Blog raw files

_old/trial_composite.js

@@ -0,0 +1,35 @@
+window.onload=function(){
+    var canvas = document.getElementById("canvas");
+    x_drawn=0
+    ctx = canvas.getContext("2d");
+    cW = canvas.width;
+    cH = canvas.height;
+    ctx.fillStyle="violet";
+    ctx.font="60px lato light";
+    ctx.fillText("hello world",50,150);
+    ctx.fillStyle="blue";
+    ctx.globalCompositeOperation="source-atop";
+    ctx.save()
+    var step=1
+    var x_middle=50+ctx.measureText("hello").width
+    var w_last=ctx.measureText(" world").width
+    var y_height=1;
+    function drawUpdate(){
+        if (step==1){
+            ctx.fillRect(x_middle+x_drawn,0,1,200);
+            x_drawn-=1;
+        }
+        else{
+
+            ctx.fillRect(x_middle+1,150,w_last,-y_height);
+            y_height+=1;
+        }
+
+
+        if (x_middle+x_drawn<50){
+            step=2
+        }
+    }
+
+    window.setInterval(drawUpdate, 8);
+}