Implement drawing mode (\p)

Finally implement the drawing mode, which allows drawing of custom
vector graphics.  Drawings are intercepted in ass_render_event; a hash
of the drawing string is generated which is then used for looking
up drawings and bitmaps of drawings in the cache.  The drawings
itself are "fake" glyphs.  They are created by parsing the simple
drawing description language, evaluating the curves described (lines,
cubic beziers and/or a special kind of b-splines) and creating vector
outlines.  Afterwards, these drawings are (with a few exceptions, e.g.
ascender/descender) exactly handled like regular glyphs.

Support for vector clippings is still missing, but otherwise the
implementation should be complete and compatible with VSFilter.

The libass integration of the drawing parsing/processing code is still a
bit sketchy and should be refactored.

History:
WIP: Drawing mode infrastructure
WIP: Drawing tokenizer
WIP: Parse drawing tokens, call evaluators
WIP: Bezier/b-spline evaluator
WIP: Final pieces for the drawing mode
WIP: Heavy modifications to the drawing parser/tokenizer
WIP: Dynamic outline memory allocation
WIP: Drawing position fixes
WIP: more drawing position fixup (similar to VSFilter now)
WIP: Lots of cleanup and fixes for drawings.
WIP: Drawing mode integration into ass_render_event

1 files changed, 76 insertions, 0 deletions

diff --git a/libass/ass_drawing.h b/libass/ass_drawing.h
new file mode 100644
index 0000000..323c05d
--- /dev/null
+++ b/libass/ass_drawing.h
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2009 Grigori Goronzy <greg@geekmind.org>
+ *
+ * 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_DRAWING_H
+#define LIBASS_DRAWING_H
+
+#include <ft2build.h>
+#include FT_GLYPH_H
+
+#include "ass.h"
+
+#define DRAWING_INITIAL_SIZE 256
+
+enum ass_token_type {
+    TOKEN_MOVE,
+    TOKEN_MOVE_NC,
+    TOKEN_LINE,
+    TOKEN_CUBIC_BEZIER,
+    TOKEN_CONIC_BEZIER,
+    TOKEN_B_SPLINE,
+    TOKEN_EXTEND_SPLINE,
+    TOKEN_CLOSE
+};
+
+typedef struct ass_drawing_token_s {
+    enum ass_token_type type;
+    FT_Vector point;
+    struct ass_drawing_token_s *next;
+    struct ass_drawing_token_s *prev;
+} ass_drawing_token_t;
+
+typedef struct ass_drawing_s {
+    char *text; // drawing string
+    int i;      // text index
+    int scale;  // scale (1-64) for subpixel accuracy
+    double pbo; // drawing will be shifted in y direction by this amount
+    double scale_x;     // FontScaleX
+    double scale_y;     // FontScaleY
+    int asc;            // ascender
+    int desc;           // descender
+    FT_OutlineGlyph glyph;  // the "fake" glyph created for later rendering
+    int hash;           // hash value (for caching)
+
+    // private
+    FT_Library ftlibrary;   // FT library instance, needed for font ops
+    int size;           // current buffer size
+    ass_drawing_token_t *tokens;    // tokenized drawing
+    int max_points;     // current maximum size
+    int max_contours;
+    double point_scale_x;
+    double point_scale_y;
+} ass_drawing_t;
+
+ass_drawing_t *ass_drawing_new(void *fontconfig_priv, ass_font_t *font,
+                               ass_hinting_t hint, FT_Library lib);
+void ass_drawing_free(ass_drawing_t* drawing);
+void ass_drawing_add_char(ass_drawing_t* drawing, char symbol);
+void ass_drawing_hash(ass_drawing_t* drawing);
+FT_OutlineGlyph *ass_drawing_parse(ass_drawing_t *drawing);
+
+#endif /* LIBASS_DRAWING_H */