Add initial support for HighDPI on Wayland

src/flutter/shell/platform/linux_embedded/public/flutter_elinux.h

@@ -76,10 +76,10 @@ enum FlutterDesktopViewRotation {
 
 // Properties for configuring a Flutter view instance.
 typedef struct {
-  // View width.
+  // View width in logical pixels.
   int width;
 
-  // View height.
+  // View height in logical pixels.
   int height;
 
   // View rotation setting.

src/flutter/shell/platform/linux_embedded/window/elinux_window.h

@@ -18,10 +18,14 @@ class ELinuxWindow {
   virtual bool IsValid() const = 0;
 
   // Get current window width in physical pixels.
-  uint32_t GetCurrentWidth() const { return view_properties_.width; }
+  uint32_t GetCurrentWidth() const {
+    return view_properties_.width * current_scale_;
+  }
 
   // Get current window height in physical pixels.
-  uint32_t GetCurrentHeight() const { return view_properties_.height; }
+  uint32_t GetCurrentHeight() const {
+    return view_properties_.height * current_scale_;
+  }
 
   void SetRotation(FlutterDesktopViewRotation rotation) {
     if (rotation == FlutterDesktopViewRotation::kRotation_90) {

src/flutter/shell/platform/linux_embedded/window/elinux_window_wayland.cc

@@ -135,12 +135,14 @@ const xdg_toplevel_listener ELinuxWindowWayland::kXdgToplevelListener = {
           self->view_properties_.width = next_width;
           self->view_properties_.height = next_height;
           if (self->window_decorations_) {
-            self->window_decorations_->Resize(next_width, next_height);
+            self->window_decorations_->Resize(next_width, next_height,
+                                              self->current_scale_);
           }
           if (self->binding_handler_delegate_) {
             self->binding_handler_delegate_->OnWindowSizeChanged(
-                next_width,
-                next_height - self->WindowDecorationsPhysicalHeight());
+                next_width * self->current_scale_,
+                next_height * self->current_scale_ -
+                    self->WindowDecorationsPhysicalHeight());
           }
         },
     .close =
@@ -313,11 +315,11 @@ const wl_pointer_listener ELinuxWindowWayland::kWlPointerListener = {
       }
 
       if (self->binding_handler_delegate_) {
-        double x = wl_fixed_to_double(surface_x);
-        double y = wl_fixed_to_double(surface_y);
-        self->binding_handler_delegate_->OnPointerMove(x, y);
-        self->pointer_x_ = x;
-        self->pointer_y_ = y;
+        double x_px = wl_fixed_to_double(surface_x) * self->current_scale_;
+        double y_px = wl_fixed_to_double(surface_y) * self->current_scale_;
+        self->binding_handler_delegate_->OnPointerMove(x_px, y_px);
+        self->pointer_x_ = x_px;
+        self->pointer_y_ = y_px;
       }
     },
     .leave = [](void* data,
@@ -347,11 +349,11 @@ const wl_pointer_listener ELinuxWindowWayland::kWlPointerListener = {
                  wl_fixed_t surface_y) -> void {
       auto self = reinterpret_cast<ELinuxWindowWayland*>(data);
       if (self->binding_handler_delegate_) {
-        double x = wl_fixed_to_double(surface_x);
-        double y = wl_fixed_to_double(surface_y);
-        self->binding_handler_delegate_->OnPointerMove(x, y);
-        self->pointer_x_ = x;
-        self->pointer_y_ = y;
+        double x_px = wl_fixed_to_double(surface_x) * self->current_scale_;
+        double y_px = wl_fixed_to_double(surface_y) * self->current_scale_;
+        self->binding_handler_delegate_->OnPointerMove(x_px, y_px);
+        self->pointer_x_ = x_px;
+        self->pointer_y_ = y_px;
       }
     },
     .button = [](void* data,
@@ -604,7 +606,10 @@ const wl_output_listener ELinuxWindowWayland::kWlOutputListener = {
           self->view_properties_.height = height;
 
