1 files changed, 109 insertions, 0 deletions
diff --git a/src/mbgl/renderer/pattern_atlas.cpp b/src/mbgl/renderer/pattern_atlas.cpp
new file mode 100644
index 0000000000..320412685b
--- /dev/null
+++ b/src/mbgl/renderer/pattern_atlas.cpp
@@ -0,0 +1,109 @@
+#include <mbgl/renderer/pattern_atlas.hpp>
+#include <mbgl/gfx/upload_pass.hpp>
+#include <mbgl/gfx/context.hpp>
+
+namespace mbgl {
+
+namespace {
+
+// When copied into the atlas texture, image data is padded by one pixel on each side. Icon
+// images are padded with fully transparent pixels, while pattern images are padded with a
+// copy of the image data wrapped from the opposite side. In both cases, this ensures the
+// correct behavior of GL_LINEAR texture sampling mode.
+const uint16_t padding = 1;
+
+mapbox::ShelfPack::ShelfPackOptions shelfPackOptions() {
+    mapbox::ShelfPack::ShelfPackOptions options;
+    options.autoResize = true;
+    return options;
+}
+
+} // namespace
+
+PatternAtlas::PatternAtlas()
+    : shelfPack(64, 64, shelfPackOptions()) {
+}
+
+PatternAtlas::~PatternAtlas() = default;
+
+optional<ImagePosition> PatternAtlas::getPattern(const std::string& id) const {
+    auto it = patterns.find(id);
+    if (it != patterns.end()) {
+        return it->second.position;
+    }
+    return nullopt;
+}
+
+optional<ImagePosition> PatternAtlas::addPattern(const style::Image::Impl& image) {
+    if (patterns.find(image.id) != patterns.end()) {
+        return nullopt;
+    }
+    const uint16_t width = image.image.size.width + padding * 2;
+    const uint16_t height = image.image.size.height + padding * 2;
+
+    mapbox::Bin* bin = shelfPack.packOne(-1, width, height);
+    if (!bin) {
+        return nullopt;
+    }
+
+    atlasImage.resize(getPixelSize());
+
+    const PremultipliedImage& src = image.image;
+
+    const uint32_t x = bin->x + padding;
+    const uint32_t y = bin->y + padding;
+    const uint32_t w = src.size.width;
+    const uint32_t h = src.size.height;
+
+    PremultipliedImage::copy(src, atlasImage, { 0, 0 }, { x, y }, { w, h });
+
+    // Add 1 pixel wrapped padding on each side of the image.
+    PremultipliedImage::copy(src, atlasImage, { 0, h - 1 }, { x, y - 1 }, { w, 1 }); // T
+    PremultipliedImage::copy(src, atlasImage, { 0,     0 }, { x, y + h }, { w, 1 }); // B
+    PremultipliedImage::copy(src, atlasImage, { w - 1, 0 }, { x - 1, y }, { 1, h }); // L
+    PremultipliedImage::copy(src, atlasImage, { 0,     0 }, { x + w, y }, { 1, h }); // R
+
+    dirty = true;
+
+    return patterns.emplace(image.id, Pattern { bin, { *bin, image } }).first->second.position;
+}
+
+void PatternAtlas::removePattern(const std::string& id) {
+    auto it = patterns.find(id);
+    if (it != patterns.end()) {
+        // Clear pattern from the atlas image.
+        const uint32_t x = it->second.bin->x;
+        const uint32_t y = it->second.bin->y;
+        const uint32_t w = it->second.bin->w;
+        const uint32_t h = it->second.bin->h;
+        PremultipliedImage::clear(atlasImage, { x, y }, { w, h });
+
+        shelfPack.unref(*it->second.bin);
+        patterns.erase(it);
+    }
+}
+
+Size PatternAtlas::getPixelSize() const {
+    return {
+        static_cast<uint32_t>(shelfPack.width()),
+        static_cast<uint32_t>(shelfPack.height())
+    };
+}
+
+void PatternAtlas::upload(gfx::UploadPass& uploadPass) {
+    if (!atlasTexture) {
+        atlasTexture = uploadPass.createTexture(atlasImage);
+    } else if (dirty) {
+        uploadPass.updateTexture(*atlasTexture, atlasImage);
+    }
+
+    dirty = false;
+}
+
+gfx::TextureBinding PatternAtlas::textureBinding() const {
+    assert(atlasTexture);
+    assert(!dirty);
+    return { atlasTexture->getResource(), gfx::TextureFilterType::Linear };
+}
+
+} // namespace mbgl