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chafa: Introduce --margin-bottom and --margin-right options
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These allow you to control bottom and right margins to subtract from
the detected terminal size. In particular, '--margin-bottom 0'
eliminates the cursor parking row so that every last character cell
can be used.

Fixes #61 (GitHub).
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@hpjansson
hpjansson committed Mar 10, 2022
1 parent 37614e8 commit cf15d59
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Showing 2 changed files with 150 additions and 36 deletions.
17 changes: 17 additions & 0 deletions docs/chafa.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -212,6 +212,23 @@ none. Swaps --fg and --bg.
</para></listitem>
</varlistentry>

<varlistentry>
<term><option>--margin-bottom <replaceable>num</replaceable></option></term>
<listitem><para>
When terminal size is detected, reserve at least this many rows at the bottom
as a safety margin. Can be used to prevent images from scrolling out.
Defaults to 1.
</para></listitem>
</varlistentry>

<varlistentry>
<term><option>--margin-right <replaceable>num</replaceable></option></term>
<listitem><para>
When terminal size is detected, reserve at least this many rows on the
right-hand side as a safety margin. Defaults to 0.
</para></listitem>
</varlistentry>

<varlistentry>
<term><option>-O <replaceable>num</replaceable>, --optimize <replaceable>num</replaceable></option></term>
<listitem><para>
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169 changes: 133 additions & 36 deletions tools/chafa/chafa.c
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Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,7 @@ typedef struct
gboolean fg_only;
gint width, height;
gint cell_width, cell_height;
gint margin_bottom, margin_right;
gdouble font_ratio;
gint work_factor;
gint optimization_level;
Expand All @@ -88,10 +89,21 @@ typedef struct
* eliminate interframe delay altogether. */
gdouble anim_speed_multiplier;

/* Automatically set if terminal size is detected and there is
* zero bottom margin. */
gboolean have_parking_row;

ChafaTermInfo *term_info;
}
GlobalOptions;

typedef struct
{
gint width_cells, height_cells;
gint width_pixels, height_pixels;
}
TermSize;

static GlobalOptions options;
static volatile sig_atomic_t interrupted_by_user = FALSE;

Expand Down Expand Up @@ -253,6 +265,12 @@ print_summary (void)
" font file supported by FreeType (TTF, PCF, etc).\n"
" --invert Invert video. For display with bright backgrounds in\n"
" color modes 2 and none. Swaps --fg and --bg.\n"
" --margin-bottom=NUM When terminal size is detected, reserve at least NUM\n"
" rows at the bottom as a safety margin. Can be used to\n"
" prevent images from scrolling out. Defaults to 1.\n"
" --margin-right=NUM When terminal size is detected, reserve at least NUM\n"
" rows on the right-hand side as a safety margin. Defaults\n"
" to 0.\n"
" -O, --optimize=NUM Compress the output by using control sequences\n"
" intelligently [0-9]. 0 disables, 9 enables every\n"
" available optimization. Defaults to 5, except for when\n"
Expand Down Expand Up @@ -770,11 +788,17 @@ parse_bg_color_arg (G_GNUC_UNUSED const gchar *option_name, const gchar *value,
}

static void
get_tty_size (void)
get_tty_size (TermSize *term_size_out)
{
struct winsize w;
gboolean have_winsz = FALSE;

term_size_out->width_cells
= term_size_out->height_cells
= term_size_out->width_pixels
= term_size_out->height_pixels
= -1;

/* FIXME: Use tcgetwinsize() when it becomes more widely available.
* See: https://www.austingroupbugs.net/view.php?id=1151#c3856 */

Expand Down Expand Up @@ -805,23 +829,19 @@ get_tty_size (void)
return;

if (w.ws_col > 0)
options.width = w.ws_col;
term_size_out->width_cells = w.ws_col;

/* We subtract one line for the user's prompt */
if (w.ws_row > 2)
options.height = w.ws_row - 1;
term_size_out->height_cells = w.ws_row;

/* If .ws_xpixel and .ws_ypixel are filled out, we can calculate
* aspect information for the font used. Sixel-capable terminals
* like mlterm set these fields, but most others do not. */

if (w.ws_xpixel > 0 && w.ws_ypixel > 0)
{
options.cell_width = w.ws_xpixel / w.ws_col;
options.cell_height = w.ws_ypixel / w.ws_row;

if (options.cell_width > 0 && options.cell_height > 0)
options.font_ratio = (gfloat) options.cell_width / (gfloat) options.cell_height;
term_size_out->width_pixels = w.ws_xpixel;
term_size_out->height_pixels = w.ws_ypixel;
}
}

