本例效果圖:
代碼文件:unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm1 = class(TForm)
CheckBox1: TCheckBox;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure FormPaint(Sender: TObject);
procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
var
img: TGPImage;
rt: TGPRectF;
n: Single = 2.0; {放大的倍數}
procedure TForm1.FormCreate(Sender: TObject);
begin
img := TGPImage.Create('c:\temp\test.png');
ClientWidth := img.GetWidth;
ClientHeight := img.GetHeight;
Position := poDesktopCenter;
DoubleBuffered := True;
CheckBox1.Caption := '使用放大鏡';
CheckBox1.Left := ClientWidth - CheckBox1.Width;
CheckBox1.Top := ClientHeight - CheckBox1.Height - 2;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
img.Free;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
g: TGPGraphics;
p: TGPPen;
b: TGPSolidBrush;
begin
g := TGPGraphics.Create(Canvas.Handle);
p := TGPPen.Create(MakeColor(128, 255, 255, 255));
b := TGPSolidBrush.Create(aclBlack);
{原圖像}
g.DrawImage(img, 0, 0, img.GetWidth, img.GetHeight);
if CheckBox1.Checked then
begin
{放大鏡的陰影}
g.FillRectangle(b, MakeRect(rt.X + 2, rt.Y + 2, rt.Width, rt.Height));
{放大後的局部圖像: 參數2是放大後的范圍; 參數3-6是要被放大的范圍; 參數7是單位}
g.DrawImage(img, rt, rt.X, rt.Y, rt.Width / n, rt.Height / n, UnitPixel);
{放大鏡的邊框}
g.DrawRectangle(p, rt);
end;
b.Free;
p.Free;
g.Free;
end;
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
begin
if CheckBox1.Checked then
begin
rt := MakeRect(X, Y, 150.0, 150);
Repaint;
end;
end;
end.
窗體文件:object Form1: TForm1
Left = 0
Top = 0
Caption = 'Form1'
ClientHeight = 206
ClientWidth = 339
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'Tahoma'
Font.Style = []
OldCreateOrder = False
OnCreate = FormCreate
OnDestroy = FormDestroy
OnMouseMove = FormMouseMove
OnPaint = FormPaint
PixelsPerInch = 96
TextHeight = 13
object CheckBox1: TCheckBox
Left = 240
Top = 181
Width = 97
Height = 17
Caption = 'CheckBox1'
TabOrder = 0
end
end
