WindowServer: Load multiple scaled versions of Bitmaps and Cursors

This enables rendering of mixed-scale screen layouts with e.g. high
resolution cursors and window button icons on high-dpi screens while
using lower resolution bitmaps on regular screens.

Userland/Services/WindowServer/Button.cpp

@@ -9,6 +9,7 @@
 #include <LibGfx/StylePainter.h>
 #include <WindowServer/Button.h>
 #include <WindowServer/Event.h>
+#include <WindowServer/Screen.h>
 #include <WindowServer/WindowManager.h>
 
 namespace WindowServer {
@@ -23,7 +24,7 @@ Button::~Button()
 {
 }
 
-void Button::paint(Gfx::Painter& painter)
+void Button::paint(Screen& screen, Gfx::Painter& painter)
 {
     auto palette = WindowManager::the().palette();
     Gfx::PainterStateSaver saver(painter);
@@ -31,10 +32,11 @@ void Button::paint(Gfx::Painter& painter)
     Gfx::StylePainter::paint_button(painter, rect(), palette, Gfx::ButtonStyle::Normal, m_pressed, m_hovered);
 
     if (m_icon) {
-        auto icon_location = rect().center().translated(-(m_icon->width() / 2), -(m_icon->height() / 2));
+        auto& bitmap = m_icon->bitmap(screen.scale_factor());
+        auto icon_location = rect().center().translated(-(bitmap.width() / 2), -(bitmap.height() / 2));
         if (m_pressed)
             painter.translate(1, 1);
-        painter.blit(icon_location, *m_icon, m_icon->rect());
+        painter.blit(icon_location, bitmap, bitmap.rect());
     }
 }
 

Userland/Services/WindowServer/Button.h

@@ -11,10 +11,12 @@
 #include <LibGfx/Bitmap.h>
 #include <LibGfx/Forward.h>
 #include <LibGfx/Rect.h>
+#include <WindowServer/MultiScaleBitmaps.h>
 
 namespace WindowServer {
 
 class MouseEvent;
+class Screen;
 class WindowFrame;
 
 class Button : public Weakable<Button> {
@@ -28,7 +30,7 @@ public:
     Gfx::IntRect rect() const { return { {}, m_relative_rect.size() }; }
     Gfx::IntRect screen_rect() const;
 
-    void paint(Gfx::Painter&);
+    void paint(Screen&, Gfx::Painter&);
 
     void on_mouse_event(const MouseEvent&);
 
@@ -38,12 +40,12 @@ public:
 
     bool is_visible() const { return m_visible; }
 
-    void set_icon(const Gfx::Bitmap& icon) { m_icon = icon; }
+    void set_icon(const RefPtr<MultiScaleBitmaps>& icon) { m_icon = icon; }
 
 private:
     WindowFrame& m_frame;
     Gfx::IntRect m_relative_rect;
-    RefPtr<Gfx::Bitmap> m_icon;
+    RefPtr<MultiScaleBitmaps> m_icon;
     bool m_pressed { false };
     bool m_visible { true };
     bool m_hovered { false };

Userland/Services/WindowServer/CMakeLists.txt

@@ -21,6 +21,7 @@ set(SOURCES
     Menu.cpp
     MenuItem.cpp
     MenuManager.cpp
+    MultiScaleBitmaps.cpp
     Screen.cpp
     ScreenLayout.cpp
     Window.cpp

Userland/Services/WindowServer/ClientConnection.cpp

@@ -682,7 +682,7 @@ void ClientConnection::set_window_custom_cursor(i32 window_id, Gfx::ShareableBit
         return;
     }
 
-    window.set_cursor(Cursor::create(*cursor.bitmap()));
+    window.set_cursor(Cursor::create(*cursor.bitmap(), 1));
     Compositor::the().invalidate_cursor();
 }
 

Userland/Services/WindowServer/Compositor.cpp

@@ -919,7 +919,7 @@ void Compositor::ScreenData::draw_cursor(Screen& screen, const Gfx::IntRect& cur
     auto& current_cursor = compositor.m_current_cursor ? *compositor.m_current_cursor : wm.active_cursor();
     auto screen_rect = screen.rect();
     m_cursor_back_painter->blit({ 0, 0 }, *m_back_bitmap, current_cursor.rect().translated(cursor_rect.location()).intersected(screen_rect).translated(-screen_rect.location()));
-    m_back_painter->blit(cursor_rect.location(), current_cursor.bitmap(), current_cursor.source_rect(compositor.m_current_cursor_frame));
+    m_back_painter->blit(cursor_rect.location(), current_cursor.bitmap(screen.scale_factor()), current_cursor.source_rect(compositor.m_current_cursor_frame));
     m_last_cursor_rect = cursor_rect;
     VERIFY(compositor.m_current_cursor_screen == &screen);
     m_cursor_back_is_valid = true;

