We split the grid init into a seperate function, and use that as the

controlling mechanism, to reduce code duplication between Grid/KaMap/other
layers that need a different grid origin. r=euzuro (Closes #1349)


git-svn-id: http://svn.openlayers.org/trunk/openlayers@6231 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/Grid.js

@@ -299,6 +299,43 @@ OpenLayers.Layer.Grid = OpenLayers.Class(OpenLayers.Layer.HTTPRequest, {
         this.removeExcessTiles(1,1);
     },
 
+    /** 
+     * Method: calculateGridLayout
+     * Generate parameters for the grid layout. This  
+     *
+     * Parameters:
+     * bounds - {<OpenLayers.Bound>}
+     * extent - {<OpenLayers.Bounds>}
+     * resolution - {Number}
+     *
+     * Returns:
+     * Object containing properties tilelon, tilelat, tileoffsetlat,
+     * tileoffsetlat, tileoffsetx, tileoffsety
+     */
+    calculateGridLayout: function(bounds, extent, resolution) {
+        var tilelon = resolution * this.tileSize.w;
+        var tilelat = resolution * this.tileSize.h;
+        
+        var offsetlon = bounds.left - extent.left;
+        var tilecol = Math.floor(offsetlon/tilelon) - this.buffer;
+        var tilecolremain = offsetlon/tilelon - tilecol;
+        var tileoffsetx = -tilecolremain * this.tileSize.w;
+        var tileoffsetlon = extent.left + tilecol * tilelon;
+        
+        var offsetlat = bounds.top - (extent.bottom + tilelat);  
+        var tilerow = Math.ceil(offsetlat/tilelat) + this.buffer;
+        var tilerowremain = tilerow - offsetlat/tilelat;
+        var tileoffsety = -tilerowremain * this.tileSize.h;
+        var tileoffsetlat = extent.bottom + tilerow * tilelat;
+        
+        return { 
+          tilelon: tilelon, tilelat: tilelat,
+          tileoffsetlon: tileoffsetlon, tileoffsetlat: tileoffsetlat,
+          tileoffsetx: tileoffsetx, tileoffsety: tileoffsety
+        }  
+
+    },
+
     /**
      * Method: initGriddedTiles
      * 
@@ -318,23 +355,17 @@ OpenLayers.Layer.Grid = OpenLayers.Class(OpenLayers.Layer.HTTPRequest, {
         
         var extent = this.map.getMaxExtent();
         var resolution = this.map.getResolution();
-        var tilelon = resolution * this.tileSize.w;
-        var tilelat = resolution * this.tileSize.h;
         
-        var offsetlon = bounds.left - extent.left;
+        var tileLayout = this.calculateGridLayout(bounds, extent, resolution);
-        var tilecol = Math.floor(offsetlon/tilelon) - this.buffer;
-        var tilecolremain = offsetlon/tilelon - tilecol;
-        var tileoffsetx = -tilecolremain * this.tileSize.w;
-        var tileoffsetlon = extent.left + tilecol * tilelon;
 
-        var offsetlat = bounds.top - (extent.bottom + tilelat);  
+        var tileoffsetx = Math.round(tileLayout.tileoffsetx); // heaven help us
-        var tilerow = Math.ceil(offsetlat/tilelat) + this.buffer;
+        var tileoffsety = Math.round(tileLayout.tileoffsety);
-        var tilerowremain = tilerow - offsetlat/tilelat;
-        var tileoffsety = -tilerowremain * this.tileSize.h;
-        var tileoffsetlat = extent.bottom + tilerow * tilelat;
 
-        tileoffsetx = Math.round(tileoffsetx); // heaven help us
+        var tileoffsetlon = tileLayout.tileoffsetlon;
-        tileoffsety = Math.round(tileoffsety);
+        var tileoffsetlat = tileLayout.tileoffsetlat;
+        
+        var tilelon = tileLayout.tilelon;
+        var tilelat = tileLayout.tilelat;
 
         this.origin = new OpenLayers.Pixel(tileoffsetx, tileoffsety);
 

lib/OpenLayers/Layer/KaMap.js

@@ -114,16 +114,21 @@ OpenLayers.Layer.KaMap = OpenLayers.Class(OpenLayers.Layer.Grid, {
     },
 
