[core] Virtualize Source::load

1 files changed, 62 insertions, 0 deletions

diff --git a/src/mbgl/style/tile_source.cpp b/src/mbgl/style/tile_source.cpp
index 22739035a9..90f4b54d96 100644
--- a/src/mbgl/style/tile_source.cpp
+++ b/src/mbgl/style/tile_source.cpp
@@ -1,4 +1,7 @@
 #include <mbgl/style/tile_source.hpp>
+#include <mbgl/style/source_observer.hpp>
+#include <mbgl/style/parser.hpp>
+#include <mbgl/storage/file_source.hpp>
 
 namespace mbgl {
 namespace style {
@@ -11,5 +14,64 @@ TileSource::TileSource(SourceType type_,
     : Source(type_, std::move(id_), std::move(url_), tileSize_, std::move(tileset_)) {
 }
 
+void TileSource::load(FileSource& fileSource) {
+    if (url.empty()) {
+        // If the URL is empty, the TileJSON was specified inline in the stylesheet.
+        loaded = true;
+        return;
+    }
+
+    if (req) {
+        return;
+    }
+
+    // URL may either be a TileJSON file, or a GeoJSON file.
+    req = fileSource.request(Resource::source(url), [this](Response res) {
+        if (res.error) {
+            observer->onSourceError(*this, std::make_exception_ptr(std::runtime_error(res.error->message)));
+        } else if (res.notModified) {
+            return;
+        } else if (res.noContent) {
+            observer->onSourceError(*this, std::make_exception_ptr(std::runtime_error("unexpectedly empty TileJSON")));
+        } else {
+            std::unique_ptr<Tileset> newTileset;
+
+            // Create a new copy of the Tileset object that holds the base values we've parsed
+            // from the stylesheet. Then merge in the values parsed from the TileJSON we retrieved
+            // via the URL.
+            try {
+                newTileset = style::parseTileJSON(*res.data, url, type, tileSize);
+            } catch (...) {
+                observer->onSourceError(*this, std::current_exception());
+                return;
+            }
+
+            // Check whether previous information specifies different tile
+            if (tileset && tileset->tiles != newTileset->tiles) {
+                // Tile URLs changed: force tiles to be reloaded.
+                invalidateTiles();
+
+                // Tile size changed: We need to recalculate the tiles we need to load because we
+                // might have to load tiles for a different zoom level
+                // This is done automatically when we trigger the onSourceLoaded observer below.
+
+                // Min/Max zoom changed: We need to recalculate what tiles to load, if we have tiles
+                // loaded that are outside the new zoom range
+                // This is done automatically when we trigger the onSourceLoaded observer below.
+
+                // Attribution changed: We need to notify the embedding application that this
+                // changed. See https://github.com/mapbox/mapbox-gl-native/issues/2723
+                // This is not yet implemented.
+
+                // Center/bounds changed: We're not using these values currently
+            }
+
+            tileset = std::move(newTileset);
+            loaded = true;
+            observer->onSourceLoaded(*this);
+        }
+    });
+}
+
 } // namespace style
 } // namespace mbgl