CCClippingNodeCanvasRenderCmd.js

/****************************************************************************
 Copyright (c) 2013-2014 Chukong Technologies Inc.

 http://www.cocos2d-x.org

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 THE SOFTWARE.
 ****************************************************************************/

//-------------------------- ClippingNode's canvas render cmd --------------------------------
(function(){
    cc.ClippingNode.CanvasRenderCmd = function(renderable){
        cc.Node.CanvasRenderCmd.call(this, renderable);
        this._needDraw = false;

        this._godhelpme = false;
        this._clipElemType = false;

        this._rendererSaveCmd = new cc.CustomRenderCmd(this, this._saveCmdCallback);
        this._rendererClipCmd = new cc.CustomRenderCmd(this, this._clipCmdCallback);
        this._rendererRestoreCmd = new cc.CustomRenderCmd(this, this._restoreCmdCallback);
    };
    var proto = cc.ClippingNode.CanvasRenderCmd.prototype = Object.create(cc.Node.CanvasRenderCmd.prototype);
    proto.constructor = cc.ClippingNode.CanvasRenderCmd;

    proto.initStencilBits = function(){};

    proto.setStencil = function(stencil){
        if(stencil == null)
            return;

        this._node._stencil = stencil;

        // For shape stencil, rewrite the draw of stencil ,only init the clip path and draw nothing.
        //else
        if (stencil instanceof cc.DrawNode) {
            if(stencil._buffer){
                for(var i=0; i<stencil._buffer.length; i++){
                    stencil._buffer[i].isFill = false;
                    stencil._buffer[i].isStroke = false;
                }
            }

            stencil._renderCmd.rendering = function (ctx, scaleX, scaleY) {
                scaleX = scaleX || cc.view.getScaleX();
                scaleY = scaleY ||cc.view.getScaleY();
                var wrapper = ctx || cc._renderContext, context = wrapper.getContext();
                var t = this._transform;                                              //note: use local transform
                wrapper.save();
                context.transform(t.a, t.b, t.c, t.d, t.tx * scaleX, -t.ty * scaleY);
                context.beginPath();
                for (var i = 0; i < stencil._buffer.length; i++) {
                    var vertices = stencil._buffer[i].verts;
                    //TODO: need support circle etc
                    //cc.assert(cc.vertexListIsClockwise(vertices),
                    //    "Only clockwise polygons should be used as stencil");

                    var firstPoint = vertices[0];
                    context.moveTo(firstPoint.x * scaleX, -firstPoint.y * scaleY);
                    for (var j = 1, len = vertices.length; j < len; j++)
                        context.lineTo(vertices[j].x * scaleX, -vertices[j].y * scaleY);
                }
                wrapper.restore();
            };
        }else{
            stencil._parent = this._node;
        }
    };

    proto._saveCmdCallback  = function(ctx, scaleX, scaleY) {
        var wrapper = ctx || cc._renderContext, context = wrapper.getContext();

        if (this._clipElemType) {
            var locCache = cc.ClippingNode.CanvasRenderCmd._getSharedCache();
            var canvas = context.canvas;
            locCache.width = canvas.width;
            locCache.height = canvas.height;                     //note: on some browser, it can't clear the canvas, e.g. baidu
            var locCacheCtx = locCache.getContext("2d");
            locCacheCtx.drawImage(canvas, 0, 0);                //save the result to shareCache canvas
        } else {
            wrapper.save();
            wrapper.save();                                                               //save for clip
            //Because drawNode's content size is zero
            wrapper.setTransform(this._worldTransform, scaleX, scaleY);
        }
    };

    proto._setStencilCompositionOperation = function(stencil){
         if(!stencil)
            return;
        var node = this._node;
        if(stencil._renderCmd && stencil._renderCmd._blendFuncStr)          //it is a hack way.
            stencil._renderCmd._blendFuncStr = (node.inverted ? "destination-out" : "destination-in");

        if(!stencil._children)
            return;
        var children = stencil._children;
        for(var i = 0, len = children.length; i < len; i++){
             this._setStencilCompositionOperation(children[i]);
        }
    };

