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/* Copyright (c) 2006-2013 by OpenLayers Contributors (see authors.txt for
* full list of contributors). Published under the 2-clause BSD license.
* See license.txt in the OpenLayers distribution or repository for the
* full text of the license. */
/**
* @requires OpenLayers/Renderer.js
*/
/**
* Class: OpenLayers.Renderer.Canvas
* A renderer based on the 2D 'canvas' drawing element.
*
* Inherits:
* - <OpenLayers.Renderer>
*/
OpenLayers.Renderer.Canvas = OpenLayers.Class(OpenLayers.Renderer, {
/**
* APIProperty: hitDetection
* {Boolean} Allow for hit detection of features. Default is true.
*/
hitDetection: true,
/**
* Property: hitOverflow
* {Number} The method for converting feature identifiers to color values
* supports 16777215 sequential values. Two features cannot be
* predictably detected if their identifiers differ by more than this
* value. The hitOverflow allows for bigger numbers (but the
* difference in values is still limited).
*/
hitOverflow: 0,
/**
* Property: canvas
* {Canvas} The canvas context object.
*/
canvas: null,
/**
* Property: features
* {Object} Internal object of feature/style pairs for use in redrawing the layer.
*/
features: null,
/**
* Property: pendingRedraw
* {Boolean} The renderer needs a redraw call to render features added while
* the renderer was locked.
*/
pendingRedraw: false,
/**
* Property: cachedSymbolBounds
* {Object} Internal cache of calculated symbol extents.
*/
cachedSymbolBounds: {},
/**
* Constructor: OpenLayers.Renderer.Canvas
*
* Parameters:
* containerID - {<String>}
* options - {Object} Optional properties to be set on the renderer.
*/
initialize: function(containerID, options) {
OpenLayers.Renderer.prototype.initialize.apply(this, arguments);
this.root = document.createElement("canvas");
this.container.appendChild(this.root);
this.canvas = this.root.getContext("2d");
this.features = {};
if (this.hitDetection) {
this.hitCanvas = document.createElement("canvas");
this.hitContext = this.hitCanvas.getContext("2d");
}
},
/**
* Method: setExtent
* Set the visible part of the layer.
*
* Parameters:
* extent - {<OpenLayers.Bounds>}
* resolutionChanged - {Boolean}
*
* Returns:
* {Boolean} true to notify the layer that the new extent does not exceed
* the coordinate range, and the features will not need to be redrawn.
* False otherwise.
*/
setExtent: function() {
OpenLayers.Renderer.prototype.setExtent.apply(this, arguments);
// always redraw features
return false;
},
/**
* Method: eraseGeometry
* Erase a geometry from the renderer. Because the Canvas renderer has
* 'memory' of the features that it has drawn, we have to remove the
* feature so it doesn't redraw.
*
* Parameters:
* geometry - {<OpenLayers.Geometry>}
* featureId - {String}
*/
eraseGeometry: function(geometry, featureId) {
this.eraseFeatures(this.features[featureId][0]);
},
/**
* APIMethod: supported
*
* Returns:
* {Boolean} Whether or not the browser supports the renderer class
*/
supported: function() {
return OpenLayers.CANVAS_SUPPORTED;
},
/**
* Method: setSize
* Sets the size of the drawing surface.
*
* Once the size is updated, redraw the canvas.
*
* Parameters:
* size - {<OpenLayers.Size>}
*/
setSize: function(size) {
this.size = size.clone();
var root = this.root;
root.style.width = size.w + "px";
root.style.height = size.h + "px";
root.width = size.w;
root.height = size.h;
this.resolution = null;
if (this.hitDetection) {
var hitCanvas = this.hitCanvas;
hitCanvas.style.width = size.w + "px";
hitCanvas.style.height = size.h + "px";
hitCanvas.width = size.w;
hitCanvas.height = size.h;
}
},
/**
* Method: drawFeature
* Draw the feature. Stores the feature in the features list,
* then redraws the layer.
