WindowServer: In HighDPI mode, load high-res window buttons and high-res cursors

Bitmap::load_from_file("foo.png", 2) will now look for "foo-2x.png" and
try load that as a bitmap with scale factor 2 if it exists. If it
doesn't, it falls back to the 1x bitmap as normal.
Only places that know that they'll draw the bitmap to a 2x painter
should pass "2" for the second argument.

Use this new API in WindowServer for loading window buttons and
cursors.

As a testing aid, ctrl-shift-super-i can force HighDPI icons off in
HighDPI mode. Toggling between low-res and high-res icons makes it easy
to see if the high-res version of an icon looks right: It should look
like the low-res version, just less jaggy.

We'll likely have to grow a better API for loading scaled resources, but
for now this suffices.

Things to check:
- `chres 640 480` followed by `chres 640 480 2` followed by
  `chres 640 480`
- window buttons in window context menu (in task bar and on title bar)
  still have low-res icons
- ctrl-shift-super-i in high-res mode toggles sharpness of window
  buttons and of arrow cursorf
- arrow cursor hotspot is still where you'd expect

Userland/Services/WindowServer/Compositor.cpp

@@ -713,7 +713,10 @@ bool Compositor::set_resolution(int desired_width, int desired_height, int scale
         return false;
     }
 
+    int old_scale_factor = Screen::the().scale_factor();
     bool success = Screen::the().set_resolution(desired_width, desired_height, scale_factor);
+    if (success && old_scale_factor != scale_factor)
+        WindowManager::the().reload_icon_bitmaps_after_scale_change();
     init_bitmaps();
     invalidate_occlusions();
     compose();

Userland/Services/WindowServer/Cursor.cpp

@@ -46,7 +46,8 @@ CursorParams CursorParams::parse_from_file_name(const StringView& cursor_path, c
     auto params_str = file_title.substring_view(last_dot_in_title.value() + 1);
 
     CursorParams params(default_hotspot);
-    for (size_t i = 0; i + 1 < params_str.length();) {
+    bool in_display_scale_part = false;
+    for (size_t i = 0; i + 1 < params_str.length() && !in_display_scale_part;) {
         auto property = params_str[i++];
 
         auto value = [&]() -> Optional<size_t> {
@@ -88,6 +89,9 @@ CursorParams CursorParams::parse_from_file_name(const StringView& cursor_path, c
             else
                 dbgln("Cursor frame rate outside of valid range (100-1000ms)");
             break;
+        case '-':
+            in_display_scale_part = true;
+            break;
         default:
             dbg() << "Ignore unknown property '" << property << "' with value " << value.value() << " parsed from cursor path: " << cursor_path;
             return { default_hotspot };

Userland/Services/WindowServer/WindowFrame.cpp

@@ -57,6 +57,7 @@ static Gfx::Bitmap* s_restore_icon;
 static Gfx::Bitmap* s_close_icon;
 
 static String s_last_title_button_icons_path;
+static int s_last_title_button_icons_scale;
 
 WindowFrame::WindowFrame(Window& window)
     : m_window(window)
@@ -96,34 +97,35 @@ void WindowFrame::set_button_icons()
         return;
 
     String icons_path = WindowManager::the().palette().title_button_icons_path();
+    int icons_scale = WindowManager::the().compositor_icon_scale();
 
