canvas_lib.js

colorjack.currentWindow = {
	getWindowView: function() {
    return colorjack.document.defaultView.window;
  },
	
	createCanvasLayer: function(w,h) {
		var layer = colorjack.document.createElement('canvas');
		layer.style.position = "absolute";	// containing block
		layer.style.visibility = "hidden";		
		if (w && h) {
			colorjack.currentWindow.setCanvasSize(layer, w, h);
		}		
		return layer;
	},
	
	setCanvasSize: function(layer,w,h) {
		layer.setAttribute('width', w);
		layer.setAttribute('height', h);
	},
	
	setBorder: function(layer, width, color, style) {
		var border = width + "px " + color;
		if (style !== undefined) {
			border += " solid";
		}
		layer.style.border = border;
	},
	
	getBackgroundColor: function() {
		var bg;
		try {
			bg = colorjack.document.body.bgColor;
		}	catch (ignore) {}
		return bg || white;
	},

  /* GraphicsLib */
  
	createBufferImage: function(x,y,w,h,image) {
		var canvas = colorjack.document.createElement('canvas');
		//canvas.width = w;
		//canvas.height = h;
		//canvas.style.width = w + "px";
		//canvas.style.height = h + "px";
		canvas.setAttribute('width', w);
		canvas.setAttribute('height', h);

		var context = canvas.getContext('2d');

		x = Math.round(x);
		y = Math.round(y);
		w = Math.round(w);
		h = Math.round(h);

		context.drawImage(image, x,y,w,h, 0,0,w,h);
		var result = context.canvas;
		return result;
	},

	restoreBufferImage: function(ctx,buffer,x,y,w,h) {
		ctx.save();
		ctx.globalCompositeOperation = "copy";
		ctx.drawImage(buffer, 0, 0, w, h, x, y, w, h);
		ctx.restore();
	}
};