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, 110 insertions, 40 deletions

diff --git a/libass/ass_render.c b/libass/ass_render.c
index cc8242f2..c112399b 100644
--- a/libass/ass_render.c
+++ b/libass/ass_render.c
@@ -36,6 +36,7 @@
 #include "ass_utils.h"
 #include "ass_fontconfig.h"
 #include "ass_library.h"
+#include "ass_drawing.h"
 
 #define MAX_GLYPHS_INITIAL 1024
 #define MAX_LINES_INITIAL 64
@@ -171,6 +172,7 @@ typedef struct render_context_s {
     double shadow_x;
     double shadow_y;
     int drawing_mode;           // not implemented; when != 0 text is discarded, except for style override tags
+    ass_drawing_t *drawing;     // current drawing
 
     effect_t effect_type;
     int effect_timing;
@@ -1560,12 +1562,15 @@ static char *parse_tag(ass_renderer_t *render_priv, char *p, double pwr)
             val = 0.;
         render_priv->state.shadow_x = render_priv->state.shadow_y = val;
     } else if (mystrcmp(&p, "pbo")) {
-        int val = 0;
-        mystrtoi(&p, &val);     // ignored
+        double val = 0;
+        if (mystrtod(&p, &val))
+            render_priv->state.drawing->pbo = val;
     } else if (mystrcmp(&p, "p")) {
         int val;
         if (!mystrtoi(&p, &val))
             val = 0;
+        if (val)
+            render_priv->state.drawing->scale = val;
         render_priv->state.drawing_mode = !!val;
     }
 
@@ -1765,12 +1770,18 @@ init_render_context(ass_renderer_t *render_priv, ass_event_t *event)
     render_priv->state.effect_type = EF_NONE;
     render_priv->state.effect_timing = 0;
     render_priv->state.effect_skip_timing = 0;
+    render_priv->state.drawing =
+        ass_drawing_new(render_priv->fontconfig_priv,
+                        render_priv->state.font,
+                        render_priv->settings.hinting,
+                        render_priv->ftlibrary);
 
     apply_transition_effects(render_priv, event);
 }
 
-static void free_render_context(void)
+static void free_render_context(ass_renderer_t *render_priv)
 {
+    ass_drawing_free(render_priv->state.drawing);
 }
 
 // Calculate the cbox of a series of points
@@ -1867,23 +1878,33 @@ static void fix_freetype_stroker(FT_OutlineGlyph glyph, int border_x,
  */
 static void
 get_outline_glyph(ass_renderer_t *render_priv, int symbol,
-                  glyph_info_t *info, FT_Vector *advance)
+                  glyph_info_t *info, FT_Vector *advance,
+                  ass_drawing_t *drawing)
 {
     int error;
     glyph_hash_val_t *val;
     glyph_hash_key_t key;
     memset(&key, 0, sizeof(key));
-    key.font = render_priv->state.font;
-    key.size = render_priv->state.font_size;
-    key.ch = symbol;
-    key.scale_x = double_to_d16(render_priv->state.scale_x);
-    key.scale_y = double_to_d16(render_priv->state.scale_y);
-    key.advance = *advance;
-    key.bold = render_priv->state.bold;
-    key.italic = render_priv->state.italic;
-    key.outline.x = render_priv->state.border_x * 0xFFFF;
-    key.outline.y = render_priv->state.border_y * 0xFFFF;
 
+    if (drawing->hash) {
+        key.scale_x = double_to_d16(render_priv->state.scale_x);
+        key.scale_y = double_to_d16(render_priv->state.scale_y);
+        key.advance = *advance;
+        key.outline.x = render_priv->state.border_x * 0xFFFF;
+        key.outline.y = render_priv->state.border_y * 0xFFFF;
+        key.drawing_hash = drawing->hash;
+    } else {
+        key.font = render_priv->state.font;
+        key.size = render_priv->state.font_size;
+        key.ch = symbol;
+        key.bold = render_priv->state.bold;
+        key.italic = render_priv->state.italic;
+        key.scale_x = double_to_d16(render_priv->state.scale_x);
+        key.scale_y = double_to_d16(render_priv->state.scale_y);
+        key.advance = *advance;
+        key.outline.x = render_priv->state.border_x * 0xFFFF;
+        key.outline.y = render_priv->state.border_y * 0xFFFF;
+    }
     memset(info, 0, sizeof(glyph_info_t));
 
