PixelPaint: Add loading and saving of color palettes

Color palettes can now be stored in and read from files. The default
palette will be read from `/res/color-palettes/default.palette`
instead of being hard-coded in PaletteWidget.

The file format is one color per line, in any format that can be
understood by `Gfx::Color::from_string`.

5 files changed, 214 insertions, 42 deletions

diff --git a/Base/res/color-palettes/default.palette b/Base/res/color-palettes/default.palette
new file mode 100644
index 0000000000..21598d9763
--- /dev/null
+++ b/Base/res/color-palettes/default.palette
@@ -0,0 +1,28 @@
+#000000
+#808080
+#800000
+#808000
+#008000
+#008080
+#000080
+#800080
+#808040
+#004040
+#0080ff
+#004080
+#8000ff
+#804000
+#ffffff
+#c0c0c0
+#ff0000
+#ffff00
+#00ff00
+#00ffff
+#0000ff
+#ff00ff
+#ffff80
+#00ff80
+#80ffff
+#8080ff
+#ff0080
+#ff8040
diff --git a/Base/res/color-palettes/greyscale.palette b/Base/res/color-palettes/greyscale.palette
new file mode 100644
index 0000000000..13730ad3b3
--- /dev/null
+++ b/Base/res/color-palettes/greyscale.palette
@@ -0,0 +1,16 @@
+#000000
+#111111
+#222222
+#333333
+#444444
+#555555
+#666666
+#777777
+#888888
+#999999
+#aaaaaa
+#bbbbbb
+#cccccc
+#dddddd
+#eeeeee
+#ffffff
diff --git a/Userland/Applications/PixelPaint/PaletteWidget.cpp b/Userland/Applications/PixelPaint/PaletteWidget.cpp
index 794a0c2298..3ecfa084c4 100644
--- a/Userland/Applications/PixelPaint/PaletteWidget.cpp
+++ b/Userland/Applications/PixelPaint/PaletteWidget.cpp
@@ -1,13 +1,18 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Felix Rauch <noreply@felixrau.ch>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #include "PaletteWidget.h"
 #include "ImageEditor.h"
+#include <AK/Result.h>
+#include <AK/Vector.h>
+#include <LibCore/File.h>
 #include <LibGUI/BoxLayout.h>
 #include <LibGUI/ColorPicker.h>
+#include <LibGUI/MessageBox.h>
 #include <LibGfx/Palette.h>
 
 REGISTER_WIDGET(PixelPaint, PaletteWidget);
@@ -29,6 +34,8 @@ public:
     {
     }
 
+    virtual Color color() { return m_color; }
+
     virtual void mousedown_event(GUI::MouseEvent& event) override
     {
         if (event.modifiers() & KeyModifier::Mod_Ctrl && event.button() == GUI::MouseButton::Left) {
@@ -73,56 +80,30 @@ PaletteWidget::PaletteWidget()
     m_primary_color_widget->set_relative_rect(rect);
     m_primary_color_widget->set_fill_with_background_color(true);
 
-    auto& color_container = add<GUI::Widget>();
-    color_container.set_relative_rect(m_secondary_color_widget->relative_rect().right() + 2, 2, 500, 32);
-    color_container.set_layout<GUI::VerticalBoxLayout>();
-    color_container.layout()->set_spacing(1);
+    m_color_container = add<GUI::Widget>();
+    m_color_container->set_relative_rect(m_secondary_color_widget->relative_rect().right() + 2, 2, 500, 32);
+    m_color_container->set_layout<GUI::VerticalBoxLayout>();
+    m_color_container->layout()->set_spacing(1);
 
-    auto& top_color_container = color_container.add<GUI::Widget>();
+    auto& top_color_container = m_color_container->add<GUI::Widget>();
+    top_color_container.set_name("top_color_container");
     top_color_container.set_layout<GUI::HorizontalBoxLayout>();
     top_color_container.layout()->set_spacing(1);
 
-    auto& bottom_color_container = color_container.add<GUI::Widget>();
+    auto& bottom_color_container = m_color_container->add<GUI::Widget>();
+    bottom_color_container.set_name("bottom_color_container");
     bottom_color_container.set_layout<GUI::HorizontalBoxLayout>();
     bottom_color_container.layout()->set_spacing(1);
 
-    auto add_color_widget = [&](GUI::Widget& container, Color color) {
-        auto& color_widget = container.add<ColorWidget>(color, *this);
-        color_widget.set_fill_with_background_color(true);
-        auto pal = color_widget.palette();
-        pal.set_color(ColorRole::Background, color);
-        color_widget.set_palette(pal);
-    };
+    auto result = load_palette_file("/res/color-palettes/default.palette");
+    if (result.is_error()) {
+        GUI::MessageBox::show_error(window(), String::formatted("Loading default palette failed: {}", result.error()));
+        display_color_list(fallback_colors());
 
