[core] Make Image safer

Provide Image::copy, which handles copying rectangles from a source to a destination, with thorough bounds checking.

Also fixes an indexing error in SpriteAtlas, where the top row of pixels in a wrapped image was copied from the wrong source row.

2 files changed, 2 insertions, 2 deletions

diff --git a/src/mbgl/renderer/frame_history.cpp b/src/mbgl/renderer/frame_history.cpp
index 1ee53d87b2..a933a9004a 100644
--- a/src/mbgl/renderer/frame_history.cpp
+++ b/src/mbgl/renderer/frame_history.cpp
@@ -8,7 +8,7 @@ namespace mbgl {
 
 FrameHistory::FrameHistory() {
     changeOpacities.fill(0);
-    std::fill(opacities.data.get(), opacities.data.get() + opacities.bytes(), 0);
+    opacities.fill(0);
 }
 
 void FrameHistory::record(const TimePoint& now, float zoom, const Duration& duration) {
diff --git a/src/mbgl/renderer/frame_history.hpp b/src/mbgl/renderer/frame_history.hpp
index fffbd113ed..f2b11f5f41 100644
--- a/src/mbgl/renderer/frame_history.hpp
+++ b/src/mbgl/renderer/frame_history.hpp
@@ -26,7 +26,7 @@ public:
 private:
     std::array<TimePoint, 256> changeTimes;
     std::array<uint8_t, 256> changeOpacities;
-    const AlphaImage opacities{ { 256, 1 } };
+    AlphaImage opacities{ { 256, 1 } };
 
     int16_t previousZoomIndex = 0;
     TimePoint previousTime;