     StringBuilder full_path;
-    if (!s_minimize_icon || s_last_title_button_icons_path != icons_path) {
+    if (!s_minimize_icon || s_last_title_button_icons_path != icons_path || s_last_title_button_icons_scale != icons_scale) {
         full_path.append(icons_path);
         full_path.append("window-minimize.png");
-        if (!(s_minimize_icon = Gfx::Bitmap::load_from_file(full_path.to_string()).leak_ref()))
-            s_minimize_icon = Gfx::Bitmap::load_from_file("/res/icons/16x16/downward-triangle.png").leak_ref();
+        if (!(s_minimize_icon = Gfx::Bitmap::load_from_file(full_path.to_string(), icons_scale).leak_ref()))
+            s_minimize_icon = Gfx::Bitmap::load_from_file("/res/icons/16x16/downward-triangle.png", icons_scale).leak_ref();
         full_path.clear();
     }
-    if (!s_maximize_icon || s_last_title_button_icons_path != icons_path) {
+    if (!s_maximize_icon || s_last_title_button_icons_path != icons_path || s_last_title_button_icons_scale != icons_scale) {
         full_path.append(icons_path);
         full_path.append("window-maximize.png");
-        if (!(s_maximize_icon = Gfx::Bitmap::load_from_file(full_path.to_string()).leak_ref()))
-            s_maximize_icon = Gfx::Bitmap::load_from_file("/res/icons/16x16/upward-triangle.png").leak_ref();
+        if (!(s_maximize_icon = Gfx::Bitmap::load_from_file(full_path.to_string(), icons_scale).leak_ref()))
+            s_maximize_icon = Gfx::Bitmap::load_from_file("/res/icons/16x16/upward-triangle.png", icons_scale).leak_ref();
         full_path.clear();
     }
-    if (!s_restore_icon || s_last_title_button_icons_path != icons_path) {
+    if (!s_restore_icon || s_last_title_button_icons_path != icons_path || s_last_title_button_icons_scale != icons_scale) {
         full_path.append(icons_path);
         full_path.append("window-restore.png");
-        if (!(s_restore_icon = Gfx::Bitmap::load_from_file(full_path.to_string()).leak_ref()))
-            s_restore_icon = Gfx::Bitmap::load_from_file("/res/icons/16x16/window-restore.png").leak_ref();
+        if (!(s_restore_icon = Gfx::Bitmap::load_from_file(full_path.to_string(), icons_scale).leak_ref()))
+            s_restore_icon = Gfx::Bitmap::load_from_file("/res/icons/16x16/window-restore.png", icons_scale).leak_ref();
         full_path.clear();
     }
-    if (!s_close_icon || s_last_title_button_icons_path != icons_path) {
+    if (!s_close_icon || s_last_title_button_icons_path != icons_path || s_last_title_button_icons_scale != icons_scale) {
         full_path.append(icons_path);
         full_path.append("window-close.png");
-        if (!(s_close_icon = Gfx::Bitmap::load_from_file(full_path.to_string()).leak_ref()))
-            s_close_icon = Gfx::Bitmap::load_from_file("/res/icons/16x16/window-close.png").leak_ref();
+        if (!(s_close_icon = Gfx::Bitmap::load_from_file(full_path.to_string(), icons_scale).leak_ref()))
+            s_close_icon = Gfx::Bitmap::load_from_file("/res/icons/16x16/window-close.png", icons_scale).leak_ref();
         full_path.clear();
     }
 
@@ -134,6 +136,7 @@ void WindowFrame::set_button_icons()
         m_maximize_button->set_icon(m_window.is_maximized() ? *s_restore_icon : *s_maximize_icon);
 
     s_last_title_button_icons_path = icons_path;
+    s_last_title_button_icons_scale = icons_scale;
 }
 
 void WindowFrame::did_set_maximized(Badge<Window>, bool maximized)

Userland/Services/WindowServer/WindowManager.cpp

@@ -35,6 +35,7 @@
 #include <AK/LogStream.h>
 #include <AK/StdLibExtras.h>
 #include <AK/Vector.h>
+#include <LibGfx/Bitmap.h>
 #include <LibGfx/CharacterBitmap.h>
 #include <LibGfx/Font.h>
 #include <LibGfx/Painter.h>
@@ -84,7 +85,7 @@ NonnullRefPtr<Cursor> WindowManager::get_cursor(const String& name)
 {
     static const auto s_default_cursor_path = "/res/cursors/arrow.x2y2.png";
     auto path = m_config->read_entry("Cursor", name, s_default_cursor_path);
-    auto gb = Gfx::Bitmap::load_from_file(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);
@@ -1092,6 +1093,12 @@ void WindowManager::event(Core::Event& event)
             return;
         }
 
+        if (key_event.type() == Event::KeyDown && (key_event.modifiers() == (Mod_Ctrl | Mod_Logo | Mod_Shift) && key_event.key() == Key_I)) {
+            reload_icon_bitmaps_after_scale_change(!m_allow_hidpi_icons);
+            Compositor::the().invalidate_screen();
+            return;
+        }
+
         if (MenuManager::the().current_menu()) {
             MenuManager::the().dispatch_event(event);
             return;
@@ -1486,4 +1493,21 @@ Gfx::IntPoint WindowManager::get_recommended_window_position(const Gfx::IntPoint
 
     return point;
 }
+
+int WindowManager::compositor_icon_scale() const
+{
+    if (!m_allow_hidpi_icons)
+        return 1;
+    return scale_factor();
+}
+
+void WindowManager::reload_icon_bitmaps_after_scale_change(bool allow_hidpi_icons)
+{
+    m_allow_hidpi_icons = allow_hidpi_icons;
+    reload_config();
+    for_each_window([&](Window& window) {
+        window.frame().set_button_icons();
+        return IterationDecision::Continue;
+    });
+}
 }

Userland/Services/WindowServer/WindowManager.h

@@ -230,6 +230,9 @@ public:
 
     Gfx::IntPoint get_recommended_window_position(const Gfx::IntPoint& desired);
 
+    int compositor_icon_scale() const;
+    void reload_icon_bitmaps_after_scale_change(bool allow_hidpi_icons = true);
+
 private:
     NonnullRefPtr<Cursor> get_cursor(const String& name);
 
@@ -263,6 +266,7 @@ 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;