Support for image or pixel operations

externs/olx.js

@@ -4500,7 +4500,8 @@ olx.source.ImageVectorOptions.prototype.style;
 
 /**
  * @typedef {{sources: Array.<ol.source.Source>,
- *     operations: (Array.<ol.raster.Operation>|undefined)}}
+ *     operations: (Array.<ol.raster.Operation>|undefined),
+ *     operationType: (ol.raster.OperationType|undefined)}}
  * @api
  */
 olx.source.RasterOptions;
@@ -4515,7 +4516,7 @@ olx.source.RasterOptions.prototype.sources;
 
 
 /**
- * Pixel operations.  Operations will be called with pixels from input sources
+ * Pixel operations.  Operations will be called with data from input sources
  * and the final output will be assigned to the raster source.
  * @type {Array.<ol.raster.Operation>|undefined}
  * @api
@@ -4523,6 +4524,17 @@ olx.source.RasterOptions.prototype.sources;
 olx.source.RasterOptions.prototype.operations;
 
 
+/**
+ * Operation type.  Supported values are `'pixel'` and `'image'`.  By default,
+ * `'pixel'` operations are assumed, and operations will be called with an
+ * array of pixels from input sources.  If set to `'image'`, operations will
+ * be called with an array of ImageData objects from input sources.
+ * @type {ol.raster.OperationType|undefined}
+ * @api
+ */
+olx.source.RasterOptions.prototype.operationType;
+
+
 /**
  * @typedef {{attributions: (Array.<ol.Attribution>|undefined),
  *     crossOrigin: (null|string|undefined),

src/ol/raster/operation.js

@@ -1,23 +1,39 @@
 goog.provide('ol.raster.IdentityOp');
 goog.provide('ol.raster.Operation');
+goog.provide('ol.raster.OperationType');
 
 
 /**
- * A function that takes an array of {@link ol.raster.Pixel} as inputs, performs
- * some operation on them, and returns an array of {@link ol.raster.Pixel} as
- * outputs.
+ * Raster operation type. Supported values are `'pixel'` and `'image'`.
+ * @enum {string}
+ * @api
+ */
+ol.raster.OperationType = {
+  PIXEL: 'pixel',
+  IMAGE: 'image'
+};
+
+
+/**
+ * A function that takes an array of input data, performs some operation, and
+ * returns an array of ouput data.  For `'pixel'` type operations, functions
+ * will be called with an array of {@link ol.raster.Pixel} data and should
+ * return an array of the same.  For `'image'` type operations, functions will
+ * be called with an array of {@link ImageData
+ * https://developer.mozilla.org/en-US/docs/Web/API/ImageData} and should return
+ * an array of the same.
  *
- * @typedef {function(Array.<ol.raster.Pixel>): Array.<ol.raster.Pixel>}
+ * @typedef {function((Array.<ol.raster.Pixel>|Array.<ImageData>)):
+ *     (Array.<ol.raster.Pixel>|Array.<ImageData>)}
  * @api
  */
 ol.raster.Operation;
 
 
 /**
- * The identity operation for pixels.  Returns the supplied input pixels as
- * outputs.
- * @param {Array.<ol.raster.Pixel>} inputs Input pixels.
- * @return {Array.<ol.raster.Pixel>} The input pixels as output.
+ * The identity operation.  Returns the supplied input data as output.
+ * @param {(Array.<ol.raster.Pixel>|Array.<ImageData>)} inputs Input data.
+ * @return {(Array.<ol.raster.Pixel>|Array.<ImageData>)} The output data.
  */
 ol.raster.IdentityOp = function(inputs) {
   return inputs;

src/ol/source/rastersource.js

@@ -13,6 +13,7 @@ goog.require('ol.extent');
 goog.require('ol.layer.Image');
 goog.require('ol.layer.Tile');
 goog.require('ol.raster.IdentityOp');
+goog.require('ol.raster.OperationType');
 goog.require('ol.renderer.canvas.ImageLayer');
 goog.require('ol.renderer.canvas.TileLayer');
 goog.require('ol.source.Image');
@@ -41,6 +42,13 @@ ol.source.Raster = function(options) {
   this.operations_ = goog.isDef(options.operations) ?
       options.operations : [ol.raster.IdentityOp];
 
