openlayers/src/ol/renderer/canvas/canvasvectorlayerrenderer.js

goog.provide('ol.renderer.canvas.VectorLayer');

goog.require('goog.array');
goog.require('goog.asserts');
goog.require('goog.events');
goog.require('ol.ViewHint');
goog.require('ol.dom');
goog.require('ol.extent');
goog.require('ol.feature');
goog.require('ol.layer.Vector');
goog.require('ol.render.EventType');
goog.require('ol.render.canvas.ReplayGroup');
goog.require('ol.renderer.canvas.Layer');
goog.require('ol.renderer.vector');
goog.require('ol.source.Vector');



/**
 * @constructor
 * @extends {ol.renderer.canvas.Layer}
 * @param {ol.renderer.Map} mapRenderer Map renderer.
 * @param {ol.layer.Vector} vectorLayer Vector layer.
 */
ol.renderer.canvas.VectorLayer = function(mapRenderer, vectorLayer) {

  goog.base(this, mapRenderer, vectorLayer);

  /**
   * @private
   * @type {boolean}
   */
  this.dirty_ = false;

  /**
   * @private
   * @type {number}
   */
  this.renderedRevision_ = -1;

  /**
   * @private
   * @type {number}
   */
  this.renderedResolution_ = NaN;

  /**
   * @private
   * @type {ol.Extent}
   */
  this.renderedExtent_ = ol.extent.createEmpty();

  /**
   * @private
   * @type {function(ol.Feature, ol.Feature): number|null}
   */
  this.renderedRenderOrder_ = null;

  /**
   * @private
   * @type {ol.render.canvas.ReplayGroup}
   */
  this.replayGroup_ = null;

  /**
   * @private
   * @type {CanvasRenderingContext2D}
   */
  this.context_ = ol.dom.createCanvasContext2D();

};
goog.inherits(ol.renderer.canvas.VectorLayer, ol.renderer.canvas.Layer);


/**
 * @inheritDoc
 */
ol.renderer.canvas.VectorLayer.prototype.composeFrame =
    function(frameState, layerState, context) {

  var transform = this.getTransform(frameState);

  this.dispatchPreComposeEvent(context, frameState, transform);

  var replayGroup = this.replayGroup_;
  if (!goog.isNull(replayGroup) && !replayGroup.isEmpty()) {
    var layer = this.getLayer();
    var replayContext;
    if (layer.hasListener(ol.render.EventType.RENDER)) {
      // resize and clear
      this.context_.canvas.width = context.canvas.width;
      this.context_.canvas.height = context.canvas.height;
      replayContext = this.context_;
    } else {
      replayContext = context;
    }
    replayContext.globalAlpha = layerState.opacity;
    replayGroup.replay(
        replayContext, frameState.extent, frameState.pixelRatio, transform,
        frameState.view2DState.rotation, frameState.skippedFeatureUids_);

    if (replayContext != context) {
      this.dispatchRenderEvent(replayContext, frameState, transform);
      context.drawImage(replayContext.canvas, 0, 0);
    }
  }

  this.dispatchPostComposeEvent(context, frameState, transform);

};


/**
 * @inheritDoc
 */
ol.renderer.canvas.VectorLayer.prototype.forEachFeatureAtPixel =
    function(coordinate, frameState, callback, thisArg) {
  if (goog.isNull(this.replayGroup_)) {
    return undefined;
  } else {
    var extent = frameState.extent;
    var resolution = frameState.view2DState.resolution;
    var rotation = frameState.view2DState.rotation;
    var layer = this.getLayer();
    return this.replayGroup_.forEachGeometryAtPixel(extent, resolution,
        rotation, coordinate, frameState.skippedFeatureUids_,
        /**
         * @param {ol.geom.Geometry} geometry Geometry.
         * @param {Object} data Data.
         * @return {?} Callback result.
         */
        function(geometry, data) {
          var feature = /** @type {ol.Feature} */ (data);
          goog.asserts.assert(goog.isDef(feature));
          return callback.call(thisArg, feature, layer);
        });
  }
};


/**
 * Handle changes in image style state.
 * @param {goog.events.Event} event Image style change event.
 * @private
 */
ol.renderer.canvas.VectorLayer.prototype.handleImageChange_ =
    function(event) {
  this.renderIfReadyAndVisible();
};


