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drawtext: add 'fix_bounds' option on coords fixing

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Before, drawtext filter deliberately altered given text coordinates if
text didn't fully fit on the picture. This breaks the use case of
scrolling large text, e.g. movie closing credits.
Add 'fix_bounds', to make it usable in such cases (by setting its value to 0).
Default behavior is not changed, and non-fitting text coords are fixed.

Signed-off-by: Anton Khirnov <anton@khirnov.net>
This commit is contained in:
Andrey Utkin 2012-02-05 14:41:01 +02:00 committed by Anton Khirnov
parent 2b43dfce36
commit e496c45d9b
2 changed files with 14 additions and 6 deletions
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3
doc/filters.texi
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@ -598,6 +598,9 @@ libfreetype flags.
@item tabsize
The size in number of spaces to use for rendering the tab.
Default value is 4.
@item fix_bounds
If true, check and fix text coords to avoid clipping.
@end table
For example the command:

5
libavfilter/vf_drawtext.c
View File

@ -122,6 +122,7 @@ typedef struct {
short int draw_box; ///< draw box around text - true or false
int use_kerning; ///< font kerning is used - true/false
int tabsize; ///< tab size
int fix_bounds; ///< do we let it go out of frame bounds - t/f
FT_Library library; ///< freetype font library handle
FT_Face face; ///< freetype font face handle
@ -157,6 +158,8 @@ static const AVOption drawtext_options[]= {
{"shadowy", "set y", OFFSET(shadowy), AV_OPT_TYPE_INT, {.dbl=0}, INT_MIN, INT_MAX },
{"tabsize", "set tab size", OFFSET(tabsize), AV_OPT_TYPE_INT, {.dbl=4}, 0, INT_MAX },
{"draw", "if false do not draw", OFFSET(d_expr), AV_OPT_TYPE_STRING, {.str="1"}, CHAR_MIN, CHAR_MAX },
{"fix_bounds", "if true, check and fix text coords to avoid clipping",
OFFSET(fix_bounds), AV_OPT_TYPE_INT, {.dbl=1}, 0, 1 },
/* FT_LOAD_* flags */
{"ft_load_flags", "set font loading flags for libfreetype", OFFSET(ft_load_flags), AV_OPT_TYPE_FLAGS, {.dbl=FT_LOAD_DEFAULT|FT_LOAD_RENDER}, 0, INT_MAX, 0, "ft_load_flags" },
@ -828,12 +831,14 @@ static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *inpicref)
normalize_double(&dtext->x, dtext->var_values[VAR_X]);
normalize_double(&dtext->y, dtext->var_values[VAR_Y]);
if (dtext->fix_bounds) {
if (dtext->x < 0) dtext->x = 0;
if (dtext->y < 0) dtext->y = 0;
if ((unsigned)dtext->x + (unsigned)dtext->w > inlink->w)
dtext->x = inlink->w - dtext->w;
if ((unsigned)dtext->y + (unsigned)dtext->h > inlink->h)
dtext->y = inlink->h - dtext->h;
}
dtext->x &= ~((1 << dtext->hsub) - 1);
dtext->y &= ~((1 << dtext->vsub) - 1);