*
* Parameters:
* feature - {<OpenLayers.Feature.Vector>}
* style - {<Object>}
*
* Returns:
* {Boolean} The feature has been drawn completely. If the feature has no
* geometry, undefined will be returned. If the feature is not rendered
* for other reasons, false will be returned.
*/
drawFeature: function(feature, style) {
var rendered;
if (feature.geometry) {
style = this.applyDefaultSymbolizer(style || feature.style);
// don't render if display none or feature outside extent
var bounds = feature.geometry.getBounds();
var worldBounds;
if (this.map.baseLayer && this.map.baseLayer.wrapDateLine) {
worldBounds = this.map.getMaxExtent();
}
var intersects = bounds && bounds.intersectsBounds(this.extent, {worldBounds: worldBounds});
rendered = (style.display !== "none") && !!bounds && intersects;
if (rendered) {
// keep track of what we have rendered for redraw
this.features[feature.id] = [feature, style];
}
else {
// remove from features tracked for redraw
delete(this.features[feature.id]);
}
this.pendingRedraw = true;
}
if (this.pendingRedraw && !this.locked) {
this.redraw();
this.pendingRedraw = false;
}
return rendered;
},
/**
* Method: drawGeometry
* Used when looping (in redraw) over the features; draws
* the canvas.
*
* Parameters:
* geometry - {<OpenLayers.Geometry>}
* style - {Object}
*/
drawGeometry: function(geometry, style, featureId) {
var className = geometry.CLASS_NAME;
if ((className == "OpenLayers.Geometry.Collection") ||
(className == "OpenLayers.Geometry.MultiPoint") ||
(className == "OpenLayers.Geometry.MultiLineString") ||
(className == "OpenLayers.Geometry.MultiPolygon")) {
for (var i = 0; i < geometry.components.length; i++) {
this.drawGeometry(geometry.components[i], style, featureId);
}
return;
}
switch (geometry.CLASS_NAME) {
case "OpenLayers.Geometry.Point":
this.drawPoint(geometry, style, featureId);
break;
case "OpenLayers.Geometry.LineString":
this.drawLineString(geometry, style, featureId);
break;
case "OpenLayers.Geometry.LinearRing":
this.drawLinearRing(geometry, style, featureId);
break;
case "OpenLayers.Geometry.Polygon":
this.drawPolygon(geometry, style, featureId);
break;
default:
break;
}
},
/**
* Method: drawExternalGraphic
* Called to draw External graphics.
*
* Parameters:
* geometry - {<OpenLayers.Geometry>}
* style - {Object}
* featureId - {String}
*/
drawExternalGraphic: function(geometry, style, featureId) {
var img = new Image();
var title = style.title || style.graphicTitle;
if (title) {
img.title = title;
}
var width = style.graphicWidth || style.graphicHeight;
var height = style.graphicHeight || style.graphicWidth;
width = width ? width : style.pointRadius * 2;
height = height ? height : style.pointRadius * 2;
var xOffset = (style.graphicXOffset != undefined) ?
style.graphicXOffset : -(0.5 * width);
var yOffset = (style.graphicYOffset != undefined) ?
style.graphicYOffset : -(0.5 * height);
var opacity = style.graphicOpacity || style.fillOpacity;
var onLoad = function() {
if(!this.features[featureId]) {
return;
}
var pt = this.getLocalXY(geometry);
var p0 = pt[0];
var p1 = pt[1];
if(!isNaN(p0) && !isNaN(p1)) {
var x = (p0 + xOffset) | 0;
var y = (p1 + yOffset) | 0;
var canvas = this.canvas;
canvas.globalAlpha = opacity;
var factor = OpenLayers.Renderer.Canvas.drawImageScaleFactor ||
(OpenLayers.Renderer.Canvas.drawImageScaleFactor =
/android 2.1/.test(navigator.userAgent.toLowerCase()) ?
// 320 is the screen width of the G1 phone, for
// which drawImage works out of the box.