Userland/Services/WindowServer/Cursor.cpp

@@ -6,6 +6,7 @@
 
 #include <AK/LexicalPath.h>
 #include <WindowServer/Cursor.h>
+#include <WindowServer/Screen.h>
 #include <WindowServer/WindowManager.h>
 
 namespace WindowServer {
@@ -77,6 +78,7 @@ CursorParams CursorParams::parse_from_filename(const StringView& cursor_path, co
             return { default_hotspot };
         }
     }
+
     return params;
 }
 
@@ -93,37 +95,66 @@ CursorParams CursorParams::constrained(const Gfx::Bitmap& bitmap) const
         }
     }
     if (params.m_have_hotspot)
-        params.m_hotspot = params.m_hotspot.constrained(rect);
+        params.m_hotspot.constrain(rect);
     else
         params.m_hotspot = rect.center();
     return params;
 }
 
-Cursor::Cursor(NonnullRefPtr<Gfx::Bitmap>&& bitmap, const CursorParams& cursor_params)
+Cursor::Cursor(NonnullRefPtr<Gfx::Bitmap>&& bitmap, int scale_factor, const CursorParams& cursor_params)
-    : m_bitmap(move(bitmap))
+    : m_params(cursor_params.constrained(*bitmap))
-    , m_params(cursor_params.constrained(*m_bitmap))
+    , m_rect(bitmap->rect())
-    , m_rect(m_bitmap->rect())
 {
+    m_bitmaps.set(scale_factor, move(bitmap));
     if (m_params.frames() > 1) {
         VERIFY(m_rect.width() % m_params.frames() == 0);
         m_rect.set_width(m_rect.width() / m_params.frames());
     }
 }
 
-Cursor::~Cursor()
+NonnullRefPtr<Cursor> Cursor::create(NonnullRefPtr<Gfx::Bitmap>&& bitmap, int scale_factor)
-{
-}
-
-NonnullRefPtr<Cursor> Cursor::create(NonnullRefPtr<Gfx::Bitmap>&& bitmap)
 {
     auto hotspot = bitmap->rect().center();
-    return adopt_ref(*new Cursor(move(bitmap), CursorParams(hotspot)));
+    return adopt_ref(*new Cursor(move(bitmap), scale_factor, CursorParams(hotspot)));
 }
 
-NonnullRefPtr<Cursor> Cursor::create(NonnullRefPtr<Gfx::Bitmap>&& bitmap, const StringView& filename)
+RefPtr<Cursor> Cursor::create(const StringView& filename, const StringView& default_filename)
 {
-    auto default_hotspot = bitmap->rect().center();
+    auto cursor = adopt_ref(*new Cursor());
-    return adopt_ref(*new Cursor(move(bitmap), CursorParams::parse_from_filename(filename, default_hotspot)));
+    if (cursor->load(filename, default_filename))
+        return cursor;
+    return {};
+}
+
+bool Cursor::load(const StringView& filename, const StringView& default_filename)
+{
+    bool did_load_any = false;
+    bool first = true;
+
+    auto load_bitmap = [&](const StringView& path, int scale_factor) {
+        auto bitmap = Gfx::Bitmap::load_from_file(path, scale_factor);
+        if (bitmap) {
+            did_load_any = true;
+            if (first) {
+                m_params = CursorParams::parse_from_filename(filename, bitmap->rect().center());
+                m_rect = bitmap->rect();
+                first = false;
+            }
+            m_bitmaps.set(scale_factor, bitmap.release_nonnull());
+        }
+    };
+
+    Screen::for_each_scale_factor_in_use([&](int scale_factor) {
+        load_bitmap(filename, scale_factor);
+        return IterationDecision::Continue;
+    });
+    if (!did_load_any) {
+        Screen::for_each_scale_factor_in_use([&](int scale_factor) {
+            load_bitmap(default_filename, scale_factor);
+            return IterationDecision::Continue;
+        });
+    }
+    return did_load_any;
 }
 
 RefPtr<Cursor> Cursor::create(Gfx::StandardCursor standard_cursor)

