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diff --git a/libass/ass_rasterizer.h b/libass/ass_rasterizer.h
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+/*
+ * Copyright (C) 2014 Vabishchevich Nikolay <vabnick@gmail.com>
+ *
+ * This file is part of libass.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef LIBASS_RASTERIZER_H
+#define LIBASS_RASTERIZER_H
+
+#include <ft2build.h>
+#include FT_FREETYPE_H
+#include <stddef.h>
+#include <stdint.h>
+
+
+enum {
+    SEGFLAG_UP = 1,
+    SEGFLAG_UR_DL = 2,
+    SEGFLAG_EXACT_LEFT = 4,
+    SEGFLAG_EXACT_RIGHT = 8,
+    SEGFLAG_EXACT_BOTTOM = 16,
+    SEGFLAG_EXACT_TOP = 32
+};
+
+// Polyline segment struct
+struct segment {
+    int64_t c;
+    int32_t a, b, scale, flags;
+    int32_t x_min, x_max, y_min, y_max;
+};
+
+
+typedef void (*FillSolidTileFunc)(uint8_t *buf, ptrdiff_t stride);
+typedef void (*FillHalfplaneTileFunc)(uint8_t *buf, ptrdiff_t stride,
+                                      int32_t a, int32_t b, int64_t c, int32_t scale);
+typedef void (*FillGenericTileFunc)(uint8_t *buf, ptrdiff_t stride,
+                                    const struct segment *line, size_t n_lines,
+                                    int winding);
+
+void ass_fill_solid_tile16_c(uint8_t *buf, ptrdiff_t stride);
+void ass_fill_solid_tile32_c(uint8_t *buf, ptrdiff_t stride);
+void ass_fill_halfplane_tile16_c(uint8_t *buf, ptrdiff_t stride,
+                                 int32_t a, int32_t b, int64_t c, int32_t scale);
+void ass_fill_halfplane_tile32_c(uint8_t *buf, ptrdiff_t stride,
+                                 int32_t a, int32_t b, int64_t c, int32_t scale);
+void ass_fill_generic_tile16_c(uint8_t *buf, ptrdiff_t stride,
+                               const struct segment *line, size_t n_lines,
+                               int winding);
+void ass_fill_generic_tile32_c(uint8_t *buf, ptrdiff_t stride,
+                               const struct segment *line, size_t n_lines,
+                               int winding);
+
+typedef struct ass_rasterizer {
+    int outline_error;  // acceptable error (in 1/64 pixel units)
+
+    int tile_order;  // log2(tile_size)
+    FillSolidTileFunc fill_solid;
+    FillHalfplaneTileFunc fill_halfplane;
+    FillGenericTileFunc fill_generic;
+
+    int32_t x_min, x_max, y_min, y_max;  // usable after rasterizer_set_outline
+
+    // internal buffers
+    struct segment *linebuf[2];
+    size_t size[2], capacity[2];
+} ASS_Rasterizer;
+
+void rasterizer_init(ASS_Rasterizer *rst);
+void rasterizer_done(ASS_Rasterizer *rst);
+/**
+ * \brief Convert FreeType outline to polyline and calculate exact bounds
+ */
+int rasterizer_set_outline(ASS_Rasterizer *rst, const FT_Outline *path);
+/**
+ * \brief Polyline rasterization function
+ * \param x0, y0, width, height in: source window (full pixel units)
+ * \param buf out: aligned output buffer (size = stride * height)
+ * \param stride output buffer stride (aligned)
+ * \param vert_flip vertical flip flag
+ * \return zero on error
+ * Deletes preprocessed polyline after work.
+ */
+int rasterizer_fill(ASS_Rasterizer *rst, uint8_t *buf, int x0, int y0,
+                    int width, int height, ptrdiff_t stride, int vert_flip);
+
+
+#endif                          /* LIBASS_RASTERIZER_H */