2 files changed, 39 insertions, 0 deletions

diff --git a/minui/include/minui/minui.h b/minui/include/minui/minui.h
index 017ddde75..27e603136 100644
--- a/minui/include/minui/minui.h
+++ b/minui/include/minui/minui.h
@@ -21,6 +21,7 @@
 
 #include <functional>
 #include <string>
+#include <vector>
 
 //
 // Graphics.
@@ -129,6 +130,9 @@ int res_create_alpha_surface(const char* name, GRSurface** pSurface);
 int res_create_localized_alpha_surface(const char* name, const char* locale,
                                        GRSurface** pSurface);
 
+// Return a list of locale strings embedded in |png_name|. Return a empty list in case of failure.
+std::vector<std::string> get_locales_in_png(const std::string& png_name);
+
 // Free a surface allocated by any of the res_create_*_surface()
 // functions.
 void res_free_surface(GRSurface* surface);
diff --git a/minui/resources.cpp b/minui/resources.cpp
index 8f8d36d27..756f29d21 100644
--- a/minui/resources.cpp
+++ b/minui/resources.cpp
@@ -396,6 +396,41 @@ bool matches_locale(const std::string& prefix, const std::string& locale) {
   return std::regex_match(locale, loc_regex);
 }
 
+std::vector<std::string> get_locales_in_png(const std::string& png_name) {
+  png_structp png_ptr = nullptr;
+  png_infop info_ptr = nullptr;
+  png_uint_32 width, height;
+  png_byte channels;
+
+  int status = open_png(png_name.c_str(), &png_ptr, &info_ptr, &width, &height, &channels);
+  if (status < 0) {
+    printf("Failed to open %s\n", png_name.c_str());
+    return {};
+  }
+  if (channels != 1) {
+    printf("Expect input png to have 1 data channel, this file has %d\n", channels);
+    png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
+    return {};
+  }
+
+  std::vector<std::string> result;
+  std::vector<unsigned char> row(width);
+  for (png_uint_32 y = 0; y < height; ++y) {
+    png_read_row(png_ptr, row.data(), nullptr);
+    int h = (row[3] << 8) | row[2];
+    std::string loc(reinterpret_cast<char*>(&row[5]));
+    if (!loc.empty()) {
+      result.push_back(loc);
+    }
+    for (int i = 0; i < h; ++i, ++y) {
+      png_read_row(png_ptr, row.data(), NULL);
+    }
+  }
+
+  png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
+  return result;
+}
+
 int res_create_localized_alpha_surface(const char* name,
                                        const char* locale,
                                        GRSurface** pSurface) {