Add support for setting a tab's color at runtime w/ context menu

.github/actions/spell-check/dictionary/apis.txt

@@ -7,4 +7,5 @@ NCLBUTTONDBLCLK
 NCRBUTTONDBLCLK
 NOREDIRECTIONBITMAP
 rfind
+roundf
 SIZENS

.github/actions/spell-check/patterns/patterns.txt

@@ -1,5 +1,6 @@
 https://(?:(?:[-a-zA-Z0-9?&=]*\.|)microsoft\.com)/[-a-zA-Z0-9?&=_\/.]*
 https://aka\.ms/[-a-zA-Z0-9?&=\/_]*
+http://www.w3.org/[-a-zA-Z0-9?&=\/_]*
 https://(?:(?:www\.|)youtube\.com|youtu.be)/[-a-zA-Z0-9?&=]*
 (?:0[Xx]|U\+|#)[a-f0-9A-FGgRr]{2,}[Uu]?[Ll]?\b
 \{[0-9A-FA-F]{8}-(?:[0-9A-FA-F]{4}-){3}[0-9A-FA-F]{12}\}

.github/actions/spell-check/whitelist/web.txt

@@ -2,3 +2,4 @@ http
 td
 www
 ecma
+rapidtables

src/cascadia/LocalTests_TerminalApp/TabTests.cpp

@@ -17,6 +17,7 @@ using namespace winrt::TerminalApp;
 using namespace WEX::Logging;
 using namespace WEX::TestExecution;
 using namespace WEX::Common;
+using namespace winrt::Windows::ApplicationModel::DataTransfer;
 
 namespace TerminalAppLocalTests
 {

src/cascadia/LocalTests_TerminalApp/pch.h

@@ -39,6 +39,8 @@ Author(s):
 #include "../../types/inc/utils.hpp"
 #include "../../inc/DefaultSettings.h"
 
+#include <winrt/Windows.ApplicationModel.Resources.Core.h>
+#include "winrt/Windows.UI.Xaml.Markup.h"
 #include <winrt/Windows.system.h>
 #include <winrt/Windows.Foundation.h>
 #include <winrt/Windows.Foundation.Collections.h>

