From fe7462cf460c21a4a425ed3b2ff116f1605ef1d5 Mon Sep 17 00:00:00 2001
From: Andrea Bogazzi <andreabogazzi79@gmail.com>
Date: Wed, 18 Nov 2015 14:23:52 +0100
Subject: [PATCH] General code clean up

we do not need to create a temporary canvas to call its createImageData, when normal canvas we are filtering can provide same method.
Removed 2 unused variables ( w and sw, h and sh where copies of each other and used in read only)
---
 src/filters/convolute_filter.class.js | 41 ++++++++-------------------
 1 file changed, 12 insertions(+), 29 deletions(-)

diff --git a/src/filters/convolute_filter.class.js b/src/filters/convolute_filter.class.js
index 8a131116..be8965bd 100644
--- a/src/filters/convolute_filter.class.js
+++ b/src/filters/convolute_filter.class.js
@@ -71,16 +71,6 @@
         0, 1, 0,
         0, 0, 0
       ];
-
-      var canvasEl = fabric.util.createCanvasElement();
-      this.tmpCtx = canvasEl.getContext('2d');
-    },
-
-    /**
-     * @private
-     */
-    _createImageData: function(w, h) {
-      return this.tmpCtx.createImageData(w, h);
     },
 
     /**
@@ -98,39 +88,32 @@
           src = pixels.data,
           sw = pixels.width,
           sh = pixels.height,
-
-          // pad output by the convolution matrix
-          w = sw,
-          h = sh,
-          output = this._createImageData(w, h),
-
+          output = context.createImageData(sw, sh),
           dst = output.data,
-
           // go through the destination image pixels
-          alphaFac = this.opaque ? 1 : 0;
+          alphaFac = this.opaque ? 1 : 0,
+          r, g, b, a, dstOff,
+          scx, scy, srcOff, wt;
 
-      for (var y = 0; y < h; y++) {
-        for (var x = 0; x < w; x++) {
-          var sy = y,
-              sx = x,
-              dstOff = (y * w + x) * 4,
+      for (var y = 0; y < sh; y++) {
+        for (var x = 0; x < sw; x++) {
+          dstOff = (y * sh + x) * 4;
               // calculate the weighed sum of the source image pixels that
               // fall under the convolution matrix
-              r = 0, g = 0, b = 0, a = 0;
+          r = 0; g = 0; b = 0; a = 0;
 
           for (var cy = 0; cy < side; cy++) {
             for (var cx = 0; cx < side; cx++) {
-
-              var scy = sy + cy - halfSide,
-                  scx = sx + cx - halfSide;
+              scy = y + cy - halfSide;
+              scx = x + cx - halfSide;
 
               /* jshint maxdepth:5 */
               if (scy < 0 || scy > sh || scx < 0 || scx > sw) {
                 continue;
               }
 
-              var srcOff = (scy * sw + scx) * 4,
-                  wt = weights[cy * side + cx];
+              srcOff = (scy * sw + scx) * 4;
+              wt = weights[cy * side + cx];
 
               r += src[srcOff] * wt;
               g += src[srcOff + 1] * wt;