restore last screen on reopen instead of always landing on home

Source/LcdPanel.cpp

@@ -191,7 +191,7 @@ LcdPanel::LcdPanel (RMX19AudioProcessor& p)
     }
     else
     {
-        screen = Screen::Home;
+        restoreUiState();
     }
     lastMidi = proc.getLastMidiTime();
     startTimerHz (22);
@@ -199,6 +199,7 @@ LcdPanel::LcdPanel (RMX19AudioProcessor& p)
 
 LcdPanel::~LcdPanel()
 {
+    rememberUiState();
     stopTimer();
 }
 
@@ -221,10 +222,101 @@ bool LcdPanel::firstRunEver()
     return true;
 }
 
+// ---------------------------------------------------------------------------
+// The panel remembers where the user was (screen + cursors) when the editor is
+// closed, and reopens there instead of always dumping them back on Home.
+// ---------------------------------------------------------------------------
+
+juce::File LcdPanel::uiStateFile()
+{
+    return welcomeFlagFile().getParentDirectory().getChildFile ("ui.state");
+}
+
+void LcdPanel::rememberUiState()
+{
+    if (screen == Screen::Splash)
+        return;
+    const juce::String txt = juce::String ((int) screen) + " "
+        + juce::String (cursor) + " "
+        + juce::String (patchCursor) + " "
+        + juce::String (paramScreenIdx) + " "
+        + juce::String (catCursor);
+    const auto f = uiStateFile();
+    f.getParentDirectory().createDirectory();
+    f.replaceWithText (txt);
+}
+
+bool LcdPanel::restoreUiState()
+{
+    const auto f = uiStateFile();
+    if (! f.existsAsFile())
+    {
+        screen = Screen::Home;
+        return false;
+    }
+    const auto toks = juce::StringArray::fromTokens (f.loadFileAsString(), juce::StringRef (" \t\r\n"), "");
+    if (toks.size() < 5)
+    {
+        screen = Screen::Home;
+        return false;
+    }
+    const int s = toks[0].getIntValue();
+    const int cu = toks[1].getIntValue();
+    const int pc = toks[2].getIntValue();
+    const int pm = toks[3].getIntValue();
+    const int cc = toks[4].getIntValue();
+
+    if (s <= (int) Screen::Splash || s > (int) Screen::Category)
+    {
+        screen = Screen::Home;
+        return false;
+    }
+    screen = (Screen) s;
+
+    const int cats = (int) proc.getBank().categories().names.size();
+    switch (screen)
+    {
+        case Screen::Param:
+            paramScreenIdx = juce::jlimit (0, 6, pm);
+            cursor = juce::jlimit (0, paramCountForScreen (paramScreenIdx) - 1, cu);
+            break;
+        case Screen::Patch:
+            catCursor = juce::jlimit (0, cats - 1, cc);
+            buildFilteredPatches (catCursor);
+            patchCursor = juce::jlimit (0, patchCountForCurrentView() - 1, pc);
+            cursor = 0;
+            break;
+        case Screen::Patches:
+            catCursor = juce::jlimit (0, cats - 1, cc);
+            cursor = 0;
+            break;
+        case Screen::Category:
+            catCursor = juce::jlimit (0, cats, cc);   // +1 SETTINGS row
+            cursor = 0;
+            break;
+        case Screen::Home:
+            cursor = 0;
+            break;
+        default:
+            cursor = juce::jlimit (0, rowCountForScreen() - 1, cu);
+            break;
+    }
+    return true;
+}
+
 void LcdPanel::timerCallback()
 {
     bool needsRedraw = (screen == Screen::Splash);
 
+    // debounce the last-screen write so navigation during tweaking doesn't
+    // hammer the disk
+    if (uiDirty && (juce::Time::getMillisecondCounter() - lastUiWrite) > 700)
+    {
+        rememberUiState();
+        uiDirty = false;
+        lastUiWrite = juce::Time::getMillisecondCounter();
+    }
+
     if (proc.getLastMidiTime() != lastMidi)
     {
         lastMidi = proc.getLastMidiTime();
@@ -843,6 +935,7 @@ void LcdPanel::moveCursor (int d)
         cursor = cyclicStep (cursor, rowCountForScreen(), d);
         setDirty();
     }
+    uiDirty = true;
 }
 
 void LcdPanel::stepDelaySync (int dir)