src/cascadia/TerminalApp/ColorHelper.cpp

@@ -0,0 +1,269 @@
+#include "pch.h"
+#include "ColorHelper.h"
+#include <limits>
+
+using namespace winrt::TerminalApp;
+
+// Method Description:
+// Determines whether or not a given color is light
+// Arguments:
+// - color: this color is going to be examined whether it
+// is light or not
+// Return Value:
+// - true of light, false if dark
+bool ColorHelper::IsBrightColor(const winrt::Windows::UI::Color& color)
+{
+    // http://www.w3.org/TR/AERT#color-contrast
+    auto brightness = (color.R * 299 + color.G * 587 + color.B * 114) / 1000.f;
+    return brightness > 128.f;
+}
+
+// Method Description:
+// Converts a rgb color to an hsl one
+// Arguments:
+// - color: the rgb color, which is going to be converted
+// Return Value:
+// - a hsl color with the following ranges
+//      - H: [0.f -360.f]
+//      - L: [0.f - 1.f] (rounded to the third decimal place)
+//      - S: [0.f - 1.f] (rounded to the third decimal place)
+HSL ColorHelper::RgbToHsl(const winrt::Windows::UI::Color& color)
+{
+    // https://www.rapidtables.com/convert/color/rgb-to-hsl.html
+    auto epsilon = std::numeric_limits<float>::epsilon();
+    auto r = color.R / 255.f;
+    auto g = color.G / 255.f;
+    auto b = color.B / 255.f;
+
+    auto max = std::max(r, std::max(g, b));
+    auto min = std::min(r, std::min(g, b));
+
+    auto delta = max - min;
+
+    auto h = 0.f;
+    auto s = 0.f;
+    auto l = (max + min) / 2;
+
+    if (delta < epsilon || max < epsilon) /* delta == 0 || max == 0*/
+    {
+        l = std::roundf(l * 1000) / 1000;
+        return HSL{ h, s, l };
+    }
+
+    s = l > 0.5 ? delta / (2 - max - min) : delta / (max + min);
+
+    if (max - r < epsilon) // max == r
+    {
+        h = (g - b) / delta + (g < b ? 6 : 0);
+    }
+    else if (max - g < epsilon) // max == g
+    {
+        h = (b - r) / delta + 2;
+    }
+    else if (max - b < epsilon) // max == b
+    {
+        h = (r - g) / delta + 4;
+    }
+
+    // three decimal places after the comma ought
+    // to be enough for everybody - Bill Gates, 1981
+    float finalH = std::roundf(h * 60);
+    float finalS = std::roundf(s * 1000) / 1000;
+    float finalL = std::roundf(l * 1000) / 1000;
+
+    return HSL{ finalH, finalS, finalL };
+}
+
+// Method Description:
+// Converts a hsl color to rgb one
+// Arguments:
+// - color: the hsl color, which is going to be converted
+// Return Value:
+// - the rgb color (r,g,b - [0, 255] range)
+winrt::Windows::UI::Color ColorHelper::HslToRgb(const HSL& color)
+{
+    auto epsilon = std::numeric_limits<float>::epsilon();
+
+    auto h = (color.H - 1.f > epsilon) ? color.H / 360.f : color.H;
+    auto s = (color.S - 1.f > epsilon) ? color.S / 100.f : color.S;
+    auto l = (color.L - 1.f > epsilon) ? color.L / 100.f : color.L;
+
+    auto r = l;
+    auto g = l;
+    auto b = l;
+
+    if (s > epsilon)
+    {
+        auto q = l < 0.5 ? l * (1 + s) : l + s - l * s;
+        auto p = 2 * l - q;
+        r = HueToRgb(p, q, h + 1.f / 3.f);
+        g = HueToRgb(p, q, h);
+        b = HueToRgb(p, q, h - 1.f / 3.f);
+    }
+
+    auto finalR = static_cast<uint8_t>(std::roundf(r * 255));
+    auto finalG = static_cast<uint8_t>(std::roundf(g * 255));
+    auto finalB = static_cast<uint8_t>(std::roundf(b * 255));
+    uint8_t finalA = 255; //opaque
+
+    return winrt::Windows::UI::ColorHelper::FromArgb(finalA, finalR, finalG, finalB);
+}
+
+float ColorHelper::HueToRgb(float p, float q, float t)
+{
+    auto epsilon = std::numeric_limits<float>::epsilon();
+
+    if (t < 0)
+        t += 1;
+    if (t > 1)
+        t -= 1;
+    if (t - (1.f / 6.f) < epsilon)
+        return p + (q - p) * 6 * t;
+    if (t - .5f < epsilon)
+        return q;
+    if (t - 2.f / 3.f < epsilon)
+        return p + (q - p) * (2.f / 3.f - t) * 6;
+    return p;
+}
+
+// Method Description:
+// Lightens a color by a given amount
+// Arguments:
+// - color: the color which is going to be lightened
+// - amount: the lighten amount (0-100)
+// Return Value:
+// - the lightened color in RGB format
+winrt::Windows::UI::Color ColorHelper::Lighten(const winrt::Windows::UI::Color& color, float amount /* = 10.f*/)
+{
+    auto hsl = RgbToHsl(color);
+    hsl.L += amount / 100;
+    hsl.L = std::clamp(hsl.L, 0.f, 1.f);
+    return HslToRgb(hsl);
+}
+
+// Method Description:
+// Darkens a color by a given amount
+// Arguments:
+// - color: the color which is going to be darkened
+// - amount: the darken amount (0-100)
+// Return Value:
+// - the darkened color in RGB format
+winrt::Windows::UI::Color ColorHelper::Darken(const winrt::Windows::UI::Color& color, float amount /* = 10.f*/)
+{
+    auto hsl = RgbToHsl(color);
+    hsl.L -= amount / 100;
+    hsl.L = std::clamp(hsl.L, 0.f, 1.f);
+    return HslToRgb(hsl);