     /** 
-     * Method: initGriddedTiles
+     * Method: calculateGridLayout
+     * ka-Map uses the center point of the map as an origin for 
+     * its tiles. Override calculateGridLayout to center tiles 
+     * correctly for this case.
+     *
+     * Parameters:
+     * bounds - {<OpenLayers.Bound>}
+     * extent - {<OpenLayers.Bounds>}
+     * resolution - {Number}
+     *
+     * Returns:
+     * Object containing properties tilelon, tilelat, tileoffsetlat,
+     * tileoffsetlat, tileoffsetx, tileoffsety
      */
-    initGriddedTiles:function(bounds) {
+    calculateGridLayout: function(bounds, extent, resolution) {
-
-        var viewSize = this.map.getSize();
-        var minRows = Math.ceil(viewSize.h/this.tileSize.h) + Math.max(1, 2*this.buffer);
-        var minCols = Math.ceil(viewSize.w/this.tileSize.w) + Math.max(1, 2*this.buffer);
-        
-        var extent = this.map.getMaxExtent();
-        var resolution = this.map.getResolution();
         var tilelon = resolution*this.tileSize.w;
         var tilelat = resolution*this.tileSize.h;
         
@@ -139,67 +144,11 @@ OpenLayers.Layer.KaMap = OpenLayers.Class(OpenLayers.Layer.Grid, {
         var tileoffsety = -(tilerowremain+1) * this.tileSize.h;
         var tileoffsetlat = tilerow * tilelat;
         
-        tileoffsetx = Math.round(tileoffsetx); // heaven help us
+        return { 
-        tileoffsety = Math.round(tileoffsety);
+          tilelon: tilelon, tilelat: tilelat,
-
+          tileoffsetlon: tileoffsetlon, tileoffsetlat: tileoffsetlat,
-        this.origin = new OpenLayers.Pixel(tileoffsetx,tileoffsety);
+          tileoffsetx: tileoffsetx, tileoffsety: tileoffsety
-
-        var startX = tileoffsetx; 
-        var startLon = tileoffsetlon;
-        
-        var rowidx = 0;
-        
-        do {
-            var row = this.grid[rowidx++];
-            if (!row) {
-                row = [];
-                this.grid.push(row);
         }  
-
-            tileoffsetlon = startLon;
-            tileoffsetx = startX;
-
-            var colidx = 0;
- 
-            do {
-                var tileBounds = 
-                    new OpenLayers.Bounds(tileoffsetlon, 
-                                          tileoffsetlat, 
-                                          tileoffsetlon + tilelon,
-                                          tileoffsetlat + tilelat);
-
-                var x = tileoffsetx;
-                x -= parseInt(this.map.layerContainerDiv.style.left);
-
-                var y = tileoffsety;
-                y -= parseInt(this.map.layerContainerDiv.style.top);
-
-                var px = new OpenLayers.Pixel(x, y);
-                var tile = row[colidx++];
-                if (!tile) {
-                    tile = this.addTile(tileBounds, px);
-                    this.addTileMonitoringHooks(tile); 
-                    row.push(tile);
-                } else {
-                    tile.moveTo(tileBounds, px, false);
-                }
-     
-                tileoffsetlon += tilelon;       
-                tileoffsetx += this.tileSize.w;
-            } while (tileoffsetlon <= bounds.right + tilelon * this.buffer
-                     || colidx < minCols)
-            
-            tileoffsetlat -= tilelat;
-            tileoffsety += this.tileSize.h;
-        } while(tileoffsetlat >= bounds.bottom - tilelat * this.buffer
-                || rowidx < minRows)
-        
-        //shave off exceess rows and colums
-        this.removeExcessTiles(rowidx, colidx);
-        
-        //now actually draw the tiles
-        this.spiralTileLoad();
-
     },    
 
     /**