Userland/Services/WindowServer/Cursor.h

@@ -6,12 +6,15 @@
 
 #pragma once
 
+#include <AK/HashMap.h>
 #include <LibGfx/Bitmap.h>
 #include <LibGfx/StandardCursor.h>
 
 namespace WindowServer {
 
 class CursorParams {
+    friend class Cursor;
+
 public:
     static CursorParams parse_from_filename(const StringView&, const Gfx::IntPoint&);
     CursorParams(const Gfx::IntPoint& hotspot)
@@ -34,13 +37,27 @@ private:
 
 class Cursor : public RefCounted<Cursor> {
 public:
-    static NonnullRefPtr<Cursor> create(NonnullRefPtr<Gfx::Bitmap>&&, const StringView&);
+    static RefPtr<Cursor> create(const StringView&, const StringView&);
-    static NonnullRefPtr<Cursor> create(NonnullRefPtr<Gfx::Bitmap>&&);
+    static NonnullRefPtr<Cursor> create(NonnullRefPtr<Gfx::Bitmap>&&, int);
     static RefPtr<Cursor> create(Gfx::StandardCursor);
-    ~Cursor();
+    ~Cursor() = default;
 
     const CursorParams& params() const { return m_params; }
-    const Gfx::Bitmap& bitmap() const { return *m_bitmap; }
+    const Gfx::Bitmap& bitmap(int scale_factor) const
+    {
+        auto it = m_bitmaps.find(scale_factor);
+        if (it == m_bitmaps.end()) {
+            it = m_bitmaps.find(1);
+            if (it == m_bitmaps.end())
+                it = m_bitmaps.begin();
+        }
+        // We better found something
+        if (it == m_bitmaps.end()) {
+            dbgln("Could not find any bitmap in this Cursor");
+            VERIFY_NOT_REACHED();
+        }
+        return it->value;
+    }
 
     Gfx::IntRect source_rect(unsigned frame) const
     {
@@ -51,9 +68,12 @@ public:
     Gfx::IntSize size() const { return m_rect.size(); }
 
 private:
-    Cursor(NonnullRefPtr<Gfx::Bitmap>&&, const CursorParams&);
+    Cursor() { }
+    Cursor(NonnullRefPtr<Gfx::Bitmap>&&, int, const CursorParams&);
 
-    RefPtr<Gfx::Bitmap> m_bitmap;
+    bool load(const StringView&, const StringView&);
+
+    HashMap<int, NonnullRefPtr<Gfx::Bitmap>> m_bitmaps;
     CursorParams m_params;
     Gfx::IntRect m_rect;
 };

Userland/Services/WindowServer/MultiScaleBitmaps.cpp

@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "MultiScaleBitmaps.h"
+#include "Screen.h"
+
+namespace WindowServer {
+
+const Gfx::Bitmap& MultiScaleBitmaps::bitmap(int scale_factor) const
+{
+    auto it = m_bitmaps.find(scale_factor);
+    if (it == m_bitmaps.end()) {
+        it = m_bitmaps.find(1);
+        if (it == m_bitmaps.end())
+            it = m_bitmaps.begin();
+    }
+    // We better found *something*
+    if (it == m_bitmaps.end()) {
+        dbgln("Could not find any bitmap in this MultiScaleBitmaps");
+        VERIFY_NOT_REACHED();
+    }
+    return it->value;
+}
+
+RefPtr<MultiScaleBitmaps> MultiScaleBitmaps::create(StringView const& filename, StringView const& default_filename)
+{
+    auto per_scale_bitmap = adopt_ref(*new MultiScaleBitmaps());
+    if (per_scale_bitmap->load(filename, default_filename))
+        return per_scale_bitmap;
+    return {};
+}
+
+bool MultiScaleBitmaps::load(StringView const& filename, StringView const& default_filename)
+{
+    Optional<Gfx::BitmapFormat> bitmap_format;
+    bool did_load_any = false;
+
+    auto add_bitmap = [&](StringView const& path, int scale_factor) {
+        auto bitmap = Gfx::Bitmap::load_from_file(path, scale_factor);
+        if (bitmap) {
+            auto bitmap_format = bitmap->format();
+            if (m_format == Gfx::BitmapFormat::Invalid || m_format == bitmap_format) {
+                if (m_format == Gfx::BitmapFormat::Invalid)
+                    m_format = bitmap_format;
+
+                did_load_any = true;
+                m_bitmaps.set(scale_factor, bitmap.release_nonnull());
+            } else {
+                dbgln("Bitmap {} (scale {}) has format inconsistent with the other per-scale bitmaps", path, bitmap->scale());
+            }
+        }
+    };
+
+    Screen::for_each_scale_factor_in_use([&](int scale_factor) {
+        add_bitmap(filename, scale_factor);
+        return IterationDecision::Continue;
+    });
+    if (!did_load_any && !default_filename.is_null() && !default_filename.is_empty()) {
+        Screen::for_each_scale_factor_in_use([&](int scale_factor) {
+            add_bitmap(default_filename, scale_factor);
+            return IterationDecision::Continue;
+        });
+    }
+    return did_load_any;
+}
+
+}

