再学 GDI+[41]: 文本输出 - 控制输出字符的个数

本例效果图:

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代码文件:

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unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs;



type

  TForm1 = class(TForm)

    procedure FormPaint(Sender: TObject);

    procedure FormClick(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



uses GDIPOBJ,GDIPAPI;



var

  pc: PChar = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';

  num: Integer;



procedure TForm1.FormPaint(Sender: TObject);

var

  g: TGPGraphics;

  b: TGPBrush;

  font: TGPFont;

begin

  g := TGPGraphics.Create(Canvas.Handle);

  b := TGPSolidBrush.Create(aclGoldenrod);



  font := TGPFont.Create('Arial Black', 18, FontStyleRegular);

  

  {参数 2 为输出字符的个数, -1 表示全部输出}

  g.DrawString(pc, num, font, MakePoint(5.0, 5), b);



  b.Free;

  font.Free;

  g.Free;

end;



procedure TForm1.FormClick(Sender: TObject);

var

  i,n: Integer;

begin

  n := Length(pc);

  num := 0;

  for i:= 1 to n do

  begin

    num := i;

    Repaint;

    Sleep(100);

    Application.ProcessMessages;

  end;



  num := -1;

  for i:= 1 to Length(pc) do

  begin

    Inc(pc);

    Repaint;

    Sleep(100);

    Application.ProcessMessages;

  end;



  Dec(pc,n);

end;



end.


 
   

窗体文件:

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object Form1: TForm1

  Left = 0

  Top = 0

  Caption = 'Form1'

  ClientHeight = 42

  ClientWidth = 501

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  Position = poDesktopCenter

  OnClick = FormClick

  OnPaint = FormPaint

  PixelsPerInch = 96

  TextHeight = 13

end