fix: frameless mica/acrylic windows (#39708)

* fix: backgroundMaterial works with frameless

* TODO: fix frameless mica/acrylic windows

* update caption color appropriately

* set background color properly

* refactor translucency method

* actualization

shell/browser/api/electron_api_browser_window.cc

@@ -42,19 +42,11 @@ BrowserWindow::BrowserWindow(gin::Arguments* args,
   auto web_preferences = gin_helper::Dictionary::CreateEmpty(isolate);
   options.Get(options::kWebPreferences, &web_preferences);
 
-  bool transparent = false;
-  options.Get(options::kTransparent, &transparent);
-
-  std::string vibrancy_type;
-#if BUILDFLAG(IS_MAC)
-  options.Get(options::kVibrancyType, &vibrancy_type);
-#endif
-
   // Copy the backgroundColor to webContents.
   std::string color;
   if (options.Get(options::kBackgroundColor, &color)) {
     web_preferences.SetHidden(options::kBackgroundColor, color);
-  } else if (!vibrancy_type.empty() || transparent) {
+  } else if (window_->IsTranslucent()) {
     // If the BrowserWindow is transparent or a vibrancy type has been set,
     // also propagate transparency to the WebContents unless a separate
     // backgroundColor has been set.

shell/browser/native_window.cc

@@ -13,6 +13,7 @@
 #include "base/strings/utf_string_conversions.h"
 #include "base/values.h"
 #include "content/public/browser/web_contents_user_data.h"
+#include "include/core/SkColor.h"
 #include "shell/browser/browser.h"
 #include "shell/browser/native_window_features.h"
 #include "shell/browser/ui/drag_util.h"
@@ -259,13 +260,15 @@ void NativeWindow::InitFromOptions(const gin_helper::Dictionary& options) {
     SetBackgroundMaterial(material);
   }
 #endif
-  std::string color;
-  if (options.Get(options::kBackgroundColor, &color)) {
-    SetBackgroundColor(ParseCSSColor(color));
-  } else if (!transparent()) {
-    // For normal window, use white as default background.
-    SetBackgroundColor(SK_ColorWHITE);
+
+  SkColor background_color = SK_ColorWHITE;
+  if (std::string color; options.Get(options::kBackgroundColor, &color)) {
+    background_color = ParseCSSColor(color);
+  } else if (IsTranslucent()) {
+    background_color = SK_ColorTRANSPARENT;
   }
+  SetBackgroundColor(background_color);
+
   std::string title(Browser::Get()->GetName());
   options.Get(options::kTitle, &title);
   SetTitle(title);
@@ -472,9 +475,13 @@ bool NativeWindow::AddTabbedWindow(NativeWindow* window) {
   return true;  // for non-Mac platforms
 }
 
-void NativeWindow::SetVibrancy(const std::string& type) {}
+void NativeWindow::SetVibrancy(const std::string& type) {
+  vibrancy_ = type;
+}
 
-void NativeWindow::SetBackgroundMaterial(const std::string& type) {}
+void NativeWindow::SetBackgroundMaterial(const std::string& type) {
+  background_material_ = type;
+}
 
 void NativeWindow::SetTouchBar(
     std::vector<gin_helper::PersistentDictionary> items) {}
@@ -798,6 +805,30 @@ void NativeWindow::HandlePendingFullscreenTransitions() {
 // static
 int32_t NativeWindow::next_id_ = 0;
 
+bool NativeWindow::IsTranslucent() const {
+  // Transparent windows are translucent
+  if (transparent()) {
+    return true;
+  }
+
+#if BUILDFLAG(IS_MAC)
+  // Windows with vibrancy set are translucent
+  if (!vibrancy().empty()) {
+    return true;
+  }
+#endif
+
+#if BUILDFLAG(IS_WIN)
+  // Windows with certain background materials may be translucent
+  const std::string& bg_material = background_material();
+  if (!bg_material.empty() && bg_material != "none") {
+    return true;
+  }
+#endif
+
+  return false;
+}
+
 // static
 void NativeWindowRelay::CreateForWebContents(
     content::WebContents* web_contents,

shell/browser/native_window.h

@@ -218,8 +218,12 @@ class NativeWindow : public base::SupportsUserData,
   virtual void SetAutoHideCursor(bool auto_hide);
 
