Drawing Graphics In ASP

A common issue with developing web sites for customers is sometimes the unfortunate inability to install server side components for performing specific tasks. A common question asked by beginners to ASP is how to draw graphics and send them to the browser. Normally, this task requires either client-side Java or server side COM objects to get the job done, and it has generally been accepted that th ... A common issue with developing web sites for customers is sometimes the unfortunate inability to install server side components for performing specific tasks. A common question asked by beginners to ASP is how to draw graphics and send them to the browser. Normally, this task requires either client-side Java or server side COM objects to get the job done, and it has generally been accepted that this will always be the case in pre-.NET environments.

The following class can change your attitude towards creating images

ASPCanvas

This is a self-extracting zip file, unzip into an area on your web server. There are two files that are needed to use this class:

canvas.asp (The main class)
font.asp (The font used for rendering text)

This class provides a simple canvas with which you draw things on, it is written in ASP and is initialised simply by:

<!--#include file="canvas.asp"-->
<%

Set objCanvas = New Canvas ' Create the object

objCanvas.GlobalColourTable(0) = RGB(255,255,255) ' First colour index to white
objCanvas.GlobalColourTable(1) = RGB(0,0,0) ' Second colour index to black

objCanvas.Resize 160,120,false ' Resize the canvas to 160x120, don't preserve the existing image

objCanvas.ForegroundColourIndex = 1 ' Set the drawing pen colour index to 1 (black)

objCanvas.Ellipse 100,100,30,20 ' Draw an ellipse in black, with two radii, 30 and 20 pixels
objCanvas.Circle 50,50,10 ' Draw a circle in black, radii of 10 pixels

objCanvas.Write ' Send the image to the browser
%>


Further instructions on using the class are included with the source files. This class supports the following drawing methods:

Copy X1,Y1,X2,Y2,X3,Y3 - Copy a region from X1,Y1,X2,Y2 to X3,Y3
Flood X,Y - Floodfill a region with the drawing pen colour, starting at X,Y
Line X1,Y1,X2,Y2 - Draw a line with the pen colour, from X1,Y1 to X2,Y2
Circle X,Y,Radius - Draw a circle at X,Y with a radius in pixels
Ellipse X,Y,Radius1,Radius2 - Draw an ellipse at X,Y with the two radii of Radius1 and Radius2
DrawTextWE X,Y,Text - Draw text from west to east at X,Y. Text is a string
DrawTextNS X,Y,Text - Draw text from north to south at X,Y. Text is a string
Clear - Clear the canvas to the current background colour index
Resize Width,Height,Preserve - Resize the canvas to Width and Height, set preserve to keep the current canvas image
Write - Send the image to the browser

And also the following properties:

Pixel(X,Y) - Sets or retrieves the current pixel colour index value
GlobalColourTable(Index) - Sets or retrieves the current global colour table RGB value
ForegroundColourIndex - Sets or retrieves the current drawing pen colour index
BackgroundColourIndex - Sets or retrieves the current background colour index
Version - Retrieves the current version of the class

Hi,
Where can I find the files, canvas.asp and font.asp? Where can I download it?

Thank you,

Hi, It's my first time in this forum, I don't know if i'm Ok, but I have a problem using Aspcanvas class.
I included a data_chart.asp page where i read my database and tried to show a linechart but It didn't show me anything.
My code is :

rs.Open str,cn,adOpenStatic,adLockReadOnly
RS.MoveFirst
cont = 0
acont = 0
do while not rs.EOF
if cont = 0 then
arr1 = cint(rs(0)) & "," & cdbl(rs(1))
arr2 = cint(rs(0)) & "," & cdbl(rs(2))
arr3 = cint(rs(0)) & "," & cdbl(rs(3))
arr4 = cint(rs(0)) & "," & cdbl(rs(4))
cont = 1
else
arr1 = arr1 & "," & cint(rs(0)) & "," & cdbl(rs(1))
arr2 = arr2 & "," & cint(rs(0)) & "," & cdbl(rs(2))
arr3 = arr3 & "," & cint(rs(0)) & "," & cdbl(rs(3))
arr4 = arr4 & "," & cint(rs(0)) & "," & cdbl(rs(4))
end if
acont = acont + 2
if wMaxX < rs(0) then wMaxX = rs(0)
if cdbl(wMinx) > cdbl(rs(0)) then wMinX = rs(0)
if wMaxY < cdbl(rs(1)) then wMaxY = cdbl(rs(1))
if wMaxY < cdbl(rs(2)) then wMaxY = cdbl(rs(2))
if wMaxY < cdbl(rs(3)) then wMaxY = cdbl(rs(3))
if wMaxY < cdbl(rs(4)) then wMaxY = cdbl(rs(4))
rs.MoveNext
loop

Then in the the page : graph_example.asp, I change this:
.
.
.
Set objSet = objChart.AddSet()
objSet.Name = " Prom. Velocidad"
objSet.DotColourIndex = 3
objSet.AddPoints array(Arr1)
objSet.LinePattern = "3"
objSet.DrawRoot = False
objSet.DrawValues = False
objSet.DrawName = False
objSet.DrawLines = True
objSet.DotCrossSize = 1
.
.
.

I'll appreciate so much if anybody could help me.

Thanks.