initial commit, 4.5 stable

thirdparty/msdfgen/core/MSDFErrorCorrection.h

@@ -0,0 +1,55 @@
+
+#pragma once
+
+#include "SDFTransformation.h"
+#include "Shape.h"
+#include "BitmapRef.hpp"
+
+namespace msdfgen {
+
+/// Performs error correction on a computed MSDF to eliminate interpolation artifacts. This is a low-level class, you may want to use the API in msdf-error-correction.h instead.
+class MSDFErrorCorrection {
+
+public:
+    /// Stencil flags.
+    enum Flags {
+        /// Texel marked as potentially causing interpolation errors.
+        ERROR = 1,
+        /// Texel marked as protected. Protected texels are only given the error flag if they cause inversion artifacts.
+        PROTECTED = 2
+    };
+
+    MSDFErrorCorrection();
+    explicit MSDFErrorCorrection(const BitmapRef<byte, 1> &stencil, const SDFTransformation &transformation);
+    /// Sets the minimum ratio between the actual and maximum expected distance delta to be considered an error.
+    void setMinDeviationRatio(double minDeviationRatio);
+    /// Sets the minimum ratio between the pre-correction distance error and the post-correction distance error.
+    void setMinImproveRatio(double minImproveRatio);
+    /// Flags all texels that are interpolated at corners as protected.
+    void protectCorners(const Shape &shape);
+    /// Flags all texels that contribute to edges as protected.
+    template <int N>
+    void protectEdges(const BitmapConstRef<float, N> &sdf);
+    /// Flags all texels as protected.
+    void protectAll();
+    /// Flags texels that are expected to cause interpolation artifacts based on analysis of the SDF only.
+    template <int N>
+    void findErrors(const BitmapConstRef<float, N> &sdf);
+    /// Flags texels that are expected to cause interpolation artifacts based on analysis of the SDF and comparison with the exact shape distance.
+    template <template <typename> class ContourCombiner, int N>
+    void findErrors(const BitmapConstRef<float, N> &sdf, const Shape &shape);
+    /// Modifies the MSDF so that all texels with the error flag are converted to single-channel.
+    template <int N>
+    void apply(const BitmapRef<float, N> &sdf) const;
+    /// Returns the stencil in its current state (see Flags).
+    BitmapConstRef<byte, 1> getStencil() const;
+
+private:
+    BitmapRef<byte, 1> stencil;
+    SDFTransformation transformation;
+    double minDeviationRatio;
+    double minImproveRatio;
+
+};
+
+}