make eink screen look nicer

src/graphics/EInkDisplay.cpp

@@ -54,8 +54,10 @@ EInkDisplay::EInkDisplay(uint8_t address, int sda, int scl)
 // FIXME quick hack to limit drawing to a very slow rate
 uint32_t lastDrawMsec;
 
-// Write the buffer to the display memory
+/**
-void EInkDisplay::display(void)
+ * Force a display update if we haven't drawn within the specified msecLimit
+ */
+bool EInkDisplay::forceDisplay(uint32_t msecLimit)
 {
     // No need to grab this lock because we are on our own SPI bus
     // concurrency::LockGuard g(spiLock);
@@ -63,7 +65,7 @@ void EInkDisplay::display(void)
     uint32_t now = millis();
     uint32_t sinceLast = now - lastDrawMsec;
 
-    if (framePtr && (sinceLast > 60 * 1000 || lastDrawMsec == 0)) {
+    if (framePtr && (sinceLast > msecLimit || lastDrawMsec == 0)) {
         lastDrawMsec = now;
 
         // FIXME - only draw bits have changed (use backbuf similar to the other displays)
@@ -84,11 +86,26 @@ void EInkDisplay::display(void)
         updateDisplay(); // Send image to display and refresh
         DEBUG_MSG("done\n");
 
-        // Put screen to sleep to save power 
+        // Put screen to sleep to save power
         ePaper.Sleep();
+        return true;
+    } else {
+        // DEBUG_MSG("Skipping eink display\n");
+        return false;
     }
 }
 
+// Write the buffer to the display memory
+void EInkDisplay::display(void)
+{
+    // We don't allow regular 'dumb' display() calls to draw on eink until we've shown
+    // at least one forceDisplay() keyframe.  This prevents flashing when we should the critical
+    // bootscreen (that we want to look nice)
+    if (lastDrawMsec)
+        if (forceDisplay(slowUpdateMsec)) // Show the first screen a few seconds after boot, then slower
+            slowUpdateMsec = 5 * 60 * 1000;
+}
+
 // Send a command to the display (low level function)
 void EInkDisplay::sendCommand(uint8_t com)
 {

src/graphics/EInkDisplay.h

@@ -14,15 +14,26 @@
  */
 class EInkDisplay : public OLEDDisplay
 {
+    /// How often should we update the display, at first we do an update 5 secs after boot,
+    /// thereafter we do once per 5 minutes
+    uint32_t slowUpdateMsec = 5 * 1000;
+    
   public:
     /* constructor
     FIXME - the parameters are not used, just a temporary hack to keep working like the old displays
     */
     EInkDisplay(uint8_t address, int sda, int scl);
 
-    // Write the buffer to the display memory
+    // Write the buffer to the display memory (for eink we only do this occasionally)
     virtual void display(void);
 
+    /**
+     * Force a display update if we haven't drawn within the specified msecLimit
+     * 
+     * @return true if we did draw the screen
+     */
+    bool forceDisplay(uint32_t msecLimit = 2000);
+
   protected:
     // the header size of the buffer used, e.g. for the SPI command header
     virtual int getBufferOffset(void) { return 0; }
@@ -33,3 +44,5 @@ class EInkDisplay : public OLEDDisplay
     // Connect to the display
     virtual bool connect();
 };
+
+

src/graphics/Screen.cpp

@@ -72,7 +72,10 @@ static void drawBootScreen(OLEDDisplay *display, OLEDDisplayUiState *state, int1
     // draw an xbm image.
     // Please note that everything that should be transitioned
     // needs to be drawn relative to x and y
-    display->drawXbm(x + 32, y, icon_width, icon_height, (const uint8_t *)icon_bits);
+
+    // draw centered left to right and centered above the one line of app text
+    display->drawXbm(x + (SCREEN_WIDTH - icon_width) / 2, y + (SCREEN_HEIGHT - FONT_HEIGHT_16 - icon_height) / 2, icon_width,
+                     icon_height, (const uint8_t *)icon_bits);
 
     display->setFont(ArialMT_Plain_16);
     display->setTextAlignment(TEXT_ALIGN_CENTER);
@@ -85,6 +88,7 @@ static void drawBootScreen(OLEDDisplay *display, OLEDDisplayUiState *state, int1
     snprintf(buf, sizeof(buf), "%s",
              xstr(APP_VERSION)); // Note: we don't bother printing region or now, it makes the string too long
     display->drawString(SCREEN_WIDTH - 20, 0, buf);
+    screen->forceDisplay();
 }
 
 static void drawFrameBluetooth(OLEDDisplay *display, OLEDDisplayUiState *state, int16_t x, int16_t y)
@@ -570,7 +574,8 @@ void _screen_header()
 }
 #endif
 
-Screen::Screen(uint8_t address, int sda, int scl) : OSThread("Screen"), cmdQueue(32), dispdev(address, sda, scl), ui(&dispdev) {
+Screen::Screen(uint8_t address, int sda, int scl) : OSThread("Screen"), cmdQueue(32), dispdev(address, sda, scl), ui(&dispdev)
+{
     cmdQueue.setReader(this);
 }
 
@@ -608,7 +613,7 @@ void Screen::setup()
 
     displayWidth = dispdev.width();
     displayHeight = dispdev.height();
-    
+
     ui.setTimePerTransition(300); // msecs
     ui.setIndicatorPosition(BOTTOM);
     // Defines where the first frame is located in the bar.
@@ -658,6 +663,14 @@ void Screen::setup()
     nodeStatusObserver.observe(&nodeStatus->onNewStatus);
 }
 
+void Screen::forceDisplay()
+{
+    // Nasty hack to force epaper updates for 'key' frames.  FIXME, cleanup.
+#ifdef HAS_EINK
+    dispdev.forceDisplay();
+#endif
+}
+
 int32_t Screen::runOnce()
 {
     // If we don't have a screen, don't ever spend any CPU for us.
@@ -722,6 +735,7 @@ int32_t Screen::runOnce()
         DEBUG_MSG("Setting idle framerate\n");
         targetFramerate = IDLE_FRAMERATE;
         ui.setTargetFPS(targetFramerate);
+        forceDisplay();
     }
 
     // While showing the bootscreen or Bluetooth pair screen all of our

src/graphics/Screen.h

@@ -180,6 +180,9 @@ class Screen : public concurrency::OSThread
 
     int handleStatusUpdate(const meshtastic::Status *arg);
 
+    /// Used to force (super slow) eink displays to draw critical frames
+    void forceDisplay();
+
   protected:
     /// Updates the UI.
     //