Hello.
I am developing evince backend for hwp document file.
I want to apply pango layout to evince hwp backend.
so, I tried to apply "Example 1. Using Pango with Cairo"
(
https://developer.gnome.org/pango/stable/pango-Cairo-Rendering.html)
to SAMPLE evince backend and EXAMPLE library.
/* Example 1. Using Pango with Cairo */
/*
https://developer.gnome.org/pango/1.34/pango-Cairo-Rendering.html */
#include <math.h>
#include <pango/pangocairo.h>
static void
draw_text (cairo_t *cr)
{
#define RADIUS 150
#define N_WORDS 10
#define FONT "Sans Bold 27"
PangoLayout *layout;
PangoFontDescription *desc;
int i;
/* Center coordinates on the middle of the region we are drawing
*/
cairo_translate (cr, RADIUS, RADIUS);
/* Create a PangoLayout, set the font and text */
layout = pango_cairo_create_layout (cr);
pango_layout_set_text (layout, "Text", -1);
desc = pango_font_description_from_string (FONT);
pango_layout_set_font_description (layout, desc);
pango_font_description_free (desc);
/* Draw the layout N_WORDS times in a circle */
for (i = 0; i < N_WORDS; i++)
{
int width, height;
double angle = (360. * i) / N_WORDS;
double red;
cairo_save (cr);
/* Gradient from red at angle == 60 to blue at angle == 240 */
red = (1 + cos ((angle - 60) * G_PI / 180.)) / 2;
cairo_set_source_rgb (cr, red, 0, 1.0 - red);
cairo_rotate (cr, angle * G_PI / 180.);
/* Inform Pango to re-layout the text with the new transformation */
pango_cairo_update_layout (cr, layout);
pango_layout_get_size (layout, &width, &height);
cairo_move_to (cr, - ((double)width / PANGO_SCALE) / 2, - RADIUS);
pango_cairo_show_layout (cr, layout);
cairo_restore (cr);
}
/* free the layout object */
g_object_unref (layout);
}
gboolean example_page_render (ExamplePage *page, cairo_t *cr)
{
g_return_val_if_fail (EXAMPLE_IS_PAGE (page), FALSE);
draw_text (cr);
return TRUE;
}
then opened the sample text file from the terminal with evince
but segmentation fault occurred intermittently.
I cannot understand the behavior that when I use cairo it works fine
but when I use pango segmentation fault occurs.
Is it because of pango_cairo_font_map_get_default() or thread ?
but considering ev_job_render_run (EvJob *job) in libview/ev-jobs.c
ev_document_fc_mutex_lock ()
...
job_render->surface = ev_document_render (job->document, rc);
...
ev_document_fc_mutex_unlock ()
Although pango is thread-safe since 1.32.6
when I tested in pango 1.30.0 / 1.32.5 / 1.34.1 / 1.35.0
segmentation fault alse occurred in all cases.
I don't know why.
Please advise me how to do.
To test libexample and evince-sample-backend please follow the below steps.
Step 1. Downloads the attachment and extract.
evince-sample-backend and libexample will be created.
Step 2. compile and install libexample
cd libexample
./autogen.sh
make
sudo make install
sudo ldconfig
cd ..
Step 3. compile and install evince-sample-backend
cd evince-sample-backend
./autogen.sh
make
sudo make install
sudo ldconfig
Step 4. open the any text file from the terminal with evince many times.
$ evince any.txt
My current environment:
debian wheezy
evince 3.4.0-3.1
libpango1.0-0 1.30.0-1
libcairo2 1.12.2-3
