Use Asp.net to draw a pie chart

// Use Asp.net to draw a pie chart (which can be used for various voting tasks) Program )
// Compared with ASP, Asp.net has more powerful functions. using GDI +, you can easily implement many graphics Functions that you previously could not do.
// First, create the library mess. MDB in c: \ and create the table title.
// Create two fields, title (char type) and point (INT type)
// Very satisfied 281
// 297 satisfied
// Merge 166
// Not satisfied: 416
<% @ Page Language = "C #" %>
<% @ Import namespace = "system. Data" %>
<% @ Import namespace = "system. Data. oledb" %>
<% @ Import namespace = "system. Drawing" %>
<% @ Import namespace = "system. Drawing. Imaging" %>
<Script language = "C #" runat = "server">
Public void page_load (Object OBJ, eventargs E)
{
// Specify the connection string as a constant.
Const string strconn = "provider = Microsoft. Jet. oledb.4.0;" +
"Data Source = c: \ mess. mdb ";
Oledbconnection conn = new oledbconnection (strconn );
Conn. open ();
String SQL = "select * From Title ";
Oledbcommand cmd = new oledbcommand (SQL, Conn );
Dataset DS = new dataset ();
Oledbdataadapter adapter1 = new oledbdataadapter (CMD );
Adapter1.fill (DS );
Conn. Close ();
Float Total = 0.0f, TMP;
Int iloop;
For (iloop = 0; iloop <Ds. Tables [0]. Rows. Count; iloop ++)
{
TMP = convert. tosingle (Ds. Tables [0]. Rows [iloop] ["point"]); // converts it to a single precision, and it is impossible to vote for half a vote. You can also write it as convert. toint32.
Total + = TMP;
}
// Response. Write (convert. tostring (total ));

Font fontlegend = new font ("verdana", 9), fonttitle = new font ("verdana", 10, fontstyle. Bold); // set the font
// Fonttitle indicates the font of the title.

Int width = 230; // white background width
Const int bufferspace = 15;
Int legendheight = fontlegend. Height * (Ds. Tables [0]. Rows. Count + 1) + bufferspace;
Int titleheight = fonttitle. height + bufferspace;
Int Height = width + legendheight + titleheight + bufferspace; // the white background height.
Int pieheight = width;
Rectangle pierect = new rectangle (0, titleheight, width, pieheight );

// Add various random colors
Arraylist colors = new arraylist ();
Random RND = new random ();
For (iloop = 0; iloop <Ds. Tables [0]. Rows. Count; iloop ++)
Colors. Add (New solidbrush (color. fromargb (RND. Next (255), RND. Next (255), RND. Next (255 ))));

Bitmap objbitmap = new Bitmap (width, height); // create a bitmap instance
// Bitmap objbitmap = new Bitmap (230,500); // create a bitmap instance
Graphics objgraphics = graphics. fromimage (objbitmap );

Objgraphics. fillrectangle (New solidbrush (color. White), 0, 0, width, height); // draw a white background
Objgraphics. fillrectangle (New solidbrush (color. lightyellow), pierect); // draw a bright yellow background
// The following is a pie chart (several rows of rows are drawn)
Float currentdegree = 0.0f;
For (iloop = 0; iloop <Ds. Tables [0]. Rows. Count; iloop ++)
{
Objgraphics. fillpie (solidbrush) colors [iloop], pierect, currentdegree,
Convert. tosingle (Ds. Tables [0]. Rows [iloop] ["point"])/Total * 360 );
Currentdegree + = convert. tosingle (Ds. Tables [0]. Rows [iloop] ["point"])/Total * 360;
}
// --- Generate the main title as follows
Solidbrush blackbrush = new solidbrush (color. Black );
String title = "this" Programmer base camp "introduced a supporting special publication. Are you satisfied with this special publication? ";
Stringformat = new stringformat ();
Stringformat. Alignment = stringalignment. Center;
Stringformat. linealignment = stringalignment. Center;

Objgraphics. drawstring (title, fonttitle, blackbrush,
New rectangle (0, 0, width, titleheight), stringformat );
// List fields and votes
Objgraphics. drawrectangle (new pen (color. Black, 2), 0, height-legendheight, width, legendheight );
For (iloop = 0; iloop <Ds. Tables [0]. Rows. Count; iloop ++)
{
Objgraphics. fillrectangle (solidbrush) colors [iloop], 5, height-legendheight + fontlegend. Height * iloop + 5, 10, 10 );
Objgraphics. drawstring (string) ds. tables [0]. rows [iloop] ["title"]) + "-" + convert. tostring (Ds. tables [0]. rows [iloop] ["point"]), fontlegend, blackbrush,
20, height-legendheight + fontlegend. Height * iloop + 1 );
}
//
Objgraphics. drawstring ("total votes:" + convert. tostring (total), fontlegend, blackbrush, 5, height-fontlegend. Height );
// The total height of the image-the height of a row of font, that is, the height of the row of the base row (height-fontlegend. Height)
Response. contenttype = "image/JPEG ";
Objbitmap. Save (response. outputstream, imageformat. JPEG );
// Objbitmap. Save ("myyyyyyyyyyy.jpg", imageformat. JPEG); // output to the file

Objgraphics. Dispose ();
Objbitmap. Dispose ();
}
</SCRIPT>