           if (self->window_decorations_) {
-            self->window_decorations_->Resize(width, height);
+            int32_t width_dip = width / self->current_scale_;
+            int32_t height_dip = height / self->current_scale_;
+            self->window_decorations_->Resize(width_dip, height_dip,
+                                              self->current_scale_);
           }
 
           if (self->binding_handler_delegate_) {
@@ -1158,8 +1163,8 @@ bool ELinuxWindowWayland::CreateRenderSurface(int32_t width_px,
   }
 
   if (view_properties_.view_mode == FlutterDesktopViewMode::kFullscreen) {
-    width_px = view_properties_.width;
-    height_px = view_properties_.height;
+    width_px = view_properties_.width * current_scale_;
+    height_px = view_properties_.height * current_scale_;
   }
 
   ELINUX_LOG(TRACE) << "Created the Wayland surface: " << width_px << "x"
@@ -1192,6 +1197,7 @@ bool ELinuxWindowWayland::CreateRenderSurface(int32_t width_px,
   xdg_toplevel_ = xdg_surface_get_toplevel(xdg_surface_);
   xdg_toplevel_set_title(xdg_toplevel_, "Flutter");
   xdg_toplevel_add_listener(xdg_toplevel_, &kXdgToplevelListener, this);
+  wl_surface_set_buffer_scale(native_window_->Surface(), current_scale_);
   wl_surface_commit(native_window_->Surface());
 
   {
@@ -1211,9 +1217,11 @@ bool ELinuxWindowWayland::CreateRenderSurface(int32_t width_px,
   render_surface_->SetNativeWindow(native_window_.get());
 
   if (view_properties_.use_window_decoration) {
+    int32_t width_dip = width_px / current_scale_;
+    int32_t height_dip = height_px / current_scale_;
     window_decorations_ = std::make_unique<WindowDecorationsWayland>(
         wl_display_, wl_compositor_, wl_subcompositor_,
-        native_window_->Surface(), width_px, height_px);
+        native_window_->Surface(), width_dip, height_dip, current_scale_);
   }
 
   return true;
@@ -1604,10 +1612,18 @@ void ELinuxWindowWayland::UpdateWindowScale() {
   ELINUX_LOG(TRACE) << "Window scale has changed: " << scale_factor;
   this->current_scale_ = scale_factor;
 
+  wl_surface_set_buffer_scale(native_window_->Surface(), current_scale_);
+
+  if (this->window_decorations_) {
+    this->window_decorations_->Resize(this->view_properties_.width,
+                                      this->view_properties_.height,
+                                      this->current_scale_);
+  }
+
   if (this->binding_handler_delegate_) {
     this->binding_handler_delegate_->OnWindowSizeChanged(
-        this->view_properties_.width,
-        this->view_properties_.height -
+        this->view_properties_.width * this->current_scale_,
+        this->view_properties_.height * this->current_scale_ -
             this->WindowDecorationsPhysicalHeight());
   }
 }

src/flutter/shell/platform/linux_embedded/window/native_window_wayland_decoration.cc

@@ -77,4 +77,13 @@ void NativeWindowWaylandDecoration::SetPosition(const int32_t x_dip,
   wl_subsurface_set_position(subsurface_, x_dip, y_dip);
 }
 
+void NativeWindowWaylandDecoration::SetScaleFactor(float scale_factor) {
+  if (!valid_) {
+    ELINUX_LOG(ERROR) << "Failed to set the scale factor of the window.";
+    return;
+  }
+
+  wl_surface_set_buffer_scale(surface_, scale_factor);
+}
+
 }  // namespace flutter

src/flutter/shell/platform/linux_embedded/window/native_window_wayland_decoration.h

@@ -29,6 +29,10 @@ class NativeWindowWaylandDecoration : public NativeWindow {
   // |NativeWindow|
   void SetPosition(const int32_t x_dip, const int32_t y_dip) override;
 
+  // Sets the scale factor for the next commit. Scale factor persists until a
+  // new one is set.
+  void SetScaleFactor(float scale_factor);
+
   wl_surface* Surface() const { return surface_; }
 
  private:

src/flutter/shell/platform/linux_embedded/window/renderer/window_decoration.h

@@ -36,6 +36,10 @@ class WindowDecoration {
   // @param[in] height_px  Physical height of the window.
   virtual void Resize(const size_t width_px, const size_t height_px) = 0;
 