-    add_color_widget(top_color_container, Color::from_rgb(0x000000));
-    add_color_widget(top_color_container, Color::from_rgb(0x808080));
-    add_color_widget(top_color_container, Color::from_rgb(0x800000));
-    add_color_widget(top_color_container, Color::from_rgb(0x808000));
-    add_color_widget(top_color_container, Color::from_rgb(0x008000));
-    add_color_widget(top_color_container, Color::from_rgb(0x008080));
-    add_color_widget(top_color_container, Color::from_rgb(0x000080));
-    add_color_widget(top_color_container, Color::from_rgb(0x800080));
-    add_color_widget(top_color_container, Color::from_rgb(0x808040));
-    add_color_widget(top_color_container, Color::from_rgb(0x004040));
-    add_color_widget(top_color_container, Color::from_rgb(0x0080ff));
-    add_color_widget(top_color_container, Color::from_rgb(0x004080));
-    add_color_widget(top_color_container, Color::from_rgb(0x8000ff));
-    add_color_widget(top_color_container, Color::from_rgb(0x804000));
-
-    add_color_widget(bottom_color_container, Color::from_rgb(0xffffff));
-    add_color_widget(bottom_color_container, Color::from_rgb(0xc0c0c0));
-    add_color_widget(bottom_color_container, Color::from_rgb(0xff0000));
-    add_color_widget(bottom_color_container, Color::from_rgb(0xffff00));
-    add_color_widget(bottom_color_container, Color::from_rgb(0x00ff00));
-    add_color_widget(bottom_color_container, Color::from_rgb(0x00ffff));
-    add_color_widget(bottom_color_container, Color::from_rgb(0x0000ff));
-    add_color_widget(bottom_color_container, Color::from_rgb(0xff00ff));
-    add_color_widget(bottom_color_container, Color::from_rgb(0xffff80));
-    add_color_widget(bottom_color_container, Color::from_rgb(0x00ff80));
-    add_color_widget(bottom_color_container, Color::from_rgb(0x80ffff));
-    add_color_widget(bottom_color_container, Color::from_rgb(0x8080ff));
-    add_color_widget(bottom_color_container, Color::from_rgb(0xff0080));
-    add_color_widget(bottom_color_container, Color::from_rgb(0xff8040));
+        return;
+    }
+
+    display_color_list(result.value());
 }
 
 void PaletteWidget::set_image_editor(ImageEditor& editor)
@@ -162,4 +143,113 @@ void PaletteWidget::set_secondary_color(Color color)
     m_secondary_color_widget->update();
 }
 
