Bug 1934439 - Make the mica prefs toggle-able at runtime. r=win-reviewers,rkraesig

Not particularly pretty but this will do.

Differential Revision: https://phabricator.services.mozilla.com/D238705

layout/style/test/chrome/test_chrome_only_media_queries.html

@@ -6,6 +6,14 @@
 <script>
 const SHEET = document.querySelector('style');
 
+let lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  WindowsVersionInfo:
+    "resource://gre/modules/components-utils/WindowsVersionInfo.sys.mjs",
+});
+
+
 SimpleTest.waitForExplicitFinish();
 
 function expect(q, shouldBeKnown) {
@@ -92,6 +100,26 @@ expectUnkown("(-moz-platform: )");
   await testMozPref('-moz-pref("foo.bar.str")', "foo.bar.str", "foo", "");
   await testMozPref('-moz-pref("foo.bar.int", 1)', "foo.bar.int", 1, 2);
   await testMozPref('-moz-pref("foo.bar.int")', "foo.bar.int", 1, 0);
+
+  let supportsMica = matchMedia('(-moz-platform: windows)').matches && lazy.WindowsVersionInfo.get().buildNumber >= 22621;
+  info(`Mica supported: ${supportsMica}`);
+  for (let [query, pref] of [['(-moz-windows-mica)', 'widget.windows.mica'], ['(-moz-windows-mica-popups)', 'widget.windows.mica.popups']]) {
+    let prefEnabled = SpecialPowers.getBoolPref("widget.windows.mica", false);
+    let mediaList = matchMedia(query);
+    is(mediaList.matches, supportsMica && prefEnabled, `Mica support is as expected ${query}`);
+    let change = new Promise(r => {
+      mediaList.addEventListener("change", r, { once: true });
+    });
+    await SpecialPowers.pushPrefEnv({
+      set:[[pref, !prefEnabled]],
+    });
+    if (supportsMica) {
+      await change;
+    }
+    is(mediaList.matches, supportsMica && !prefEnabled, `Mica query works dynamically if appropriate ${query}`);
+    await SpecialPowers.popPrefEnv();
+  }
+
   SimpleTest.finish();
 }());
 </script>

modules/libpref/init/StaticPrefList.yaml

@@ -18454,14 +18454,13 @@
 - name: widget.windows.mica
   type: bool
   value: false
-  mirror: once
+  mirror: always
 
 # Whether we use the mica backdrop for popups. Off by default for now.
-# TODO(emilio): Make these toggleable at runtime?
 - name: widget.windows.mica.popups
   type: bool
   value: false
-  mirror: once
+  mirror: always
 #endif
 
 # Whether to disable SwipeTracker (e.g. swipe-to-nav).

widget/windows/WinUtils.cpp

@@ -68,8 +68,7 @@ mozilla::LazyLogModule gWindowsLog("Widget");
 
 using namespace mozilla::gfx;
 
-namespace mozilla {
-namespace widget {
+namespace mozilla::widget {
 
 #ifdef MOZ_PLACES
 NS_IMPL_ISUPPORTS(myDownloadObserver, nsIDownloadObserver)
@@ -2005,16 +2004,43 @@ bool WinUtils::GetTimezoneName(wchar_t* aBuffer) {
   return true;
 }
 
+static constexpr nsLiteralCString kMicaPrefs[] = {
+    "widget.windows.mica"_ns,
+    "widget.windows.mica.popups"_ns,
+};
+
+static BOOL CALLBACK UpdateMicaInHwnd(HWND aHwnd, LPARAM aLParam) {
+  if (RefPtr<nsWindow> win = WinUtils::GetNSWindowPtr(aHwnd)) {
+    win->UpdateMicaBackdrop(/* aForce = */ true);
+  }
+  return TRUE;
+}
+
+static void UpdateMicaInAllWindows(const char*, void*) {
+  ::EnumWindows(&UpdateMicaInHwnd, 0);
+  LookAndFeel::NotifyChangedAllWindows(
+      widget::ThemeChangeKind::MediaQueriesOnly);
+}
+
+bool WinUtils::MicaAvailable() {
+  static bool sAvailable = [] {
+    if (!IsWin1122H2OrLater()) {
+      return false;
+    }
+    for (const auto& pref : kMicaPrefs) {
+      Preferences::RegisterCallback(UpdateMicaInAllWindows, pref);
+    }
+    return true;
+  }();
+  return sAvailable;
+}
+
 bool WinUtils::MicaEnabled() {
-  static bool sEnabled =
-      IsWin1122H2OrLater() && StaticPrefs::widget_windows_mica_AtStartup();
-  return sEnabled;
+  return MicaAvailable() && StaticPrefs::widget_windows_mica();
 }
 
 bool WinUtils::MicaPopupsEnabled() {
-  static bool sEnabled = IsWin1122H2OrLater() &&
-                         StaticPrefs::widget_windows_mica_popups_AtStartup();
-  return sEnabled;
+  return MicaAvailable() && StaticPrefs::widget_windows_mica_popups();
 }
 
