Implement startBuffering and endBuffering calls to let caller batch up screen updates.

Author: gilesp1729

src/Arduino_GigaDisplay_GFX.cpp

@@ -40,7 +40,21 @@ void GigaDisplay_GFX::startWrite() {
 
 void GigaDisplay_GFX::endWrite() {
   //refresh_sem.release();
-  _refresh_thd->flags_set(0x1);
+  if (!buffering)
+    _refresh_thd->flags_set(0x1);
+}
+
+// If buffering, defer endWrite calls until endBuffering is called.
+void GigaDisplay_GFX::startBuffering() {
+  buffering = true;
+}
+
+void GigaDisplay_GFX::endBuffering() {
+  if (buffering)
+  {
+    buffering = false;
+    endWrite();
+  }
 }
 
 void GigaDisplay_GFX::drawPixel(int16_t x, int16_t y, uint16_t color) {

src/Arduino_GigaDisplay_GFX.h

@@ -31,6 +31,8 @@ class GigaDisplay_GFX : public Adafruit_GFX {
 
     void startWrite();
     void endWrite();
+    void startBuffering();
+    void endBuffering();
 
     uint16_t color565(uint8_t red, uint8_t green, uint8_t blue) {
       return ((red & 0xF8) << 8) | ((green & 0xFC) << 3) | (blue >> 3);
@@ -45,7 +47,8 @@ class GigaDisplay_GFX : public Adafruit_GFX {
   private:
     Arduino_H7_Video* display;
     void refresh_if_needed();
-    bool need_refresh = false;
+    //bool need_refresh = false;
+    bool buffering = false;
     uint32_t last_refresh = 0;
     rtos::Thread* _refresh_thd;
 };