img: TGPImage;
 pts: array[0..2] of TGPPoint;
 flag: Integer = -1;
procedure TForm1.FormCreate(Sender: TObject);
var
 w,h: Integer;
begin
 img := TGPImage.Create('C:\temp\test.jpg');
 w := img.GetWidth;
 h := img.GetHeight;
 pts[0] := MakePoint((ClientWidth - w) div 2 + w, (ClientHeight - h) div 2);
 pts[1] := MakePoint((ClientWidth - w) div 2, (ClientHeight - h) div 2);
 pts[2] := MakePoint((ClientWidth - w) div 2 + w, (ClientHeight - h) div 2 + h);
 DoubleBuffered := True;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
 img.Free;
end;
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
 Shift: TShiftState; X, Y: Integer);
var
 i: Integer;
begin
 for i := 0 to Length(pts) do
  if PtInRect(Bounds(pts[i].X-3, pts[i].Y-3, 6, 6), Point(X, Y)) then
  begin
   flag := i;
   Exit;
  end;
end;
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
 Y: Integer);
begin
 if flag = -1 then Exit;
 pts[flag] := MakePoint(X, Y);
 Repaint;
end;
procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
 Shift: TShiftState; X, Y: Integer);
begin
 flag := -1;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
 g: TGPGraphics;
 p: TGPPen;
 i: Integer;
begin
 g := TGPGraphics.Create(Self.Canvas.Handle);
 p := TGPPen.Create(aclRed);
 {第一點: 右上角; 第二點: 左上角; 第三點: 右下角; 第四點將根據平行四邊形計算; 只能是三個點.}
 g.DrawImage(img, PGPPoint(@pts), Length(pts));
 for i := 0 to Length(pts)-1 do g.DrawRectangle(p, pts[i].X-3, pts[i].Y-3, 6, 6);
 p.Free;
 g.Free;
end;
end.

窗體文件:object Form1: TForm1
 Left = 0
 Top = 0
 Caption = 'Form1'
 ClientHeight = 206
 ClientWidth = 307
 Color = clBtnFace
 Font.Charset = DEFAULT_CHARSET
 Font.Color = clWindowText
 Font.Height = -11
 Font.Name = 'Tahoma'
 Font.Style = []
 OldCreateOrder = False
 Position = poDesktopCenter
 OnCreate = FormCreate
 OnDestroy = FormDestroy
 OnMouseDown = FormMouseDown
 OnMouseMove = FormMouseMove
 OnMouseUp = FormMouseUp
 OnPaint = FormPaint
 PixelsPerInch = 96
 TextHeight = 13
end

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