WindowServer+LibGfx: Move normal window frame painting to a WindowTheme

This patch introduces the ClassicWindowTheme, which is our default
theme implemented as a Gfx::WindowTheme subclass.

In this initial cut, we move normal window frame painting and title
bar metrics helpers out of WindowServer and into LibGfx.

This will eventually allow us much greater flexibility with theming
windows, and also makes it easier to build applications that want to
render a window with a specific style for some reason. :^)

3 files changed, 198 insertions, 0 deletions

diff --git a/Libraries/LibGfx/CMakeLists.txt b/Libraries/LibGfx/CMakeLists.txt
index e0f13a0e7a..58d50882f2 100644
--- a/Libraries/LibGfx/CMakeLists.txt
+++ b/Libraries/LibGfx/CMakeLists.txt
@@ -3,6 +3,7 @@ set(SOURCES
     Bitmap.cpp
     BMPLoader.cpp
     CharacterBitmap.cpp
+    ClassicWindowTheme.cpp
     Color.cpp
     DisjointRectSet.cpp
     Emoji.cpp
diff --git a/Libraries/LibGfx/ClassicWindowTheme.cpp b/Libraries/LibGfx/ClassicWindowTheme.cpp
new file mode 100644
index 0000000000..ccf9c9a5c2
--- /dev/null
+++ b/Libraries/LibGfx/ClassicWindowTheme.cpp
@@ -0,0 +1,139 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <LibGfx/Bitmap.h>
+#include <LibGfx/ClassicWindowTheme.h>
+#include <LibGfx/Font.h>
+#include <LibGfx/Painter.h>
+#include <LibGfx/Palette.h>
+#include <LibGfx/StylePainter.h>
+
+namespace Gfx {
+
+ClassicWindowTheme::ClassicWindowTheme()
+{
+}
+
+ClassicWindowTheme::~ClassicWindowTheme()
+{
+}
+
+Gfx::IntRect ClassicWindowTheme::title_bar_icon_rect(WindowType window_type, const IntRect& window_rect, const Palette& palette) const
+{
+    auto titlebar_rect = title_bar_rect(window_type, window_rect, palette);
+    Gfx::IntRect icon_rect {
+        titlebar_rect.x() + 2,
+        titlebar_rect.y(),
+        16,
+        16,
+    };
+    icon_rect.center_vertically_within(titlebar_rect);
+    icon_rect.move_by(0, 1);
+    return icon_rect;
+}
+
+Gfx::IntRect ClassicWindowTheme::title_bar_text_rect(WindowType window_type, const IntRect& window_rect, const Palette& palette) const
+{
+    auto titlebar_rect = title_bar_rect(window_type, window_rect, palette);
+    auto titlebar_icon_rect = title_bar_icon_rect(window_type, window_rect, palette);
+    return {
+        titlebar_rect.x() + 3 + titlebar_icon_rect.width() + 2,
+        titlebar_rect.y(),
+        titlebar_rect.width() - 5 - titlebar_icon_rect.width() - 2,
+        titlebar_rect.height()
+    };
+}
+
+void ClassicWindowTheme::paint_normal_frame(Painter& painter, WindowState window_state, const IntRect& outer_rect, const IntRect& window_rect, const StringView& title_text, const Bitmap& icon, const Palette& palette, const IntRect& leftmost_button_rect) const
+{
+    Gfx::StylePainter::paint_window_frame(painter, outer_rect, palette);
+
+    auto& title_font = Font::default_bold_font();
+
+    auto titlebar_rect = title_bar_rect(WindowType::Normal, window_rect, palette);
+    auto titlebar_icon_rect = title_bar_icon_rect(WindowType::Normal, window_rect, palette);
+    auto titlebar_inner_rect = title_bar_text_rect(WindowType::Normal, window_rect, palette);
+    auto titlebar_title_rect = titlebar_inner_rect;
+    titlebar_title_rect.set_width(Font::default_bold_font().width(title_text));
+
+    auto [title_color, border_color, border_color2, stripes_color, shadow_color] = compute_frame_colors(window_state, palette);
+
+    painter.draw_line(titlebar_rect.bottom_left().translated(0, 1), titlebar_rect.bottom_right().translated(0, 1), palette.button());
+    painter.draw_line(titlebar_rect.bottom_left().translated(0, 2), titlebar_rect.bottom_right().translated(0, 2), palette.button());
+
+    painter.fill_rect_with_gradient(titlebar_rect, border_color, border_color2);
+
+    int stripe_left = titlebar_title_rect.right() + 4;
+    int stripe_right = leftmost_button_rect.left() - 3;
+    if (stripe_left && stripe_right && stripe_left < stripe_right) {
+        for (int i = 2; i <= titlebar_inner_rect.height() - 2; i += 2) {
