[core] Rewrite image handling

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

8 files changed, 27 insertions, 216 deletions

diff --git a/include/mbgl/map/map.hpp b/include/mbgl/map/map.hpp
index c190088088..80b50c2fa4 100644
--- a/include/mbgl/map/map.hpp
+++ b/include/mbgl/map/map.hpp
@@ -2,6 +2,7 @@
 #define MBGL_MAP_MAP
 
 #include <mbgl/util/chrono.hpp>
+#include <mbgl/util/image.hpp>
 #include <mbgl/map/update.hpp>
 #include <mbgl/map/mode.hpp>
 #include <mbgl/util/geo.hpp>
@@ -21,7 +22,6 @@ class FileSource;
 class View;
 class MapData;
 class MapContext;
-class StillImage;
 class SpriteImage;
 class Transform;
 class PointAnnotation;
@@ -58,7 +58,7 @@ public:
 
     // Register a callback that will get called (on the render thread) when all resources have
     // been loaded and a complete render occurs.
-    using StillImageCallback = std::function<void(std::exception_ptr, std::unique_ptr<const StillImage>)>;
+    using StillImageCallback = std::function<void (std::exception_ptr, UnassociatedImage&&)>;
     void renderStill(StillImageCallback callback);
 
     // Triggers a synchronous render.
diff --git a/include/mbgl/map/still_image.hpp b/include/mbgl/map/still_image.hpp
deleted file mode 100644
index 36922fe95a..0000000000
--- a/include/mbgl/map/still_image.hpp
+++ /dev/null
@@ -1,19 +0,0 @@
-#ifndef MBGL_MAP_STILL_IMAGE
-#define MBGL_MAP_STILL_IMAGE
-
-#include <mbgl/util/noncopyable.hpp>
-
-#include <cstdint>
-
-namespace mbgl {
-
-class StillImage : util::noncopyable {
-public:
-    size_t width = 0;
-    size_t height = 0;
-    std::unique_ptr<uint8_t[]> pixels;
-};
-
-}
-
-#endif
diff --git a/include/mbgl/map/view.hpp b/include/mbgl/map/view.hpp
index fadd035e49..68bde5fe30 100644
--- a/include/mbgl/map/view.hpp
+++ b/include/mbgl/map/view.hpp
@@ -2,14 +2,14 @@
 #define MBGL_MAP_VIEW
 
 #include <mbgl/util/chrono.hpp>
-#include <functional>
+#include <mbgl/util/image.hpp>
 
+#include <functional>
 #include <memory>
 
 namespace mbgl {
 
 class Map;
-class StillImage;
 
 enum MapChange : uint8_t {
     MapChangeRegionWillChange = 0,
@@ -70,7 +70,7 @@ public:
 
     // Reads the pixel data from the current framebuffer. If your View implementation
     // doesn't support reading from the framebuffer, return a null pointer.
-    virtual std::unique_ptr<StillImage> readStillImage();
+    virtual UnassociatedImage readStillImage();
 
     // Notifies a watcher of map x/y/scale/rotation changes.
     // Must only be called from the same thread that caused the change.
diff --git a/include/mbgl/platform/default/headless_view.hpp b/include/mbgl/platform/default/headless_view.hpp
index 50edc48428..8b25620524 100644
--- a/include/mbgl/platform/default/headless_view.hpp
+++ b/include/mbgl/platform/default/headless_view.hpp
@@ -39,7 +39,7 @@ public:
     void invalidate() override;
     void beforeRender() override;
     void afterRender() override;
-    std::unique_ptr<StillImage> readStillImage() override;
+    UnassociatedImage readStillImage() override;
 
