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
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