/**
 * @inheritDoc
 */
ol.renderer.canvas.VectorLayer.prototype.prepareFrame =
    function(frameState, layerState) {

  var vectorLayer = this.getLayer();
  goog.asserts.assertInstanceof(vectorLayer, ol.layer.Vector);
  var vectorSource = vectorLayer.getSource();
  goog.asserts.assertInstanceof(vectorSource, ol.source.Vector);

  this.updateAttributions(
      frameState.attributions, vectorSource.getAttributions());
  this.updateLogos(frameState, vectorSource);

  if (!this.dirty_ && (frameState.viewHints[ol.ViewHint.ANIMATING] ||
      frameState.viewHints[ol.ViewHint.INTERACTING])) {
    return;
  }

  var frameStateExtent = frameState.extent;
  var view2DState = frameState.view2DState;
  var projection = view2DState.projection;
  var resolution = view2DState.resolution;
  var pixelRatio = frameState.pixelRatio;
  var vectorLayerRevision = vectorLayer.getRevision();
  var vectorLayerRenderOrder = vectorLayer.getRenderOrder();
  if (!goog.isDef(vectorLayerRenderOrder)) {
    vectorLayerRenderOrder = ol.renderer.vector.defaultOrder;
  }

  if (!this.dirty_ &&
      this.renderedResolution_ == resolution &&
      this.renderedRevision_ == vectorLayerRevision &&
      this.renderedRenderOrder_ == vectorLayerRenderOrder &&
      ol.extent.containsExtent(this.renderedExtent_, frameStateExtent)) {
    return;
  }

  var extent = this.renderedExtent_;
  var xBuffer = ol.extent.getWidth(frameStateExtent) / 4;
  var yBuffer = ol.extent.getHeight(frameStateExtent) / 4;
  extent[0] = frameStateExtent[0] - xBuffer;
  extent[1] = frameStateExtent[1] - yBuffer;
  extent[2] = frameStateExtent[2] + xBuffer;
  extent[3] = frameStateExtent[3] + yBuffer;

  // FIXME dispose of old replayGroup in post render
  goog.dispose(this.replayGroup_);
  this.replayGroup_ = null;

  this.dirty_ = false;

  var styleFunction = vectorLayer.getStyleFunction();
  if (!goog.isDef(styleFunction)) {
    styleFunction = ol.feature.defaultStyleFunction;
  }
  var tolerance = resolution / (2 * pixelRatio);
  var replayGroup =
      new ol.render.canvas.ReplayGroup(tolerance, extent, resolution);
  vectorSource.loadFeatures(extent, resolution, projection);
  var renderFeature =
      /**
       * @param {ol.Feature} feature Feature.
       * @this {ol.renderer.canvas.VectorLayer}
       */
      function(feature) {
    goog.asserts.assert(goog.isDef(styleFunction));
    var dirty = this.renderFeature(
        feature, resolution, pixelRatio, styleFunction, replayGroup);
    this.dirty_ = this.dirty_ || dirty;
  };
  if (!goog.isNull(vectorLayerRenderOrder)) {
    /** @type {Array.<ol.Feature>} */
    var features = [];
    vectorSource.forEachFeatureInExtentAtResolution(extent, resolution,
        /**
         * @param {ol.Feature} feature Feature.
         */
        function(feature) {
          features.push(feature);
        }, this);
    goog.array.sort(features, vectorLayerRenderOrder);
    goog.array.forEach(features, renderFeature, this);
  } else {
    vectorSource.forEachFeatureInExtentAtResolution(
        extent, resolution, renderFeature, this);
  }
  replayGroup.finish();

  this.renderedResolution_ = resolution;
  this.renderedRevision_ = vectorLayerRevision;
  this.renderedRenderOrder_ = vectorLayerRenderOrder;
  this.replayGroup_ = replayGroup;

};


/**
 * @param {ol.Feature} feature Feature.
 * @param {number} resolution Resolution.
 * @param {number} pixelRatio Pixel ratio.
 * @param {ol.feature.StyleFunction} styleFunction Style function.
 * @param {ol.render.canvas.ReplayGroup} replayGroup Replay group.
 * @return {boolean} `true` if an image is loading.
 */
ol.renderer.canvas.VectorLayer.prototype.renderFeature =
    function(feature, resolution, pixelRatio, styleFunction, replayGroup) {
  var styles = styleFunction(feature, resolution);
  if (!goog.isDefAndNotNull(styles)) {
    return false;
  }
  // simplify to a tolerance of half a device pixel
  var squaredTolerance =
      resolution * resolution / (4 * pixelRatio * pixelRatio);
  var i, ii, loading = false;
  for (i = 0, ii = styles.length; i < ii; ++i) {
    loading = ol.renderer.vector.renderFeature(
        replayGroup, feature, styles[i], squaredTolerance, feature,
        this.handleImageChange_, this) || loading;
  }
  return loading;
};