320 / window.screen.width : 1
);
canvas.drawImage(
img, x*factor, y*factor, width*factor, height*factor
);
if (this.hitDetection) {
this.setHitContextStyle("fill", featureId);
this.hitContext.fillRect(x, y, width, height);
}
}
};
img.onload = OpenLayers.Function.bind(onLoad, this);
img.src = style.externalGraphic;
},
/**
* Method: drawNamedSymbol
* Called to draw Well Known Graphic Symbol Name.
* This method is only called by the renderer itself.
*
* Parameters:
* geometry - {<OpenLayers.Geometry>}
* style - {Object}
* featureId - {String}
*/
drawNamedSymbol: function(geometry, style, featureId) {
var x, y, cx, cy, i, symbolBounds, scaling, angle;
var unscaledStrokeWidth;
var deg2rad = Math.PI / 180.0;
var symbol = OpenLayers.Renderer.symbol[style.graphicName];
if (!symbol) {
throw new Error(style.graphicName + ' is not a valid symbol name');
}
if (!symbol.length || symbol.length < 2) return;
var pt = this.getLocalXY(geometry);
var p0 = pt[0];
var p1 = pt[1];
if (isNaN(p0) || isNaN(p1)) return;
// Use rounded line caps
this.canvas.lineCap = "round";
this.canvas.lineJoin = "round";
if (this.hitDetection) {
this.hitContext.lineCap = "round";
this.hitContext.lineJoin = "round";
}
// Scale and rotate symbols, using precalculated bounds whenever possible.
if (style.graphicName in this.cachedSymbolBounds) {
symbolBounds = this.cachedSymbolBounds[style.graphicName];
} else {
symbolBounds = new OpenLayers.Bounds();
for(i = 0; i < symbol.length; i+=2) {
symbolBounds.extend(new OpenLayers.LonLat(symbol[i], symbol[i+1]));
}
this.cachedSymbolBounds[style.graphicName] = symbolBounds;
}
// Push symbol scaling, translation and rotation onto the transformation stack in reverse order.
// Don't forget to apply all canvas transformations to the hitContext canvas as well(!)
this.canvas.save();
if (this.hitDetection) { this.hitContext.save(); }
// Step 3: place symbol at the desired location
this.canvas.translate(p0,p1);
if (this.hitDetection) { this.hitContext.translate(p0,p1); }
// Step 2a. rotate the symbol if necessary
angle = deg2rad * style.rotation; // will be NaN when style.rotation is undefined.
if (!isNaN(angle)) {
this.canvas.rotate(angle);
if (this.hitDetection) { this.hitContext.rotate(angle); }
}
// // Step 2: scale symbol such that pointRadius equals half the maximum symbol dimension.
scaling = 2.0 * style.pointRadius / Math.max(symbolBounds.getWidth(), symbolBounds.getHeight());
this.canvas.scale(scaling,scaling);
if (this.hitDetection) { this.hitContext.scale(scaling,scaling); }
// Step 1: center the symbol at the origin
cx = symbolBounds.getCenterLonLat().lon;
cy = symbolBounds.getCenterLonLat().lat;
this.canvas.translate(-cx,-cy);
if (this.hitDetection) { this.hitContext.translate(-cx,-cy); }
// Don't forget to scale stroke widths, because they are affected by canvas scale transformations as well(!)
// Alternative: scale symbol coordinates manually, so stroke width scaling is not needed anymore.
