# Canvas wrapper component for Pyjamas
# Ported by Willie Gollino from Canvas component for GWT - Originally by Alexei Sokolov http://gwt.components.googlepages.com/
#
# Canvas API reference:
# http://developer.apple.com/documentation/AppleApplications/Reference/SafariJSRef/Classes/Canvas.html#//apple_ref/js/Canvas.clearRect
#
# Usage Notes:
#   - IE support requires ExplorerCanvas from excanvas.sourceforge.net
#   - place excanvas.js in your apps public folder
#   - add this to your MainModule.html: <!--[if IE]><script src="excanvas.js" type="text/javascript"></script><![endif]-->

import DOM
from ui import Image, Widget

class Canvas(Widget):
    def __init__(self, width, height):
        self.context = None
        
        self.setElement(DOM.createDiv())
        canvas = DOM.createElement("canvas")
        self.setWidth(width)
        self.setHeight(height)
        
        canvas.width=width
        canvas.height=height
        
        DOM.appendChild(self.getElement(), canvas)
        self.setStyleName("gwt-Canvas")
        
        self.init()
        
        self.context.fillStyle = "black"
        self.context.strokeStyle = "black"

    def getContext(self):
        return self.context

    def isEmulation(self):
        JS("""
        return (typeof $wnd.G_vmlCanvasManager != "undefined");
        """)

    def init(self):
        JS("""
        var el = this.getElement().firstChild;
        if (typeof $wnd.G_vmlCanvasManager != "undefined") {
            var parent = el.parent;
            
            el = $wnd.G_vmlCanvasManager.fixElement_(el);
            el.getContext = function () {
                if (this.context_) {
                    return this.context_;
                }
                return this.context_ = new $wnd.CanvasRenderingContext2D(el);
            };
        
            el.attachEvent("onpropertychange", function (e) {
                // we need to watch changes to width and height
                switch (e.propertyName) {
                    case "width":
                    case "height":
                    // coord size changed?
                    break;
                }
            });

            // if style.height is set
            
            var attrs = el.attributes;
            if (attrs.width && attrs.width.specified) {
                // TODO: use runtimeStyle and coordsize
                // el.getContext().setWidth_(attrs.width.nodeValue);
                el.style.width = attrs.width.nodeValue + "px";
            }
            if (attrs.height && attrs.height.specified) {
                // TODO: use runtimeStyle and coordsize
                // el.getContext().setHeight_(attrs.height.nodeValue);
                el.style.height = attrs.height.nodeValue + "px";
            }
        }
        var ctx = el.getContext("2d");
        
        ctx._createPattern = ctx.createPattern;
        ctx.createPattern = function(img, rep) {
            if (!(img instanceof Image)) img = img.getElement(); 
            return this._createPattern(img, rep);
            }

        ctx._drawImage = ctx.drawImage;
        ctx.drawImage = function() {
            var a=arguments;
            if (!(a[0] instanceof Image)) a[0] = a[0].getElement();
            if (a.length==9) return this._drawImage(a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8]);
            else if (a.length==5) return this._drawImage(a[0], a[1], a[2], a[3], a[4]);
            return this._drawImage(a[0], a[1], a[2]);
            }
        
        this.context = ctx;
        """)

class CanvasImage(Image):
    def __init__(self, url="", load_listener = None):
        Image.__init__(self, url)
        if load_listener:
            self.addLoadListener(load_listener)     
        self.onAttach()

    def isLoaded(self):
        return self.getElement().complete


class ImageLoadListener:
    def __init__(self, listener = None):
        self.wait_list = []
        self.loadListeners = []
        
        if listener:
            self.addLoadListener(listener)  

    def add(self, sender):
        self.wait_list.append(sender)
        sender.addLoadListener(self)
    
    def addLoadListener(self, listener):
        self.loadListeners.append(listener)

    def isLoaded(self):
        if len(self.wait_list):
            return False
        return True

    def onError(self, sender):
        for listener in self.loadListeners:
            listener.onError(sender)
        
    def onLoad(self, sender):
        self.wait_list.remove(sender)
        
        if self.isLoaded():
            for listener in self.loadListeners:
                listener.onLoad(self)