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

Build tools and sources for developing OpenLayers based mapping applications

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

goog.require('ol');
goog.require('ol.View');
goog.require('ol.extent');
goog.require('ol.proj');
goog.require('ol.renderer.canvas.IntermediateCanvas');
goog.require('ol.transform');


/**
 * @constructor
 * @extends {ol.renderer.canvas.IntermediateCanvas}
 * @param {ol.layer.Image} imageLayer Single image layer.
 */
ol.renderer.canvas.ImageLayer = function(imageLayer) {

  ol.renderer.canvas.IntermediateCanvas.call(this, imageLayer);

  /**
   * @private
   * @type {?ol.ImageBase}
   */
  this.image_ = null;

  /**
   * @private
   * @type {ol.Transform}
   */
  this.imageTransform_ = ol.transform.create();

};
ol.inherits(ol.renderer.canvas.ImageLayer, ol.renderer.canvas.IntermediateCanvas);


/**
 * @inheritDoc
 */
ol.renderer.canvas.ImageLayer.prototype.getImage = function() {
  return !this.image_ ? null : this.image_.getImage();
};


/**
 * @inheritDoc
 */
ol.renderer.canvas.ImageLayer.prototype.getImageTransform = function() {
  return this.imageTransform_;
};


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

  var pixelRatio = frameState.pixelRatio;
  var size = frameState.size;
  var viewState = frameState.viewState;
  var viewCenter = viewState.center;
  var viewResolution = viewState.resolution;

  var image;
  var imageLayer = /** @type {ol.layer.Image} */ (this.getLayer());
  var imageSource = imageLayer.getSource();

  var hints = frameState.viewHints;

  var renderedExtent = frameState.extent;
  if (layerState.extent !== undefined) {
    renderedExtent = ol.extent.getIntersection(
        renderedExtent, layerState.extent);
  }

  if (!hints[ol.View.Hint.ANIMATING] && !hints[ol.View.Hint.INTERACTING] &&
      !ol.extent.isEmpty(renderedExtent)) {
    var projection = viewState.projection;
    if (!ol.ENABLE_RASTER_REPROJECTION) {
      var sourceProjection = imageSource.getProjection();
      if (sourceProjection) {
        ol.DEBUG && console.assert(ol.proj.equivalent(projection, sourceProjection),
            'projection and sourceProjection are equivalent');
        projection = sourceProjection;
      }
    }
    image = imageSource.getImage(
        renderedExtent, viewResolution, pixelRatio, projection);
    if (image) {
      var loaded = this.loadImage(image);
      if (loaded) {
        this.image_ = image;
        this.renderedResolution = viewResolution;
      }
    }
  }

  if (this.image_) {
    image = this.image_;
    var imageExtent = image.getExtent();
    var imageResolution = image.getResolution();
    var imagePixelRatio = image.getPixelRatio();
    var scale = pixelRatio * imageResolution /
        (viewResolution * imagePixelRatio);
    var transform = ol.transform.compose(this.imageTransform_,
        pixelRatio * size[0] / 2, pixelRatio * size[1] / 2,
        scale, scale,
        0,
        imagePixelRatio * (imageExtent[0] - viewCenter[0]) / imageResolution,
        imagePixelRatio * (viewCenter[1] - imageExtent[3]) / imageResolution);
    ol.transform.compose(this.coordinateToCanvasPixelTransform,
        pixelRatio * size[0] / 2 - transform[4], pixelRatio * size[1] / 2 - transform[5],
        pixelRatio / viewResolution, -pixelRatio / viewResolution,
        0,
        -viewCenter[0], -viewCenter[1]);

    this.updateAttributions(frameState.attributions, image.getAttributions());
    this.updateLogos(frameState, imageSource);
  }

  return !!this.image_;
};