+  // Sets the scale factor for the next commit. Scale factor persists until a
+  // new one is set.
+  virtual void SetScaleFactor(float scale_factor) = 0;
+
   void DestroyContext() const { render_surface_->DestroyContext(); };
 
   wl_surface* Surface() const { return native_window_->Surface(); };

src/flutter/shell/platform/linux_embedded/window/renderer/window_decoration_button.cc

@@ -208,6 +208,10 @@ void WindowDecorationButton::Resize(const size_t width_px,
   render_surface_->Resize(width_px, height_px);
 }
 
+void WindowDecorationButton::SetScaleFactor(float scale_factor) {
+  native_window_->SetScaleFactor(scale_factor);
+}
+
 void WindowDecorationButton::LoadShader() {
   if (shader_) {
     return;

src/flutter/shell/platform/linux_embedded/window/renderer/window_decoration_button.h

@@ -26,6 +26,9 @@ class WindowDecorationButton : public WindowDecoration {
   // |WindowDecoration|
   void Resize(const size_t width_px, const size_t height_px) override;
 
+  // |WindowDecoration|
+  void SetScaleFactor(float scale_factor) override;
+
  private:
   void LoadShader();
 

src/flutter/shell/platform/linux_embedded/window/renderer/window_decoration_titlebar.cc

@@ -79,4 +79,8 @@ void WindowDecorationTitlebar::Resize(const size_t width_px,
   render_surface_->Resize(width_px, height_px);
 }
 
+void WindowDecorationTitlebar::SetScaleFactor(float scale_factor) {
+  native_window_->SetScaleFactor(scale_factor);
+}
+
 }  // namespace flutter

src/flutter/shell/platform/linux_embedded/window/renderer/window_decoration_titlebar.h

@@ -23,6 +23,9 @@ class WindowDecorationTitlebar : public WindowDecoration {
 
   // |WindowDecoration|
   void Resize(const size_t width_px, const size_t height_px) override;
+
+  // |WindowDecoration|
+  void SetScaleFactor(float scale_factor) override;
 };
 
 }  // namespace flutter

src/flutter/shell/platform/linux_embedded/window/renderer/window_decorations_wayland.cc

@@ -23,14 +23,15 @@ WindowDecorationsWayland::WindowDecorationsWayland(
     wl_subcompositor* subcompositor,
     wl_surface* root_surface,
     int32_t width_dip,
-    int32_t height_dip) {
+    int32_t height_dip,
+    double pixel_ratio) {
   constexpr bool sub_egl_display = true;
 
