[core] Rewrite image handling

* Consolidate Image and StillImage
* Typecheck unassociated vs premultiplied images
* Rewrite default platform image decoding implementation

1 files changed, 21 insertions, 14 deletions

diff --git a/include/mbgl/util/image.hpp b/include/mbgl/util/image.hpp
index fc4078501e..0604691dd1 100644
--- a/include/mbgl/util/image.hpp
+++ b/include/mbgl/util/image.hpp
@@ -5,30 +5,37 @@
 #include <memory>
 
 namespace mbgl {
-namespace util {
-
-std::string compress_png(size_t width, size_t height, const uint8_t* rgba);
 
+enum ImageAlphaMode {
+    Unassociated,
+    Premultiplied
+};
 
+template <ImageAlphaMode Mode>
 class Image {
 public:
-    explicit Image(const std::string& img);
+    Image() {}
 
-    inline const uint8_t* getData() const { return img.get(); }
-    inline uint32_t getWidth() const { return width; }
-    inline uint32_t getHeight() const { return height; }
-    inline operator bool() const { return img && width && height; }
+    Image(size_t w, size_t h)
+        : width(w),
+          height(h),
+          data(std::make_unique<uint8_t[]>(size())) {}
 
-private:
-    // loaded image dimensions
-    uint32_t width = 0, height = 0;
+    size_t stride() const { return width * 4; }
+    size_t size() const { return width * height * 4; }
 
-    // the raw image data
-    std::unique_ptr<uint8_t[]> img;
+    size_t width = 0;
+    size_t height = 0;
+    std::unique_ptr<uint8_t[]> data;
 };
 
+using UnassociatedImage = Image<ImageAlphaMode::Unassociated>;
+using PremultipliedImage = Image<ImageAlphaMode::Premultiplied>;
+
+// TODO: don't use std::string for binary data.
+PremultipliedImage decodeImage(const std::string&);
+std::string encodePNG(const UnassociatedImage&);
 
-}
 }
 
 #endif