necessary adaptations to the Tile.IFrame mixin - back buffering is disabled when using POST and iframe tiles

lib/OpenLayers/Tile/Image/IFrame.js

@@ -29,38 +29,50 @@ OpenLayers.Tile.Image.IFrame = {
     useIFrame: null,
 
     /**
-    * Method: updateBackBuffer
+     * Method: draw
-    * Update the <backBufferData>, and return a new or reposition the
+     * Set useIFrame in the instance, and operate the to/from image from/to
-    * backBuffer. When a backbuffer is returned, the tile's markup is not
+     * iframe switch, if necessary. Then call the parent function.
-    * available any more.
      *
      * Returns:
-    * {HTMLDivElement} the tile's markup in a cloned element, or undefined if
+     * {Boolean}
-    *     no backbuffer is currently available or needed
      */
-    updateBackBuffer: function() {
+    draw: function() {
-        this.url = this.layer.getURL(this.bounds);
+        var draw = OpenLayers.Tile.Image.prototype.shouldDraw.call(this);
+        if(draw) {
+
+            // this.url isn't set to the currect value yet, so we call getURL
+            // on the layer and store the result in a local variable
+            var url = this.layer.getURL(this.bounds);
+
             var usedIFrame = this.useIFrame;
-        this.useIFrame = this.maxGetUrlLength !== null && !this.layer.async &&
+            this.useIFrame = this.maxGetUrlLength !== null &&
-            this.url.length > this.maxGetUrlLength;
+                             !this.layer.async &&
+                             url.length > this.maxGetUrlLength;
+
             var fromIFrame = usedIFrame && !this.useIFrame;
             var toIFrame = !usedIFrame && this.useIFrame;
-        if (fromIFrame || toIFrame) {
+
-            // switch between get (image) and post (iframe)
+            if(fromIFrame || toIFrame) {
-            this.clear();
+
-            if (this.imgDiv && this.imgDiv.parentNode === this.frame) {
+                // Switching between GET (image) and POST (iframe).
+
+                // We remove the imgDiv (really either an image or an iframe)
+                // from the frame and set it to null to make sure initImage
+                // will call createImage.
+
+                if(this.imgDiv && this.imgDiv.parentNode === this.frame) {
                     this.frame.removeChild(this.imgDiv);
                 }
                 this.imgDiv = null;
-            if (fromIFrame) {
+
-                // remove eventPane
+                // And if we had an iframe we also remove the event pane.
+
+                if(fromIFrame) {
                     this.frame.removeChild(this.frame.firstChild);
-                this.resetBackBuffer();
                 }
             }
-        if (!this.useIFrame) {
-            OpenLayers.Tile.Image.prototype.updateBackBuffer.apply(this, arguments);
         }
+        return OpenLayers.Tile.Image.prototype.draw.apply(this, arguments);
     },
 
     /**
@@ -183,6 +195,22 @@ OpenLayers.Tile.Image.IFrame = {
         } else {
             OpenLayers.Tile.Image.prototype.setImgSrc.apply(this, arguments);
         }
-    }
+    },
 
+    /**
+     * Method: cloneMarkup
+     * Override cloneMarkup to not attempt cloning when we use an iframe.
+     * Moving an iframe from one element to another makes it necessary to
+     * reload the iframe because its content is lost. So we just give up.
+     *
+     * Returns:
+     * {DOMElement}
+     */
+    cloneMarkup: function() {
+        var clone;
+        if(!this.useIFrame) {
+            clone = OpenLayers.Tile.Image.prototype.cloneMarkup.call(this);
+        }
+        return clone;
+    }
 };