[core] tileCover zoom is uint8_t

3 files changed, 23 insertions, 20 deletions

diff --git a/src/mbgl/renderer/tile_pyramid.cpp b/src/mbgl/renderer/tile_pyramid.cpp
index 89c4aa0007..4f5a89f4d5 100644
--- a/src/mbgl/renderer/tile_pyramid.cpp
+++ b/src/mbgl/renderer/tile_pyramid.cpp
@@ -93,15 +93,15 @@ void TilePyramid::update(const std::vector<Immutable<style::Layer::Impl>>& layer
     handleWrapJump(parameters.transformState.getLatLng().longitude());
 
     // Determine the overzooming/underzooming amounts and required tiles.
-    int32_t overscaledZoom = util::coveringZoomLevel(parameters.transformState.getZoom(), type, tileSize);
-    int32_t tileZoom = overscaledZoom;
-    int32_t panZoom = zoomRange.max;
+    uint8_t overscaledZoom = util::coveringZoomLevel(parameters.transformState.getZoom(), type, tileSize);
+    uint8_t tileZoom = overscaledZoom;
+    uint8_t panZoom = zoomRange.max;
 
     std::vector<UnwrappedTileID> idealTiles;
     std::vector<UnwrappedTileID> panTiles;
 
     if (overscaledZoom >= zoomRange.min) {
-        int32_t idealZoom = std::min<int32_t>(zoomRange.max, overscaledZoom);
+        uint8_t idealZoom = std::min(zoomRange.max, overscaledZoom);
 
 
         // Make sure we're not reparsing overzoomed raster tiles.
@@ -114,7 +114,10 @@ void TilePyramid::update(const std::vector<Immutable<style::Layer::Impl>>& layer
             // Request lower zoom level tiles (if configured to do so) in an attempt
             // to show something on the screen faster at the cost of a little of bandwidth.
             if (parameters.prefetchZoomDelta) {
-                panZoom = std::max<int32_t>(tileZoom - parameters.prefetchZoomDelta, zoomRange.min);
+                panZoom = util::clamp(
+                        util::min(uint8_t(tileZoom - parameters.prefetchZoomDelta), tileZoom),
+                        zoomRange.min,
+                        util::min(uint8_t(zoomRange.max - parameters.prefetchZoomDelta), zoomRange.max));
             }
 
             if (panZoom < idealZoom) {
@@ -151,7 +154,7 @@ void TilePyramid::update(const std::vector<Immutable<style::Layer::Impl>>& layer
     // tiles are used from the cache, but not created.
     optional<util::TileRange> tileRange = {};
     if (bounds) {
-        tileRange = util::TileRange::fromLatLngBounds(*bounds, zoomRange.min, std::min(tileZoom, (int32_t)zoomRange.max));
+        tileRange = util::TileRange::fromLatLngBounds(*bounds, zoomRange.min, std::min(tileZoom, zoomRange.max));
     }
     auto createTileFn = [&](const OverscaledTileID& tileID) -> Tile* {
         if (tileRange && !tileRange->contains(tileID.canonical)) {
diff --git a/src/mbgl/util/tile_cover.cpp b/src/mbgl/util/tile_cover.cpp
index 3f39e53d40..64d1fb374e 100644
--- a/src/mbgl/util/tile_cover.cpp
+++ b/src/mbgl/util/tile_cover.cpp
@@ -83,7 +83,7 @@ std::vector<UnwrappedTileID> tileCover(const Point<double>& tl,
                                        const Point<double>& br,
                                        const Point<double>& bl,
                                        const Point<double>& c,
-                                       int32_t z) {
+                                       uint8_t z) {
     const int32_t tiles = 1 << z;
 
     struct ID {
@@ -129,7 +129,7 @@ std::vector<UnwrappedTileID> tileCover(const Point<double>& tl,
 
 } // namespace
 
-int32_t coveringZoomLevel(double zoom, style::SourceType type, uint16_t size) {
+uint8_t coveringZoomLevel(double zoom, style::SourceType type, uint16_t size) {
     zoom += ::log2(util::tileSize / size);
     if (type == style::SourceType::Raster || type == style::SourceType::Video) {
         return ::round(zoom);
@@ -138,7 +138,7 @@ int32_t coveringZoomLevel(double zoom, style::SourceType type, uint16_t size) {
     }
 }
 
