Use Base objects for drawing params, so we can use param.extend() on them for easier overriding.

src/item/Group.js

@@ -167,16 +167,14 @@ var Group = Item.extend(/** @lends Group# */{
 	},
 
 	_draw: function(ctx, param) {
-		var clipItem = this._getClipItem();
-		if (clipItem) {
-			param.clip = true;
-			clipItem.draw(ctx, param);
-			param.clip = false;
-		}
+		var clipItem = param.clipItem = this._getClipItem();
+		if (clipItem)
+			clipItem.draw(ctx, param.extend({ clip: true }));
 		for (var i = 0, l = this._children.length; i < l; i++) {
 			var item = this._children[i];
 			if (item !== clipItem)
 				item.draw(ctx, param);
 		}
+		param.clipItem = null;
 	}
 });

src/item/Item.js

@@ -1270,7 +1270,8 @@ var Item = Base.extend(Callback, /** @lends Item# */{
 			matrix = new Matrix().scale(scale).translate(-bounds.x, -bounds.y);
 		ctx.save();
 		matrix.applyToContext(ctx);
-		this.draw(ctx, { transforms: [matrix] });
+		// See Project#draw() for an explanation of Base.merge()
+		this.draw(ctx, Base.merge({ transforms: [matrix] }));
 		var raster = new Raster(canvas);
 		raster.setBounds(bounds);
 		ctx.restore();

src/item/Raster.js

@@ -412,8 +412,9 @@ var Raster = Item.extend(/** @lends Raster# */{
 				.translate(-bounds.x, -bounds.y);
 		matrix.applyToContext(ctx);
 		// If a path was passed, draw it as a clipping mask:
+		// See Project#draw() for an explanation of Base.merge()
 		if (path)
-			path.draw(ctx, { clip: true, transforms: [matrix] });
+			path.draw(ctx, Base.merge({ clip: true, transforms: [matrix] }));
 		// Now draw the image clipped into it.
 		this._matrix.applyToContext(ctx);
 		ctx.drawImage(this.getElement(),

src/path/CompoundPath.js

@@ -241,10 +241,9 @@ var CompoundPath = PathItem.extend(/** @lends CompoundPath# */{
 		if (children.length === 0)
 			return;
 		ctx.beginPath();
-		param.compound = true;
+		param = param.extend({ compound: true });
 		for (var i = 0, l = children.length; i < l; i++)
 			children[i].draw(ctx, param);
-		param.compound = false;
 		if (!param.clip) {
 			this._setStyles(ctx);
 			if (style.getFillColor())

src/path/Path.js

@@ -1809,7 +1809,9 @@ var Path = PathItem.extend(/** @lends Path# */{
 
 	return {
 		_draw: function(ctx, param) {
-			if (!param.compound)
+			var clip = param.clip,
+				compound = param.compound;
+			if (!compound)
 				ctx.beginPath();
 
 			// We can access styles directly on the internal _styles object,
@@ -1824,14 +1826,13 @@ var Path = PathItem.extend(/** @lends Path# */{
 
 			// Prepare the canvas path if we have any situation that requires it
 			// to be defined.
-			if (fillColor || strokeColor && !drawDash || param.compound
-					|| param.clip)
+			if (fillColor || strokeColor && !drawDash || compound || clip)
 				drawSegments(ctx, this);
 
 			if (this._closed)
 				ctx.closePath();
 
-			if (!param.clip && !param.compound && (fillColor || strokeColor)) {
+			if (!clip && !compound && (fillColor || strokeColor)) {
 				// If the path is part of a compound path or doesn't have a fill
 				// or stroke, there is no need to continue.
 				this._setStyles(ctx);

src/project/Project.js

@@ -299,12 +299,14 @@ var Project = PaperScopeItem.extend(/** @lends Project# */{
 		this._drawCount++;
 		ctx.save();
 		matrix.applyToContext(ctx);
-		var param = {
+		// Use Base.merge() so we can use param.extend() to easily override
+		// values
+		var param = Base.merge({
 			offset: new Point(0, 0),
 			// A stack of concatenated matrices, to keep track of the current
 			// global matrix, since Canvas is not able tell us (yet).
 			transforms: [matrix]
-		};
+		});
 		for (var i = 0, l = this.layers.length; i < l; i++)
 			this.layers[i].draw(ctx, param);
 		ctx.restore();