     val = cache_find_glyph(render_priv->cache.glyph_cache, &key);
@@ -1894,12 +1915,21 @@ get_outline_glyph(ass_renderer_t *render_priv, int symbol,
         info->bbox = val->bbox_scaled;
         info->advance.x = val->advance.x;
         info->advance.y = val->advance.y;
+        if (drawing->hash) {
+            drawing->asc = val->asc;
+            drawing->desc = val->desc;
+        }
     } else {
         glyph_hash_val_t v;
-        info->glyph =
-            ass_font_get_glyph(render_priv->fontconfig_priv,
-                               render_priv->state.font, symbol,
-                               render_priv->settings.hinting);
+        if (drawing->hash) {
+            ass_drawing_parse(drawing);
+            FT_Glyph_Copy((FT_Glyph) drawing->glyph, &info->glyph);
+        } else {
+            info->glyph =
+                ass_font_get_glyph(render_priv->fontconfig_priv,
+                                   render_priv->state.font, symbol,
+                                   render_priv->settings.hinting);
+        }
         if (!info->glyph)
             return;
         info->advance.x = d16_to_d6(info->glyph->advance.x);
@@ -1953,6 +1983,10 @@ get_outline_glyph(ass_renderer_t *render_priv, int symbol,
             FT_Glyph_Copy(info->outline_glyph, &v.outline_glyph);
         v.advance = info->advance;
         v.bbox_scaled = info->bbox;
+        if (drawing->hash) {
+            v.asc = drawing->asc;
+            v.desc = drawing->desc;
+        }
         cache_add_glyph(render_priv->cache.glyph_cache, &key, &v);
     }
 }
@@ -2433,6 +2467,7 @@ ass_render_event(ass_renderer_t *render_priv, ass_event_t *event,
     double device_x = 0;
     double device_y = 0;
     text_info_t *text_info = &render_priv->text_info;
+    ass_drawing_t *drawing;
 
     if (event->Style >= render_priv->track->n_styles) {
         ass_msg(MSGL_WARN, MSGTR_LIBASS_NoStyleFound);
@@ -2445,6 +2480,7 @@ ass_render_event(ass_renderer_t *render_priv, ass_event_t *event,
 
     init_render_context(render_priv, event);
 
+    drawing = render_priv->state.drawing;
     text_info->length = 0;
     pen.x = 0;
     pen.y = 0;
@@ -2457,11 +2493,25 @@ ass_render_event(ass_renderer_t *render_priv, ass_event_t *event,
         // this affects render_context
         do {
             code = get_next_char(render_priv, &p);
+            if (render_priv->state.drawing_mode && code)
+                ass_drawing_add_char(drawing, (char) code);
         } while (code && render_priv->state.drawing_mode);      // skip everything in drawing mode
 
+        // Parse drawing
+        if (drawing->i) {
+            drawing->scale_x = render_priv->state.scale_x *
+                                     render_priv->font_scale_x *
+                                     render_priv->font_scale;
+            drawing->scale_y = render_priv->state.scale_y *
+                                     render_priv->font_scale;
+            ass_drawing_hash(drawing);
+            p--;
+            code = -1;
+        }
+
         // face could have been changed in get_next_char
         if (!render_priv->state.font) {
-            free_render_context();
+            free_render_context(render_priv);
             return 1;
         }
 
@@ -2485,7 +2535,7 @@ ass_render_event(ass_renderer_t *render_priv, ass_event_t *event,
         }
 
         // Add kerning to pen
-        if (previous && code) {
+        if (previous && code && !drawing->hash) {
             FT_Vector delta;
             delta =
                 ass_font_get_kerning(render_priv->state.font, previous,
@@ -2500,7 +2550,8 @@ ass_render_event(ass_renderer_t *render_priv, ass_event_t *event,
                                render_priv->state.scale_y, &shift);
 
         get_outline_glyph(render_priv, code,
-                          text_info->glyphs + text_info->length, &shift);
+                          text_info->glyphs + text_info->length, &shift,
+                          drawing);
 
