ThemeEditor: Implement a way to simulate color blindness in preview

Implement a mechanism that allows us to alter colors so that they
mimic those a colorblind person would see. From the color we can then
alter the colors for the whole preview so we can simulate everything
in the theme including icons/decorations.

This filter is also available as a Filter in LibGfx so it can be
reused in multiple other places.

The color simulation algorithm is based on this one
https://github.com/MaPePeR/jsColorblindSimulator publicly available.

Userland/Libraries/LibGfx/CMakeLists.txt

@@ -13,6 +13,7 @@ set(SOURCES
     DDSLoader.cpp
     DisjointRectSet.cpp
     Emoji.cpp
+    Filters/ColorBlindnessFilter.cpp
     Filters/FastBoxBlurFilter.cpp
     FontDatabase.cpp
     GIFLoader.cpp

Userland/Libraries/LibGfx/Filters/ColorBlindnessFilter.cpp

@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2021, Antonio Di Stefano <tonio9681@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "ColorBlindnessFilter.h"
+
+namespace Gfx {
+
+NonnullOwnPtr<ColorBlindnessFilter> ColorBlindnessFilter::create_protanopia()
+{
+    return make<ColorBlindnessFilter>(
+        .56, .44, .0,
+        .55, .45, .0,
+        .0, .24, .76);
+}
+
+NonnullOwnPtr<ColorBlindnessFilter> ColorBlindnessFilter::create_protanomaly()
+{
+    return make<ColorBlindnessFilter>(
+        .82, .18, .0,
+        .33, .67, .0,
+        .0, .13, .87);
+}
+
+NonnullOwnPtr<ColorBlindnessFilter> ColorBlindnessFilter::create_deuteranopia()
+{
+    return make<ColorBlindnessFilter>(
+        .63, .37, .0,
+        .7, .3, .0,
+        .0, .3, .7);
+}
+
+NonnullOwnPtr<ColorBlindnessFilter> ColorBlindnessFilter::create_deuteranomaly()
+{
+    return make<ColorBlindnessFilter>(
+        .8, .2, .0,
+        .26, .74, .0,
+        .0, .15, .85);
+}
+
+NonnullOwnPtr<ColorBlindnessFilter> ColorBlindnessFilter::create_tritanopia()
+{
+    return make<ColorBlindnessFilter>(
+        .95, .05, .0,
+        .0, .44, .56,
+        .0, .48, .52);
+}
+
+NonnullOwnPtr<ColorBlindnessFilter> ColorBlindnessFilter::create_tritanomaly()
+{
+    return make<ColorBlindnessFilter>(
+        .97, .03, .0,
+        .0, .73, .27,
+        .0, .18, .82);
+}
+
+NonnullOwnPtr<ColorBlindnessFilter> ColorBlindnessFilter::create_achromatopsia()
+{
+    return make<ColorBlindnessFilter>(
+        .3, .59, .11,
+        .3, .59, .11,
+        .3, .59, .11);
+}
+
+NonnullOwnPtr<ColorBlindnessFilter> ColorBlindnessFilter::create_achromatomaly()
+{
+    return make<ColorBlindnessFilter>(
+        .62, .32, .06,
+        .16, .78, .06,
+        .16, .32, .52);
+}
+
+Color ColorBlindnessFilter::convert_color(Color original)
+{
+    return Color(
+        (u8)(original.red() * m_red_in_red_band + original.green() * m_green_in_red_band + original.blue() * m_blue_in_red_band),
+        (u8)(original.red() * m_red_in_green_band + original.green() * m_green_in_green_band + original.blue() * m_blue_in_green_band),
+        (u8)(original.red() * m_red_in_blue_band + original.green() * m_green_in_blue_band + original.blue() * m_blue_in_blue_band),
+        original.alpha());
+};
+
+}

Userland/Libraries/LibGfx/Filters/ColorBlindnessFilter.h

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2021, Antonio Di Stefano <tonio9681@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include "ColorFilter.h"
+#include <AK/NonnullOwnPtr.h>
+
+namespace Gfx {
+class ColorBlindnessFilter : public ColorFilter {
+public:
+    ColorBlindnessFilter(
+        double red_in_red_band,
+        double green_in_red_band,
+        double blue_in_red_band,
+        double red_in_green_band,
+        double green_in_green_band,
+        double blue_in_green_band,
+        double red_in_blue_band,
+        double green_in_blue_band,
+        double blue_in_blue_band)
+        : m_red_in_red_band(red_in_red_band)
+        , m_green_in_red_band(green_in_red_band)
+        , m_blue_in_red_band(blue_in_red_band)
+        , m_red_in_green_band(red_in_green_band)
+        , m_green_in_green_band(green_in_green_band)
+        , m_blue_in_green_band(blue_in_green_band)
+        , m_red_in_blue_band(red_in_blue_band)
+        , m_green_in_blue_band(green_in_blue_band)
+        , m_blue_in_blue_band(blue_in_blue_band)
+    {
+    }
+
+    virtual ~ColorBlindnessFilter() = default;
+    virtual char const* class_name() const override { return "ColorBlindnessFilter"; }
+
+    static NonnullOwnPtr<ColorBlindnessFilter> create_protanopia();
+    static NonnullOwnPtr<ColorBlindnessFilter> create_protanomaly();
+    static NonnullOwnPtr<ColorBlindnessFilter> create_deuteranopia();
+    static NonnullOwnPtr<ColorBlindnessFilter> create_deuteranomaly();
+    static NonnullOwnPtr<ColorBlindnessFilter> create_tritanopia();
+    static NonnullOwnPtr<ColorBlindnessFilter> create_tritanomaly();
+    static NonnullOwnPtr<ColorBlindnessFilter> create_achromatopsia();
+    static NonnullOwnPtr<ColorBlindnessFilter> create_achromatomaly();
+
+protected:
+    Color convert_color(Color original) override;
+
+private:
+    double m_red_in_red_band;
+    double m_green_in_red_band;
+    double m_blue_in_red_band;
+    double m_red_in_green_band;
+    double m_green_in_green_band;
+    double m_blue_in_green_band;
+    double m_red_in_blue_band;
+    double m_green_in_blue_band;
+    double m_blue_in_blue_band;
+};
+}

Userland/Libraries/LibGfx/Filters/ColorFilter.h

@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2021, Antonio Di Stefano <tonio9681@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include "Filter.h"
+
+namespace Gfx {
+
+class ColorFilter : public Filter {
+public:
+    virtual ~ColorFilter() = default;
+
+    virtual void apply(Bitmap& target_bitmap, IntRect const& target_rect, Bitmap const& source_bitmap, IntRect const& source_rect) override
+    {
+        VERIFY(source_rect.size() == target_rect.size());
+        VERIFY(target_bitmap.rect().contains(target_rect));
+        VERIFY(source_bitmap.rect().contains(source_rect));
+
+        for (auto y = 0; y < source_rect.height(); ++y) {
+            ssize_t source_y = y + source_rect.y();
+            ssize_t target_y = y + target_rect.y();
+            for (auto x = 0; x < source_rect.width(); ++x) {
+                ssize_t source_x = x + source_rect.x();
+                ssize_t target_x = x + target_rect.x();
+
+                auto source_pixel = source_bitmap.get_pixel(source_x, source_y);
+                auto target_color = convert_color(source_pixel);
+
+                target_bitmap.set_pixel(target_x, target_y, target_color);
+            }
+        }
+    }
+
+protected:
+    ColorFilter() = default;
+
+    virtual Color convert_color(Color) = 0;
+};
+
+}