Set up example for ignoreClearRect

Author: MrRio

examples/canvg_context2d/bar_graph_with_text_and_lines.html

@@ -664,6 +664,10 @@ <h1>Bar Graph With Text And Lines</h1>
             var c = pdf.canvas;
             c.width = 1000;
             c.height = 500;
+            var ctx = c.getContext('2d');
+            ctx.ignoreClearRect = true;
+            ctx.fillStyle = '#ffffff';
+            ctx.fillRect(0, 0, 1000, 700);
 
             //load a svg snippet in the canvas with id = 'drawingArea'
             canvg(c, document.getElementById('svg').outerHTML, {
@@ -678,7 +682,6 @@ <h1>Bar Graph With Text And Lines</h1>
         document.getElementById('source').innerText = makePdf().output();
         //makePdf().save();
     };
-
 </script>
 
 </body>