[core] move ColorMode to gfx namespace

1 files changed, 99 insertions, 0 deletions

diff --git a/src/mbgl/gfx/color_mode.hpp b/src/mbgl/gfx/color_mode.hpp
new file mode 100644
index 0000000000..97bbc24096
--- /dev/null
+++ b/src/mbgl/gfx/color_mode.hpp
@@ -0,0 +1,99 @@
+#pragma once
+
+#include <mbgl/util/variant.hpp>
+#include <mbgl/util/color.hpp>
+
+namespace mbgl {
+namespace gfx {
+
+class ColorMode {
+public:
+    enum class BlendEquation {
+        Add,
+        Subtract,
+        ReverseSubtract
+    };
+
+    enum class BlendFactor {
+        Zero,
+        One,
+        SrcColor,
+        OneMinusSrcColor,
+        SrcAlpha,
+        OneMinusSrcAlpha,
+        DstAlpha,
+        OneMinusDstAlpha,
+        DstColor,
+        OneMinusDstColor,
+        SrcAlphaSaturate,
+        ConstantColor,
+        OneMinusConstantColor,
+        ConstantAlpha,
+        OneMinusConstantAlpha
+    };
+
+    template <BlendEquation E>
+    struct ConstantBlend {
+        static constexpr BlendEquation equation = E;
+        static constexpr BlendFactor srcFactor = BlendFactor::One;
+        static constexpr BlendFactor dstFactor = BlendFactor::One;
+    };
+
+    template <BlendEquation E>
+    struct LinearBlend {
+        static constexpr BlendEquation equation = E;
+        BlendFactor srcFactor;
+        BlendFactor dstFactor;
+    };
+
+    struct Replace {
+        static constexpr BlendEquation equation = BlendEquation::Add;
+        static constexpr BlendFactor srcFactor = BlendFactor::One;
+        static constexpr BlendFactor dstFactor = BlendFactor::Zero;
+    };
+
+    using Add              = LinearBlend<BlendEquation::Add>;
+    using Subtract         = LinearBlend<BlendEquation::Subtract>;
+    using ReverseSubtract  = LinearBlend<BlendEquation::ReverseSubtract>;
+
+    using BlendFunction = variant<
+        Replace,
+        Add,
+        Subtract,
+        ReverseSubtract>;
+
+    BlendFunction blendFunction;
+    Color blendColor;
+
+    struct Mask {
+        bool r;
+        bool g;
+        bool b;
+        bool a;
+    };
+
+    Mask mask;
+
+    static ColorMode disabled() {
+       return { Replace{}, {}, { false, false, false, false } };
+    }
+
+    static ColorMode unblended() {
+       return { Replace{}, {}, { true, true, true, true } };
+    }
+
+    static ColorMode alphaBlended() {
+        return { Add{ BlendFactor::One, BlendFactor::OneMinusSrcAlpha }, {}, { true, true, true, true } };
+    }
+
+    static ColorMode additive() {
+        return { Add{ BlendFactor::One, BlendFactor::One }, {}, { true, true, true, true } };
+    }
+};
+
+constexpr bool operator!=(const ColorMode::Mask& a, const ColorMode::Mask& b) {
+    return a.r != b.r || a.g != b.g || a.b != b.b || a.a != b.a;
+}
+
+} // namespace gfx
+} // namespace mbgl