1 files changed, 68 insertions, 0 deletions
diff --git a/src/mbgl/renderer/image_atlas.cpp b/src/mbgl/renderer/image_atlas.cpp
new file mode 100644
index 0000000000..b53c2162ea
--- /dev/null
+++ b/src/mbgl/renderer/image_atlas.cpp
@@ -0,0 +1,68 @@
+#include <mbgl/renderer/image_atlas.hpp>
+
+#include <mapbox/shelf-pack.hpp>
+
+namespace mbgl {
+
+static constexpr uint32_t padding = 1;
+
+ImagePosition::ImagePosition(const mapbox::Bin& bin, const style::Image::Impl& image)
+    : pixelRatio(image.pixelRatio),
+      textureRect(
+        bin.x + padding,
+        bin.y + padding,
+        bin.w - padding * 2,
+        bin.h - padding * 2
+      ) {
+}
+
+ImageAtlas makeImageAtlas(const ImageMap& images) {
+    ImageAtlas result;
+
+    mapbox::ShelfPack::ShelfPackOptions options;
+    options.autoResize = true;
+    mapbox::ShelfPack pack(0, 0, options);
+
+    std::vector<const style::Image::Impl*> pointers;
+    pointers.reserve(images.size());
+
+    std::vector<mapbox::Bin> bins;
+    bins.reserve(images.size());
+
+    for (const auto& entry : images) {
+        const style::Image::Impl& image = *entry.second;
+        pointers.emplace_back(&image);
+        bins.emplace_back(pointers.size() - 1,
+                          image.image.size.width + 2 * padding,
+                          image.image.size.height + 2 * padding);
+    }
+
+    mapbox::ShelfPack::PackOptions packOptions;
+    packOptions.inPlace = true;
+    pack.pack(bins, packOptions);
+
+    result.image = PremultipliedImage({
+        static_cast<uint32_t>(pack.width()),
+        static_cast<uint32_t>(pack.height())
+    });
+
+    for (const auto& bin : bins) {
+        const style::Image::Impl& image = *pointers.at(bin.id);
+
+        PremultipliedImage::copy(image.image,
+                                 result.image,
+                                 { 0, 0 },
+                                 {
+                                    bin.x + padding,
+                                    bin.y + padding
+                                 },
+                                 image.image.size);
+
+        result.positions.emplace(image.id,
+                                 ImagePosition { bin, image });
+    }
+
+    return result;
+}
+
+} // namespace mbgl