add label priority migration

mapbox · Aug 13, 2015 · d6a0c08 · d6a0c08
1 parent 87c4620
commit d6a0c08
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Showing 3 changed files with 72 additions and 40 deletions.
diff --git a/migrations/v8.js b/migrations/v8.js
@@ -236,5 +236,31 @@ module.exports = function(style) {
         });
     });
 
+    // Reverse order of symbol layers. This is an imperfect migration.
+    //
+    // The order of a symbol layer in the layers list affects two things:
+    // - how it is drawn relative to other layers (like oneway arrows below bridges)
+    // - the placement priority compared to other layers
+    //
+    // It's impossible to reverse the placement priority without breaking the draw order
+    // in some cases. This migration only reverses the order of symbol layers that
+    // are above all other types of layers.
+    //
+    // Symbol layers that are at the top of the map preserve their priority.
+    // Symbol layers that are below another type (line, fill) of layer preserve their draw order.
+
+    var firstSymbolLayer = 0;
+    for (var i = style.layers.length - 1; i >= 0; i--) {
+        var layer = style.layers[i];
+        if (layer.type !== 'symbol') {
+            firstSymbolLayer = i + 1;
+            break;
+        }
+    }
+
+    var symbolLayers = style.layers.splice(firstSymbolLayer);
+    symbolLayers.reverse();
+    style.layers = style.layers.concat(symbolLayers);
+
     return style;
 };
diff --git a/test/fixture/v7-migrate/style-basic.output.json b/test/fixture/v7-migrate/style-basic.output.json
@@ -79,39 +79,6 @@
         "line-width": 1
       }
     },
-    {
-      "id": "poi",
-      "type": "symbol",
-      "source": "mapbox.mapbox-streets-v5",
-      "source-layer": "poi_label",
-      "layout": {
-        "icon-rotation-alignment": "viewport"
-      }
-    },
-    {
-      "id": "country_label",
-      "type": "symbol",
-      "source": "mapbox.mapbox-streets-v5",
-      "source-layer": "country_label",
-      "filter": [
-        "==",
-        "$type",
-        "Point"
-      ],
-      "layout": {
-        "text-field": "{name}",
-        "text-font": [
-          "Open Sans Regular",
-          "Arial Unicode MS Regular"
-        ],
-        "text-padding": 10
-      },
-      "paint": {
-        "text-halo-color": "rgba(255,255,255,0.7)",
-        "text-halo-width": 0.25,
-        "text-color": "#000000"
-      }
-    },
     {
       "id": "road_label",
       "type": "symbol",
@@ -148,6 +115,39 @@
         "text-halo-color": "rgba(255,255,255,0.7)",
         "text-halo-width": 0.25
       }
+    },
+    {
+      "id": "country_label",
+      "type": "symbol",
+      "source": "mapbox.mapbox-streets-v5",
+      "source-layer": "country_label",
+      "filter": [
+        "==",
+        "$type",
+        "Point"
+      ],
+      "layout": {
+        "text-field": "{name}",
+        "text-font": [
+          "Open Sans Regular",
+          "Arial Unicode MS Regular"
+        ],
+        "text-padding": 10
+      },
+      "paint": {
+        "text-halo-color": "rgba(255,255,255,0.7)",
+        "text-halo-width": 0.25,
+        "text-color": "#000000"
+      }
+    },
+    {
+      "id": "poi",
+      "type": "symbol",
+      "source": "mapbox.mapbox-streets-v5",
+      "source-layer": "poi_label",
+      "layout": {
+        "icon-rotation-alignment": "viewport"
+      }
     }
   ]
-}
+}
diff --git a/test/migrations/v8.js b/test/migrations/v8.js
@@ -103,7 +103,8 @@ t('renames urls', function (t) {
                 "type": "video", "url": ["foo"],
                 coordinates: [[1, 0], [1, 0], [1, 0], [1, 0]]
             }
-        }
+        },
+        "layers": []
     };
 
     var output = {
@@ -113,7 +114,8 @@ t('renames urls', function (t) {
                 "type": "video", "urls": ["foo"],
                 coordinates: [[0, 1], [0, 1], [0, 1], [0, 1]]
             }
-        }
+        },
+        "layers": []
     };
 
     t.deepEqual(migrate(input), output, 'renames url and flips coordinates of of video');
@@ -486,12 +488,14 @@ t('update fontstack function constant', function (t) {
 t('migrate UNversioned fontstack urls', function (t) {
     var input = {
         "version": 7,
-        "glyphs": "mapbox://fontstack/{fontstack}/{range}.pbf"
+        "glyphs": "mapbox://fontstack/{fontstack}/{range}.pbf",
+        "layers": []
     };
 
     var output = {
         "version": 8,
-        "glyphs": "mapbox://fonts/mapbox/{fontstack}/{range}.pbf"
+        "glyphs": "mapbox://fonts/mapbox/{fontstack}/{range}.pbf",
+        "layers": []
     };
 
     t.deepEqual(migrate(input), output);
@@ -501,12 +505,14 @@ t('migrate UNversioned fontstack urls', function (t) {
 t('migrate versioned fontstack urls', function (t) {
     var input = {
         "version": 7,
-        "glyphs": "mapbox://fonts/v1/boxmap/{fontstack}/{range}.pbf"
+        "glyphs": "mapbox://fonts/v1/boxmap/{fontstack}/{range}.pbf",
+        "layers": []
     };
 
     var output = {
         "version": 8,
-        "glyphs": "mapbox://fonts/boxmap/{fontstack}/{range}.pbf"
+        "glyphs": "mapbox://fonts/boxmap/{fontstack}/{range}.pbf",
+        "layers": []
     };
 
     t.deepEqual(migrate(input), output);