unscaledStrokeWidth = style.strokeWidth;
style.strokeWidth = unscaledStrokeWidth / scaling;
if (style.fill !== false) {
this.setCanvasStyle("fill", style);
this.canvas.beginPath();
for (i=0; i<symbol.length; i=i+2) {
x = symbol[i];
y = symbol[i+1];
if (i == 0) this.canvas.moveTo(x,y);
this.canvas.lineTo(x,y);
}
this.canvas.closePath();
this.canvas.fill();
if (this.hitDetection) {
this.setHitContextStyle("fill", featureId, style);
this.hitContext.beginPath();
for (i=0; i<symbol.length; i=i+2) {
x = symbol[i];
y = symbol[i+1];
if (i == 0) this.canvas.moveTo(x,y);
this.hitContext.lineTo(x,y);
}
this.hitContext.closePath();
this.hitContext.fill();
}
}
if (style.stroke !== false) {
this.setCanvasStyle("stroke", style);
this.canvas.beginPath();
for (i=0; i<symbol.length; i=i+2) {
x = symbol[i];
y = symbol[i+1];
if (i == 0) this.canvas.moveTo(x,y);
this.canvas.lineTo(x,y);
}
this.canvas.closePath();
this.canvas.stroke();
if (this.hitDetection) {
this.setHitContextStyle("stroke", featureId, style, scaling);
this.hitContext.beginPath();
for (i=0; i<symbol.length; i=i+2) {
x = symbol[i];
y = symbol[i+1];
if (i == 0) this.hitContext.moveTo(x,y);
this.hitContext.lineTo(x,y);
}
this.hitContext.closePath();
this.hitContext.stroke();
}
}
style.strokeWidth = unscaledStrokeWidth;
this.canvas.restore();
if (this.hitDetection) { this.hitContext.restore(); }
this.setCanvasStyle("reset");
},
/**
* Method: setCanvasStyle
* Prepare the canvas for drawing by setting various global settings.
*
* Parameters:
* type - {String} one of 'stroke', 'fill', or 'reset'
* style - {Object} Symbolizer hash
*/
setCanvasStyle: function(type, style) {
if (type === "fill") {
this.canvas.globalAlpha = style['fillOpacity'];
this.canvas.fillStyle = style['fillColor'];
} else if (type === "stroke") {
this.canvas.globalAlpha = style['strokeOpacity'];
this.canvas.strokeStyle = style['strokeColor'];
this.canvas.lineWidth = style['strokeWidth'];
} else {
this.canvas.globalAlpha = 0;
this.canvas.lineWidth = 1;
}
},
/**
* Method: featureIdToHex
* Convert a feature ID string into an RGB hex string.
*
* Parameters:
* featureId - {String} Feature id
*
* Returns:
* {String} RGB hex string.
*/
featureIdToHex: function(featureId) {
var id = Number(featureId.split("_").pop()) + 1; // zero for no feature
if (id >= 16777216) {
this.hitOverflow = id - 16777215;
id = id % 16777216 + 1;
}
var hex = "000000" + id.toString(16);
var len = hex.length;
hex = "#" + hex.substring(len-6, len);
return hex;
},
/**
* Method: setHitContextStyle
* Prepare the hit canvas for drawing by setting various global settings.
*
* Parameters:
* type - {String} one of 'stroke', 'fill', or 'reset'
* featureId - {String} The feature id.
* symbolizer - {<OpenLayers.Symbolizer>} The symbolizer.
*/
setHitContextStyle: function(type, featureId, symbolizer, strokeScaling) {
var hex = this.featureIdToHex(featureId);
if (type == "fill") {
this.hitContext.globalAlpha = 1.0;
this.hitContext.fillStyle = hex;
} else if (type == "stroke") {
this.hitContext.globalAlpha = 1.0;
this.hitContext.strokeStyle = hex;
// bump up stroke width to deal with antialiasing. If strokeScaling is defined, we're rendering a symbol
// on a transformed canvas, so the antialias width bump has to scale as well.
if (typeof strokeScaling === "undefined") {
this.hitContext.lineWidth = symbolizer.strokeWidth + 2;
} else {
if (!isNaN(strokeScaling)) { this.hitContext.lineWidth = symbolizer.strokeWidth + 2.0 / strokeScaling; }
}
} else {
this.hitContext.globalAlpha = 0;
this.hitContext.lineWidth = 1;
}
},
/**
* Method: drawPoint
* This method is only called by the renderer itself.
