Add dithering algorithms

src/activities/util/BmpViewerActivity.h

@@ -1,5 +1,8 @@
 #pragma once
 
+#include <Epub/converters/ImageToFramebufferDecoder.h>
+#include <I18nKeys.h>
+
 #include <functional>
 #include <string>
 
@@ -16,8 +19,12 @@ class BmpViewerActivity final : public Activity {
 
  private:
   std::string filePath;
+  uint8_t imageDitherMode;
+  bool renderCurrentImage(bool showControls = true);
   bool renderBmpImage(bool showControls = true);
   bool renderDecodedImage(bool showControls = true);
+  void cycleDitherMode();
+  StrId getCurrentDitherModeLabel() const;
   void renderError(const char* message);
   void setAsSleepScreen();
-};
+};