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<%--
Pro ASP.NET Web Forms Techniques, Second Edition
By Alex Homer
ISBN: 1-59059-317-0
Published: Dec 2003
Publisher: Apress.com
--%>
<%@Page Language="C#" %>
<%@Import Namespace="System.Drawing" %>
<%@Import Namespace="System.Drawing.Imaging" %>
<%@Import Namespace="System.Data" %>
<script runat="server">
void Page_Load() {
Response.ContentType="image/gif";
String sCaption = "Chart caption";
DrawPieChart(GetDataSet(), 420, 250, sCaption);
}
void DrawPieChart(DataSet dsData, int iWidth, int iHeight, String sCaption) {
Bitmap oBitMap = new Bitmap(iWidth, iHeight);
Graphics oGraphics = Graphics.FromImage(oBitMap);
Pen oPen = new Pen(Color.Black, 1);
SolidBrush oBrush = new SolidBrush(Color.White);
oGraphics.FillRectangle(oBrush, 0, 0, oBitMap.Width,
oBitMap.Height);
DrawText(oGraphics, 0, 0, oBitMap.Width, 20, sCaption,
FontStyle.Bold, 10, "", StringAlignment.Center, 0);
Color[] aColors = GetColorArray();
int iCaptionHeight = 30;
int iPieTopOffset = iCaptionHeight;
int iPieDiameter = oBitMap.Height - iCaptionHeight - 6;
if (iPieDiameter > (oBitMap.Width * 0.6)) {
iPieDiameter = (int)(oBitMap.Width * 0.6);
iPieTopOffset = ((oBitMap.Height - iPieDiameter) / 2) + iCaptionHeight;
}
Rectangle oRectPie = new Rectangle(0, iPieTopOffset,
iPieDiameter, iPieDiameter);
Rectangle oRectShadow = new Rectangle(5, iPieTopOffset + 5,
iPieDiameter, iPieDiameter);
// create color for shadows to objects
Color cShadow = Color.FromArgb(153, 153, 153);
// set brush color and draw circle for shadow
oBrush.Color = cShadow;
oGraphics.FillEllipse(oBrush, oRectShadow);
// get reference to collection of data rows
DataRowCollection colRows = dsData.Tables[0].Rows;
// calculate left positin of "value key" boxes
int iKeyBoxLeft = iPieDiameter + 45;
// calculate vertical spacing for "value key" boxes
int iKeyBoxSpace = (oBitMap.Height - iCaptionHeight - 15) / (colRows.Count - 1);
// declare variables we'll need
DataRow oRow; // reference to data row
int iRowIndex = 0; // index for current row
float fSliceStart = 0; // start degrees of slice
float fSliceDegrees; // number of degrees for slice
int iKeyBoxTop; // vertical offset of "key" box
Double fTotalValue = 0; // total of all values in table
// variables to hold values extracted from rows
String sSliceCaption;
Double fSliceValue;
// calculate total of all values in data table
// iterate through the rows in the table
foreach (DataRow oERow in colRows) {
try {
fTotalValue += (Double)oERow[1];
}
catch {}
}
// now ready to draw the pie chart itself
// iterate through the rows in the table again
foreach (DataRow oERow in colRows) {
// calculate vertical position of "key" box
iKeyBoxTop = iCaptionHeight + (iKeyBoxSpace * iRowIndex);
// draw shadow for "key" box
oBrush.Color = cShadow;
oGraphics.FillRectangle(oBrush, iKeyBoxLeft + 3, iKeyBoxTop + 3, 15, 14);
// get values from data row
try {
sCaption = (String)oERow[0];
fSliceValue = (Double)oERow[1];
}
catch {
sCaption = "Error";
fSliceValue = 0;
}
// convert to number of degrees for this value
fSliceDegrees = (float)((fSliceValue / fTotalValue) * 360);
// set brush color from array of colors
oBrush.Color = aColors[iRowIndex];
// draw filled pie slice and then outline in black
oGraphics.FillPie(oBrush, oRectPie, fSliceStart, fSliceDegrees);
oGraphics.DrawPie(oPen, oRectPie, fSliceStart, fSliceDegrees);
// draw filled "key" rectangle and then outline in black
oGraphics.FillRectangle(oBrush, iKeyBoxLeft, iKeyBoxTop, 15, 14);
oGraphics.DrawRectangle(oPen, iKeyBoxLeft, iKeyBoxTop, 15, 14);
// draw caption text next to "key" box
DrawText(oGraphics, iKeyBoxLeft + 22, iKeyBoxTop,
oBitMap.Width - iKeyBoxLeft + 22, 14, sCaption,
FontStyle.Bold, 9, "", null, 0);
// save start position for next slice and increment row index
fSliceStart += fSliceDegrees;
iRowIndex += 1;
}
// write bitmap to response
oBitMap.Save(Response.OutputStream, ImageFormat.Gif);
oBitMap.Save(MapPath("piechart.gif"), ImageFormat.Gif);
// dispose of objects
oPen.Dispose();
oBrush.Dispose();
oGraphics.Dispose();
oBitMap.Dispose();
}
// -------------------------------------------------------------------
// routine to draw text string in rectangle on bitmap