*
* Parameters:
* geometry - {<OpenLayers.Geometry>}
* style - {Object}
* featureId - {String}
*/
drawPoint: function(geometry, style, featureId) {
if(style.graphic !== false) {
if(style.externalGraphic) {
this.drawExternalGraphic(geometry, style, featureId);
} else if (style.graphicName && (style.graphicName != "circle")) {
this.drawNamedSymbol(geometry, style, featureId);
} else {
var pt = this.getLocalXY(geometry);
var p0 = pt[0];
var p1 = pt[1];
if(!isNaN(p0) && !isNaN(p1)) {
var twoPi = Math.PI*2;
var radius = style.pointRadius;
if(style.fill !== false) {
this.setCanvasStyle("fill", style);
this.canvas.beginPath();
this.canvas.arc(p0, p1, radius, 0, twoPi, true);
this.canvas.fill();
if (this.hitDetection) {
this.setHitContextStyle("fill", featureId, style);
this.hitContext.beginPath();
this.hitContext.arc(p0, p1, radius, 0, twoPi, true);
this.hitContext.fill();
}
}
if(style.stroke !== false) {
this.setCanvasStyle("stroke", style);
this.canvas.beginPath();
this.canvas.arc(p0, p1, radius, 0, twoPi, true);
this.canvas.stroke();
if (this.hitDetection) {
this.setHitContextStyle("stroke", featureId, style);
this.hitContext.beginPath();
this.hitContext.arc(p0, p1, radius, 0, twoPi, true);
this.hitContext.stroke();
}
this.setCanvasStyle("reset");
}
}
}
}
},
/**
* Method: drawLineString
* This method is only called by the renderer itself.
*
* Parameters:
* geometry - {<OpenLayers.Geometry>}
* style - {Object}
* featureId - {String}
*/
drawLineString: function(geometry, style, featureId) {
style = OpenLayers.Util.applyDefaults({fill: false}, style);
this.drawLinearRing(geometry, style, featureId);
},
/**
* Method: drawLinearRing
* This method is only called by the renderer itself.
*
* Parameters:
* geometry - {<OpenLayers.Geometry>}
* style - {Object}
* featureId - {String}
*/
drawLinearRing: function(geometry, style, featureId) {
if (style.fill !== false) {
this.setCanvasStyle("fill", style);
this.renderPath(this.canvas, geometry, style, featureId, "fill");
if (this.hitDetection) {
this.setHitContextStyle("fill", featureId, style);
this.renderPath(this.hitContext, geometry, style, featureId, "fill");
}
}
if (style.stroke !== false) {
this.setCanvasStyle("stroke", style);
this.renderPath(this.canvas, geometry, style, featureId, "stroke");
if (this.hitDetection) {
this.setHitContextStyle("stroke", featureId, style);
this.renderPath(this.hitContext, geometry, style, featureId, "stroke");
}
}
this.setCanvasStyle("reset");
},
/**
* Method: renderPath
* Render a path with stroke and optional fill.
*/
renderPath: function(context, geometry, style, featureId, type) {
var components = geometry.components;
var len = components.length;
context.beginPath();
var start = this.getLocalXY(components[0]);
var x = start[0];
var y = start[1];
if (!isNaN(x) && !isNaN(y)) {
context.moveTo(start[0], start[1]);
for (var i=1; i<len; ++i) {
var pt = this.getLocalXY(components[i]);
context.lineTo(pt[0], pt[1]);
}
if (type === "fill") {
context.fill();
} else {
context.stroke();
}
}
},
/**
* Method: drawPolygon
* This method is only called by the renderer itself.
*
* Parameters:
* geometry - {<OpenLayers.Geometry>}
* style - {Object}
* featureId - {String}
*/
drawPolygon: function(geometry, style, featureId) {
var components = geometry.components;
var len = components.length;
this.drawLinearRing(components[0], style, featureId);
// erase inner rings
for (var i=1; i<len; ++i) {
/**
* Note that this is overly agressive. Here we punch holes through
* all previously rendered features on the same canvas. A better
* solution for polygons with interior rings would be to draw the
* polygon on a sketch canvas first. We could erase all holes
* there and then copy the drawing to the layer canvas.
* TODO: http://trac.osgeo.org/openlayers/ticket/3130
*/
this.canvas.globalCompositeOperation = "destination-out";
if (this.hitDetection) {
this.hitContext.globalCompositeOperation = "destination-out";
}
this.drawLinearRing(
components[i],
OpenLayers.Util.applyDefaults({stroke: false, fillOpacity: 1.0}, style),
featureId
);
this.canvas.globalCompositeOperation = "source-over";
if (this.hitDetection) {
this.hitContext.globalCompositeOperation = "source-over";
}
this.drawLinearRing(
components[i],
OpenLayers.Util.applyDefaults({fill: false}, style),
featureId
);
}
},
/**
* Method: drawText
* This method is only called by the renderer itself.
