[core] Make Map.addImage tests pass (#8843)

Fix Node tests suite implementation to parse pixelRatio from style json
Premultiply images in the node binding before sending to mbgl core

2 files changed, 16 insertions, 1 deletions

diff --git a/include/mbgl/util/image.hpp b/include/mbgl/util/image.hpp
index c019bb949c..a41b8462bd 100644
--- a/include/mbgl/util/image.hpp
+++ b/include/mbgl/util/image.hpp
@@ -40,11 +40,14 @@ public:
 
     Image(Image&& o)
         : size(o.size),
-          data(std::move(o.data)) {}
+          data(std::move(o.data)) {
+        o.size.width = o.size.height = 0;
+    }
 
     Image& operator=(Image&& o) {
         size = o.size;
         data = std::move(o.data);
+        o.size.width = o.size.height = 0;
         return *this;
     }
 
diff --git a/include/mbgl/util/premultiply.hpp b/include/mbgl/util/premultiply.hpp
new file mode 100644
index 0000000000..532c7cb11d
--- /dev/null
+++ b/include/mbgl/util/premultiply.hpp
@@ -0,0 +1,12 @@
+#pragma once
+
+#include <mbgl/util/image.hpp>
+
+namespace mbgl {
+namespace util {
+
+PremultipliedImage premultiply(UnassociatedImage&&);
+UnassociatedImage unpremultiply(PremultipliedImage&&);
+
+} // namespace util
+} // namespace mbgl