feat: implement win.setAspectRatio() on Windows

docs/api/browser-window.md

@@ -946,7 +946,7 @@ Returns `Boolean` - Whether the window is in simple (pre-Lion) fullscreen mode.
 
 Returns `Boolean` - Whether the window is in normal state (not maximized, not minimized, not in fullscreen mode).
 
-#### `win.setAspectRatio(aspectRatio[, extraSize])` _macOS_ _Linux_
+#### `win.setAspectRatio(aspectRatio[, extraSize])` _macOS_ _Linux_ _Windows_
 
 * `aspectRatio` Float - The aspect ratio to maintain for some portion of the
 content view.

shell/browser/native_window_views.h

@@ -191,6 +191,7 @@ class NativeWindowViews : public NativeWindow,
 
 #if defined(OS_WIN)
   void HandleSizeEvent(WPARAM w_param, LPARAM l_param);
+  void HandleSizingEvent(WPARAM w_param, LPARAM l_param);
   void SetForwardMouseMessages(bool forward);
   static LRESULT CALLBACK SubclassProc(HWND hwnd,
                                        UINT msg,

shell/browser/native_window_views_win.cc

@@ -425,6 +425,7 @@ bool NativeWindowViews::PreHandleMSG(UINT message,
       return false;
     case WM_SIZING: {
       bool prevent_default = false;
+      HandleSizingEvent(w_param, l_param);
       NotifyWindowWillResize(gfx::Rect(*reinterpret_cast<RECT*>(l_param)),
                              &prevent_default);
       if (prevent_default) {
@@ -476,6 +477,58 @@ bool NativeWindowViews::PreHandleMSG(UINT message,
   }
 }
 
+void NativeWindowViews::HandleSizingEvent(WPARAM w_param, LPARAM l_param) {
+  double aspect_ratio = GetAspectRatio();
+  if (aspect_ratio <= 0.0) {
+    return;
+  }
+
+  RECT* window_rect = reinterpret_cast<RECT*>(l_param);
+  int width = window_rect->right - window_rect->left;
+  int height = window_rect->bottom - window_rect->top;
+
+  double result_width = 0;
+  double result_height = 0;
+
+  gfx::Size win_fit_size(width, height);
+  const gfx::Size min_fit_size = GetMinimumSize();
+  win_fit_size.SetToMax(min_fit_size);
+
+  switch ((UINT)w_param) {
+    case WMSZ_LEFT:
+    case WMSZ_RIGHT:
+      result_width = win_fit_size.width();
+      result_height = result_width / aspect_ratio;
+      break;
+    case WMSZ_TOP:
+    case WMSZ_BOTTOM:
+      result_height = win_fit_size.height();
+      result_width = result_height * aspect_ratio;
+      break;
+    case WMSZ_TOPLEFT:
+    case WMSZ_TOPRIGHT:
+    case WMSZ_BOTTOMLEFT:
+    case WMSZ_BOTTOMRIGHT: {
+      result_width = height * aspect_ratio;
+      result_height = height;
+
+      double temp_width = width;
+      double temp_height = width / aspect_ratio;
+
+      if (abs(temp_width * temp_height) > abs(result_width * result_height)) {
+        result_width = temp_width;
+        result_height = temp_height;
+      }
+      break;
+    }
+    default:
+      return;
+  }
+
+  window_rect->right = window_rect->left + result_width;
+  window_rect->bottom = window_rect->top + result_height;
+}
+
 void NativeWindowViews::HandleSizeEvent(WPARAM w_param, LPARAM l_param) {
   // Here we handle the WM_SIZE event in order to figure out what is the current
   // window state and notify the user accordingly.