*
* Parameters:
* location - {<OpenLayers.Point>}
* style - {Object}
*/
drawText: function(location, style) {
var pt = this.getLocalXY(location);
this.setCanvasStyle("reset");
this.canvas.fillStyle = style.fontColor;
this.canvas.globalAlpha = style.fontOpacity || 1.0;
var fontStyle = [style.fontStyle ? style.fontStyle : "normal",
"normal", // "font-variant" not supported
style.fontWeight ? style.fontWeight : "normal",
style.fontSize ? style.fontSize : "1em",
style.fontFamily ? style.fontFamily : "sans-serif"].join(" ");
var labelRows = style.label.split('\n');
var numRows = labelRows.length;
if (this.canvas.fillText) {
// HTML5
this.canvas.font = fontStyle;
this.canvas.textAlign =
OpenLayers.Renderer.Canvas.LABEL_ALIGN[style.labelAlign[0]] ||
"center";
this.canvas.textBaseline =
OpenLayers.Renderer.Canvas.LABEL_ALIGN[style.labelAlign[1]] ||
"middle";
var vfactor =
OpenLayers.Renderer.Canvas.LABEL_FACTOR[style.labelAlign[1]];
if (vfactor == null) {
vfactor = -.5;
}
var lineHeight =
this.canvas.measureText('Mg').height ||
this.canvas.measureText('xx').width;
pt[1] += lineHeight*vfactor*(numRows-1);
for (var i = 0; i < numRows; i++) {
if (style.labelOutlineWidth) {
this.canvas.save();
this.canvas.globalAlpha = style.labelOutlineOpacity || style.fontOpacity || 1.0;
this.canvas.strokeStyle = style.labelOutlineColor;
this.canvas.lineWidth = style.labelOutlineWidth;
this.canvas.strokeText(labelRows[i], pt[0], pt[1] + (lineHeight*i) + 1);
this.canvas.restore();
}
this.canvas.fillText(labelRows[i], pt[0], pt[1] + (lineHeight*i));
}
} else if (this.canvas.mozDrawText) {
// Mozilla pre-Gecko1.9.1 (<FF3.1)
this.canvas.mozTextStyle = fontStyle;
// No built-in text alignment, so we measure and adjust the position
var hfactor =
OpenLayers.Renderer.Canvas.LABEL_FACTOR[style.labelAlign[0]];
if (hfactor == null) {
hfactor = -.5;
}
var vfactor =
OpenLayers.Renderer.Canvas.LABEL_FACTOR[style.labelAlign[1]];
if (vfactor == null) {
vfactor = -.5;
}
var lineHeight = this.canvas.mozMeasureText('xx');
pt[1] += lineHeight*(1 + (vfactor*numRows));
for (var i = 0; i < numRows; i++) {
var x = pt[0] + (hfactor*this.canvas.mozMeasureText(labelRows[i]));
var y = pt[1] + (i*lineHeight);
this.canvas.translate(x, y);
this.canvas.mozDrawText(labelRows[i]);
this.canvas.translate(-x, -y);
}
}
this.setCanvasStyle("reset");
},
/**
* Method: getLocalXY
* transform geographic xy into pixel xy
*
* Parameters:
* point - {<OpenLayers.Geometry.Point>}
*/
getLocalXY: function(point) {
var resolution = this.getResolution();
var extent = this.extent;
var x = ((point.x - this.featureDx) / resolution + (-extent.left / resolution));
var y = ((extent.top / resolution) - point.y / resolution);
return [x, y];
},
/**
* Method: clear
* Clear all vectors from the renderer.
