New BufferedWindow class for avoiding redrawing a window which doesn't need

radio/src/thirdparty/libopenui/src/bitmapbuffer.h

@@ -241,7 +241,6 @@ class BitmapBuffer: public BitmapBufferBase<uint16_t>
 #endif
 
   public:
-
     BitmapBuffer(uint8_t format, uint16_t width, uint16_t height):
       BitmapBufferBase<uint16_t>(format, width, height, nullptr),
       dataAllocated(true)
@@ -390,7 +389,7 @@ class BitmapBuffer: public BitmapBufferBase<uint16_t>
     coord_t drawNumber(coord_t x, coord_t y, int32_t val, LcdFlags flags = 0, uint8_t len = 0, const char * prefix = nullptr, const char * suffix = nullptr);
 
     template<class T>
-    void drawBitmap(coord_t x, coord_t y, const T * bmp, coord_t srcx=0, coord_t srcy=0, coord_t w=0, coord_t h=0, float scale=0)
+    void drawBitmap(coord_t x, coord_t y, const T * bmp, coord_t srcx = 0, coord_t srcy = 0, coord_t w = 0, coord_t h = 0, float scale = 0)
     {
       if (!data || !bmp)
         return;

radio/src/thirdparty/libopenui/src/bufferedwindow.h

@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) OpenTX
+ *
+ * Source:
+ *  https://github.com/opentx/libopenui
+ *
+ * This file is a part of libopenui library.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ */
+
+#ifndef _BUFFERED_WINDOW_H_
+#define _BUFFERED_WINDOW_H_
+
+#include "window.h"
+
+class BufferedWindow: public Window
+{
+  public:
+    BufferedWindow(Window * parent, const rect_t & rect):
+      Window(parent, rect, OPAQUE)
+    {
+    }
+
+    ~BufferedWindow() override
+    {
+      delete bitmap;
+    }
+
+    void paint(BitmapBuffer * dc) override
+    {
+      if (!bitmap) {
+        paintInit(dc);
+        bitmap = new BitmapBuffer(BMP_RGB565, width(), height());
+        bitmap->drawBitmap(0, 0, dc, dc->getOffsetX(), dc->getOffsetY());
+      }
+      else {
+        dc->drawBitmap(0, 0, bitmap);
+      }
+    }
+
+  protected:
+    BitmapBuffer * bitmap = nullptr;
+    virtual void paintInit(BitmapBuffer * dc) = 0;
+};
+
+#endif // _BUFFERED_WINDOW_H_