[evince] djvu: Ignore text regions that are missing text

[Jason Crain <jcrain src gnome org>]

commit 2a297354efffafbd52ff3c4ed9a191534bbeff8d
Author: Jason Crain <jcrain src gnome org>
Date:   Sat Aug 25 19:08:30 2018 -0600

    djvu: Ignore text regions that are missing text
    
    The DjVu document in issue #948 has text regions that cover the entire
    page but only contain an empty string. This makes selecting text with
    either the mouse or the Control+A shortcut difficult because the entire
    page gets selected. Fix this by ignoring empty strings when determining
    the selection region.

 backend/djvu/djvu-text-page.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)
---
diff --git a/backend/djvu/djvu-text-page.c b/backend/djvu/djvu-text-page.c
index 243bd3e0..af858cf2 100644
--- a/backend/djvu/djvu-text-page.c
+++ b/backend/djvu/djvu-text-page.c
@@ -63,20 +63,24 @@ djvu_text_page_selection_process_box (DjvuTextPage *page,
 {
        if (page->results || p == page->start) {
                EvRectangle box;
+               const char *text;
 
                box.x1 = miniexp_to_int (miniexp_nth (1, p));
                box.y1 = miniexp_to_int (miniexp_nth (2, p));
                box.x2 = miniexp_to_int (miniexp_nth (3, p));
                box.y2 = miniexp_to_int (miniexp_nth (4, p));
+               text = miniexp_to_str (miniexp_nth (5, p));
 
-               if (!(delimit & 2) && page->results != NULL) {
-                       EvRectangle *union_box = (EvRectangle *)page->results->data;
+               if (text != NULL && text[0] != '\0') {
+                       if (!(delimit & 2) && page->results != NULL) {
+                               EvRectangle *union_box = (EvRectangle *)page->results->data;
 
-                        /* If still on the same line, add box to union */
-                       djvu_text_page_union (union_box, &box);
-               } else {
-                       /* A new line, a new box */
-                       page->results = g_list_prepend (page->results, ev_rectangle_copy (&box));
+                                /* If still on the same line, add box to union */
+                               djvu_text_page_union (union_box, &box);
+                       } else {
+                               /* A new line, a new box */
+                               page->results = g_list_prepend (page->results, ev_rectangle_copy (&box));
+                       }
                }
 
                if (p == page->end)
@@ -171,13 +175,16 @@ djvu_text_page_limits_process (DjvuTextPage *page,
                               EvRectangle  *rect)
 {
        EvRectangle current;
+       const char *text;
        
        current.x1 = miniexp_to_int (miniexp_nth (1, p));
        current.y1 = miniexp_to_int (miniexp_nth (2, p));
        current.x2 = miniexp_to_int (miniexp_nth (3, p));
        current.y2 = miniexp_to_int (miniexp_nth (4, p));
+       text = miniexp_to_str (miniexp_nth (5, p));
        if (current.x2 >= rect->x1 && current.y1 <= rect->y2 &&
-           current.x1 <= rect->x2 && current.y2 >= rect->y1) {
+           current.x1 <= rect->x2 && current.y2 >= rect->y1 &&
+           text != NULL && text[0] != '\0') {
                if (page->start == miniexp_nil)
                        page->start = p;
                page->end = p;