Userland/Services/WindowServer/MultiScaleBitmaps.h

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/HashMap.h>
+#include <AK/RefCounted.h>
+#include <AK/RefPtr.h>
+#include <LibGfx/Bitmap.h>
+
+namespace WindowServer {
+
+class MultiScaleBitmaps : public RefCounted<MultiScaleBitmaps> {
+public:
+    static RefPtr<MultiScaleBitmaps> create(StringView const& filename, StringView const& default_filename = {});
+
+    Gfx::Bitmap const& default_bitmap() const { return bitmap(1); }
+    Gfx::Bitmap const& bitmap(int scale_factor) const;
+    Gfx::BitmapFormat format() const { return m_format; }
+
+private:
+    MultiScaleBitmaps() = default;
+    bool load(StringView const& filename, StringView const& default_filename);
+
+    HashMap<int, NonnullRefPtr<Gfx::Bitmap>> m_bitmaps;
+    Gfx::BitmapFormat m_format { Gfx::BitmapFormat::Invalid };
+};
+
+}

Userland/Services/WindowServer/Screen.cpp

@@ -23,6 +23,7 @@ NonnullOwnPtrVector<Screen, default_screen_count> Screen::s_screens;
 Screen* Screen::s_main_screen { nullptr };
 Gfx::IntRect Screen::s_bounding_screens_rect {};
 ScreenLayout Screen::s_layout;
+Vector<int, default_scale_factors_in_use_count> Screen::s_scale_factors_in_use;
 
 ScreenInput& ScreenInput::the()
 {
@@ -83,9 +84,25 @@ bool Screen::apply_layout(ScreenLayout&& screen_layout, String& error_msg)
 
     rollback.disarm();
     update_bounding_rect();
+    update_scale_factors_in_use();
     return true;
 }
 
+void Screen::update_scale_factors_in_use()
+{
+    s_scale_factors_in_use.clear();
+    for_each([&](auto& screen) {
+        auto scale_factor = screen.scale_factor();
+        // The This doesn't have to be extremely efficient as this
+        // code is only run when we start up or the screen configuration
+        // changes. But using a vector allows for efficient iteration,
+        // which is the most common use case.
+        if (!s_scale_factors_in_use.contains_slow(scale_factor))
+            s_scale_factors_in_use.append(scale_factor);
+        return IterationDecision::Continue;
+    });
+}
+
 Screen::Screen(ScreenLayout::Screen& screen_info)
     : m_virtual_rect(screen_info.location, { screen_info.resolution.width() / screen_info.scale_factor, screen_info.resolution.height() / screen_info.scale_factor })
     , m_info(screen_info)

Userland/Services/WindowServer/Screen.h

@@ -9,6 +9,7 @@
 #include "ScreenLayout.h"
 #include <AK/NonnullOwnPtrVector.h>
 #include <Kernel/API/KeyCode.h>
+#include <LibGfx/Bitmap.h>
 #include <LibGfx/Color.h>
 #include <LibGfx/Rect.h>
 #include <LibGfx/Size.h>
@@ -23,6 +24,8 @@ constexpr unsigned scroll_step_size_min = 1;
 
 // Most people will probably have 4 screens or less
 constexpr size_t default_screen_count = 4;
+// We currently only support 2 scale factors: 1x and 2x
+constexpr size_t default_scale_factors_in_use_count = 2;
 
 class Screen;
 
@@ -125,6 +128,17 @@ public:
         return IterationDecision::Continue;
     }
 
+    template<typename F>
+    static IterationDecision for_each_scale_factor_in_use(F f)
+    {
+        for (auto& scale_factor : s_scale_factors_in_use) {
+            IterationDecision decision = f(scale_factor);
+            if (decision != IterationDecision::Continue)
+                return decision;
+        }
+        return IterationDecision::Continue;
+    }
+
     void make_main_screen() { s_main_screen = this; }
     bool is_main_screen() const { return s_main_screen == this; }
 
@@ -158,6 +172,7 @@ private:
             s_screens[i].m_index = i;
     }
     static void update_bounding_rect();
+    static void update_scale_factors_in_use();
 
     bool is_opened() const { return m_framebuffer_fd >= 0; }
 
@@ -165,6 +180,7 @@ private:
     static Screen* s_main_screen;
     static Gfx::IntRect s_bounding_screens_rect;
     static ScreenLayout s_layout;
+    static Vector<int, default_scale_factors_in_use_count> s_scale_factors_in_use;
     size_t m_index { 0 };
 
     size_t m_size_in_bytes;

