[evince/gnome_3_36_tooltip_feature] pdf: add back 'de facto' tooltip feature

[Nelson Ben <nbenitez src gnome org>]

commit 6b22eeb418bbe5647c27ed5bce02ce6d866ee39d
Author: Nelson Benítez León <nbenitezl gmail com>
Date:   Fri Jun 19 23:30:58 2020 -0400

    pdf: add back 'de facto' tooltip feature
    
    without breaking ABI in gnome-3-36 branch.
    By setting the tooltip on the EvFormField
    via g_object_set_data() instead of using
    a new EvFormField struct field.
    
    Evince issue #842

 backend/pdf/ev-poppler.cc |  7 +++++++
 libview/ev-view.c         | 37 ++++++++++++++++++++++++++++++++++++-
 2 files changed, 43 insertions(+), 1 deletion(-)
---
diff --git a/backend/pdf/ev-poppler.cc b/backend/pdf/ev-poppler.cc
index a6383a15..dac2bb62 100644
--- a/backend/pdf/ev-poppler.cc
+++ b/backend/pdf/ev-poppler.cc
@@ -2763,6 +2763,13 @@ ev_form_field_from_poppler_field (PdfDocument      *pdf_document,
        if (action)
                ev_field->activation_link = ev_link_from_action (pdf_document, action);
 
+#if POPPLER_CHECK_VERSION(0, 88, 0)
+       gchar *alt_name = poppler_form_field_get_alternate_ui_name (poppler_field);
+       if (alt_name) {
+               g_object_set_data_full (G_OBJECT (ev_field), "alt-name", alt_name, (GDestroyNotify) g_free);
+       }
+#endif
+
        return ev_field;
 }
 
diff --git a/libview/ev-view.c b/libview/ev-view.c
index 032414e3..8485d142 100644
--- a/libview/ev-view.c
+++ b/libview/ev-view.c
@@ -2205,7 +2205,7 @@ ev_view_handle_cursor_over_xy (EvView *view, gint x, gint y)
                        ev_view_set_cursor (view, EV_VIEW_CURSOR_NORMAL);
        }
 
-       if (link || annot)
+       if (link || annot || (field && g_object_get_data (G_OBJECT (field), "alt-name")))
                g_object_set (view, "has-tooltip", TRUE, NULL);
 }
 
@@ -4961,6 +4961,26 @@ get_annot_area (EvView       *view,
                                       annot, area);
 }
 
+static void
+get_field_area (EvView       *view,
+               gint          x,
+               gint          y,
+               EvFormField  *field,
+               GdkRectangle *area)
+{
+       EvMappingList *field_mapping;
+       gint           page;
+       gint           x_offset = 0, y_offset = 0;
+
+       x += view->scroll_x;
+       y += view->scroll_y;
+
+       find_page_at_location (view, x, y, &page, &x_offset, &y_offset);
+
+       field_mapping = ev_page_cache_get_form_field_mapping (view->page_cache, page);
+       ev_view_get_area_from_mapping (view, page, field_mapping, field, area);
+}
+
 static gboolean
 ev_view_query_tooltip (GtkWidget  *widget,
                       gint        x,
@@ -4969,6 +4989,7 @@ ev_view_query_tooltip (GtkWidget  *widget,
                       GtkTooltip *tooltip)
 {
        EvView       *view = EV_VIEW (widget);
+       EvFormField  *field;
        EvLink       *link;
        EvAnnotation *annot;
        gchar        *text;
@@ -4989,6 +5010,20 @@ ev_view_query_tooltip (GtkWidget  *widget,
                }
        }
 
+       field = ev_view_get_form_field_at_location (view, x, y);
+       if (field) {
+               text = g_object_get_data (G_OBJECT (field), "alt-name");
+               if (text && *text != '\0') {
+                       GdkRectangle field_area;
+
+                       get_field_area (view, x, y, field, &field_area);
+                       gtk_tooltip_set_text (tooltip, text);
+                       gtk_tooltip_set_tip_area (tooltip, &field_area);
+
+                       return TRUE;
+               }
+       }
+
        link = ev_view_get_link_at_location (view, x, y);
        if (!link)
                return FALSE;