     void resizeFramebuffer();
     void resize(uint16_t width, uint16_t height);
diff --git a/include/mbgl/platform/default/image_reader.hpp b/include/mbgl/platform/default/image_reader.hpp
deleted file mode 100644
index e46bb08ea2..0000000000
--- a/include/mbgl/platform/default/image_reader.hpp
+++ /dev/null
@@ -1,40 +0,0 @@
-#ifndef MBGL_UTIL_IMAGE_READER_HPP
-#define MBGL_UTIL_IMAGE_READER_HPP
-
-#include <mbgl/util/noncopyable.hpp>
-// stl
-#include <stdexcept>
-#include <string>
-#include <memory>
-
-namespace mbgl { namespace util {
-
-class ImageReaderException : public std::exception
-{
-private:
-    std::string message_;
-public:
-    ImageReaderException(std::string const& message)
-        : message_(message) {}
-
-    ~ImageReaderException() throw() {}
-
-    virtual const char* what() const throw()
-    {
-        return message_.c_str();
-    }
-};
-
-struct ImageReader : private noncopyable
-{
-    virtual unsigned width() const=0;
-    virtual unsigned height() const=0;
-    virtual std::unique_ptr<uint8_t[]> read()=0;
-    virtual ~ImageReader() {}
-};
-
-std::unique_ptr<ImageReader> getImageReader(const uint8_t* data, size_t size);
-
-}}
-
-#endif
diff --git a/include/mbgl/platform/default/jpeg_reader.hpp b/include/mbgl/platform/default/jpeg_reader.hpp
deleted file mode 100644
index 2f988374c3..0000000000
--- a/include/mbgl/platform/default/jpeg_reader.hpp
+++ /dev/null
@@ -1,72 +0,0 @@
-#ifndef MBGL_UTIL_JPEG_READER_HPP
-#define MBGL_UTIL_JPEG_READER_HPP
-
-#include <mbgl/platform/default/image_reader.hpp>
-
-// jpeg
-extern "C"
-{
-#include <jpeglib.h>
-}
-
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wunknown-pragmas"
-#pragma GCC diagnostic ignored "-Wunused-local-typedefs"
-#pragma GCC diagnostic ignored "-Wshadow"
-#include <boost/iostreams/stream.hpp>
-#pragma GCC diagnostic pop
-
-namespace mbgl { namespace util {
-
-template <typename T>
-class JpegReader : public ImageReader
-{
-public:
-    using source_type = T;
-    using input_stream = boost::iostreams::stream<source_type>;
-    const static unsigned BUF_SIZE = 4096;
-private:
-    struct jpeg_stream_wrapper
-    {
-        jpeg_source_mgr manager;
-        input_stream * stream;
-        JOCTET buffer[BUF_SIZE];
-    };
-
-    struct jpeg_info_guard
-    {
-        jpeg_info_guard(jpeg_decompress_struct * cinfo)
-            : i_(cinfo) {}
-
-        ~jpeg_info_guard()
-        {
-            jpeg_destroy_decompress(i_);
-        }
-        jpeg_decompress_struct * i_;
-    };
-
-private:
-    source_type source_;
-    input_stream stream_;
-    unsigned width_;
-    unsigned height_;
-public:
-    JpegReader(const uint8_t* data, size_t size);
-    ~JpegReader();
-    unsigned width() const;
-    unsigned height() const;
-    std::unique_ptr<uint8_t[]> read();
-private:
-    void init();
-    static void on_error(j_common_ptr cinfo);
-    static void on_error_message(j_common_ptr cinfo);
-    static void init_source(j_decompress_ptr cinfo);
-    static boolean fill_input_buffer(j_decompress_ptr cinfo);
-    static void skip(j_decompress_ptr cinfo, long count);
-    static void term(j_decompress_ptr cinfo);
-    static void attach_stream(j_decompress_ptr cinfo, input_stream* in);
-};
-
-}}
-
-#endif // MBGL_UTIL_JPEG_READER_HPP
diff --git a/include/mbgl/platform/default/png_reader.hpp b/include/mbgl/platform/default/png_reader.hpp
deleted file mode 100644
index c869e78ea4..0000000000
--- a/include/mbgl/platform/default/png_reader.hpp
+++ /dev/null
@@ -1,65 +0,0 @@
-#ifndef MBGL_UTIL_PNG_READER_HPP
-#define MBGL_UTIL_PNG_READER_HPP
-
-#include <mbgl/platform/default/image_reader.hpp>
-
-extern "C"
-{
-#include <png.h>
-}
-
-#include <cstring>
-#include <memory>
-
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wunknown-pragmas"
-#pragma GCC diagnostic ignored "-Wunused-local-typedefs"
-#pragma GCC diagnostic ignored "-Wshadow"
-#include <boost/iostreams/stream.hpp>
-#pragma GCC diagnostic pop
-
-namespace mbgl { namespace util {
-
-template <typename T>
-class PngReader : public ImageReader
-{
-    using source_type = T;
-    using input_stream = boost::iostreams::stream<source_type>;
-
-    struct png_struct_guard
-    {
-        png_struct_guard(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
-            : p_(png_ptr_ptr),
-              i_(info_ptr_ptr) {}
-
-        ~png_struct_guard()
-        {
-            png_destroy_read_struct(p_,i_,0);
-        }
-        png_structpp p_;
-        png_infopp i_;
-    };
-
-private:
-    source_type source_;
-    input_stream stream_;
-    unsigned width_;
-    unsigned height_;
-    int bit_depth_;
-    int color_type_;
-    bool has_alpha_;
-public:
-    PngReader(const uint8_t* data, std::size_t size);
-    ~PngReader();
-    unsigned width() const;
-    unsigned height() const;
-    std::unique_ptr<uint8_t[]> read();
-private:
-    void init();
-    static void png_read_data(png_structp png_ptr, png_bytep data, png_size_t length);
-};
-
-
-}}
-
-#endif // MBGL_UTIL_PNG_READER_HPP
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