再学 GDI+[60]: TGPGraphics.SetSmoothingMode - 绘图质量

本例效果图:

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代码文件:

---

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.


 
   

窗体文件:

---

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


 
   

绘图质量参数:

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SmoothingModeInvalid     = -1; {指定一个无效模式}

SmoothingModeDefault     = 0;  {指定不消除锯齿}

SmoothingModeHighSpeed   = 1;  {指定高速度、低质量呈现}

SmoothingModeHighQuality = 2;  {指定高质量、低速度呈现}

SmoothingModeNone        = 3;  {指定不消除锯齿}

SmoothingModeAntiAlias   = 4;  {指定消除锯齿的呈现}