WindowServer: Implement cursor highlighting

This allows drawing a nice cursor highlight with an arbitrary color
and radius in the compositor. The highlight circle is, of course,
antialiased :^).

3 files changed, 55 insertions, 4 deletions

diff --git a/Userland/Services/WindowServer/Compositor.cpp b/Userland/Services/WindowServer/Compositor.cpp
index 7a5243b45b..645b98f176 100644
--- a/Userland/Services/WindowServer/Compositor.cpp
+++ b/Userland/Services/WindowServer/Compositor.cpp
@@ -17,6 +17,7 @@
 #include <AK/Memory.h>
 #include <AK/ScopeGuard.h>
 #include <LibCore/Timer.h>
+#include <LibGfx/AntiAliasingPainter.h>
 #include <LibGfx/Font/Font.h>
 #include <LibGfx/Painter.h>
 #include <LibGfx/StylePainter.h>
@@ -849,7 +850,14 @@ Gfx::IntRect Compositor::current_cursor_rect() const
 {
     auto& wm = WindowManager::the();
     auto& current_cursor = m_current_cursor ? *m_current_cursor : wm.active_cursor();
-    return { ScreenInput::the().cursor_location().translated(-current_cursor.params().hotspot()), current_cursor.size() };
+    Gfx::IntRect cursor_rect { ScreenInput::the().cursor_location().translated(-current_cursor.params().hotspot()), current_cursor.size() };
+    if (wm.is_cursor_highlight_enabled()) {
+        auto highlight_diameter = wm.cursor_highlight_radius() * 2;
+        cursor_rect.inflate(
+            highlight_diameter - cursor_rect.width(),
+            highlight_diameter - cursor_rect.height());
+    }
+    return cursor_rect;
 }
 
 void Compositor::invalidate_cursor(bool compose_immediately)
@@ -956,10 +964,17 @@ void CompositorScreenData::draw_cursor(Screen& screen, Gfx::IntRect const& curso
     auto& compositor = Compositor::the();
     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_cursor_back_painter->blit({ 0, 0 }, *m_back_bitmap, cursor_rect.intersected(screen_rect).translated(-screen_rect.location()));
     auto cursor_src_rect = current_cursor.source_rect(compositor.m_current_cursor_frame);
-    m_back_painter->blit(cursor_rect.location(), current_cursor.bitmap(screen.scale_factor()), cursor_src_rect);
-    m_flush_special_rects.add(Gfx::IntRect(cursor_rect.location(), cursor_src_rect.size()).intersected(screen.rect()));
+    auto cursor_blit_pos = current_cursor.rect().centered_within(cursor_rect).location();
+
+    if (wm.is_cursor_highlight_enabled()) {
+        Gfx::AntiAliasingPainter aa_back_painter { *m_back_painter };
+        aa_back_painter.fill_ellipse(cursor_rect, wm.cursor_highlight_color());
+    }
+    m_back_painter->blit(cursor_blit_pos, current_cursor.bitmap(screen.scale_factor()), cursor_src_rect);
+
+    m_flush_special_rects.add(Gfx::IntRect(cursor_rect.location(), cursor_rect.size()).intersected(screen.rect()));
     m_have_flush_rects = true;
     m_last_cursor_rect = cursor_rect;
     VERIFY(compositor.m_current_cursor_screen == &screen);
diff --git a/Userland/Services/WindowServer/WindowManager.cpp b/Userland/Services/WindowServer/WindowManager.cpp
index a6dfafd15f..463fdfc4e6 100644
--- a/Userland/Services/WindowServer/WindowManager.cpp
+++ b/Userland/Services/WindowServer/WindowManager.cpp
@@ -82,6 +82,10 @@ void WindowManager::reload_config()
 
     m_double_click_speed = m_config->read_num_entry("Input", "DoubleClickSpeed", 250);
     m_buttons_switched = m_config->read_bool_entry("Mouse", "ButtonsSwitched", false);
+    m_cursor_highlight_radius = m_config->read_num_entry("Mouse", "CursorHighlightRadius", 0);
+    Color default_highlight_color = Color::NamedColor::Yellow;
+    default_highlight_color.set_alpha(80);
+    m_cursor_highlight_color = Color::from_string(m_config->read_entry("Mouse", "CursorHighlightColor")).value_or(default_highlight_color);
     apply_cursor_theme(m_config->read_entry("Mouse", "CursorTheme", "Default"));
 
     auto reload_graphic = [&](RefPtr<MultiScaleBitmaps>& bitmap, String const& name) {
@@ -2273,6 +2277,28 @@ void WindowManager::apply_cursor_theme(String const& theme_name)
     sync_config_to_disk();
 }
 
+void WindowManager::set_cursor_highlight_radius(int radius)
+{
+    // TODO: Validate radius
+    m_cursor_highlight_radius = radius;
+    Compositor::the().invalidate_cursor();
+    m_config->write_num_entry("Mouse", "CursorHighlightRadius", radius);
+    sync_config_to_disk();
+}
+
+void WindowManager::set_cursor_highlight_color(Gfx::Color const& color)
+{
+    m_cursor_highlight_color = color;
+    Compositor::the().invalidate_cursor();
+    m_config->write_entry("Mouse", "CursorHighlightColor", color.to_string());
+    sync_config_to_disk();
+}
+
+bool WindowManager::is_cursor_highlight_enabled() const
+{
+    return m_cursor_highlight_radius > 0 && m_cursor_highlight_color.alpha() > 0;
+}
+
 bool WindowManager::sync_config_to_disk()
 {
     if (auto result = m_config->sync(); result.is_error()) {
diff --git a/Userland/Services/WindowServer/WindowManager.h b/Userland/Services/WindowServer/WindowManager.h
index c5632b0d4c..035348f819 100644
--- a/Userland/Services/WindowServer/WindowManager.h
+++ b/Userland/Services/WindowServer/WindowManager.h
@@ -153,6 +153,9 @@ public:
     Cursor const& eyedropper_cursor() const { return *m_eyedropper_cursor; }
     Cursor const& zoom_cursor() const { return *m_zoom_cursor; }
 
+    int cursor_highlight_radius() const { return m_cursor_highlight_radius; }
+    Gfx::Color cursor_highlight_color() const { return m_cursor_highlight_color; }
+
     Gfx::Font const& font() const;
     Gfx::Font const& window_title_font() const;
 
@@ -323,6 +326,11 @@ public:
 
     void apply_cursor_theme(String const& name);
 
+    void set_cursor_highlight_radius(int radius);
+    void set_cursor_highlight_color(Gfx::Color const& color);
+
+    bool is_cursor_highlight_enabled() const;
+
 private:
     explicit WindowManager(Gfx::PaletteImpl const&);
 
@@ -376,6 +384,8 @@ private:
     RefPtr<Cursor> m_crosshair_cursor;
     RefPtr<Cursor> m_eyedropper_cursor;
     RefPtr<Cursor> m_zoom_cursor;
+    int m_cursor_highlight_radius { 0 };
+    Gfx::Color m_cursor_highlight_color;
 
     RefPtr<MultiScaleBitmaps> m_overlay_rect_shadow;