asp:can i enable user to draw a line in webform

is there a way to program in asp c# to enable user draw shapes (line,reqta开发者_如何转开发ngle) on the page I am wrking on drawing project in asp c#.

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Yes you can generate on fly the graphics using have to use System.Drawing API. You can also use SGV (Scalable Vector Graphics) standard - Build Flexible, Lightweight XML-Based Images for ASP.NET Using Scalable Vector Graphics

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The namespace of system.Drawing provides the access to basic GDI+ graphic function. In the namespace of System.Drawing.Drawing2D, System.Drawing.Imaging and System.Drawing.Text , .Net provides more advanced functionalities.

using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Text;  

Create canvas and fill the background

Bitmap  objBitmap;  
Graphics  objGraphics; 

objBitmap  =  new  Bitmap(400,  440);  
objGraphics  =  Graphics.FromImage(objBitmap);   
objGraphics.Clear(Color.White);  

Draw the pie and fill

Pen p=new Pen(Color.Yellow,0);
Rectangle rect=new Rectangle(10,10,280,280);
objGraphics.DrawEllipse(p,rect);

Brush b1=new SolidBrush(Color.Red);
Brush b2=new SolidBrush(Color.Green);
Brush b3=new SolidBrush(Color.Blue);
objGraphics.FillPie(b1, rect, 0f, 60f);
objGraphics.FillPie(b2, rect, 60f, 150f);
objGraphics.FillPie(b3, rect, 210f, 150f); 

Draw font

FontFamily fontfml = new FontFamily(GenericFontFamilies.Serif);
Font font = new Font(fontfml, 16);
SolidBrush brush = new SolidBrush(Color.Blue);
objGraphics.DrawString("Drawing Graphics", font, brush, 70, 300); 

Export and save to picture

objBitmap.Save(Response.OutputStream, ImageFormat.Gif);
objBitmap.Save(Server.MapPath("x.jpg"), ImageFormat.Jpeg); 

End drawing

objBitmap.Dispose();
objGraphics.Dispose();

Here is the refrence: http://programmingdiscussions.blogspot.com/2010/07/aspnet-graphics-tutorial.html

http://www.developerfusion.com/article/2569/creating-images-on-the-fly-with-aspnet/

http://www.c-sharpcorner.com/UploadFile/steve_hall/drawinglinechart02072007053420AM/drawinglinechart.aspx

Hope this helps.

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maybe it will be easier to draw in client side with the canvas element, see html5 canvas

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Try this javascript library, which you add to your page and allows the user to create shapes etc.

http://www.draw2d.org/draw2d/about

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Yes, you can draw shapes. See the following code as sample. More on this link also refer to this namespace

private void Page_Load(object sender, System.EventArgs e) 
{ 
        // Put user code to initialize the page here 
        Bitmap objBitmap = new Bitmap(500, 500); 
        Graphics objGraphics = Graphics.FromImage(objBitmap);  
        objGraphics.Clear(Color.White); 
        objGraphics.FillRectangle(new SolidBrush(Color.Black), 0, 0, 400, 1); 
        objBitmap.Save(Response.OutputStream, ImageFormat.Jpeg); 
}

EDIT:

You can use the Paint event handler of a control (ex: Image) to draw a line