         text_info->glyphs[text_info->length].pos.x = pen.x;
         text_info->glyphs[text_info->length].pos.y = pen.y;
@@ -2539,19 +2590,34 @@ ass_render_event(ass_renderer_t *render_priv, ass_event_t *event,
         text_info->glyphs[text_info->length].frz = render_priv->state.frz;
         text_info->glyphs[text_info->length].fax = render_priv->state.fax;
         text_info->glyphs[text_info->length].fay = render_priv->state.fay;
-        ass_font_get_asc_desc(render_priv->state.font, code,
-                              &text_info->glyphs[text_info->length].asc,
-                              &text_info->glyphs[text_info->length].desc);
-        text_info->glyphs[text_info->length].asc *=
-            render_priv->state.scale_y;
-        text_info->glyphs[text_info->length].desc *=
-            render_priv->state.scale_y;
+        if (drawing->hash) {
+            text_info->glyphs[text_info->length].asc = drawing->asc;
+            text_info->glyphs[text_info->length].desc = drawing->desc;
+        } else {
+            ass_font_get_asc_desc(render_priv->state.font, code,
+                                  &text_info->glyphs[text_info->length].asc,
+                                  &text_info->glyphs[text_info->length].desc);
+
+            text_info->glyphs[text_info->length].asc *=
+                render_priv->state.scale_y;
+            text_info->glyphs[text_info->length].desc *=
+                render_priv->state.scale_y;
+        }
 
         // fill bitmap_hash_key
-        text_info->glyphs[text_info->length].hash_key.font =
-            render_priv->state.font;
-        text_info->glyphs[text_info->length].hash_key.size =
-            render_priv->state.font_size;
+        if (!drawing->hash) {
+            text_info->glyphs[text_info->length].hash_key.font =
+                render_priv->state.font;
+            text_info->glyphs[text_info->length].hash_key.size =
+                render_priv->state.font_size;
+            text_info->glyphs[text_info->length].hash_key.bold =
+                render_priv->state.bold;
+            text_info->glyphs[text_info->length].hash_key.italic =
+                render_priv->state.italic;
+        } else
+            text_info->glyphs[text_info->length].hash_key.drawing_hash =
+                drawing->hash;
+        text_info->glyphs[text_info->length].hash_key.ch = code;
         text_info->glyphs[text_info->length].hash_key.outline.x =
             render_priv->state.border_x * 0xFFFF;
         text_info->glyphs[text_info->length].hash_key.outline.y =
@@ -2570,11 +2636,6 @@ ass_render_event(ass_renderer_t *render_priv, ass_event_t *event,
             render_priv->state.fax * 0xFFFF;
         text_info->glyphs[text_info->length].hash_key.fay =
             render_priv->state.fay * 0xFFFF;
-        text_info->glyphs[text_info->length].hash_key.bold =
-            render_priv->state.bold;
-        text_info->glyphs[text_info->length].hash_key.italic =
-            render_priv->state.italic;
-        text_info->glyphs[text_info->length].hash_key.ch = code;
         text_info->glyphs[text_info->length].hash_key.advance.x = pen.x;
         text_info->glyphs[text_info->length].hash_key.advance.y = pen.y;
         text_info->glyphs[text_info->length].hash_key.be =
@@ -2597,11 +2658,20 @@ ass_render_event(ass_renderer_t *render_priv, ass_event_t *event,
         render_priv->state.effect_type = EF_NONE;
         render_priv->state.effect_timing = 0;
         render_priv->state.effect_skip_timing = 0;
+
+        if (drawing->hash) {
+            ass_drawing_free(drawing);
+            drawing = render_priv->state.drawing =
+                ass_drawing_new(render_priv->fontconfig_priv,
+                    render_priv->state.font,
+                    render_priv->settings.hinting,
+                    render_priv->ftlibrary);
+        }
     }
 
     if (text_info->length == 0) {
         // no valid symbols in the event; this can be smth like {comment}
-        free_render_context();
+        free_render_context(render_priv);
         return 1;
     }
     // depends on glyph x coordinates being monotonous, so it should be done before line wrap
@@ -2813,7 +2883,7 @@ ass_render_event(ass_renderer_t *render_priv, ass_event_t *event,
             d6_to_double(g->pos.y & SUBPIXEL_MASK));
         get_bitmap_glyph(render_priv, text_info->glyphs + i);
     }
-    
+
     memset(event_images, 0, sizeof(*event_images));
     event_images->top = device_y - text_info->lines[0].asc;
     event_images->height = text_info->height;
@@ -2822,7 +2892,7 @@ ass_render_event(ass_renderer_t *render_priv, ass_event_t *event,
     event_images->event = event;
     event_images->imgs = render_text(render_priv, (int) device_x, (int) device_y);
 
-    free_render_context();
+    free_render_context(render_priv);
 
     return 0;
 }