Expand Down Expand Up @@ -906,7 +926,6 @@ parse_options (int *argc, char **argv [])
{
GError *error = NULL;
GOptionContext *context;
gint detected_width;
gboolean result = TRUE;
const GOptionEntry option_entries [] =
{
Expand All @@ -931,6 +950,8 @@ parse_options (int *argc, char **argv [])
{ "font-ratio", '\0', 0, G_OPTION_ARG_CALLBACK, parse_font_ratio_arg, "Font ratio", NULL },
{ "glyph-file", '\0', 0, G_OPTION_ARG_CALLBACK, parse_glyph_file_arg, "Glyph file", NULL },
{ "invert", '\0', 0, G_OPTION_ARG_NONE, &options.invert, "Invert foreground/background", NULL },
{ "margin-bottom", '\0', 0, G_OPTION_ARG_INT, &options.margin_bottom, "Bottom margin", NULL },
{ "margin-right", '\0', 0, G_OPTION_ARG_INT, &options.margin_right, "Right margin", NULL },
{ "optimize", 'O', 0, G_OPTION_ARG_INT, &options.optimization_level, "Optimization", NULL },
{ "polite", '\0', 0, G_OPTION_ARG_CALLBACK, parse_polite_arg, "Polite", NULL },
{ "preprocess", 'p', 0, G_OPTION_ARG_CALLBACK, parse_preprocess_arg, "Preprocessing", NULL },
Expand All @@ -947,6 +968,8 @@ parse_options (int *argc, char **argv [])
};
ChafaCanvasMode canvas_mode;
ChafaPixelMode pixel_mode;
TermSize detected_term_size;
gboolean using_detected_size = FALSE;

memset (&options, 0, sizeof (options));

Expand Down Expand Up @@ -979,9 +1002,11 @@ parse_options (int *argc, char **argv [])
options.fg_only = FALSE;
options.color_extractor = CHAFA_COLOR_EXTRACTOR_AVERAGE;
options.color_space = CHAFA_COLOR_SPACE_RGB;
options.width = 80;
options.height = 25;
options.width = -1; /* Unset */
options.height = -1; /* Unset */
options.font_ratio = -1.0; /* Unset */
options.margin_bottom = -1; /* Unset */
options.margin_right = -1; /* Unset */
options.work_factor = 5;
options.optimization_level = G_MININT; /* Unset */
options.n_threads = -1;
Expand All @@ -991,16 +1016,93 @@ parse_options (int *argc, char **argv [])
options.file_duration_s = G_MAXDOUBLE;
options.anim_fps = -1.0;
options.anim_speed_multiplier = 1.0;
get_tty_size ();

detected_width = options.width;

if (!g_option_context_parse (context, argc, argv, &error))
{
g_printerr ("%s: %s\n", options.executable_name, error->message);
return FALSE;
}

/* Detect terminal geometry */

get_tty_size (&detected_term_size);

if (detected_term_size.width_cells > 0
&& detected_term_size.height_cells > 0
&& detected_term_size.width_pixels > 0
&& detected_term_size.height_pixels > 0)
{
options.cell_width = detected_term_size.width_pixels / detected_term_size.width_cells;
options.cell_height = detected_term_size.height_pixels / detected_term_size.height_cells;

if (options.font_ratio <= 0.0
&& options.cell_width > 0
&& options.cell_height > 0)
{
options.font_ratio = (gfloat) options.cell_width / (gfloat) options.cell_height;
}
}

/* Assign detected or default dimensions if none specified */

if (options.width < 0 && options.height < 0)
{
using_detected_size = TRUE;
}

if (options.margin_bottom < 0)
{
options.margin_bottom = 1; /* Default */
}

/* Sixel output always leaves the cursor below the image, so force a bottom
* margin of at least one even if the user wanted less. */
if (options.margin_bottom < 1
&& options.pixel_mode == CHAFA_PIXEL_MODE_SIXELS)
options.margin_bottom = 1;

