再學 GDI+[87]: TGPImage(7) - 調整圖像大小

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:temptest.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