*/
clear: function() {
var height = this.root.height;
var width = this.root.width;
this.canvas.clearRect(0, 0, width, height);
this.features = {};
if (this.hitDetection) {
this.hitContext.clearRect(0, 0, width, height);
}
},
/**
* Method: getFeatureIdFromEvent
* Returns a feature id from an event on the renderer.
*
* Parameters:
* evt - {<OpenLayers.Event>}
*
* Returns:
* {<OpenLayers.Feature.Vector} A feature or undefined. This method returns a
* feature instead of a feature id to avoid an unnecessary lookup on the
* layer.
*/
getFeatureIdFromEvent: function(evt) {
var featureId, feature;
if (this.hitDetection && this.root.style.display !== "none") {
// this dragging check should go in the feature handler
if (!this.map.dragging) {
var xy = evt.xy;
var x = xy.x | 0;
var y = xy.y | 0;
var data = this.hitContext.getImageData(x, y, 1, 1).data;
if (data[3] === 255) { // antialiased
var id = data[2] + (256 * (data[1] + (256 * data[0])));
if (id) {
featureId = "OpenLayers_Feature_Vector_" + (id - 1 + this.hitOverflow);
try {
feature = this.features[featureId][0];
} catch(err) {
// Because of antialiasing on the canvas, when the hit location is at a point where the edge of
// one symbol intersects the interior of another symbol, a wrong hit color (and therefore id) results.
// todo: set Antialiasing = 'off' on the hitContext as soon as browsers allow it.
}
}
}
}
}
return feature;
},
/**
* Method: eraseFeatures
* This is called by the layer to erase features; removes the feature from
* the list, then redraws the layer.
*
* Parameters:
* features - {Array(<OpenLayers.Feature.Vector>)}
*/
eraseFeatures: function(features) {
if(!(OpenLayers.Util.isArray(features))) {
features = [features];
}
for(var i=0; i<features.length; ++i) {
delete this.features[features[i].id];
}
this.redraw();
},
/**
* Method: redraw
* The real 'meat' of the function: any time things have changed,
* redraw() can be called to loop over all the data and (you guessed
* it) redraw it. Unlike Elements-based Renderers, we can't interact
* with things once they're drawn, to remove them, for example, so
* instead we have to just clear everything and draw from scratch.
*/
redraw: function() {
if (!this.locked) {
var height = this.root.height;
var width = this.root.width;
this.canvas.clearRect(0, 0, width, height);
if (this.hitDetection) {
this.hitContext.clearRect(0, 0, width, height);
}
var labelMap = [];
var feature, geometry, style;
var worldBounds = (this.map.baseLayer && this.map.baseLayer.wrapDateLine) && this.map.getMaxExtent();
for (var id in this.features) {
if (!this.features.hasOwnProperty(id)) { continue; }
feature = this.features[id][0];
geometry = feature.geometry;
this.calculateFeatureDx(geometry.getBounds(), worldBounds);
style = this.features[id][1];
this.drawGeometry(geometry, style, feature.id);
if(style.label) {
labelMap.push([feature, style]);
}
}
var item;
for (var i=0, len=labelMap.length; i<len; ++i) {
item = labelMap[i];
this.drawText(item[0].geometry.getCentroid(), item[1]);
}
}
},
CLASS_NAME: "OpenLayers.Renderer.Canvas"
});
/**
* Constant: OpenLayers.Renderer.Canvas.LABEL_ALIGN
* {Object}
*/
OpenLayers.Renderer.Canvas.LABEL_ALIGN = {
"l": "left",
"r": "right",
"t": "top",
"b": "bottom"
};
/**
* Constant: OpenLayers.Renderer.Canvas.LABEL_FACTOR
* {Object}
*/
OpenLayers.Renderer.Canvas.LABEL_FACTOR = {
"l": 0,
"r": -1,
"t": 0,
"b": -1
};
/**
* Constant: OpenLayers.Renderer.Canvas.drawImageScaleFactor
* {Number} Scale factor to apply to the canvas drawImage arguments. This
* is always 1 except for Android 2.1 devices, to work around
* http://code.google.com/p/android/issues/detail?id=5141.
*/
OpenLayers.Renderer.Canvas.drawImageScaleFactor = null;