+void PaletteWidget::display_color_list(Vector<Color> const& colors)
+{
+    int colors_to_add = colors.size();
+    if (colors_to_add == 0) {
+        dbgln("Empty color list given. Using fallback colors.");
+        display_color_list(fallback_colors());
+        return;
+    }
+
+    auto& top_color_container = *m_color_container->find_descendant_of_type_named<GUI::Widget>("top_color_container");
+    top_color_container.remove_all_children();
+
+    auto& bottom_color_container = *m_color_container->find_descendant_of_type_named<GUI::Widget>("bottom_color_container");
+    bottom_color_container.remove_all_children();
+
+    auto add_color_widget = [&](GUI::Widget& container, Color color) {
+        auto& color_widget = container.add<ColorWidget>(color, *this);
+        color_widget.set_fill_with_background_color(true);
+        auto pal = color_widget.palette();
+        pal.set_color(ColorRole::Background, color);
+        color_widget.set_palette(pal);
+    };
+
+    int colors_per_row = ceil(colors_to_add / 2);
+    int number_of_added_colors = 0;
+    for (auto& color : colors) {
+        if (number_of_added_colors < colors_per_row)
+            add_color_widget(top_color_container, color);
+        else
+            add_color_widget(bottom_color_container, color);
+
+        ++number_of_added_colors;
+    }
+}
+
+Vector<Color> PaletteWidget::colors()
+{
+    Vector<Color> colors;
+
+    for (auto& color_container : m_color_container->child_widgets()) {
+        color_container.for_each_child_of_type<ColorWidget>([&](auto& color_widget) {
+            colors.append(color_widget.color());
+            return IterationDecision::Continue;
+        });
+    }
+
+    return colors;
+}
+
+Result<Vector<Color>, String> PaletteWidget::load_palette_file(String const& file_path)
+{
+    auto file_or_error = Core::File::open(file_path, Core::OpenMode::ReadOnly);
+    if (file_or_error.is_error())
+        return file_or_error.error();
+
+    auto& file = *file_or_error.value();
+
+    Vector<Color> palette;
+
+    while (file.can_read_line()) {
+        auto line = file.read_line();
+        if (line.is_whitespace())
+            continue;
+
+        auto color = Color::from_string(line);
+        if (!color.has_value()) {
+            dbgln("Could not parse \"{}\" as a color", line);
+            continue;
+        }
+
+        palette.append(color.value());
+    }
+
+    file.close();
+
+    if (palette.is_empty())
+        return String { "The palette file did not contain any usable colors"sv };
+
+    return palette;
+}
+
+Result<void, String> PaletteWidget::save_palette_file(Vector<Color> palette, String const& file_path)
+{
+    auto file_or_error = Core::File::open(file_path, Core::OpenMode::WriteOnly);
+    if (file_or_error.is_error())
+        return file_or_error.error();
+
+    auto& file = *file_or_error.value();
+
+    for (auto& color : palette) {
+        file.write(color.to_string_without_alpha());
+        file.write("\n");
+    }
+
+    file.close();
+
+    return {};
+}
+
+Vector<Color> PaletteWidget::fallback_colors()
+{
+    Vector<Color> fallback_colors;
+
+    fallback_colors.append(Color::from_rgb(0x000000));
+    fallback_colors.append(Color::from_rgb(0xffffff));
+
+    return fallback_colors;
+}
+
 }
diff --git a/Userland/Applications/PixelPaint/PaletteWidget.h b/Userland/Applications/PixelPaint/PaletteWidget.h
index 2a52627577..022909e54e 100644
--- a/Userland/Applications/PixelPaint/PaletteWidget.h
+++ b/Userland/Applications/PixelPaint/PaletteWidget.h
@@ -1,11 +1,14 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Felix Rauch <noreply@felixrau.ch>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #pragma once
 
+#include <AK/Result.h>
+#include <AK/Vector.h>
 #include <LibGUI/Frame.h>
 
 namespace PixelPaint {
@@ -21,6 +24,14 @@ public:
     void set_primary_color(Color);
     void set_secondary_color(Color);
 
+    void display_color_list(Vector<Color> const&);
+
+    Vector<Color> colors();
+
+    static Result<Vector<Color>, String> load_palette_file(String const&);
+    static Result<void, String> save_palette_file(Vector<Color>, String const&);
+    static Vector<Color> fallback_colors();
+
     void set_image_editor(ImageEditor&);
 
 private:
@@ -29,6 +40,7 @@ private:
     ImageEditor* m_editor { nullptr };
     RefPtr<GUI::Frame> m_primary_color_widget;
     RefPtr<GUI::Frame> m_secondary_color_widget;
+    RefPtr<GUI::Widget> m_color_container;
 };
 
 }
diff --git a/Userland/Applications/PixelPaint/main.cpp b/Userland/Applications/PixelPaint/main.cpp
index 6aa591ad2d..76d413fa42 100644
--- a/Userland/Applications/PixelPaint/main.cpp
+++ b/Userland/Applications/PixelPaint/main.cpp
@@ -265,6 +265,32 @@ int main(int argc, char** argv)
             }
         },
         window));
+    edit_menu.add_action(GUI::Action::create(
+        "&Load Color Palette", [&](auto&) {
+            auto open_path = GUI::FilePicker::get_open_filepath(window, "Load Color Palette");
+            if (!open_path.has_value())
+                return;
+
+            auto result = PixelPaint::PaletteWidget::load_palette_file(open_path.value());
+            if (result.is_error()) {
+                GUI::MessageBox::show_error(window, String::formatted("Loading color palette failed: {}", result.error()));
+                return;
+            }
+
+            palette_widget.display_color_list(result.value());
+        },
+        window));
+    edit_menu.add_action(GUI::Action::create(
+        "Sa&ve Color Palette", [&](auto&) {
+            auto save_path = GUI::FilePicker::get_save_filepath(window, "untitled", "palette");
+            if (!save_path.has_value())
+                return;
+
+            auto result = PixelPaint::PaletteWidget::save_palette_file(palette_widget.colors(), save_path.value());
+            if (result.is_error())
+                GUI::MessageBox::show_error(window, String::formatted("Writing color palette failed: {}", result.error()));
+        },
+        window));
 
     auto& view_menu = menubar->add_menu("&View");