add image_reader abstraction layer to hanfle multiple image formats

(work-in-progress)

1 files changed, 15 insertions, 113 deletions

diff --git a/platform/default/image.cpp b/platform/default/image.cpp
index eb4b3e8f55..bc9e720069 100644
--- a/platform/default/image.cpp
+++ b/platform/default/image.cpp
@@ -8,7 +8,7 @@
 #include <cstdlib>
 #include <stdexcept>
 #include <cstring>
-
+#include <mbgl/util/image_reader.hpp>
 
 // Check png library version.
 const static bool png_version_check = []() {
@@ -73,121 +73,23 @@ std::string compress_png(int width, int height, void *rgba) {
     return result;
 }
 
-
-struct Buffer {
-    Buffer(const std::string& data_)
-    : data(data_.data()), length(data_.size()) {}
-    const char *const data = 0;
-    const size_t length = 0;
-    size_t pos = 0;
-};
-
-void readCallback(png_structp png, png_bytep data, png_size_t length) {
-    Buffer *reader = static_cast<Buffer *>(png_get_io_ptr(png));
-
-    // Read `length` bytes into `data`.
-    if (reader->pos + length > reader->length) {
-        png_error(png, "Read Error");
-    } else {
-        std::memcpy(data, reader->data + reader->pos, length);
-        reader->pos += length;
-    }
-}
-
-void errorHandler(png_structp, png_const_charp error_msg) {
-    Log::Error(Event::Image, "PNG: %s", error_msg);
-    throw std::runtime_error(error_msg);
-}
-
-void warningHandler(png_structp, png_const_charp error_msg) {
-    Log::Warning(Event::General, "PNG: %s", error_msg);
-}
-
-Image::Image(const std::string &data) {
-    Buffer buffer(data);
-
-    if (buffer.length < 8 || !png_check_sig((const png_bytep)buffer.data, 8)) {
-        Log::Error(Event::Image, "image is not a valid PNG image");
-        return;
-    }
-
-    png_structp png = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, errorHandler, warningHandler);
-    assert(png);
-
-    png_infop info = png_create_info_struct(png);
-    assert(info);
-
-    int depth, color, interlace;
-
-    try {
-        png_set_read_fn(png, (png_voidp)&buffer, readCallback);
-        png_read_info(png, info);
-        png_get_IHDR(png, info, (png_uint_32*)&width, (png_uint_32*)&height, &depth, &color, &interlace, nullptr, nullptr);
-        bool alpha = (color & PNG_COLOR_MASK_ALPHA) || png_get_valid(png, info, PNG_INFO_tRNS);
-
-        // From http://trac.mapnik.org/browser/trunk/src/png_reader.cpp
-        if (color == PNG_COLOR_TYPE_PALETTE)
-            png_set_expand(png);
-        if (color == PNG_COLOR_TYPE_GRAY)
-            png_set_expand(png);
-        if (png_get_valid(png, info, PNG_INFO_tRNS))
-            png_set_expand(png);
-        if (depth == 16)
-            png_set_strip_16(png);
-        if (depth < 8)
-            png_set_packing(png);
-        if (color == PNG_COLOR_TYPE_GRAY ||
-            color == PNG_COLOR_TYPE_GRAY_ALPHA)
-            png_set_gray_to_rgb(png);
-
-        if (interlace == PNG_INTERLACE_ADAM7)
-            png_set_interlace_handling(png);
-
-        // Always add an alpha channel.
-        if (!alpha) {
-            png_set_add_alpha(png, 0xFF, PNG_FILLER_AFTER);
-        }
-
-        // FIXME work around gamma crash
-        double gamma;
-        if (png_get_gAMA(png, info, &gamma))
-            png_set_gamma(png, 2.2, gamma);
-
-        png_set_alpha_mode(png, PNG_ALPHA_PREMULTIPLIED, 2.2);
-
-        png_read_update_info(png, info);
-
-        png_size_t rowbytes = png_get_rowbytes(png, info);
-        assert(width * 4 == rowbytes);
-
+Image::Image(std::string const& data)
+{
+    try
+    {
+        std::unique_ptr<image_reader> reader(get_image_reader(data.c_str(), data.size()));
+        width = reader->width();
+        height = reader->height();
         img = ::std::unique_ptr<char[]>(new char[width * height * 4]());
-
-        char *surface = img.get();
-        assert(surface);
-
-        struct ptrs {
-            ptrs(size_t count) : rows(new png_bytep[count]) {}
-            ~ptrs() { delete[] rows; }
-            png_bytep *rows = nullptr;
-        } pointers(height);
-        for (unsigned i = 0; i < height; ++i) {
-            pointers.rows[i] = (png_bytep)(surface + (i * rowbytes));
-        }
-
-        // Read image data
-        png_read_image(png, pointers.rows);
-
-        png_read_end(png, nullptr);
-
-        png_destroy_read_struct(&png, &info, nullptr);
-    } catch (std::exception& e) {
-        Log::Error(Event::Image, "loading PNG failed: %s", e.what());
-        png_destroy_read_struct(&png, &info, nullptr);
-        if (img) {
-            img.reset();
-        }
+        reader->read(0, 0, width, height, img.get());
+    }
+    catch (image_reader_exception const& ex)
+    {
+        fprintf(stderr, "ImageReader: %s\n", ex.what());
+        img.reset();
         width = 0;
         height = 0;
+
     }
 }