[linux] Added WebP tile support

- Android support is currently disabled due to a libwebp build issue.
- iOS and OS X support will appear after the next Mapbox iOS SDK release.

Related: #https://github.com/mapbox/mapbox-gl-native/issues/2354

1 files changed, 17 insertions, 3 deletions

diff --git a/platform/default/image.cpp b/platform/default/image.cpp
index bf8071af5c..71fb5414b3 100644
--- a/platform/default/image.cpp
+++ b/platform/default/image.cpp
@@ -70,6 +70,10 @@ std::string encodePNG(const PremultipliedImage& pre) {
     return result;
 }
 
+#if !defined(__ANDROID__) && !defined(__APPLE__)
+PremultipliedImage decodeWebP(const uint8_t*, size_t);
+#endif // !defined(__ANDROID__) && !defined(__APPLE__)
+
 PremultipliedImage decodePNG(const uint8_t*, size_t);
 PremultipliedImage decodeJPEG(const uint8_t*, size_t);
 
@@ -77,16 +81,26 @@ PremultipliedImage decodeImage(const std::string& string) {
     const uint8_t* data = reinterpret_cast<const uint8_t*>(string.data());
     const size_t size = string.size();
 
+#if !defined(__ANDROID__) && !defined(__APPLE__)
+    if (size >= 12) {
+        uint32_t riff_magic = (data[0] << 24) | (data[1] << 16) | (data[2] << 8) | data[3];
+        uint32_t webp_magic = (data[8] << 24) | (data[9] << 16) | (data[10] << 8) | data[11];
+        if (riff_magic == 0x52494646 && webp_magic == 0x57454250) {
+            return decodeWebP(data, size);
+        }
+    }
+#endif // !defined(__ANDROID__) && !defined(__APPLE__)
+
     if (size >= 4) {
-        unsigned int magic = (data[0] << 24) | (data[1] << 16) | (data[2] << 8) | data[3];
+        uint32_t magic = (data[0] << 24) | (data[1] << 16) | (data[2] << 8) | data[3];
         if (magic == 0x89504E47U) {
             return decodePNG(data, size);
         }
     }
 
     if (size >= 2) {
-        unsigned int magic = ((data[0] << 8) | data[1]) & 0xffff;
-        if (magic == 0xffd8) {
+        uint16_t magic = ((data[0] << 8) | data[1]) & 0xffff;
+        if (magic == 0xFFD8) {
             return decodeJPEG(data, size);
         }
     }