[core][ios][android][macos] Use premultiplied image directly for RasterTile and ImageSource, un-premultiply in the shader for blending

8 files changed, 24 insertions, 19 deletions

diff --git a/src/mbgl/renderer/buckets/raster_bucket.cpp b/src/mbgl/renderer/buckets/raster_bucket.cpp
index 61548ee333..8a2f1227a5 100644
--- a/src/mbgl/renderer/buckets/raster_bucket.cpp
+++ b/src/mbgl/renderer/buckets/raster_bucket.cpp
@@ -9,11 +9,11 @@ namespace mbgl {
 
 using namespace style;
 
-RasterBucket::RasterBucket(UnassociatedImage&& image_) {
-    image = std::make_shared<UnassociatedImage>(std::move(image_));
+RasterBucket::RasterBucket(PremultipliedImage&& image_) {
+    image = std::make_shared<PremultipliedImage>(std::move(image_));
 }
 
-RasterBucket::RasterBucket(std::shared_ptr<UnassociatedImage> image_): image(image_) {
+RasterBucket::RasterBucket(std::shared_ptr<PremultipliedImage> image_): image(image_) {
 
 }
 void RasterBucket::upload(gl::Context& context) {
@@ -40,7 +40,7 @@ void RasterBucket::clear() {
     uploaded = false;
 }
 
-void RasterBucket::setImage(std::shared_ptr<UnassociatedImage> image_) {
+void RasterBucket::setImage(std::shared_ptr<PremultipliedImage> image_) {
     image = std::move(image_);
     texture = {};
     uploaded = false;
diff --git a/src/mbgl/renderer/buckets/raster_bucket.hpp b/src/mbgl/renderer/buckets/raster_bucket.hpp
index e92e4b51f7..1b0d787bcd 100644
--- a/src/mbgl/renderer/buckets/raster_bucket.hpp
+++ b/src/mbgl/renderer/buckets/raster_bucket.hpp
@@ -13,8 +13,8 @@ namespace mbgl {
 
 class RasterBucket : public Bucket {
 public:
-    RasterBucket(UnassociatedImage&&);
-    RasterBucket(std::shared_ptr<UnassociatedImage>);
+    RasterBucket(PremultipliedImage&&);
+    RasterBucket(std::shared_ptr<PremultipliedImage>);
     void upload(gl::Context&) override;
     void render(Painter&, PaintParameters&, const RenderLayer&, const RenderTile&) override;
     void render(Painter& painter,
@@ -24,8 +24,8 @@ public:
     bool hasData() const override;
 
     void clear();
-    void setImage(std::shared_ptr<UnassociatedImage>);
-    std::shared_ptr<UnassociatedImage> image;
+    void setImage(std::shared_ptr<PremultipliedImage>);
+    std::shared_ptr<PremultipliedImage> image;
     optional<gl::Texture> texture;
 
     // Bucket specific vertices are used for Image Sources only
diff --git a/src/mbgl/renderer/sources/render_image_source.cpp b/src/mbgl/renderer/sources/render_image_source.cpp
index a17f97ee2f..3ffff5c8c6 100644
--- a/src/mbgl/renderer/sources/render_image_source.cpp
+++ b/src/mbgl/renderer/sources/render_image_source.cpp
@@ -82,7 +82,7 @@ void RenderImageSource::update(Immutable<style::Source::Impl> baseImpl_,
     std::swap(baseImpl, baseImpl_);
 
     auto coords = impl().getCoordinates();
-    std::shared_ptr<UnassociatedImage> image = impl().getImage();
+    std::shared_ptr<PremultipliedImage> image = impl().getImage();
 
     if (!image || !image->valid()) {
         enabled = false;
diff --git a/src/mbgl/shaders/raster.cpp b/src/mbgl/shaders/raster.cpp
index eb7a2db240..f454078310 100644
--- a/src/mbgl/shaders/raster.cpp
+++ b/src/mbgl/shaders/raster.cpp
@@ -45,6 +45,12 @@ void main() {
     // read and cross-fade colors from the main and parent tiles
     vec4 color0 = texture2D(u_image0, v_pos0);
     vec4 color1 = texture2D(u_image1, v_pos1);
+    if (color0.a > 0.0) {
+        color0.rgb = color0.rgb / color0.a;
+    }
+    if (color1.a > 0.0) {
+        color1.rgb = color1.rgb / color1.a;
+    }
     vec4 color = mix(color0, color1, u_fade_t);
     color.a *= u_opacity;
     vec3 rgb = color.rgb;
diff --git a/src/mbgl/style/sources/image_source.cpp b/src/mbgl/style/sources/image_source.cpp
index 9313d8da4a..9b60ba1a48 100644
--- a/src/mbgl/style/sources/image_source.cpp
+++ b/src/mbgl/style/sources/image_source.cpp
@@ -37,7 +37,7 @@ void ImageSource::setURL(const std::string& url_) {
     }
 }
 