   // Vibrancy API
+  const std::string& vibrancy() const { return vibrancy_; }
   virtual void SetVibrancy(const std::string& type);
 
+  const std::string& background_material() const {
+    return background_material_;
+  }
   virtual void SetBackgroundMaterial(const std::string& type);
 
   // Traffic Light API
@@ -395,6 +399,8 @@ class NativeWindow : public base::SupportsUserData,
   void AddDraggableRegionProvider(DraggableRegionProvider* provider);
   void RemoveDraggableRegionProvider(DraggableRegionProvider* provider);
 
+  bool IsTranslucent() const;
+
  protected:
   friend class api::BrowserView;
 
@@ -492,6 +498,9 @@ class NativeWindow : public base::SupportsUserData,
   // Accessible title.
   std::u16string accessible_title_;
 
+  std::string vibrancy_;
+  std::string background_material_;
+
   gfx::Rect overlay_rect_;
 
   base::WeakPtrFactory<NativeWindow> weak_factory_{this};

shell/browser/native_window_mac.mm

@@ -1456,6 +1456,8 @@ void NativeWindowMac::UpdateWindowOriginalFrame() {
 }
 
 void NativeWindowMac::SetVibrancy(const std::string& type) {
+  NativeWindow::SetVibrancy(type);
+
   NSVisualEffectView* vibrantView = [window_ vibrantView];
 
   if (type.empty()) {

shell/browser/native_window_views.cc

@@ -284,12 +284,12 @@ NativeWindowViews::NativeWindowViews(const gin_helper::Dictionary& options,
   params.remove_standard_frame = !has_frame() || has_client_frame();
 
   // If a client frame, we need to draw our own shadows.
-  if (transparent() || has_client_frame())
+  if (IsTranslucent() || has_client_frame())
     params.opacity = views::Widget::InitParams::WindowOpacity::kTranslucent;
 
-  // The given window is most likely not rectangular since it uses
-  // transparency and has no standard frame, don't show a shadow for it.
-  if (transparent() && !has_frame())
+  // The given window is most likely not rectangular since it is translucent and
+  // has no standard frame, don't show a shadow for it.
+  if (IsTranslucent() && !has_frame())
     params.shadow_type = views::Widget::InitParams::ShadowType::kNone;
 
   bool focusable;
@@ -1457,6 +1457,8 @@ bool NativeWindowViews::IsMenuBarVisible() {
 }
 
 void NativeWindowViews::SetBackgroundMaterial(const std::string& material) {
+  NativeWindow::SetBackgroundMaterial(material);
+
 #if BUILDFLAG(IS_WIN)
   // DWMWA_USE_HOSTBACKDROPBRUSH is only supported on Windows 11 22H2 and up.
   if (base::win::GetVersion() < base::win::Version::WIN11_22H2)
@@ -1468,6 +1470,20 @@ void NativeWindowViews::SetBackgroundMaterial(const std::string& material) {
                             &backdrop_type, sizeof(backdrop_type));
   if (FAILED(result))
     LOG(WARNING) << "Failed to set background material to " << material;
+
+  // For frameless windows with a background material set, we also need to
+  // remove the caption color so it doesn't render a caption bar (since the
+  // window is frameless)
+  COLORREF caption_color = DWMWA_COLOR_DEFAULT;
+  if (backdrop_type != DWMSBT_NONE && backdrop_type != DWMSBT_AUTO &&
+      !has_frame()) {
+    caption_color = DWMWA_COLOR_NONE;
+  }
+  result = DwmSetWindowAttribute(GetAcceleratedWidget(), DWMWA_CAPTION_COLOR,
+                                 &caption_color, sizeof(caption_color));
+
+  if (FAILED(result))
+    LOG(WARNING) << "Failed to set caption color to transparent";
 #endif
 }