+  /**
+   * @private
+   * @type {ol.raster.OperationType}
+   */
+  this.operationType_ = goog.isDef(options.operationType) ?
+      options.operationType : ol.raster.OperationType.PIXEL;
+
   /**
    * @private
    * @type {Array.<ol.renderer.canvas.Layer>}
@@ -215,29 +223,36 @@ ol.source.Raster.prototype.composeFrame_ = function(frameState) {
         this.renderers_[i], frameState, frameState.layerStatesArray[i]);
   }
 
-  var targetImageData = context.getImageData(0, 0, canvas.width, canvas.height);
-  var target = targetImageData.data;
-
-
   var resolution = frameState.viewState.resolution / frameState.pixelRatio;
   this.dispatchEvent(new ol.source.RasterEvent(
       ol.source.RasterEventType.BEFOREOPERATIONS, resolution));
 
-  var source, pixel;
-  for (var j = 0, jj = target.length; j < jj; j += 4) {
-    for (var k = 0; k < len; ++k) {
-      source = imageDatas[k].data;
-      pixel = pixels[k];
-      pixel[0] = source[j];
-      pixel[1] = source[j + 1];
-      pixel[2] = source[j + 2];
-      pixel[3] = source[j + 3];
+  var targetImageData = null;
+  if (this.operationType_ === ol.raster.OperationType.PIXEL) {
+    targetImageData = context.getImageData(0, 0, canvas.width,
+        canvas.height);
+    var target = targetImageData.data;
+
+    var source, pixel;
+    for (var j = 0, jj = target.length; j < jj; j += 4) {
+      for (var k = 0; k < len; ++k) {
+        source = imageDatas[k].data;
+        pixel = pixels[k];
+        pixel[0] = source[j];
+        pixel[1] = source[j + 1];
+        pixel[2] = source[j + 2];
+        pixel[3] = source[j + 3];
+      }
+      pixel = this.runPixelOperations_(pixels)[0];
+      target[j] = pixel[0];
+      target[j + 1] = pixel[1];
+      target[j + 2] = pixel[2];
+      target[j + 3] = pixel[3];
     }
-    pixel = this.runOperations_(pixels)[0];
-    target[j] = pixel[0];
-    target[j + 1] = pixel[1];
-    target[j + 2] = pixel[2];
-    target[j + 3] = pixel[3];
+  } else if (this.operationType_ === ol.raster.OperationType.IMAGE) {
+    targetImageData = this.runImageOperations_(imageDatas)[0];
+  } else {
+    goog.asserts.fail('unsupported operation type: ' + this.operationType_);
   }
 
   this.dispatchEvent(new ol.source.RasterEvent(
@@ -255,7 +270,7 @@ ol.source.Raster.prototype.composeFrame_ = function(frameState) {
  * @return {Array.<ol.raster.Pixel>} The modified pixels.
  * @private
  */
-ol.source.Raster.prototype.runOperations_ = function(pixels) {
+ol.source.Raster.prototype.runPixelOperations_ = function(pixels) {
   for (var i = 0, ii = this.operations_.length; i < ii; ++i) {
     pixels = this.operations_[i](pixels);
   }
@@ -263,6 +278,20 @@ ol.source.Raster.prototype.runOperations_ = function(pixels) {
 };
 
 
+/**
+ * Run image operations.
+ * @param {Array.<ImageData>} imageDatas The input image data.
+ * @return {Array.<ImageData>} The output image data.
+ * @private
+ */
+ol.source.Raster.prototype.runImageOperations_ = function(imageDatas) {
+  for (var i = 0, ii = this.operations_.length; i < ii; ++i) {
+    imageDatas = this.operations_[i](imageDatas);
+  }
+  return imageDatas;
+};
+
+
 /**
  * Get image data from a renderer.
  * @param {ol.renderer.canvas.Layer} renderer Layer renderer.