---- Delphi 4.0对Internet编程提供了强大的支持，Delphi 4.0编写CGI非常容易， Delphi 4.0本身提供了例程。但是笔者在实践中遇到需要CGI程序根据数据库动态 返回图象的情况，很多文章推进使用Cgi-Expert或有关的OCX控件，使用控件不仅 带来额外的开销，且缺乏灵活性，那么能否不使用这些控件自己编写代码实现，现 推荐一种方法，代码如下：

unit ChartMod;





interface





uses

Windows, Messages, SysUtils, Classes,

HTTPApp, Db, DBTables,

DbChart, Series, Jpeg, ExtCtrls;





type

TWebModule1 = class(TWebModule)

Table1: TTable;

procedure WebModule1ActionAreaAction

(Sender: TObject;

Request: TWebRequest; Response:

TWebResponse; var Handled:

Boolean);

procedure WebModule1ActionPopulationAction

(Sender: TObject;

Request: TWebRequest; Response:

TWebResponse; var Handled:

Boolean);

procedure WebModule1Create(Sender: TObject);

procedure WebModule1Destroy(Sender: TObject);

procedure WebModule1AfterDispatch(Sender: TObject;

Request: TWebRequest; Response:

TWebResponse; var Handled: Boolean);

private

Chart: TDBChart;

Series: TPieSeries;

Image: TImage;

public

{ Public declarations }

end;





var

WebModule1: TWebModule1;





implementation





{$R *.DFM}





procedure TWebModule1.WebModule1ActionAreaAction(

Sender: TObject;

Request: TWebRequest; Response: TWebResponse;

var Handled: Boolean);





begin

// set specific values

Chart.Title.Text.Clear;

Chart.Title.Text.Add ('Area of Countries');

Chart.LeftAxis.Title.Caption := 'Area';

Series.Title := 'Area';

Series.PieValues.ValueSource := 'Area';

end;





procedure TWebModule1.WebModule1ActionPopulationAction(

Sender: TObject;

Request: TWebRequest; Response: TWebResponse;

var Handled: Boolean);





begin

// set specific values

Chart.Title.Text.Clear;

Chart.Title.Text.Add ('Population of Countries');

Chart.LeftAxis.Title.Caption := 'Population';

Series.Title := 'Population';

Series.PieValues.ValueSource := 'Population';

end;





procedure TWebModule1.WebModule1Create(Sender: TObject);

begin

// open the database table

Table1.Open;

// create the chart

Chart := TDBChart.Create (nil);

Chart.Width := 600;

Chart.Height := 400;

Chart.AxisVisible := False;

Chart.Legend.Visible := False;

Chart.BottomAxis.Title.Caption := 'Name';

// create the pie series

Series := TPieSeries.Create (Chart);

Series.ParentChart := Chart;

Series.DataSource := Table1;

Series.XLabelsSource := 'Name';

Series.OtherSlice.Style := poBelowPercent;

Series.OtherSlice.Text := 'Others';

Series.OtherSlice.Value := 2;

Chart.AddSeries (Series);

// create the memory bitmap

Image := TImage.Create (nil);

Image.Width := Chart.Width;

Image.Height := Chart.Height;

end;





procedure TWebModule1.WebModule1Destroy(

Sender: TObject);





begin

Chart.Free;

Series.Free;

Image.Free;

end;





procedure TWebModule1.WebModule1AfterDispatch(

Sender: TObject;

Request: TWebRequest; Response: TWebResponse;

var Handled: Boolean);





var

Jpeg: TJpegImage;

MemStr: TMemoryStream;

begin

// paint the chart on the memory bitmap

Chart.Draw (Image.Canvas, Image.BoundsRect);

// create the jpeg and copy the iamge to it

Jpeg := TJpegImage.Create;

try

Jpeg.Assign (Image.Picture.Bitmap);

MemStr := TMemoryStream.Create;

try

// save to a stream and return it

Jpeg.SaveToStream (MemStr);

MemStr.Position := 0;

Response.ContentType := 'image/jpeg';

Response.ContentStream := MemStr;

Response.SendResponse;

finally

MemStr.Free;

end;

finally

Jpeg.Free;

end;

end;





end.

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