+            painter.draw_line({ stripe_left, titlebar_inner_rect.y() + i }, { stripe_right, titlebar_inner_rect.y() + i }, stripes_color);
+        }
+    }
+
+    auto clipped_title_rect = titlebar_title_rect;
+    clipped_title_rect.set_width(stripe_right - clipped_title_rect.x());
+    if (!clipped_title_rect.is_empty()) {
+        painter.draw_text(clipped_title_rect.translated(1, 2), title_text, title_font, Gfx::TextAlignment::CenterLeft, shadow_color, Gfx::TextElision::Right);
+        // FIXME: The translated(0, 1) wouldn't be necessary if we could center text based on its baseline.
+        painter.draw_text(clipped_title_rect.translated(0, 1), title_text, title_font, Gfx::TextAlignment::CenterLeft, title_color, Gfx::TextElision::Right);
+    }
+
+    painter.blit(titlebar_icon_rect.location(), icon, icon.rect());
+}
+
+IntRect ClassicWindowTheme::title_bar_rect(WindowType window_type, const IntRect& window_rect, const Palette& palette) const
+{
+    auto& title_font = Font::default_bold_font();
+    auto window_titlebar_height = palette.window_title_height();
+    int total_vertical_padding = window_titlebar_height - title_font.glyph_height();
+
+    if (window_type == WindowType::Notification)
+        return { window_rect.width() + 3, total_vertical_padding / 2 - 1, window_titlebar_height, window_rect.height() };
+    return { 4, total_vertical_padding / 2, window_rect.width(), window_titlebar_height };
+}
+
+ClassicWindowTheme::FrameColors ClassicWindowTheme::compute_frame_colors(WindowState state, const Palette& palette) const
+{
+    switch (state) {
+    case WindowState::Highlighted:
+        return { palette.highlight_window_title(), palette.highlight_window_border1(), palette.highlight_window_border2(), palette.highlight_window_title_stripes(), palette.highlight_window_title_shadow() };
+    case WindowState::Moving:
+        return { palette.moving_window_title(), palette.moving_window_border1(), palette.moving_window_border2(), palette.moving_window_title_stripes(), palette.moving_window_title_shadow() };
+    case WindowState::Active:
+        return { palette.active_window_title(), palette.active_window_border1(), palette.active_window_border2(), palette.active_window_title_stripes(), palette.active_window_title_shadow() };
+    case WindowState::Inactive:
+        return { palette.inactive_window_title(), palette.inactive_window_border1(), palette.inactive_window_border2(), palette.inactive_window_title_stripes(), palette.inactive_window_title_shadow() };
+    default:
+        ASSERT_NOT_REACHED();
+    }
+}
+
+void ClassicWindowTheme::paint_notification_frame(Painter&, const IntRect&, const Palette&) const
+{
+}
+
+}
diff --git a/Libraries/LibGfx/ClassicWindowTheme.h b/Libraries/LibGfx/ClassicWindowTheme.h
new file mode 100644
index 0000000000..f425bcfcac
--- /dev/null
+++ b/Libraries/LibGfx/ClassicWindowTheme.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <LibGfx/WindowTheme.h>
+#include <LibGfx/Color.h>
+
+namespace Gfx {
+
+class ClassicWindowTheme final : public WindowTheme {
+public:
+    ClassicWindowTheme();
+    virtual ~ClassicWindowTheme() override;
+
+    virtual void paint_normal_frame(Painter&, WindowState, const IntRect& outer_rect, const IntRect& window_rect, const StringView& title, const Bitmap& icon, const Palette&, const IntRect& leftmost_button_rect) const override;
+    virtual void paint_notification_frame(Painter&, const IntRect&, const Palette&) const override;
+
+    virtual IntRect title_bar_rect(WindowType, const IntRect& window_rect, const Palette&) const override;
+    virtual IntRect title_bar_icon_rect(WindowType, const IntRect& window_rect, const Palette&) const override;
+    virtual IntRect title_bar_text_rect(WindowType, const IntRect& window_rect, const Palette&) const override;
+
+private:
+    struct FrameColors {
+        Color title_color;
+        Color border_color;
+        Color border_color2;
+        Color title_stripes_color;
+        Color title_shadow_color;
+    };
+
+    FrameColors compute_frame_colors(WindowState, const Palette&) const;
+};
+
+}