void DrawText(Graphics oGraphics, int iTop, int iLeft, int iWidth,
int iHeight, String sText, object eFontStyle,
int iFontSize, String sColor, object eAlign,
StringFormatFlags eFlag) {
// set default values if not specified
if (eFontStyle == null) eFontStyle = FontStyle.Regular;
if (iFontSize == 0) iFontSize = 8;
if (sColor == "") sColor = "Black";
if (eAlign == null) eAlign = StringAlignment.Near;
// create the rectange to hold the text
RectangleF oRect = new RectangleF(iTop, iLeft, iWidth, iHeight);
// create a Font object for the text style
Font oFont = new Font("Arial", iFontSize, (FontStyle)eFontStyle);
// create the format object to define the format and style
StringFormat oFormat = new StringFormat(eFlag);
oFormat.Alignment = (StringAlignment)eAlign; // horizontal alignment
// always center vertically within rectangle area
oFormat.LineAlignment = StringAlignment.Center;
// create a brush object and draw the text
SolidBrush oBrush = new SolidBrush(Color.FromName(sColor));
oGraphics.DrawString(sText, oFont, oBrush, oRect, oFormat);
}
// -------------------------------------------------------------------
Color[] GetColorArray() {
// declare an Array for 20 colors
Color[] aColors = new Color[20];
// fill the array of colors for chart items
// use browser-safe colors (multiples of #33)
aColors[0] = Color.FromArgb(204, 0, 0); // red
aColors[1] = Color.FromArgb(255, 153, 0); // orange
aColors[2] = Color.FromArgb(255, 255, 0); // yellow
aColors[3] = Color.FromArgb(0 ,255, 0); // green
aColors[4] = Color.FromArgb(0, 255, 255); // cyan
aColors[5] = Color.FromArgb(51, 102, 255); // blue
aColors[6] = Color.FromArgb(255, 0, 255); // magenta
aColors[7] = Color.FromArgb(102, 0, 102); // purple
aColors[8] = Color.FromArgb(153, 0, 0); // dark red
aColors[9] = Color.FromArgb(153, 153, 0); // khaki
aColors[10] = Color.FromArgb(0, 102, 0); // dark green
aColors[11] = Color.FromArgb(51, 51, 102); // dark blue
aColors[12] = Color.FromArgb(102, 51, 0); // brown
aColors[13] = Color.FromArgb(204, 204, 204); // light gray
aColors[14] = Color.FromArgb(0, 0, 0); // black
aColors[15] = Color.FromArgb(102, 204, 255); // sky
aColors[16] = Color.FromArgb(255, 204, 255); // pink
aColors[17] = Color.FromArgb(255, 255, 204); // chiffon
aColors[18] = Color.FromArgb(255, 204, 204); // flesh
aColors[19] = Color.FromArgb(153, 255, 204); // pale green
return aColors;
}
// -------------------------------------------------------------------
// function to create a DataSet containing a few values
DataSet GetDataSet() {
// create a new DataSet object and a new table
DataSet dsResult = new DataSet();
DataTable tblData = new DataTable("Data");
dsResult.Tables.Add(tblData);
// define two columns (fields) within the table
tblData.Columns.Add("Caption", System.Type.GetType("System.String"));
tblData.Columns.Add("Value", System.Type.GetType("System.Double"));
// declare a variable to hold a DataRow object
// fill in the values and add to table then repeat
DataRow oRow = tblData.NewRow();
oRow["Caption"] = "Wrampant 1.6 16V";
oRow["Value"] = 277;
tblData.Rows.Add(oRow);
oRow = tblData.NewRow();
oRow["Caption"] = "Wrampant 2.0i 16V";
oRow["Value"] = 381;
tblData.Rows.Add(oRow);
oRow = tblData.NewRow();
oRow["Caption"] = "Wranger 2.5 D V6";
oRow["Value"] = 63;
tblData.Rows.Add(oRow);
oRow = tblData.NewRow();
oRow["Caption"] = "Wranger 3.2 D V6";
oRow["Value"] = 158;
tblData.Rows.Add(oRow);
oRow = tblData.NewRow();
oRow["Caption"] = "Wranger 4.8 V8";
oRow["Value"] = 106;
tblData.Rows.Add(oRow);
oRow = tblData.NewRow();
oRow["Caption"] = "Wregal 2.8 V6";
oRow["Value"] = 63;
tblData.Rows.Add(oRow);
oRow = tblData.NewRow();
oRow["Caption"] = "Wregal 3.2 D V6";
oRow["Value"] = 19;
tblData.Rows.Add(oRow);
oRow = tblData.NewRow();
oRow["Caption"] = "Wresponse 2.8 V6";
oRow["Value"] = 28;
tblData.Rows.Add(oRow);
oRow = tblData.NewRow();
oRow["Caption"] = "Wresponse 4.8 V8";
oRow["Value"] = 42;
tblData.Rows.Add(oRow);
oRow = tblData.NewRow();
oRow["Caption"] = "Wroadster 6.2 V12";
oRow["Value"] = 17;
tblData.Rows.Add(oRow);
return dsResult; // return DataSet
}
// -------------------------------------------------------------------
</script>
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