+}
+
+// Method Description:
+// Gets an accent color to a given color. Basically, generates
+// 16 shades of the color and finds the first which has a good
+// contrast according to http://www.w3.org/TR/2008/REC-WCAG20-20081211/#contrast-ratiodef (WCAG Version 2)
+// Readability ratio of 3.5 seems to look quite nicely
+// Arguments:
+// - color: the color for which we need an accent
+// Return Value:
+// - the accent color in RGB format
+winrt::Windows::UI::Color ColorHelper::GetAccentColor(const winrt::Windows::UI::Color& color)
+{
+    auto accentColor = RgbToHsl(color);
+
+    if (accentColor.S < 0.15)
+    {
+        accentColor.S = 0.15f;
+    }
+
+    constexpr auto shadeCount = 16;
+    constexpr auto shadeStep = 1.f / shadeCount;
+    auto shades = std::map<float, HSL>();
+    for (auto i = 0; i < 15; i++)
+    {
+        auto shade = HSL{ accentColor.H, accentColor.S, i * shadeStep };
+        auto contrast = GetReadability(shade, accentColor);
+        shades.insert(std::make_pair(contrast, shade));
+    }
+
+    // 3f is quite nice if the whole non-client area is painted
+    constexpr auto readability = 1.75f;
+    for (auto shade : shades)
+    {
+        if (shade.first >= readability)
+        {
+            return HslToRgb(shade.second);
+        }
+    }
+    return HslToRgb(shades.end()->second);
+}
+
+// Method Description:
+// Gets the readability of two colors according to
+// http://www.w3.org/TR/2008/REC-WCAG20-20081211/#contrast-ratiodef (WCAG Version 2)
+// Arguments:
+// - firstColor: the first color for the readability check (hsl)
+// - secondColor: the second color for the readability check (hsl)
+// Return Value:
+// - the readability of the colors according to (WCAG Version 2)
+float ColorHelper::GetReadability(const HSL& first, const HSL& second)
+{
+    return GetReadability(HslToRgb(first), HslToRgb(second));
+}
+
+// Method Description:
+// Gets the readability of two colors according to
+// http://www.w3.org/TR/2008/REC-WCAG20-20081211/#contrast-ratiodef (WCAG Version 2)
+// Arguments:
+// - firstColor: the first color for the readability check (rgb)
+// - secondColor: the second color for the readability check (rgb)
+// Return Value:
+// - the readability of the colors according to (WCAG Version 2)
+float ColorHelper::GetReadability(const winrt::Windows::UI::Color& first, const winrt::Windows::UI::Color& second)
+{
+    auto l1 = GetLuminance(first);
+    auto l2 = GetLuminance(second);
+
+    return (std::max(l1, l2) + 0.05f) / std::min(l1, l2) + 0.05f;
+}
+
+// Method Description:
+// Calculates the luminance of a given color according to
+// http://www.w3.org/TR/2008/REC-WCAG20-20081211/#relativeluminancedef
+// Arguments:
+// - color: its luminance is going to be calculated
+// Return Value:
+// - the luminance of the color
+float ColorHelper::GetLuminance(const winrt::Windows::UI::Color& color)
+{
+    auto epsilon = std::numeric_limits<float>::epsilon();
+    float R, G, B;
+    auto RsRGB = color.R / 255.f;
+    auto GsRGB = color.G / 255.f;
+    auto BsRGB = color.B / 255.f;
+
+    if (RsRGB - 0.03928f <= epsilon)
+    {
+        R = RsRGB / 12.92f;
+    }
+    else
+    {
+        R = std::pow(((RsRGB + 0.055f) / 1.055f), 2.4f);
+    }
+    if (GsRGB - 0.03928f <= epsilon)
+    {
+        G = GsRGB / 12.92f;
+    }
+    else
+    {
+        G = std::pow(((GsRGB + 0.055f) / 1.055f), 2.4f);
+    }
+    if (BsRGB - 0.03928f <= epsilon)
+    {
+        B = BsRGB / 12.92f;
+    }
+    else
+    {
+        B = std::pow(((BsRGB + 0.055f) / 1.055f), 2.4f);
+    }
+    float luminance = (0.2126f * R) + (0.7152f * G) + (0.0722f * B);
+    return std::roundf(luminance * 10000) / 10000.f;
+}

src/cascadia/TerminalApp/ColorHelper.h

@@ -0,0 +1,32 @@
+#pragma once
+#include "pch.h"
+
+#include <winrt/windows.ui.core.h>
+
+namespace winrt::TerminalApp
+{
+    class HSL
+    {
+    public:
+        float H;
+        float S;
+        float L;
+    };
+
+    class ColorHelper
+    {
+    public:
+        static bool IsBrightColor(const Windows::UI::Color& color);
+        static HSL RgbToHsl(const Windows::UI::Color& color);
+        static Windows::UI::Color HslToRgb(const HSL& color);
+        static Windows::UI::Color Lighten(const Windows::UI::Color& color, float amount = 10.f);
+        static Windows::UI::Color Darken(const Windows::UI::Color& color, float amount = 10.f);
+        static Windows::UI::Color GetAccentColor(const Windows::UI::Color& color);
+        static float GetLuminance(const Windows::UI::Color& color);
+        static float GetReadability(const Windows::UI::Color& first, const Windows::UI::Color& second);
+        static float GetReadability(const HSL& first, const HSL& second);
+
+    private:
+        static float HueToRgb(float p, float q, float t);
+    };
+}