    proto._clipCmdCallback = function(ctx) {
        var node = this._node;
        var wrapper = ctx || cc._renderContext, context = wrapper.getContext();

        if (this._clipElemType) {
            //hack
            this._setStencilCompositionOperation(node._stencil);
        } else {
            wrapper.restore();                                 //it use for
            if (node.inverted) {
                var canvas = context.canvas;
                wrapper.save();
                context.setTransform(1, 0, 0, 1, 0, 0);

                context.moveTo(0, 0);
                context.lineTo(0, canvas.height);
                context.lineTo(canvas.width, canvas.height);
                context.lineTo(canvas.width, 0);
                context.lineTo(0, 0);

                wrapper.restore();
            }
            context.closePath();
            context.clip();
        }
    };

    proto._restoreCmdCallback = function (ctx) {
        var locCache = cc.ClippingNode.CanvasRenderCmd._getSharedCache();
        var wrapper = ctx || cc._renderContext, context = wrapper.getContext();
        if (this._clipElemType) {
            // Redraw the cached canvas, so that the clipped area shows the background etc.
            context.save();
            context.setTransform(1, 0, 0, 1, 0, 0);
            context.globalCompositeOperation = "destination-over";
            context.drawImage(locCache, 0, 0);
            context.restore();
            this._dirtyFlag = 0;
        } else {
            wrapper.restore();                             //use for restore clip operation
        }
    };

    proto.transform = function(parentCmd, recursive){
        cc.Node.CanvasRenderCmd.prototype.transform.call(this, parentCmd, recursive);
        var node = this._node;
        if(node._stencil && node._stencil._renderCmd)
            node._stencil._renderCmd.transform(this, recursive);
    };

    proto._cangodhelpme = function (godhelpme) {
        if (godhelpme === true || godhelpme === false)
            cc.ClippingNode.CanvasRenderCmd.prototype._godhelpme = godhelpme;
        return cc.ClippingNode.CanvasRenderCmd.prototype._godhelpme;
    };

    proto.visit = function(parentCmd){
        var node = this._node;
        // quick return if not visible
        if (!node._visible)
            return;

        parentCmd = parentCmd || this.getParentRenderCmd();
        if( parentCmd)
            this._curLevel = parentCmd._curLevel + 1;
        var transformRenderCmd = this;

        // Composition mode, costy but support texture stencil
        this._clipElemType = !(!this._cangodhelpme() && node._stencil instanceof cc.DrawNode);
        if (!node._stencil || !node._stencil.visible) {
            if (this.inverted)
                cc.Node.CanvasRenderCmd.prototype.visit.call(this, parentCmd);   // draw everything
            return;
        }

        this._syncStatus(parentCmd);
        cc.renderer.pushRenderCommand(this._rendererSaveCmd);
        if(this._clipElemType){
            // Draw everything first using node visit function
            cc.Node.CanvasRenderCmd.prototype.visit.call(this, parentCmd);
        }else{
            node._stencil.visit(this);
        }
        cc.renderer.pushRenderCommand(this._rendererClipCmd);

        if(this._clipElemType){
            node._stencil.visit(transformRenderCmd);
        }else{
            var i, children = node._children;
            // Clip mode doesn't support recursive stencil, so once we used a clip stencil,
            // so if it has ClippingNode as a child, the child must uses composition stencil.
            this._cangodhelpme(true);
            var len = children.length;
            if (len > 0) {
                node.sortAllChildren();
                for (i = 0; i < len; i++)
                    children[i]._renderCmd.visit(this);
            }
            this._cangodhelpme(false);
        }

        cc.renderer.pushRenderCommand(this._rendererRestoreCmd);
        this._dirtyFlag = 0;
    };

    cc.ClippingNode.CanvasRenderCmd._sharedCache = null;
    cc.ClippingNode.CanvasRenderCmd._getSharedCache = function () {
        return (cc.ClippingNode.CanvasRenderCmd._sharedCache) || (cc.ClippingNode.CanvasRenderCmd._sharedCache = document.createElement("canvas"));
    };
})();