Userland/Services/WindowServer/WindowFrame.cpp

@@ -13,6 +13,7 @@
 #include <WindowServer/Button.h>
 #include <WindowServer/Compositor.h>
 #include <WindowServer/Event.h>
+#include <WindowServer/MultiScaleBitmaps.h>
 #include <WindowServer/Screen.h>
 #include <WindowServer/Window.h>
 #include <WindowServer/WindowFrame.h>
@@ -34,20 +35,19 @@ static Gfx::WindowTheme::WindowType to_theme_window_type(WindowType type)
     }
 }
 
-static RefPtr<Gfx::Bitmap> s_minimize_icon;
+static RefPtr<MultiScaleBitmaps> s_minimize_icon;
-static RefPtr<Gfx::Bitmap> s_maximize_icon;
+static RefPtr<MultiScaleBitmaps> s_maximize_icon;
-static RefPtr<Gfx::Bitmap> s_restore_icon;
+static RefPtr<MultiScaleBitmaps> s_restore_icon;
-static RefPtr<Gfx::Bitmap> s_close_icon;
+static RefPtr<MultiScaleBitmaps> s_close_icon;
-static RefPtr<Gfx::Bitmap> s_close_modified_icon;
+static RefPtr<MultiScaleBitmaps> s_close_modified_icon;
 
 static String s_last_title_button_icons_path;
-static int s_last_title_button_icons_scale;
 
-static RefPtr<Gfx::Bitmap> s_active_window_shadow;
+static RefPtr<MultiScaleBitmaps> s_active_window_shadow;
-static RefPtr<Gfx::Bitmap> s_inactive_window_shadow;
+static RefPtr<MultiScaleBitmaps> s_inactive_window_shadow;
-static RefPtr<Gfx::Bitmap> s_menu_shadow;
+static RefPtr<MultiScaleBitmaps> s_menu_shadow;
-static RefPtr<Gfx::Bitmap> s_taskbar_shadow;
+static RefPtr<MultiScaleBitmaps> s_taskbar_shadow;
-static RefPtr<Gfx::Bitmap> s_tooltip_shadow;
+static RefPtr<MultiScaleBitmaps> s_tooltip_shadow;
 static String s_last_active_window_shadow_path;
 static String s_last_inactive_window_shadow_path;
 static String s_last_menu_shadow_path;
@@ -117,7 +117,7 @@ void WindowFrame::set_button_icons()
 
     m_close_button->set_icon(m_window.is_modified() ? *s_close_modified_icon : *s_close_icon);
     if (m_window.is_minimizable())
-        m_minimize_button->set_icon(*s_minimize_icon);
+        m_minimize_button->set_icon(s_minimize_icon);
     if (m_window.is_resizable())
         m_maximize_button->set_icon(m_window.is_maximized() ? *s_restore_icon : *s_maximize_icon);
 }
@@ -125,54 +125,47 @@ void WindowFrame::set_button_icons()
 void WindowFrame::reload_config()
 {
     String icons_path = WindowManager::the().palette().title_button_icons_path();
-    int icons_scale = WindowManager::the().compositor_icon_scale(); // TODO: We'll need to load icons for all scales in use!
 
