Merge pull request #639 from ahocevar/grid-align

When using a buffer, the grid lacks rows/columns at the top/left. r=@bartvde

lib/OpenLayers/Layer/Grid.js

@@ -983,9 +983,9 @@ OpenLayers.Layer.Grid = OpenLayers.Class(OpenLayers.Layer.HTTPRequest, {
 
         var viewSize = this.map.getSize();
         var minRows = Math.ceil(viewSize.h/this.tileSize.h) + 
-                      Math.max(1, 2 * this.buffer);
+                      2 * this.buffer + 1;
         var minCols = Math.ceil(viewSize.w/this.tileSize.w) +
-                      Math.max(1, 2 * this.buffer);
+                      2 * this.buffer + 1;
         
         var origin = this.getTileOrigin();
         var resolution = this.getServerResolution();
@@ -1193,7 +1193,7 @@ OpenLayers.Layer.Grid = OpenLayers.Class(OpenLayers.Layer.HTTPRequest, {
             );
             return;
         }
-        var buffer = this.buffer || 1;
+        var buffer = this.buffer + 1;
         var scale = this.getResolutionScale();
         while(true) {
             var tlViewPort = {

tests/Layer/Grid.html

@@ -76,8 +76,8 @@
         layer = new OpenLayers.Layer.WMS(name, url, params, {buffer:2});
         map.addLayer(layer);
         map.setCenter(new OpenLayers.LonLat(0,0),5);
-        t.eq( layer.grid.length, 7, "Grid rows is correct." );
+        t.eq( layer.grid.length, 8, "Grid rows is correct." );
-        t.eq( layer.grid[0].length, 6, "Grid cols is correct." );
+        t.eq( layer.grid[0].length, 7, "Grid cols is correct." );
         
     }
 
@@ -239,6 +239,23 @@
         t.eq( zoom, 2, "getZoomForExtent() returns correct value");
     }   
     
+    function test_moveGriddedTiles(t) {
+        t.plan(1);
+        var map = new OpenLayers.Map('map');
+        layer = new OpenLayers.Layer.WMS(name, url, params, {buffer: 2});
+        map.addLayer(layer);
+        map.setCenter([0, 0], 5);
+        var count = 0;
+        layer.shiftColumn = function(prepend) {
+            ++count;
+            OpenLayers.Layer.WMS.prototype.shiftColumn.apply(this, arguments);
+        }
+        map.moveTo([15, 0]);
+        t.delay_call(.5, function() {
+            t.eq(count, 1, "column shifted once");
+        });
+    }
+    
     function test_Layer_Grid_moveTo(t) {
 
         t.plan(17);
@@ -695,17 +712,17 @@
         map.setCenter(new OpenLayers.LonLat(0, 0), 4); 
         t.eq( layer0.grid.length, 3, "Grid rows with buffer:0" );
         map.setBaseLayer(layer1);
-        t.eq( layer1.grid.length, 4, "Grid rows with buffer:1" );
+        t.eq( layer1.grid.length, 5, "Grid rows with buffer:1" );
         map.setBaseLayer(layer2);
-        t.eq( layer2.grid.length, 6, "Grid rows with buffer:2" );
+        t.eq( layer2.grid.length, 7, "Grid rows with buffer:2" );
 
         // zooming in on Greenland exercises the bug from pre-r4313
         map.setCenter(new OpenLayers.LonLat(0, 90), 4); 
         t.eq( layer0.grid.length, 3, "Grid rows with buffer:0" );
         map.setBaseLayer(layer1);
-        t.eq( layer1.grid.length, 4, "Grid rows with buffer:1" );
+        t.eq( layer1.grid.length, 5, "Grid rows with buffer:1" );
         map.setBaseLayer(layer2);
-        t.eq( layer2.grid.length, 6, "Grid rows with buffer:2" );
+        t.eq( layer2.grid.length, 7, "Grid rows with buffer:2" );
     }
 
     function test_Layer_Grid_destroy (t) {