-std::vector<UnwrappedTileID> tileCover(const LatLngBounds& bounds_, int32_t z) {
+std::vector<UnwrappedTileID> tileCover(const LatLngBounds& bounds_, uint8_t z) {
     if (bounds_.isEmpty() ||
         bounds_.south() >  util::LATITUDE_MAX ||
         bounds_.north() < -util::LATITUDE_MAX) {
@@ -158,7 +158,7 @@ std::vector<UnwrappedTileID> tileCover(const LatLngBounds& bounds_, int32_t z) {
         z);
 }
 
-std::vector<UnwrappedTileID> tileCover(const TransformState& state, int32_t z) {
+std::vector<UnwrappedTileID> tileCover(const TransformState& state, uint8_t z) {
     assert(state.valid());
 
     const double w = state.getSize().width;
@@ -172,7 +172,7 @@ std::vector<UnwrappedTileID> tileCover(const TransformState& state, int32_t z) {
         z);
 }
 
-std::vector<UnwrappedTileID> tileCover(const Geometry<double>& geometry, int32_t z) {
+std::vector<UnwrappedTileID> tileCover(const Geometry<double>& geometry, uint8_t z) {
     std::vector<UnwrappedTileID> result;
     TileCover tc(geometry, z, true);
     while (tc.hasNext()) {
@@ -182,7 +182,7 @@ std::vector<UnwrappedTileID> tileCover(const Geometry<double>& geometry, int32_t
     return result;
 }
 
-// Taken from https://github.com/mapbox/sphericalmercator#xyzbbox-zoom-tms_style-srs
+// Taken from https://github.com/mapbox/sphericalmercator#xyzbbox-z-tms_style-srs
 // Computes the projected tiles for the lower left and upper right points of the bounds
 // and uses that to compute the tile cover count
 uint64_t tileCount(const LatLngBounds& bounds, uint8_t zoom){
@@ -212,7 +212,7 @@ uint64_t tileCount(const Geometry<double>& geometry, uint8_t z) {
     return tileCount;
 }
 
-TileCover::TileCover(const LatLngBounds&bounds_, int32_t z) {
+TileCover::TileCover(const LatLngBounds&bounds_, uint8_t z) {
     LatLngBounds bounds = LatLngBounds::hull(
         { std::max(bounds_.south(), -util::LATITUDE_MAX), bounds_.west() },
         { std::min(bounds_.north(),  util::LATITUDE_MAX), bounds_.east() });
@@ -232,7 +232,7 @@ TileCover::TileCover(const LatLngBounds&bounds_, int32_t z) {
     impl = std::make_unique<TileCover::Impl>(z, p, false);
 }
 
-TileCover::TileCover(const Geometry<double>& geom, int32_t z, bool project/* = true*/)
+TileCover::TileCover(const Geometry<double>& geom, uint8_t z, bool project/* = true*/)
  : impl( std::make_unique<TileCover::Impl>(z, geom, project)) {
 }
 
diff --git a/src/mbgl/util/tile_cover.hpp b/src/mbgl/util/tile_cover.hpp
index c953d764d2..552f252960 100644
--- a/src/mbgl/util/tile_cover.hpp
+++ b/src/mbgl/util/tile_cover.hpp
@@ -18,9 +18,9 @@ namespace util {
 // Helper class to stream tile-cover results per row
 class TileCover {
 public:
-    TileCover(const LatLngBounds&, int32_t z);
+    TileCover(const LatLngBounds&, uint8_t z);
     // When project == true, projects the geometry points to tile coordinates
-    TileCover(const Geometry<double>&, int32_t z, bool project = true);
+    TileCover(const Geometry<double>&, uint8_t z, bool project = true);
     ~TileCover();
 
     optional<UnwrappedTileID> next();
@@ -31,11 +31,11 @@ private:
     std::unique_ptr<Impl> impl;
 };
 
-int32_t coveringZoomLevel(double z, style::SourceType type, uint16_t tileSize);
+uint8_t coveringZoomLevel(double z, style::SourceType type, uint16_t tileSize);
 
-std::vector<UnwrappedTileID> tileCover(const TransformState&, int32_t z);
-std::vector<UnwrappedTileID> tileCover(const LatLngBounds&, int32_t z);
-std::vector<UnwrappedTileID> tileCover(const Geometry<double>&, int32_t z);
+std::vector<UnwrappedTileID> tileCover(const TransformState&, uint8_t z);
+std::vector<UnwrappedTileID> tileCover(const LatLngBounds&, uint8_t z);
+std::vector<UnwrappedTileID> tileCover(const Geometry<double>&, uint8_t z);
 
 // Compute only the count of tiles needed for tileCover
 uint64_t tileCount(const LatLngBounds&, uint8_t z);