     StringBuilder full_path;
-    if (!s_minimize_icon || s_last_title_button_icons_path != icons_path || s_last_title_button_icons_scale != icons_scale) {
+    if (!s_minimize_icon || s_last_title_button_icons_path != icons_path) {
         full_path.append(icons_path);
         full_path.append("window-minimize.png");
-        if (!(s_minimize_icon = Gfx::Bitmap::load_from_file(full_path.to_string(), icons_scale)))
+        s_minimize_icon = MultiScaleBitmaps::create(full_path.to_string(), "/res/icons/16x16/downward-triangle.png");
-            s_minimize_icon = Gfx::Bitmap::load_from_file("/res/icons/16x16/downward-triangle.png", icons_scale);
         full_path.clear();
     }
-    if (!s_maximize_icon || s_last_title_button_icons_path != icons_path || s_last_title_button_icons_scale != icons_scale) {
+    if (!s_maximize_icon || s_last_title_button_icons_path != icons_path) {
         full_path.append(icons_path);
         full_path.append("window-maximize.png");
-        if (!(s_maximize_icon = Gfx::Bitmap::load_from_file(full_path.to_string(), icons_scale)))
+        s_maximize_icon = MultiScaleBitmaps::create(full_path.to_string(), "/res/icons/16x16/upward-triangle.png");
-            s_maximize_icon = Gfx::Bitmap::load_from_file("/res/icons/16x16/upward-triangle.png", icons_scale);
         full_path.clear();
     }
-    if (!s_restore_icon || s_last_title_button_icons_path != icons_path || s_last_title_button_icons_scale != icons_scale) {
+    if (!s_restore_icon || s_last_title_button_icons_path != icons_path) {
         full_path.append(icons_path);
         full_path.append("window-restore.png");
-        if (!(s_restore_icon = Gfx::Bitmap::load_from_file(full_path.to_string(), icons_scale)))
+        s_restore_icon = MultiScaleBitmaps::create(full_path.to_string(), "/res/icons/16x16/window-restore.png");
-            s_restore_icon = Gfx::Bitmap::load_from_file("/res/icons/16x16/window-restore.png", icons_scale);
         full_path.clear();
     }
-    if (!s_close_icon || s_last_title_button_icons_path != icons_path || s_last_title_button_icons_scale != icons_scale) {
+    if (!s_close_icon || s_last_title_button_icons_path != icons_path) {
         full_path.append(icons_path);
         full_path.append("window-close.png");
-        if (!(s_close_icon = Gfx::Bitmap::load_from_file(full_path.to_string(), icons_scale)))
+        s_close_icon = MultiScaleBitmaps::create(full_path.to_string(), "/res/icons/16x16/window-close.png");
-            s_close_icon = Gfx::Bitmap::load_from_file("/res/icons/16x16/window-close.png", icons_scale);
         full_path.clear();
     }
-    if (!s_close_modified_icon || s_last_title_button_icons_path != icons_path || s_last_title_button_icons_scale != icons_scale) {
+    if (!s_close_modified_icon || s_last_title_button_icons_path != icons_path) {
         full_path.append(icons_path);
         full_path.append("window-close-modified.png");
-        if (!(s_close_modified_icon = Gfx::Bitmap::load_from_file(full_path.to_string(), icons_scale)))
+        s_close_modified_icon = MultiScaleBitmaps::create(full_path.to_string(), "/res/icons/16x16/window-close-modified.png");
-            s_close_modified_icon = Gfx::Bitmap::load_from_file("/res/icons/16x16/window-close-modified.png", icons_scale);
         full_path.clear();
     }
 
     s_last_title_button_icons_path = icons_path;
-    s_last_title_button_icons_scale = icons_scale;
 
-    auto load_shadow = [](const String& path, String& last_path, RefPtr<Gfx::Bitmap>& shadow_bitmap) {
+    auto load_shadow = [](const String& path, String& last_path, RefPtr<MultiScaleBitmaps>& shadow_bitmap) {
         if (path.is_empty()) {
             last_path = String::empty();
             shadow_bitmap = nullptr;
-        } else if (!shadow_bitmap || shadow_bitmap->scale() != s_last_title_button_icons_scale || last_path != path) {
+        } else if (!shadow_bitmap || last_path != path) {
-            shadow_bitmap = Gfx::Bitmap::load_from_file(path, s_last_title_button_icons_scale);
+            shadow_bitmap = MultiScaleBitmaps::create(path);
             if (shadow_bitmap)
                 last_path = path;
             else
@@ -186,7 +179,7 @@ void WindowFrame::reload_config()
     load_shadow(WindowManager::the().palette().tooltip_shadow_path(), s_last_tooltip_shadow_path, s_tooltip_shadow);
 }
 
-Gfx::Bitmap* WindowFrame::shadow_bitmap() const
+MultiScaleBitmaps* WindowFrame::shadow_bitmap() const
 {
     if (m_window.is_frameless())
         return nullptr;
@@ -317,7 +310,7 @@ void WindowFrame::paint(Screen& screen, Gfx::Painter& painter, const Gfx::IntRec
         cached->paint(*this, painter, rect);
 }
 
-void WindowFrame::RenderedCache::paint(WindowFrame& frame, Gfx::Painter& painter, const Gfx::IntRect& rect)
+void WindowFrame::PerScaleRenderedCache::paint(WindowFrame& frame, Gfx::Painter& painter, const Gfx::IntRect& rect)
 {
     auto frame_rect = frame.unconstrained_render_rect();
     auto window_rect = frame.window().rect();
@@ -357,7 +350,7 @@ void WindowFrame::RenderedCache::paint(WindowFrame& frame, Gfx::Painter& painter
     }
 }
 
-void WindowFrame::render(Screen&, Gfx::Painter& painter)
+void WindowFrame::render(Screen& screen, Gfx::Painter& painter)
 {
     if (m_window.is_frameless())
         return;
@@ -371,9 +364,8 @@ void WindowFrame::render(Screen&, Gfx::Painter& painter)
     else
         return;
 