   // title-bar.
   titlebar_ = std::make_unique<WindowDecorationTitlebar>(
-      std::make_unique<NativeWindowWaylandDecoration>(compositor, subcompositor,
-                                                      root_surface, width_dip,
-                                                      kTitleBarHeightDIP),
+      std::make_unique<NativeWindowWaylandDecoration>(
+          compositor, subcompositor, root_surface, width_dip * pixel_ratio,
+          kTitleBarHeightDIP * pixel_ratio),
       std::make_unique<SurfaceDecoration>(std::make_unique<ContextEgl>(
           std::make_unique<EnvironmentEgl>(display, sub_egl_display))));
   titlebar_->SetPosition(0, -kTitleBarHeightDIP);
@@ -40,8 +41,8 @@ WindowDecorationsWayland::WindowDecorationsWayland(
   buttons_.push_back(std::make_unique<WindowDecorationButton>(
       type,
       std::make_unique<NativeWindowWaylandDecoration>(
-          compositor, subcompositor, root_surface, kButtonWidthDIP,
-          kButtonHeightDIP),
+          compositor, subcompositor, root_surface,
+          kButtonWidthDIP * pixel_ratio, kButtonHeightDIP * pixel_ratio),
       std::make_unique<SurfaceDecoration>(std::make_unique<ContextEgl>(
           std::make_unique<EnvironmentEgl>(display, sub_egl_display)))));
   buttons_[type]->SetPosition(
@@ -53,8 +54,8 @@ WindowDecorationsWayland::WindowDecorationsWayland(
   buttons_.push_back(std::make_unique<WindowDecorationButton>(
       type,
       std::make_unique<NativeWindowWaylandDecoration>(
-          compositor, subcompositor, root_surface, kButtonWidthDIP,
-          kButtonHeightDIP),
+          compositor, subcompositor, root_surface,
+          kButtonWidthDIP * pixel_ratio, kButtonHeightDIP * pixel_ratio),
       std::make_unique<SurfaceDecoration>(std::make_unique<ContextEgl>(
           std::make_unique<EnvironmentEgl>(display, sub_egl_display)))));
   buttons_[type]->SetPosition(
@@ -66,8 +67,8 @@ WindowDecorationsWayland::WindowDecorationsWayland(
   buttons_.push_back(std::make_unique<WindowDecorationButton>(
       type,
       std::make_unique<NativeWindowWaylandDecoration>(
-          compositor, subcompositor, root_surface, kButtonWidthDIP,
-          kButtonHeightDIP),
+          compositor, subcompositor, root_surface,
+          kButtonWidthDIP * pixel_ratio, kButtonHeightDIP * pixel_ratio),
       std::make_unique<SurfaceDecoration>(std::make_unique<ContextEgl>(
           std::make_unique<EnvironmentEgl>(display, sub_egl_display)))));
   buttons_[type]->SetPosition(
@@ -91,15 +92,19 @@ void WindowDecorationsWayland::Draw() {
 }
 
 void WindowDecorationsWayland::Resize(const int32_t width_dip,
-                                      const int32_t height_dip) {
+                                      const int32_t height_dip,
+                                      double pixel_ratio) {
+  titlebar_->SetScaleFactor(pixel_ratio);
   titlebar_->SetPosition(0, -kTitleBarHeightDIP);
-  titlebar_->Resize(width_dip, kTitleBarHeightDIP);
+  titlebar_->Resize(width_dip * pixel_ratio, kTitleBarHeightDIP * pixel_ratio);
 
   for (auto i = 0; i < buttons_.size(); i++) {
+    buttons_[i]->SetScaleFactor(pixel_ratio);
     buttons_[i]->SetPosition(
         width_dip - kButtonWidthDIP * (i + 1) - kButtonMarginDIP * (i + 1),
         -(kButtonHeightDIP + (kTitleBarHeightDIP - kButtonHeightDIP) / 2));
-    buttons_[i]->Resize(kButtonWidthDIP, kButtonHeightDIP);
+    buttons_[i]->Resize(kButtonWidthDIP * pixel_ratio,
+                        kButtonHeightDIP * pixel_ratio);
   }
 }
 

src/flutter/shell/platform/linux_embedded/window/renderer/window_decorations_wayland.h

@@ -28,19 +28,24 @@ class WindowDecorationsWayland {
  public:
   // @param[in] width_dip   Logical width of the window (i.e. surface width).
   // @param[in] height_dip  Logical height of the window (i.e. surface height).
+  // @param[in] pixel_ratio Physical / logical pixels ratio.
   WindowDecorationsWayland(wl_display* display,
                            wl_compositor* compositor,
                            wl_subcompositor* subcompositor,
                            wl_surface* root_surface,
                            int32_t width_dip,
-                           int32_t height_dip);
+                           int32_t height_dip,
+                           double pixel_ratio);
   ~WindowDecorationsWayland();
 
   void Draw();
 
   // @param[in] width_dip   Logical width of the window (i.e. surface width).
   // @param[in] height_dip  Logical height of the window (i.e. surface height).
-  void Resize(const int32_t width_dip, const int32_t height_dip);
+  // @param[in] pixel_ratio Physical / logical pixels ratio.
+  void Resize(const int32_t width_dip,
+              const int32_t height_dip,
+              double pixel_ratio);
 
   bool IsMatched(wl_surface* surface,
                  WindowDecoration::DecorationType decoration_type) const;