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 程式師世界 >> 編程語言 >> 更多編程語言 >> Delphi >> 再學GDI+[87]: TGPImage(7) - 調整圖像大小

再學GDI+[87]: TGPImage(7) - 調整圖像大小

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 FormCreate(Sender: TObject);
  procedure FormDestroy(Sender: TObject);
  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);
 private
  procedure RectToPoints;
 end;
var
 Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
var
 img: TGPImage;
 flag: Integer = -1;
 ClickImg: Boolean;
 rt: TRect;
 pts: array[0..7] of TPoint;
 x1,y1: Integer;
{從矩形中獲取八個點, 因要反復使用, 故提取為一個獨立的過程}
procedure TForm1.RectToPoints;
begin
 pts[0] := rt.TopLeft;
 pts[1] := Point(rt.Left, rt.Top + (rt.Bottom - rt.Top) div 2);
 pts[2] := Point(rt.Left, rt.Bottom);
 pts[3] := Point(rt.Left + (rt.Right - rt.Left) div 2, rt.Bottom);;
 pts[4] := rt.BottomRight;
 pts[5] := Point(rt.Right, rt.Top + (rt.Bottom - rt.Top) div 2);;
 pts[6] := Point(rt.Right, rt.Top);;
 pts[7] := Point(rt.Left + (rt.Right - rt.Left) div 2, rt.Top);
end;
procedure TForm1.FormCreate(Sender: TObject);
const
 ImgPath = 'c:\temp\test.png';
var
 w,h: Integer;
begin
 if not FileExists(ImgPath) then Exit;
 img := TGPImage.Create(ImgPath);
 w := img.GetWidth;
 h := img.GetHeight;
 rt.Left := (ClientWidth - w) div 2;
 rt.Top := (ClientHeight - h) div 2;
 rt.Right := rt.Left + w;
 rt.Bottom := rt.Top + h;
 RectToPoints;
 DoubleBuffered := True;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
 img.Free;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
 g: TGPGraphics;
 p: TGPPen;
 i: Integer;
begin
 g := TGPGraphics.Create(Canvas.Handle);
 p := TGPPen.Create(aclRed);
 g.DrawImage(img, MakeRect(rt));
 if ClickImg then
  for i := 0 to Length(pts) - 1 do
   g.DrawRectangle(p, MakeRect(pts[i].X - 3, pts[i].Y - 3, 6, 6));
 p.Free;
 g.Free;
end;
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
 Shift: TShiftState; X, Y: Integer);
var
 i: Integer;
begin
 flag := -1;
 for i := 0 to Length(pts) - 1 do
  if PtInRect(Bounds(pts[i].X - 3, pts[i].Y - 3, 6, 6), Point(X, Y)) then
  begin
   flag := i;
   Break;
  end;
 if flag = -1 then
 begin
  ClickImg := PtInRect(rt, Point(X,Y));
  Repaint;
 end else begin
  x1 := X;
  y1 := Y;
 end;
end;
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
 Y: Integer);
begin
 if flag = -1 then Exit;
 case flag of
  0: begin Inc(rt.Left, X-x1); Inc(rt.Top, Y-y1) end;
  1: begin Inc(rt.Left, X-x1) end;
  2: begin Inc(rt.Left, X-x1); Inc(rt.Bottom, Y-y1) end;
  3: begin Inc(rt.Bottom, Y-y1) end;
  4: begin Inc(rt.Right, X-x1); Inc(rt.Bottom, Y-y1) end;
  5: begin Inc(rt.Right, X-x1) end;
  6: begin Inc(rt.Right, X-x1); Inc(rt.Top, Y-y1) end;
  7: begin Inc(rt.Top, Y-y1) end;
 end;
 x1 := X;
 y1 := Y;
 RectToPoints;
 Repaint;
end;
procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
 Shift: TShiftState; X, Y: Integer);
begin
 flag := -1;
end;
end.

窗體文件:object Form1: TForm1
 Left = 0
 Top = 0
 Caption = 'Form1'
 ClientHeight = 246
 ClientWidth = 346
 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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