LibGfx: Add 'IsDark' flag to SystemTheme and Palette

This explicitly states whether a given theme is a dark theme, so that
applications not using the system palette colors can still attempt to
match the overall theme.

Userland/Libraries/LibGfx/Palette.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Sam Atkins <atkinssj@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -56,6 +57,14 @@ void Palette::set_color(ColorRole role, Color color)
     theme.color[(int)role] = color.value();
 }
 
+void Palette::set_flag(FlagRole role, bool value)
+{
+    if (m_impl->ref_count() != 1)
+        m_impl = m_impl->clone();
+    auto& theme = const_cast<SystemTheme&>(impl().theme());
+    theme.flag[(int)role] = value;
+}
+
 void Palette::set_metric(MetricRole role, int value)
 {
     if (m_impl->ref_count() != 1)

Userland/Libraries/LibGfx/Palette.h

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Sam Atkins <atkinssj@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -30,6 +31,12 @@ public:
         return Color::from_rgba(theme().color[(int)role]);
     }
 
+    bool flag(FlagRole role) const
+    {
+        VERIFY((int)role < (int)FlagRole::__Count);
+        return theme().flag[(int)role];
+    }
+
     int metric(MetricRole) const;
     String path(PathRole) const;
     const SystemTheme& theme() const { return *m_theme_buffer.data<SystemTheme>(); }
@@ -118,6 +125,8 @@ public:
     Color syntax_preprocessor_statement() const { return color(ColorRole::SyntaxPreprocessorStatement); }
     Color syntax_preprocessor_value() const { return color(ColorRole::SyntaxPreprocessorValue); }
 
+    bool is_dark() const { return flag(FlagRole::IsDark); }
+
     int window_title_height() const { return metric(MetricRole::TitleHeight); }
     int window_title_button_width() const { return metric(MetricRole::TitleButtonWidth); }
     int window_title_button_height() const { return metric(MetricRole::TitleButtonHeight); }
@@ -130,10 +139,12 @@ public:
     String tooltip_shadow_path() const { return path(PathRole::TooltipShadow); }
 
     Color color(ColorRole role) const { return m_impl->color(role); }
+    bool flag(FlagRole role) const { return m_impl->flag(role); }
     int metric(MetricRole role) const { return m_impl->metric(role); }
     String path(PathRole role) const { return m_impl->path(role); }
 
     void set_color(ColorRole, Color);
+    void set_flag(FlagRole, bool);
     void set_metric(MetricRole, int);
     void set_path(PathRole, String);
 

Userland/Libraries/LibGfx/SystemTheme.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Sam Atkins <atkinssj@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -40,6 +41,11 @@ Core::AnonymousBuffer load_system_theme(Core::ConfigFile const& file)
         return color.value();
     };
 
+    auto get_flag = [&](auto& name) {
+        auto flag_string = file.read_entry("Flags", name);
+        return flag_string.equals_ignoring_case("true");
+    };
+
     auto get_metric = [&](auto& name, auto role) {
         int metric = file.read_num_entry("Metrics", name, -1);
         if (metric == -1) {
@@ -77,6 +83,12 @@ Core::AnonymousBuffer load_system_theme(Core::ConfigFile const& file)
     ENUMERATE_COLOR_ROLES(__ENUMERATE_COLOR_ROLE)
 #undef __ENUMERATE_COLOR_ROLE
 
+#undef __ENUMERATE_FLAG_ROLE
+#define __ENUMERATE_FLAG_ROLE(role) \
+    data->flag[(int)FlagRole::role] = get_flag(#role);
+    ENUMERATE_FLAG_ROLES(__ENUMERATE_FLAG_ROLE)
+#undef __ENUMERATE_FLAG_ROLE
+
 #undef __ENUMERATE_METRIC_ROLE
 #define __ENUMERATE_METRIC_ROLE(role) \
     data->metric[(int)MetricRole::role] = get_metric(#role, (int)MetricRole::role);

Userland/Libraries/LibGfx/SystemTheme.h

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Sam Atkins <atkinssj@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -89,6 +90,9 @@ namespace Gfx {
     C(Window)                      \
     C(WindowText)
 
+#define ENUMERATE_FLAG_ROLES(C) \
+    C(IsDark)
+
 #define ENUMERATE_METRIC_ROLES(C) \
     C(TitleHeight)                \
     C(TitleButtonWidth)           \
@@ -132,6 +136,17 @@ inline const char* to_string(ColorRole role)
     }
 }
 
+enum class FlagRole {
+    NoRole,
+
+#undef __ENUMERATE_FLAG_ROLE
+#define __ENUMERATE_FLAG_ROLE(role) role,
+    ENUMERATE_FLAG_ROLES(__ENUMERATE_FLAG_ROLE)
+#undef __ENUMERATE_FLAG_ROLE
+
+        __Count,
+};
+
 enum class MetricRole {
     NoRole,
 
@@ -188,6 +203,7 @@ inline const char* to_string(PathRole role)
 
 struct SystemTheme {
     RGBA32 color[(int)ColorRole::__Count];
+    bool flag[(int)FlagRole::__Count];
     int metric[(int)MetricRole::__Count];
     char path[(int)PathRole::__Count][256]; // TODO: PATH_MAX?
 };