Add compatibility with Flashcanvas (issue 368) and remove dubious octx.stroke() call

git-svn-id: https://flot.googlecode.com/svn/trunk@278 1e0a6537-2640-0410-bfb7-f154510ff394

README.txt

@@ -16,20 +16,27 @@ Installation
 
 Just include the Javascript file after you've included jQuery.
 
-Note that you need to get a version of Excanvas (e.g. the one bundled
-with Flot) which is canvas emulation on Internet Explorer. You can
+Generally, all browsers that support the HTML5 canvas tag are
+supported.
+
+For support for Internet Explorer < 9, you can use Excanvas, a canvas
+emulator; this is used in the examples bundled with Flot. You just
 include the excanvas script like this:
 
-  <!--[if IE]><script language="javascript" type="text/javascript" src="excanvas.pack.js"></script><![endif]-->
+  <!--[if IE]><script language="javascript" type="text/javascript" src="excanvas.min.js"></script><![endif]-->
 
 If it's not working on your development IE 6.0, check that it has
-support for VML which excanvas is relying on. It appears that some
+support for VML which Excanvas is relying on. It appears that some
 stripped down versions used for test environments on virtual machines
 lack the VML support.
-  
-Also note that you need at least jQuery 1.2.6 (but at least jQuery
-1.3.2 is recommended for interactive charts because of performance
-improvements in event handling).
+
+You can also try using Flashcanvas (see FlashCanvas.net), which uses
+Flash to do the emulation. It might be faster with charts with many
+points. Flot contains some wrapper code for activating Excanvas which
+Flashcanvas is compatible with.
+
+You need at least jQuery 1.2.6, but try at least 1.3.2 for interactive
+charts because of performance improvements in event handling.
 
 
 Basic usage

jquery.flot.js

@@ -697,15 +697,6 @@
         }
 
         function constructCanvas() {
-            function makeCanvas(width, height) {
-                var c = document.createElement('canvas');
-                c.width = width;
-                c.height = height;
-                if (!c.getContext) // excanvas hack
-                    c = window.G_vmlCanvasManager.initElement(c);
-                return c;
-            }
-            
             canvasWidth = placeholder.width();
             canvasHeight = placeholder.height();
             placeholder.html(""); // clear placeholder
@@ -715,17 +706,32 @@
             if (canvasWidth <= 0 || canvasHeight <= 0)
                 throw "Invalid dimensions for plot, width = " + canvasWidth + ", height = " + canvasHeight;
 
-            if (window.G_vmlCanvasManager) // excanvas hack
-                window.G_vmlCanvasManager.init_(document); // make sure everything is setup
+            if (window.G_vmlCanvasManager) // excanvas hack, make sure everything is setup
+                window.G_vmlCanvasManager.init_(document);
+            
+            function makeCanvas(skipPositioning) {
+                var c = document.createElement('canvas');
+                c.width = canvasWidth;
+                c.height = canvasHeight;
+                
+                if (!skipPositioning)
+                    $(c).css({ position: 'absolute', left: 0, top: 0 });
+                
+                $(c).appendTo(placeholder);
+                
+                if (!c.getContext) // excanvas hack
+                    c = window.G_vmlCanvasManager.initElement(c);
+
+                return c;
+            }
             
             // the canvas
-            canvas = $(makeCanvas(canvasWidth, canvasHeight)).appendTo(placeholder).get(0);
+            canvas = makeCanvas(true);
             ctx = canvas.getContext("2d");
 
             // overlay canvas for interactive features
-            overlay = $(makeCanvas(canvasWidth, canvasHeight)).css({ position: 'absolute', left: 0, top: 0 }).appendTo(placeholder).get(0);
+            overlay = makeCanvas();
             octx = overlay.getContext("2d");
-            octx.stroke();
         }
 
         function bindEvents() {