#529 give tiles gutters - all layers that use Tile.Image must now look after layer.imageSize and layer.imageOffset - this is handled by layer.setTileSize - for untiled layers, setTileSize must be defined by the subclass - gutters are currently supported in Layer.Mapserver and Layer.WMS

git-svn-id: http://svn.openlayers.org/trunk/openlayers@2979 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer.js

@@ -65,12 +65,45 @@ OpenLayers.Layer.prototype = {
      * @type Boolean
      */
     inRange: false,
+    
+    /**
+     * For layers that use Tile.Image, the image size is cached here.  For
+     * layers without a gutter, the image size is equal to the tile size.
+     * For layers with a gutter, the image is larger than the tile by twice
+     * the gutter in each dimension.
+     * 
+     * @type OpenLayers.Size
+     * @private
+     */
+    imageSize: null,
+    
+    /**
+     * For layers that use Tile.Image, the image offset is cached here.
+     * Layers without a gutter have zero offset.  For layers with a gutter,
+     * the image offset represents displacement due to the gutter.
+     * 
+     * @type OpenLayers.Pixel
+     * @private
+     */
+    imageOffset: null,
 
   // OPTIONS
 
     /** @type Array */
     options: null,
 
+    /** Determines the width (in pixels) of the gutter around image tiles 
+     * to ignore.  By setting this property to a non-zero value, images 
+     * will be requested that are wider and taller than the tile size by 
+     * a value of 2 x gutter.  This allows artifacts of rendering at tile 
+     * edges to be ignored.  Set a gutter value that is equal to half the size 
+     * of the widest symbol that needs to be displayed.  Defaults to zero.
+     * Non-tiled layers always have zero gutter.
+     *  
+     * @type Int 
+    */ 
+    gutter: 0, 
+
     /** @type String */
     projection: null,    
     
@@ -243,9 +276,41 @@ OpenLayers.Layer.prototype = {
         
         if (!this.isBaseLayer) {
             this.inRange = this.calculateInRange();
-        }    
+        }
+        
+        // deal with gutters
+        this.setTileSize();
     },
   
+    /**
+     * Set the tile size based on the map size.  This also sets layer.imageSize
+     * and layer.imageOffset for use by Tile.Image.
+     *
+     * @param OpenLayers.Size
+     */
+    setTileSize: function(size) {
+        var tileSize = (size) ? size :
+                                ((this.tileSize) ? this.tileSize :
+                                                   this.map.getTileSize());
+        this.tileSize = tileSize;
+        if(this.gutter) {
+            // layers with gutters need non-null tile sizes
+            //if(tileSize == null) {
+            //    OpenLayers.console.error("Error in layer.setMap() for " +
+            //                              this.name + ": layers with gutters " +
+            //                              "need non-null tile sizes");
+            //}
+            this.imageOffset = new OpenLayers.Pixel(-this.gutter, -this.gutter); 
+            this.imageSize = new OpenLayers.Size(tileSize.w + (2 * this.gutter), 
+                                                 tileSize.h + (2 * this.gutter)); 
+        } else {
+            // layers without gutters may have null tile size - as long
+            // as they don't rely on Tile.Image
+            this.imageSize = tileSize;
+            this.imageOffset = new OpenLayers.Pixel(0, 0);
+        }
+    },
+
     /**
     * @returns Whether or not the layer should be displayed (if in range)
     * @type Boolean
@@ -559,6 +624,23 @@ OpenLayers.Layer.prototype = {
         return px;
     },
     
+    /**
+     * Adjusts the extent of a bounds in map units by the layer's gutter
+     * in pixels.
+     * 
+     * @param {OpenLayers.Bounds} bounds
+     * @type OpenLayers.Bounds
+     * @return A bounds adjusted in height and width by the gutter
+     */
+    adjustBoundsByGutter: function(bounds) {
+        var mapGutter = this.gutter * this.map.getResolution();
+        bounds = new OpenLayers.Bounds(bounds.left - mapGutter,
+                                       bounds.bottom - mapGutter,
+                                       bounds.right + mapGutter,
+                                       bounds.top + mapGutter);
+        return bounds;
+    },
+    
     /**
      * Sets the opacity for the entire layer (all images)
      * @param {Float} opacity
@@ -566,7 +648,7 @@ OpenLayers.Layer.prototype = {
     setOpacity: function(opacity) {
         this.opacity = opacity;
         for(var i=0; i<this.div.childNodes.length; ++i) {
-            var element = this.div.childNodes[i];
+            var element = this.div.childNodes[i].firstChild;
             OpenLayers.Util.modifyDOMElement(element, null, null, null, 
                                              null, null, null, opacity);
         }