-void ImageSource::setImage(UnassociatedImage&& image_) {
+void ImageSource::setImage(PremultipliedImage&& image_) {
     url = {};
     if (req) {
         req.reset();
@@ -70,8 +70,7 @@ void ImageSource::loadDescription(FileSource& fileSource) {
             observer->onSourceError(*this, std::make_exception_ptr(std::runtime_error("unexpectedly empty image url")));
         } else {
             try {
-                UnassociatedImage image = util::unpremultiply(decodeImage(*res.data));
-                baseImpl = makeMutable<Impl>(impl(), std::move(image));
+                baseImpl = makeMutable<Impl>(impl(), decodeImage(*res.data));
             } catch (...) {
                 observer->onSourceError(*this, std::current_exception());
             }
diff --git a/src/mbgl/style/sources/image_source_impl.cpp b/src/mbgl/style/sources/image_source_impl.cpp
index eb3e2635e5..c1f31dbdc6 100644
--- a/src/mbgl/style/sources/image_source_impl.cpp
+++ b/src/mbgl/style/sources/image_source_impl.cpp
@@ -15,14 +15,14 @@ ImageSource::Impl::Impl(const Impl& other, std::array<LatLng, 4> coords_)
     image(other.image) {
 }
 
-ImageSource::Impl::Impl(const Impl& rhs, UnassociatedImage&& image_)
+ImageSource::Impl::Impl(const Impl& rhs, PremultipliedImage&& image_)
     : Source::Impl(rhs),
     coords(rhs.coords),
-    image(std::make_shared<UnassociatedImage>(std::move(image_))) {
+    image(std::make_shared<PremultipliedImage>(std::move(image_))) {
 }
 ImageSource::Impl::~Impl() = default;
 
-std::shared_ptr<UnassociatedImage> ImageSource::Impl::getImage() const {
+std::shared_ptr<PremultipliedImage> ImageSource::Impl::getImage() const {
     return image;
 }
 
diff --git a/src/mbgl/style/sources/image_source_impl.hpp b/src/mbgl/style/sources/image_source_impl.hpp
index e0999c34a5..1e1b005a32 100644
--- a/src/mbgl/style/sources/image_source_impl.hpp
+++ b/src/mbgl/style/sources/image_source_impl.hpp
@@ -13,17 +13,17 @@ class ImageSource::Impl : public Source::Impl {
 public:
     Impl(std::string id, std::array<LatLng, 4> coords);
     Impl(const Impl& rhs, std::array<LatLng, 4> coords);
-    Impl(const Impl& rhs, UnassociatedImage&& image);
+    Impl(const Impl& rhs, PremultipliedImage&& image);
 
     ~Impl() final;
 
-    std::shared_ptr<UnassociatedImage> getImage() const;
+    std::shared_ptr<PremultipliedImage> getImage() const;
     std::array<LatLng, 4> getCoordinates() const;
 
     optional<std::string> getAttribution() const final;
 private:
     std::array<LatLng, 4> coords;
-    std::shared_ptr<UnassociatedImage> image;
+    std::shared_ptr<PremultipliedImage> image;
 };
 
 } // namespace style
diff --git a/src/mbgl/tile/raster_tile_worker.cpp b/src/mbgl/tile/raster_tile_worker.cpp
index 86fb5f181d..3c8af97b40 100644
--- a/src/mbgl/tile/raster_tile_worker.cpp
+++ b/src/mbgl/tile/raster_tile_worker.cpp
@@ -17,7 +17,7 @@ void RasterTileWorker::parse(std::shared_ptr<const std::string> data) {
     }
 
     try {
-        auto bucket = std::make_unique<RasterBucket>(util::unpremultiply(decodeImage(*data)));
+        auto bucket = std::make_unique<RasterBucket>(decodeImage(*data));
         parent.invoke(&RasterTile::onParsed, std::move(bucket));
     } catch (...) {
         parent.invoke(&RasterTile::onError, std::current_exception());