-    for (auto& button : m_buttons) {
+    for (auto& button : m_buttons)
-        button.paint(painter);
+        button.paint(screen, painter);
-    }
 }
 
 void WindowFrame::theme_changed()
@@ -386,13 +378,13 @@ void WindowFrame::theme_changed()
     m_has_alpha_channel = Gfx::WindowTheme::current().frame_uses_alpha(window_state_for_theme(), WindowManager::the().palette());
 }
 
-auto WindowFrame::render_to_cache(Screen& screen) -> RenderedCache*
+auto WindowFrame::render_to_cache(Screen& screen) -> PerScaleRenderedCache*
 {
     auto scale = screen.scale_factor();
-    RenderedCache* rendered_cache;
+    PerScaleRenderedCache* rendered_cache;
     auto cached_it = m_rendered_cache.find(scale);
     if (cached_it == m_rendered_cache.end()) {
-        auto new_rendered_cache = make<RenderedCache>();
+        auto new_rendered_cache = make<PerScaleRenderedCache>();
         rendered_cache = new_rendered_cache.ptr();
         m_rendered_cache.set(scale, move(new_rendered_cache));
     } else {
@@ -402,7 +394,7 @@ auto WindowFrame::render_to_cache(Screen& screen) -> RenderedCache*
     return rendered_cache;
 }
 
-void WindowFrame::RenderedCache::render(WindowFrame& frame, Screen& screen)
+void WindowFrame::PerScaleRenderedCache::render(WindowFrame& frame, Screen& screen)
 {
     if (!m_dirty)
         return;
@@ -417,7 +409,7 @@ void WindowFrame::RenderedCache::render(WindowFrame& frame, Screen& screen)
     Gfx::IntPoint shadow_offset;
 
     if (shadow_bitmap) {
-        auto total_shadow_size = shadow_bitmap->height();
+        auto total_shadow_size = shadow_bitmap->bitmap(screen.scale_factor()).height();
         frame_rect_including_shadow.inflate(total_shadow_size, total_shadow_size);
         auto offset = total_shadow_size / 2;
         shadow_offset = { offset, offset };
@@ -481,7 +473,7 @@ void WindowFrame::RenderedCache::render(WindowFrame& frame, Screen& screen)
         painter.clear_rect({ rect.location() - frame_rect_to_update.location(), rect.size() }, { 255, 255, 255, 0 });
 
     if (m_shadow_dirty && shadow_bitmap)
-        frame.paint_simple_rect_shadow(painter, { { 0, 0 }, frame_rect_including_shadow.size() }, *shadow_bitmap);
+        frame.paint_simple_rect_shadow(painter, { { 0, 0 }, frame_rect_including_shadow.size() }, shadow_bitmap->bitmap(screen.scale_factor()));
 
     {
         Gfx::PainterStateSaver save(painter);
@@ -535,7 +527,7 @@ void WindowFrame::set_opacity(float opacity)
 Gfx::IntRect WindowFrame::inflated_for_shadow(const Gfx::IntRect& frame_rect) const
 {
     if (auto* shadow = shadow_bitmap()) {
-        auto total_shadow_size = shadow->height();
+        auto total_shadow_size = shadow->default_bitmap().height();
         return frame_rect.inflated(total_shadow_size, total_shadow_size);
     }
     return frame_rect;
@@ -678,7 +670,7 @@ Optional<HitTestResult> WindowFrame::hit_test(Gfx::IntPoint const& position)
     return cached->hit_test(*this, position, window_relative_position);
 }
 
-Optional<HitTestResult> WindowFrame::RenderedCache::hit_test(WindowFrame& frame, Gfx::IntPoint const& position, Gfx::IntPoint const& window_relative_position)
+Optional<HitTestResult> WindowFrame::PerScaleRenderedCache::hit_test(WindowFrame& frame, Gfx::IntPoint const& position, Gfx::IntPoint const& window_relative_position)
 {
     HitTestResult result {
         .window = frame.window(),

