Renames parameter to background

Adds more documentation
Changes to ES6

src/display/api.js

@@ -717,8 +717,11 @@ var PDFDocumentProxy = (function PDFDocumentProxyClosure() {
  * @property {Object} canvasFactory - (optional) The factory that will be used
  *                    when creating canvases. The default value is
  *                    {DOMCanvasFactory}.
- * @property {string} backgroundColor - (optional) Background color to use for
- *                    the canvas. The default value is 'rgb(255,255,255)'.
+ * @property {Object} background - (optional) Background to use for the canvas.
+ *                    Can use any valid canvas.fillStyle: A DOMString parsed as
+ *                    CSS <color> value, a CanvasGradient object (a linear or
+ *                    radial gradient) or a CanvasPattern object (a repetitive
+ *                    image). The default value is 'rgb(255,255,255)'.
  */
 
 /**
@@ -2134,7 +2137,7 @@ var InternalRenderTask = (function InternalRenderTaskClosure() {
         transform: params.transform,
         viewport: params.viewport,
         transparency,
-        backgroundColor: params.backgroundColor,
+        background: params.background,
       });
       this.operatorListIdx = 0;
       this.graphicsReady = true;

src/display/canvas.js

@@ -705,8 +705,8 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
 
   CanvasGraphics.prototype = {
 
-    beginDrawing: function CanvasGraphics_beginDrawing({
-      transform, viewport, transparency, backgroundColor = null,
+    beginDrawing({
+      transform, viewport, transparency, background = null,
     }) {
       // For pdfs that use blend modes we have to clear the canvas else certain
       // blend modes can look wrong since we'd be blending with a white
@@ -717,7 +717,7 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
       var height = this.ctx.canvas.height;
 
       this.ctx.save();
-      this.ctx.fillStyle = backgroundColor || 'rgb(255, 255, 255)';
+      this.ctx.fillStyle = background || 'rgb(255, 255, 255)';
       this.ctx.fillRect(0, 0, width, height);
       this.ctx.restore();
 

test/unit/custom_spec.js

@@ -94,7 +94,7 @@ describe('custom canvas rendering', function() {
     page.render({
       canvasContext: canvasAndCtx.context,
       viewport,
-      backgroundColor: 'rgba(255,0,0,1.0)'
+      background: 'rgba(255,0,0,1.0)'
     }).then(function() {
       var { r, g, b, a } = getTopLeftPixel(canvasAndCtx.context);
       CanvasFactory.destroy(canvasAndCtx);