Buffering of audio

UIThread.cpp

@@ -182,7 +182,7 @@ void handleInput() {
 void drawUI() {
     display.clearDisplay();
 
-    if (globalSynth) {
+    {
         // Copy grid state to local buffer to minimize lock time
         struct MiniCell {
             uint8_t type;
@@ -191,7 +191,7 @@ void drawUI() {
         };
         MiniCell gridCopy[SynthEngine::GRID_W][SynthEngine::GRID_H];
 
-        {
+        if (globalSynth) {
             SynthLockGuard<SynthMutex> lock(globalSynth->gridMutex);
             for(int x=0; x<SynthEngine::GRID_W; ++x) {
                 for(int y=0; y<SynthEngine::GRID_H; ++y) {
@@ -202,9 +202,9 @@ void drawUI() {
             }
         }
 
-        int cellW = 10;
+        int cellW = 8;
         int cellH = 5;
-        int marginX = (SCREEN_WIDTH - (SynthEngine::GRID_W * cellW)) / 2;
+        int marginX = 2;
         int marginY = (SCREEN_HEIGHT - (SynthEngine::GRID_H * cellH)) / 2;
 
         for(int x=0; x<SynthEngine::GRID_W; ++x) {
@@ -245,6 +245,24 @@ void drawUI() {
                 }
             }
         }
+
+        // Draw Buffer Stats
+        int barX = 110;
+        int barY = 10;
+        int barW = 8;
+        int barH = 30;
+        
+        display.drawRect(barX, barY, barW, barH, SSD1306_WHITE);
+        
+        int usage = audioBufferUsage;
+        int fillH = (usage * (barH - 2)) / AUDIO_BUFFER_SIZE;
+        if (fillH > barH - 2) fillH = barH - 2;
+        if (fillH < 0) fillH = 0;
+        
+        display.fillRect(barX + 1, barY + (barH - 1) - fillH, barW - 2, fillH, SSD1306_WHITE);
+        
+        // display.setCursor(barX - 4, barY + barH + 4);
+        // display.print(usage);
     }
 
     display.display();