/addons/Canvas.py

  1# Canvas wrapper component for Pyjamas
  2# Ported by Willie Gollino from Canvas component for GWT - Originally by Alexei Sokolov http://gwt.components.googlepages.com/
  3#
  4# Canvas API reference:
  5# http://developer.apple.com/documentation/AppleApplications/Reference/SafariJSRef/Classes/Canvas.html#//apple_ref/js/Canvas.clearRect
  6#
  7# Usage Notes:
  8#   - IE support requires ExplorerCanvas from excanvas.sourceforge.net
  9#   - place excanvas.js in your apps public folder
 10#   - add this to your MainModule.html: <!--[if IE]><script src="excanvas.js" type="text/javascript"></script><![endif]-->
 11
 12import DOM
 13from ui import Image, Widget
 14
 15class Canvas(Widget):
 16    def __init__(self, width, height):
 17        self.context = None
 18        
 19        self.setElement(DOM.createDiv())
 20        canvas = DOM.createElement("canvas")
 21        self.setWidth(width)
 22        self.setHeight(height)
 23        
 24        canvas.width=width
 25        canvas.height=height
 26        
 27        DOM.appendChild(self.getElement(), canvas)
 28        self.setStyleName("gwt-Canvas")
 29        
 30        self.init()
 31        
 32        self.context.fillStyle = "black"
 33        self.context.strokeStyle = "black"
 34
 35    def getContext(self):
 36        return self.context
 37
 38    def isEmulation(self):
 39        JS("""
 40        return (typeof $wnd.G_vmlCanvasManager != "undefined");
 41        """)
 42
 43    def init(self):
 44        JS("""
 45        var el = this.getElement().firstChild;
 46        if (typeof $wnd.G_vmlCanvasManager != "undefined") {
 47            var parent = el.parent;
 48            
 49            el = $wnd.G_vmlCanvasManager.fixElement_(el);
 50            el.getContext = function () {
 51                if (this.context_) {
 52                    return this.context_;
 53                }
 54                return this.context_ = new $wnd.CanvasRenderingContext2D(el);
 55            };
 56        
 57            el.attachEvent("onpropertychange", function (e) {
 58                // we need to watch changes to width and height
 59                switch (e.propertyName) {
 60                    case "width":
 61                    case "height":
 62                    // coord size changed?
 63                    break;
 64                }
 65            });
 66
 67            // if style.height is set
 68            
 69            var attrs = el.attributes;
 70            if (attrs.width && attrs.width.specified) {
 71                // TODO: use runtimeStyle and coordsize
 72                // el.getContext().setWidth_(attrs.width.nodeValue);
 73                el.style.width = attrs.width.nodeValue + "px";
 74            }
 75            if (attrs.height && attrs.height.specified) {
 76                // TODO: use runtimeStyle and coordsize
 77                // el.getContext().setHeight_(attrs.height.nodeValue);
 78                el.style.height = attrs.height.nodeValue + "px";
 79            }
 80        }
 81        var ctx = el.getContext("2d");
 82        
 83        ctx._createPattern = ctx.createPattern;
 84        ctx.createPattern = function(img, rep) {
 85            if (!(img instanceof Image)) img = img.getElement(); 
 86            return this._createPattern(img, rep);
 87            }
 88
 89        ctx._drawImage = ctx.drawImage;
 90        ctx.drawImage = function() {
 91            var a=arguments;
 92            if (!(a[0] instanceof Image)) a[0] = a[0].getElement();
 93            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]);
 94            else if (a.length==5) return this._drawImage(a[0], a[1], a[2], a[3], a[4]);
 95            return this._drawImage(a[0], a[1], a[2]);
 96            }
 97        
 98        this.context = ctx;
 99        """)
100
101class CanvasImage(Image):
102    def __init__(self, url="", load_listener = None):
103        Image.__init__(self, url)
104        if load_listener:
105            self.addLoadListener(load_listener)     
106        self.onAttach()
107
108    def isLoaded(self):
109        return self.getElement().complete
110
111
112class ImageLoadListener:
113    def __init__(self, listener = None):
114        self.wait_list = []
115        self.loadListeners = []
116        
117        if listener:
118            self.addLoadListener(listener)  
119
120    def add(self, sender):
121        self.wait_list.append(sender)
122        sender.addLoadListener(self)
123    
124    def addLoadListener(self, listener):
125        self.loadListeners.append(listener)
126
127    def isLoaded(self):
128        if len(self.wait_list):
129            return False
130        return True
131
132    def onError(self, sender):
133        for listener in self.loadListeners:
134            listener.onError(sender)
135        
136    def onLoad(self, sender):
137        self.wait_list.remove(sender)
138        
139        if self.isLoaded():
140            for listener in self.loadListeners:
141                listener.onLoad(self)