 // There are undocumented APIs to query/change the system DPI settings found by
@@ -2225,5 +2251,4 @@ ScopedRtlShimWindow::~ScopedRtlShimWindow() {
   }
 }
 
-}  // namespace widget
-}  // namespace mozilla
+}  // namespace mozilla::widget

widget/windows/WinUtils.h

@@ -544,6 +544,7 @@ class WinUtils {
 
   static bool GetClassName(HWND aHwnd, nsAString& aName);
 
+  static bool MicaAvailable();
   static bool MicaEnabled();
   static bool MicaPopupsEnabled();
 

widget/windows/nsWindow.cpp

@@ -668,6 +668,7 @@ nsWindow::nsWindow(bool aIsChildWindow)
       mFrameState(std::in_place, this),
       mIsChildWindow(aIsChildWindow),
       mPIPWindow(false),
+      mMicaBackdrop(false),
       mLastPaintEndTime(TimeStamp::Now()),
       mCachedHitTestTime(TimeStamp::Now()),
       mSizeConstraintsScale(GetDefaultScale().scale),
@@ -2524,14 +2525,25 @@ void nsWindow::SetColorScheme(const Maybe<ColorScheme>& aScheme) {
 }
 
 void nsWindow::SetMicaBackdrop(bool aEnabled) {
-  const bool micaEnabled =
-      IsPopup() ? WinUtils::MicaPopupsEnabled() : WinUtils::MicaEnabled();
-  if (!micaEnabled) {
+  if (aEnabled == mMicaBackdrop) {
     return;
   }
 
+  mMicaBackdrop = aEnabled;
+  UpdateMicaBackdrop();
+}
+
+void nsWindow::UpdateMicaBackdrop(bool aForce) {
+  const bool micaEnabled =
+      IsPopup() ? WinUtils::MicaPopupsEnabled() : WinUtils::MicaEnabled();
+  if (!micaEnabled && !aForce) {
+    return;
+  }
+
+  const bool useBackdrop = mMicaBackdrop && micaEnabled;
+
   const DWM_SYSTEMBACKDROP_TYPE backdrop = [&] {
-    if (!aEnabled) {
+    if (!useBackdrop) {
       return DWMSBT_AUTO;
     }
     return IsPopup() ? DWMSBT_TRANSIENTWINDOW : DWMSBT_TABBEDWINDOW;
@@ -2546,7 +2558,7 @@ void nsWindow::SetMicaBackdrop(bool aEnabled) {
     //    otherwise it'd draw the inactive window backdrop rather than
     //    acrylic). See also the WM_NCACTIVATE implementation.
     const DWM_WINDOW_CORNER_PREFERENCE corner =
-        aEnabled ? DWMWCP_ROUND : DWMWCP_DEFAULT;
+        useBackdrop ? DWMWCP_ROUND : DWMWCP_DEFAULT;
     ::DwmSetWindowAttribute(mWnd, DWMWA_WINDOW_CORNER_PREFERENCE, &corner,
                             sizeof corner);
     ::PostMessageW(mWnd, WM_NCACTIVATE, TRUE, -1);

widget/windows/nsWindow.h

@@ -340,6 +340,8 @@ class nsWindow final : public nsBaseWidget {
   void SetSmallIconNoData();
   void SetBigIconNoData();
 
+  void UpdateMicaBackdrop(bool aForce = false);
+
   static void SetIsRestoringSession(const bool aIsRestoringSession) {
     sIsRestoringSession = aIsRestoringSession;
   }
@@ -879,6 +881,9 @@ class nsWindow final : public nsBaseWidget {
   // Whether we're a PIP window.
   bool mPIPWindow : 1;
 
+  // Whether we are asked to render a mica backdrop.
+  bool mMicaBackdrop : 1;
+
   int32_t mCachedHitTestResult = 0;
 
   // The point in time at which the last paint completed. We use this to avoid