再學GDI+[60]: TGPGraphics.SetSmoothingMode - 繪圖質量

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)
　　ListBox1: TListBox;
　　procedure FormCreate(Sender: TObject);
　　procedure FormPaint(Sender: TObject);
　　procedure ListBox1Click(Sender: TObject);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
procedure TForm1.FormCreate(Sender: TObject);
begin
　ListBox1.Align := alRight;
　with ListBox1.Items do
　begin
　　Add('SmoothingModeInvalid　　');　　　
　　Add('SmoothingModeDefault　　');
　　Add('SmoothingModeHighSpeed　');　　
　　Add('SmoothingModeHighQuality');　
　　Add('SmoothingModeNone　　　 ');
　　Add('SmoothingModeAntiAlias　');　
　end;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
　g: TGPGraphics;
　p: TGPPen;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　p := TGPPen.Create(aclRed, 2);
　g.SetSmoothingMode(ListBox1.ItemIndex - 1);
　g.DrawEllipse(p, 10, 10, ClientWidth - ListBox1.Width - 20, ClientHeight - 20);
　g.DrawLine(p, 0, 0, ClientWidth - ListBox1.Width, ClientHeight);
　g.DrawLine(p, ClientWidth - ListBox1.Width, 0, 0, ClientHeight);
　p.Free;
　g.Free;
end;
procedure TForm1.ListBox1Click(Sender: TObject);
begin
　Repaint;
end;
end.

窗體文件:object Form1: TForm1
　Left = 0
　Top = 0
　Caption = 'Form1'
　ClientHeight = 108
　ClientWidth = 286
　Color = clBtnFace
　Font.Charset = DEFAULT_CHARSET
　Font.Color = clWindowText
　Font.Height = -11
　Font.Name = 'Tahoma'
　Font.Style = []
　OldCreateOrder = False
　Position = poDesktopCenter
　OnCreate = FormCreate
　OnPaint = FormPaint
　PixelsPerInch = 96
　TextHeight = 13
　object ListBox1: TListBox
　　Left = 133
　　Top = 8
　　Width = 145
　　Height = 73
　　ItemHeight = 13
　　TabOrder = 0
　　OnClick = ListBox1Click
　end
end繪圖質量參數:SmoothingModeInvalid　　 = -1; {指定一個無效模式}
SmoothingModeDefault　　 = 0;　{指定不消除鋸齒}
SmoothingModeHighSpeed　 = 1;　{指定高速度、低質量呈現}
SmoothingModeHighQuality = 2;　{指定高質量、低速度呈現}
SmoothingModeNone　　　　= 3;　{指定不消除鋸齒}
SmoothingModeAntiAlias　 = 4;　{指定消除鋸齒的呈現}