if (options.margin_right < 0)
{
options.margin_right = 0; /* Default */

/* Kitty leaves the cursor in the column trailing the last row of the
* image. However, if the image is as wide as the terminal, the cursor
* will wrap to the first column of the following row, making us lose
* track of its position.
*
* This is not a problem when instructed to clear the terminal, as we
* use absolute positioning then.
*
* If needed, trim one column from the image to make the cursor position
* predictable. */
if (options.pixel_mode == CHAFA_PIXEL_MODE_KITTY
&& using_detected_size
&& !(options.clear && options.margin_bottom >= 2))
{
options.margin_right = 1;
}
}

if (using_detected_size)
{
options.width = detected_term_size.width_cells;
options.height = detected_term_size.height_cells;

if (options.width < 0 && options.height < 0)
{
options.width = 80;
options.height = 25;
}

options.width = (options.width > options.margin_right)
? options.width - options.margin_right : 1;

options.height = (options.height > options.margin_bottom)
? options.height - options.margin_bottom : 1;
}

options.have_parking_row = (using_detected_size && options.margin_bottom == 0) ? FALSE : TRUE;

/* Now we've established the pixel mode, apply dependent defaults */

if (options.pixel_mode == CHAFA_PIXEL_MODE_SYMBOLS)
Expand Down Expand Up @@ -1030,22 +1132,6 @@ parse_options (int *argc, char **argv [])
options.font_ratio = 1.0 / 2.0;
}

/* Kitty leaves the cursor in the column trailing the last row of the
* image. However, if the image is as wide as the terminal, the cursor
* will wrap to the first column of the following row, making us lose
* track of its position.
*
* This is not a problem when instructed to clear the terminal, as we
* use absolute positioning then.
*
* If needed, trim one column from the image to make the cursor position
* predictable. */
if (options.pixel_mode == CHAFA_PIXEL_MODE_KITTY
&& !options.clear
&& options.width > 1
&& options.width == detected_width)
options.width -= 1;

if (options.work_factor < 1 || options.work_factor > 9)
{
g_printerr ("%s: Work factor must be in the range [1-9].\n", options.executable_name);
Expand Down Expand Up @@ -1227,7 +1313,7 @@ run_generic (const gchar *filename, gboolean is_first_file, gboolean is_first_fr
GTimer *timer;
gint loop_n = 0;
MediaLoader *media_loader;
gchar buf [CHAFA_TERM_SEQ_LENGTH_MAX * 2 + 1];
gchar buf [CHAFA_TERM_SEQ_LENGTH_MAX * 2 + 3];
GString *gs;
gchar *p0;

Expand Down Expand Up @@ -1313,12 +1399,18 @@ run_generic (const gchar *filename, gboolean is_first_file, gboolean is_first_fr
else if (!is_first_frame)
{
/* Cursor up N steps */
p0 = chafa_term_info_emit_cursor_up (options.term_info, p0, dest_height);
if (!options.have_parking_row)
*(p0++) = '\r';
p0 = chafa_term_info_emit_cursor_up (options.term_info, p0, dest_height - (options.have_parking_row ? 0 : 1));
}

/* Put a blank line between files in non-clear mode */
if (is_first_frame && !options.clear && !is_first_file)
{
if (!options.have_parking_row)
*(p0++) = '\n';
*(p0++) = '\n';
}

if (!write_to_stdout (buf, p0 - buf))
goto out;
Expand All @@ -1328,9 +1420,10 @@ run_generic (const gchar *filename, gboolean is_first_file, gboolean is_first_fr
g_string_free (gs, TRUE);

/* No linefeed after frame in sixel mode */
if (options.pixel_mode == CHAFA_PIXEL_MODE_SYMBOLS
|| options.pixel_mode == CHAFA_PIXEL_MODE_KITTY
|| options.pixel_mode == CHAFA_PIXEL_MODE_ITERM2)
if (options.have_parking_row
&& (options.pixel_mode == CHAFA_PIXEL_MODE_SYMBOLS
|| options.pixel_mode == CHAFA_PIXEL_MODE_KITTY
|| options.pixel_mode == CHAFA_PIXEL_MODE_ITERM2))
{
if (!write_to_stdout ("\n", 1))
goto out;
Expand Down Expand Up @@ -1441,6 +1534,10 @@ run_all (GList *filenames)
}
}

/* Emit linefeed after last image when cursor was not in parking row */
if (!options.have_parking_row)
write_to_stdout ("\n", 1);

tty_options_deinit ();
return 0;
}
Expand Down

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