From dd337f35263add3a2015fca6bbca37308ffa91a6 Mon Sep 17 00:00:00 2001
From: Andreas Hocevar <andreas.hocevar@gmail.com>
Date: Fri, 10 Oct 2014 16:17:19 +0200
Subject: [PATCH] Add a canvas for FeatureOverlay and pre-/postcompose
 rendering

---
 src/ol/renderer/dom/dommaprenderer.js | 88 ++++++++++++++++++++++++++-
 1 file changed, 87 insertions(+), 1 deletion(-)

diff --git a/src/ol/renderer/dom/dommaprenderer.js b/src/ol/renderer/dom/dommaprenderer.js
index c512454543..e15815ba99 100644
--- a/src/ol/renderer/dom/dommaprenderer.js
+++ b/src/ol/renderer/dom/dommaprenderer.js
@@ -5,18 +5,26 @@ goog.require('goog.dom');
 goog.require('goog.dom.TagName');
 goog.require('goog.functions');
 goog.require('goog.style');
+goog.require('goog.vec.Mat4');
 goog.require('ol');
 goog.require('ol.RendererType');
 goog.require('ol.css');
+goog.require('ol.dom');
 goog.require('ol.layer.Image');
 goog.require('ol.layer.Tile');
 goog.require('ol.layer.Vector');
+goog.require('ol.render.Event');
+goog.require('ol.render.EventType');
+goog.require('ol.render.canvas.Immediate');
+goog.require('ol.render.canvas.ReplayGroup');
 goog.require('ol.renderer.Map');
 goog.require('ol.renderer.dom.ImageLayer');
 goog.require('ol.renderer.dom.Layer');
 goog.require('ol.renderer.dom.TileLayer');
 goog.require('ol.renderer.dom.VectorLayer');
+goog.require('ol.renderer.vector');
 goog.require('ol.source.State');
+goog.require('ol.vec.Mat4');
 
 
 
@@ -30,6 +38,27 @@ ol.renderer.dom.Map = function(container, map) {
 
   goog.base(this, container, map);
 
+  /**
+   * @private
+   * @type {CanvasRenderingContext2D}
+   */
+  this.context_ = null;
+  if (!(ol.LEGACY_IE_SUPPORT && ol.IS_LEGACY_IE)) {
+    this.context_ = ol.dom.createCanvasContext2D();
+    var canvas = this.context_.canvas;
+    canvas.style.position = 'absolute';
+    canvas.style.width = '100%';
+    canvas.style.height = '100%';
+    canvas.className = ol.css.CLASS_UNSELECTABLE;
+    goog.dom.insertChildAt(container, canvas, 0);
+  }
+
+  /**
+   * @private
+   * @type {!goog.vec.Mat4.Number}
+   */
+  this.transform_ = goog.vec.Mat4.createNumber();
+
   /**
    * @type {!Element}
    * @private
@@ -81,6 +110,49 @@ ol.renderer.dom.Map.prototype.createLayerRenderer = function(layer) {
 };
 
 
+/**
+ * @param {ol.render.EventType} type Event type.
+ * @param {olx.FrameState} frameState Frame state.
+ * @private
+ */
+ol.renderer.dom.Map.prototype.dispatchComposeEvent_ =
+    function(type, frameState) {
+  var map = this.getMap();
+  if (!(ol.LEGACY_IE_SUPPORT && ol.IS_LEGACY_IE) && map.hasListener(type)) {
+    var extent = frameState.extent;
+    var pixelRatio = frameState.pixelRatio;
+    var viewState = frameState.viewState;
+    var resolution = viewState.resolution;
+    var rotation = viewState.rotation;
+    var context = this.context_;
+    var canvas = context.canvas;
+
+    ol.vec.Mat4.makeTransform2D(this.transform_,
+        canvas.width / 2,
+        canvas.height / 2,
+        pixelRatio / viewState.resolution,
+        -pixelRatio / viewState.resolution,
+        -viewState.rotation,
+        -viewState.center[0], -viewState.center[1]);
+    var vectorContext = new ol.render.canvas.Immediate(context, pixelRatio,
+        extent, this.transform_, rotation);
+    var replayGroup = new ol.render.canvas.ReplayGroup(
+        ol.renderer.vector.getTolerance(resolution, pixelRatio), extent,
+        resolution);
+    var composeEvent = new ol.render.Event(type, map, vectorContext,
+        replayGroup, frameState, context, null);
+    map.dispatchEvent(composeEvent);
+    replayGroup.finish();
+    if (!replayGroup.isEmpty()) {
+      replayGroup.replay(context, extent, pixelRatio, this.transform_,
+          rotation, {});
+    }
+    vectorContext.flush();
+    this.replayGroup = replayGroup;
+  }
+};
+
+
 /**
  * @inheritDoc
  */
@@ -132,6 +204,17 @@ ol.renderer.dom.Map.prototype.renderFrame = function(frameState) {
         });
   }
 
+  var map = this.getMap();
+  if (!(ol.LEGACY_IE_SUPPORT && ol.IS_LEGACY_IE) &&
+      (map.hasListener(ol.render.EventType.PRECOMPOSE) ||
+      map.hasListener(ol.render.EventType.POSTCOMPOSE))) {
+    var canvas = this.context_.canvas;
+    canvas.width = frameState.size[0];
+    canvas.height = frameState.size[1];
+  }
+
+  this.dispatchComposeEvent_(ol.render.EventType.PRECOMPOSE, frameState);
+
   var layerStatesArray = frameState.layerStatesArray;
   var i, ii, layer, layerRenderer, layerState;
   for (i = 0, ii = layerStatesArray.length; i < ii; ++i) {
@@ -142,7 +225,9 @@ ol.renderer.dom.Map.prototype.renderFrame = function(frameState) {
     goog.asserts.assertInstanceof(layerRenderer, ol.renderer.dom.Layer);
     addChild.call(this, layerRenderer.getTarget(), i);
     if (layerState.sourceState == ol.source.State.READY) {
-      layerRenderer.prepareFrame(frameState, layerState);
+      if (layerRenderer.prepareFrame(frameState, layerState)) {
+        layerRenderer.composeFrame(frameState, layerState);
+      }
     }
   }
 
@@ -165,4 +250,5 @@ ol.renderer.dom.Map.prototype.renderFrame = function(frameState) {
   this.scheduleRemoveUnusedLayerRenderers(frameState);
   this.scheduleExpireIconCache(frameState);
 
+  this.dispatchComposeEvent_(ol.render.EventType.POSTCOMPOSE, frameState);
 };