Ω-W1-T3: run the master meter on its own 60 FPS timer, and make a meter frame cost one rect

src/shell/instrument/editor_platform.cpp

@@ -31,6 +31,15 @@ constexpr const wchar_t* kChildClassName = L"ReaSampler9000VstEditor";
 // a per-window SetTimer id (any nonzero).
 constexpr UINT_PTR kSyncTimerId = 1;
 constexpr UINT     kSyncTimerIntervalMs = 500;
+
+// The meter's own clock on the same child window, because the bus meter is the one surface
+// whose value changes every block. Raising the poll above to frame rate instead is the REJECTED
+// alternative: its body costs a bridge read plus a bank parse, and its two tick-counted banners
+// (the bake message, the drop hint) are calibrated in ticks, so they would silently shorten by
+// the same factor. 16 ms is 60 FPS; what a frame costs is the meter's bar field, not the client
+// area — the whole-client invalidate is what made this rate unaffordable before.
+constexpr UINT_PTR kMeterTimerId = 2;
+constexpr UINT     kMeterTimerIntervalMs = 16;
 }  // namespace
 #endif
 
@@ -66,6 +75,17 @@ void ReaSamplerEditor::invalidate() {
     if (childHwnd_) InvalidateRect(childHwnd_, nullptr, FALSE);
 }
 
+void ReaSamplerEditor::invalidateMeter() {
+    if (!childHwnd_) return;
+    const Rect& f = meterRects_.field;
+    if (f.empty()) {  // nothing cached (see meterRects_) — the whole face has to answer
+        invalidate();
+        return;
+    }
+    RECT r{f.x, f.y, f.right(), f.bottom()};
+    InvalidateRect(childHwnd_, &r, FALSE);
+}
+
 void ReaSamplerEditor::attachedToParent() {
     HWND parent = static_cast<HWND>(systemWindow);
     if (!parent) return;
@@ -111,6 +131,9 @@ void ReaSamplerEditor::attachedToParent() {
         // created here, killed in removedFromParent — so an instance whose editor is closed
         // does not poll.
         SetTimer(childHwnd_, kSyncTimerId, kSyncTimerIntervalMs, nullptr);
+        // Bound to the same window for the same reason: an instance with no editor open runs
+        // neither clock, and the meter's accumulators simply pile up until one opens.
+        SetTimer(childHwnd_, kMeterTimerId, kMeterTimerIntervalMs, nullptr);
         // Poll once immediately so a pending assignment (an ingest fired while this editor was
         // closed) or a bank change applies the instant the editor opens, rather than waiting up
         // to one timer interval. refreshFromBank above already primed the view; this folds in
@@ -127,9 +150,11 @@ void ReaSamplerEditor::removedFromParent() {
     if (processor_) processor_->endParamGesture();
     if (childHwnd_) {
         KillTimer(childHwnd_, kSyncTimerId);  // stop the poll before the window goes away
+        KillTimer(childHwnd_, kMeterTimerId);
         DestroyWindow(childHwnd_);
         childHwnd_ = nullptr;
     }
+    releaseBackBuffer();  // a client-area bitmap outlives nothing here
 }
 
 tresult PLUGIN_API ReaSamplerEditor::onSize(ViewRect* newSize) {
@@ -137,6 +162,10 @@ tresult PLUGIN_API ReaSamplerEditor::onSize(ViewRect* newSize) {
     if (childHwnd_ && newSize) {
         MoveWindow(childHwnd_, 0, 0, newSize->getWidth(), newSize->getHeight(), TRUE);
         thumbCache_.clear();  // thumbnails are width-bound; a resize invalidates them
+        ensureBackBuffer(newSize->getWidth(), newSize->getHeight());
+        // The cached meter rects name the OLD layout; drop them so the meter tick takes the
+        // whole-client path until the resize's own full paint resolves them again.
+        meterRects_ = {};
     }
     return res;
 }
@@ -149,7 +178,7 @@ LRESULT CALLBACK ReaSamplerEditor::wndProc(HWND hwnd, UINT msg, WPARAM wParam,
         case WM_PAINT: {
             PAINTSTRUCT ps{};
             HDC hdc = BeginPaint(hwnd, &ps);
-            if (self) self->paint(hdc);
+            if (self) self->paint(hdc, ps.rcPaint);
             EndPaint(hwnd, &ps);
             return 0;
         }
@@ -293,7 +322,10 @@ LRESULT CALLBACK ReaSamplerEditor::wndProc(HWND hwnd, UINT msg, WPARAM wParam,
             return 0;
         }
         case WM_TIMER:
-            if (self && wParam == kSyncTimerId) self->onSyncTimer();
+            if (self) {
+                if (wParam == kSyncTimerId) self->onSyncTimer();
+                else if (wParam == kMeterTimerId) self->onMeterTimer();
+            }
             return 0;
         case WM_ERASEBKGND:
             return 1;  // fully repaint in WM_PAINT; skip the flicker-inducing erase