Userland/Services/WindowServer/WindowFrame.h

@@ -19,12 +19,13 @@ namespace WindowServer {
 class Button;
 class Menu;
 class MouseEvent;
-class Window;
+class MultiScaleBitmaps;
 class Screen;
+class Window;
 
 class WindowFrame {
 public:
-    class RenderedCache {
+    class PerScaleRenderedCache {
         friend class WindowFrame;
 
     public:
@@ -60,7 +61,7 @@ public:
 
     void paint(Screen&, Gfx::Painter&, const Gfx::IntRect&);
     void render(Screen&, Gfx::Painter&);
-    RenderedCache* render_to_cache(Screen&);
+    PerScaleRenderedCache* render_to_cache(Screen&);
 
     void handle_mouse_event(MouseEvent const&);
     void handle_titlebar_mouse_event(MouseEvent const&);
@@ -123,7 +124,7 @@ private:
     void paint_normal_frame(Gfx::Painter&);
     void paint_tool_window_frame(Gfx::Painter&);
     void paint_menubar(Gfx::Painter&);
-    Gfx::Bitmap* shadow_bitmap() const;
+    MultiScaleBitmaps* shadow_bitmap() const;
     Gfx::IntRect inflated_for_shadow(const Gfx::IntRect&) const;
 
     void handle_menubar_mouse_event(const MouseEvent&);
@@ -140,7 +141,7 @@ private:
     Button* m_maximize_button { nullptr };
     Button* m_minimize_button { nullptr };
 
-    HashMap<int, NonnullOwnPtr<RenderedCache>> m_rendered_cache;
+    HashMap<int, NonnullOwnPtr<PerScaleRenderedCache>> m_rendered_cache;
 
     RefPtr<Core::Timer> m_flash_timer;
     size_t m_flash_counter { 0 };

Userland/Services/WindowServer/WindowManager.cpp

@@ -48,14 +48,10 @@ WindowManager::~WindowManager()
 {
 }
 
-NonnullRefPtr<Cursor> WindowManager::get_cursor(String const& name)
+RefPtr<Cursor> WindowManager::get_cursor(String const& name)
 {
     static auto const s_default_cursor_path = "/res/cursors/arrow.x2y2.png";
-    auto path = m_config->read_entry("Cursor", name, s_default_cursor_path);
+    return Cursor::create(m_config->read_entry("Cursor", name, s_default_cursor_path), s_default_cursor_path);
-    auto gb = Gfx::Bitmap::load_from_file(path, compositor_icon_scale());
-    if (gb)
-        return Cursor::create(*gb, path);
-    return Cursor::create(*Gfx::Bitmap::load_from_file(s_default_cursor_path), s_default_cursor_path);
 }
 
 void WindowManager::reload_config()
@@ -1179,7 +1175,7 @@ void WindowManager::process_key_event(KeyEvent& event)
     }
 
     if (event.type() == Event::KeyDown && (event.modifiers() == (Mod_Ctrl | Mod_Super | Mod_Shift) && event.key() == Key_I)) {
-        reload_icon_bitmaps_after_scale_change(!m_allow_hidpi_icons);
+        reload_icon_bitmaps_after_scale_change();
         Compositor::the().invalidate_screen();
         return;
     }
@@ -1595,16 +1591,8 @@ Gfx::IntPoint WindowManager::get_recommended_window_position(Gfx::IntPoint const
     return point;
 }
 
-int WindowManager::compositor_icon_scale() const
+void WindowManager::reload_icon_bitmaps_after_scale_change()
 {
-    if (!m_allow_hidpi_icons)
-        return 1;
-    return Screen::main().scale_factor(); // TODO: There is no *one* scale factor...
-}
-
-void WindowManager::reload_icon_bitmaps_after_scale_change(bool allow_hidpi_icons)
-{
-    m_allow_hidpi_icons = allow_hidpi_icons;
     reload_config();
     m_window_stack.for_each_window([&](Window& window) {
         auto& window_frame = window.frame();

Userland/Services/WindowServer/WindowManager.h

@@ -224,8 +224,7 @@ public:
 
     Gfx::IntPoint get_recommended_window_position(Gfx::IntPoint const& desired);
 
-    int compositor_icon_scale() const;
+    void reload_icon_bitmaps_after_scale_change();
-    void reload_icon_bitmaps_after_scale_change(bool allow_hidpi_icons = true);
 
     void reevaluate_hovered_window(Window* = nullptr);
     Window* hovered_window() const { return m_hovered_window.ptr(); }
@@ -233,7 +232,7 @@ public:
     WindowStack& window_stack() { return m_window_stack; }
 
 private:
-    NonnullRefPtr<Cursor> get_cursor(String const& name);
+    RefPtr<Cursor> get_cursor(String const& name);
 
     void process_mouse_event(MouseEvent&);
     void process_event_for_doubleclick(Window& window, MouseEvent& event);
@@ -257,7 +256,6 @@ private:
 
     void do_move_to_front(Window&, bool, bool);
 
-    bool m_allow_hidpi_icons { true };
     RefPtr<Cursor> m_hidden_cursor;
     RefPtr<Cursor> m_arrow_cursor;
     RefPtr<Cursor> m_hand_cursor;