[cairo] Re: [PATCH] PS/PDF improve efficiency of text output
Adrian Johnson
ajohnson at redneon.com
Mon Oct 23 06:03:37 PDT 2006
Behdad Esfahbod wrote:
> Hi Adrian,
>
> I was making Firefox print using Pango and when looking at your
> xshow/yshow/xyshow patch I think I've found a minor bug. Namely, the
> advance vector passed to xshow/yshow should be the same length as the
> glyph vector, but your code generates one that is one entry shorter.
> I'm referring to this patch:
>
> http://lists.freedesktop.org/archives/cairo/2006-September/007930.html
>
> Of course for positioning purposes n-1 entries are enough to position n
> glyphs, but the n'th entry is needed to correctly advance the current
> position and while ghostscript doesn't warn or err about it, the HP
> Laserjet printer I was testing with refused to print any such
> PostScript. Adding a final 0 (and two zeros in case of xyshow) should
> fix it. Or you can be smarter and use this feature to eliminate the
> moveto when switching between subfonts.
>
Obviously I didn't test this patch on my LaserJet. The problem with
trying to save paper by using ghostscript is that, as you found out, it
tolerates some types of malformed PostScript.
The attached patch fixes the bug, includes the moveto optimization you
suggested, and ensures the status of the word wrap stream is checked
when destroyed.
-------------- next part --------------
diff --git a/src/cairo-ps-surface.c b/src/cairo-ps-surface.c
index cc95f2e..df319ac 100644
--- a/src/cairo-ps-surface.c
+++ b/src/cairo-ps-surface.c
@@ -2090,6 +2090,15 @@ _cairo_ps_surface_fill (void *abstract_
return status;
}
+/* This size keeps the length of the hex encoded string of glyphs
+ * within 80 columns. */
+#define MAX_GLYPHS_PER_SHOW 36
+
+typedef struct _cairo_ps_glyph_id {
+ unsigned int subset_id;
+ unsigned int glyph_id;
+} cairo_ps_glyph_id_t;
+
static cairo_int_status_t
_cairo_ps_surface_show_glyphs (void *abstract_surface,
cairo_operator_t op,
@@ -2101,9 +2110,12 @@ _cairo_ps_surface_show_glyphs (void
cairo_ps_surface_t *surface = abstract_surface;
cairo_output_stream_t *stream = surface->stream;
unsigned int current_subset_id = -1;
- unsigned int font_id, subset_id, subset_glyph_index;
+ unsigned int font_id;
+ cairo_ps_glyph_id_t *glyph_ids;
cairo_status_t status;
- int i;
+ int i, j, last, end;
+ cairo_bool_t vertical, horizontal;
+ cairo_output_stream_t *word_wrap;
if (surface->paginated_mode == CAIRO_PAGINATED_MODE_ANALYZE)
return _analyze_operation (surface, op, source);
@@ -2113,37 +2125,113 @@ _cairo_ps_surface_show_glyphs (void
_cairo_output_stream_printf (stream,
"%% _cairo_ps_surface_show_glyphs\n");
- if (num_glyphs)
- emit_pattern (surface, source, 0, 0);
+ if (num_glyphs == 0)
+ return CAIRO_STATUS_SUCCESS;
+
+ emit_pattern (surface, source, 0, 0);
+ glyph_ids = malloc (num_glyphs*sizeof(cairo_ps_glyph_id_t));
+ if (glyph_ids == NULL)
+ return CAIRO_STATUS_NO_MEMORY;
for (i = 0; i < num_glyphs; i++) {
status = _cairo_scaled_font_subsets_map_glyph (surface->font_subsets,
scaled_font, glyphs[i].index,
- &font_id, &subset_id, &subset_glyph_index);
+ &font_id,
+ &(glyph_ids[i].subset_id),
+ &(glyph_ids[i].glyph_id));
if (status)
- return status;
+ goto fail;
+ }
- if (subset_id != current_subset_id) {
+ i = 0;
+ while (i < num_glyphs) {
+ if (glyph_ids[i].subset_id != current_subset_id) {
_cairo_output_stream_printf (surface->stream,
"/CairoFont-%d-%d findfont\n"
"[ %f %f %f %f 0 0 ] makefont\n"
"setfont\n",
font_id,
- subset_id,
+ glyph_ids[i].subset_id,
scaled_font->scale.xx,
scaled_font->scale.yx,
-scaled_font->scale.xy,
-scaled_font->scale.yy);
- current_subset_id = subset_id;
+ current_subset_id = glyph_ids[i].subset_id;
}
- _cairo_output_stream_printf (surface->stream,
- "%f %f M <%02x> S\n",
- glyphs[i].x, glyphs[i].y,
- subset_glyph_index);
+ if (i == 0)
+ _cairo_output_stream_printf (stream,
+ "%f %f M\n",
+ glyphs[i].x,
+ glyphs[i].y);
+
+ horizontal = TRUE;
+ vertical = TRUE;
+ end = num_glyphs;
+ if (end - i > MAX_GLYPHS_PER_SHOW)
+ end = i + MAX_GLYPHS_PER_SHOW;
+ last = end - 1;
+ for (j = i; j < end - 1; j++) {
+ if ((glyphs[j].y != glyphs[j + 1].y))
+ horizontal = FALSE;
+ if ((glyphs[j].x != glyphs[j + 1].x))
+ vertical = FALSE;
+ if (glyph_ids[j].subset_id != glyph_ids[j + 1].subset_id) {
+ last = j;
+ break;
+ }
+ }
+
+ if (i == last) {
+ _cairo_output_stream_printf (surface->stream, "<%02x> S\n", glyph_ids[i].glyph_id);
+ } else {
+ word_wrap = _word_wrap_stream_create (surface->stream, 79);
+ _cairo_output_stream_printf (word_wrap, "<");
+ for (j = i; j <= last; j++)
+ _cairo_output_stream_printf (word_wrap, "%02x", glyph_ids[j].glyph_id);
+ _cairo_output_stream_printf (word_wrap, ">\n[");
+
+ for (j = i + 1; j <= last + 1; j++) {
+ if (j == num_glyphs) {
+ if (horizontal || vertical)
+ _cairo_output_stream_printf (word_wrap, "0 ");
+ else
+ _cairo_output_stream_printf (word_wrap, "0 0 ");
+ } else {
+ if (horizontal) {
+ _cairo_output_stream_printf (word_wrap,
+ "%f ", glyphs[j].x - glyphs[j - 1].x);
+ } else if (vertical) {
+ _cairo_output_stream_printf (word_wrap,
+ "%f ", glyphs[j].y - glyphs[j - 1].y);
+ } else {
+ _cairo_output_stream_printf (word_wrap,
+ "%f %f ",
+ glyphs[j].x - glyphs[j - 1].x,
+ glyphs[j].y - glyphs[j - 1].y);
+ }
+ }
+ }
+ if (horizontal)
+ _cairo_output_stream_printf (word_wrap, "] xshow\n");
+ else if (vertical)
+ _cairo_output_stream_printf (word_wrap, "] yshow\n");
+ else
+ _cairo_output_stream_printf (word_wrap, "] xyshow\n");
+
+ status = _cairo_output_stream_destroy (word_wrap);
+ if (status)
+ goto fail;
+ }
+ i = last + 1;
}
+ free (glyph_ids);
return _cairo_output_stream_get_status (surface->stream);
+
+fail:
+ free (glyph_ids);
+ return status;
}
static void
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