[evince/wip/gpoo/make-struct-priv] pdf: Reimplement 'de facto' tooltip feature keeping the ABI

[Germán Poo-Caamaño <gpoo src gnome org>]

commit 0b17204ff8157b02b04827cfaf0f41c253fe703e
Author: Germán Poo-Caamaño <gpoo gnome org>
Date:   Mon Jul 6 10:32:15 2020 -0400

    pdf: Reimplement 'de facto' tooltip feature keeping the ABI
    
    Structs in EvForm are not opaque, and
    Commit e2ad8611a4c introduced a ABI change

 backend/pdf/ev-poppler.cc   |  2 +-
 libdocument/ev-form-field.c | 66 ++++++++++++++++++++++++++++++++++++++++++---
 libdocument/ev-form-field.h |  4 ++-
 libview/ev-view.c           | 18 ++++++++-----
 4 files changed, 78 insertions(+), 12 deletions(-)
---
diff --git a/backend/pdf/ev-poppler.cc b/backend/pdf/ev-poppler.cc
index 216052a3..eafc0704 100644
--- a/backend/pdf/ev-poppler.cc
+++ b/backend/pdf/ev-poppler.cc
@@ -2780,7 +2780,7 @@ ev_form_field_from_poppler_field (PdfDocument      *pdf_document,
 
        ev_field->font_size = font_size;
        ev_field->is_read_only = is_read_only;
-       ev_field->alt_ui_name = alt_ui_name;
+       ev_form_field_set_alternate_name (ev_field, alt_ui_name);
 
        if (action)
                ev_field->activation_link = ev_link_from_action (pdf_document, action);
diff --git a/libdocument/ev-form-field.c b/libdocument/ev-form-field.c
index 7e0169ad..b2d9fd4e 100644
--- a/libdocument/ev-form-field.c
+++ b/libdocument/ev-form-field.c
@@ -1,6 +1,7 @@
 /* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8; c-indent-level: 8 -*- */
 /* this file is part of evince, a gnome document viewer
  *
+ *  Copyright (C) 2020 Germán Poo-Caamaño <gpoo gnome org>
  *  Copyright (C) 2007 Carlos Garcia Campos <carlosgc gnome org>
  *  Copyright (C) 2006 Julien Rebetez
  *
@@ -22,6 +23,11 @@
 #include <config.h>
 #include "ev-form-field.h"
 
+typedef struct
+{
+       gchar   *alt_ui_name;
+} EvFormFieldPrivate;
+
 static void ev_form_field_init                 (EvFormField               *field);
 static void ev_form_field_class_init           (EvFormFieldClass          *klass);
 static void ev_form_field_text_init            (EvFormFieldText           *field_text);
@@ -33,31 +39,35 @@ static void ev_form_field_choice_class_init    (EvFormFieldChoiceClass    *klass
 static void ev_form_field_signature_init       (EvFormFieldSignature      *field_choice);
 static void ev_form_field_signature_class_init (EvFormFieldSignatureClass *klass);
 
-G_DEFINE_ABSTRACT_TYPE (EvFormField, ev_form_field, G_TYPE_OBJECT)
 G_DEFINE_TYPE (EvFormFieldText, ev_form_field_text, EV_TYPE_FORM_FIELD)
 G_DEFINE_TYPE (EvFormFieldButton, ev_form_field_button, EV_TYPE_FORM_FIELD)
 G_DEFINE_TYPE (EvFormFieldChoice, ev_form_field_choice, EV_TYPE_FORM_FIELD)
+G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE (EvFormField, ev_form_field, G_TYPE_OBJECT)
 G_DEFINE_TYPE (EvFormFieldSignature, ev_form_field_signature, EV_TYPE_FORM_FIELD)
 
+#define GET_FIELD_PRIVATE(o) ev_form_field_get_instance_private (o)
 static void
 ev_form_field_init (EvFormField *field)
 {
+       EvFormFieldPrivate *priv = GET_FIELD_PRIVATE (field);
+
        field->page = NULL;
        field->changed = FALSE;
        field->is_read_only = FALSE;
-       field->alt_ui_name = NULL;
+       priv->alt_ui_name = NULL;
 }
 
 static void
 ev_form_field_finalize (GObject *object)
 {
        EvFormField *field = EV_FORM_FIELD (object);
+       EvFormFieldPrivate *priv = GET_FIELD_PRIVATE (field);
 
        g_object_unref (field->page);
        field->page = NULL;
 
        g_clear_object (&field->activation_link);
-       g_clear_pointer (&field->alt_ui_name, g_free);
+       g_clear_pointer (&priv->alt_ui_name, g_free);
 
        (* G_OBJECT_CLASS (ev_form_field_parent_class)->finalize) (object);
 }
@@ -70,6 +80,56 @@ ev_form_field_class_init (EvFormFieldClass *klass)
        object_class->finalize = ev_form_field_finalize;
 }
 
+/**
+ * ev_form_field_get_alternate_name
+ * @field: a #EvFormField
+ *
+ * Gets the alternate ui name of @field. This name is also commonly
+ * used by pdf producers/readers to show it as a tooltip when @field area
+ * is hovered by a pointing device (eg. mouse).
+ *
+ * Returns: (transfer none): a string.
+ *
+ * Since: 3.38
+ **/
+gchar *
+ev_form_field_get_alternate_name (EvFormField *field)
+{
+       EvFormFieldPrivate *priv;
+
+       g_return_val_if_fail (EV_IS_FORM_FIELD (field), NULL);
+
+       priv = GET_FIELD_PRIVATE (field);
+
+       return priv->alt_ui_name;
+}
+
+/**
+ * ev_form_field_set_alternate_name
+ * @field: a #EvFormField
+ *
+ * Sets the alternate ui name of @field. This name is also commonly
+ * used by pdf producers/readers to show it as a tooltip when @field area
+ * is hovered by a pointing device (eg. mouse).
+ *
+ * Since: 3.38
+ **/
+void
+ev_form_field_set_alternate_name (EvFormField *field,
+                                 gchar       *alternative_text)
+{
+       EvFormFieldPrivate *priv;
+
+       g_return_if_fail (EV_IS_FORM_FIELD (field));
+
+       priv = GET_FIELD_PRIVATE (field);
+
+       if (priv->alt_ui_name)
+               g_clear_pointer (&priv->alt_ui_name, g_free);
+
+       priv->alt_ui_name = alternative_text;
+}
+
 static void
 ev_form_field_text_finalize (GObject *object)
 {
diff --git a/libdocument/ev-form-field.h b/libdocument/ev-form-field.h
index 84344504..ae44b47f 100644
--- a/libdocument/ev-form-field.h
+++ b/libdocument/ev-form-field.h
@@ -113,7 +113,6 @@ struct _EvFormField
 
        EvPage  *page;
        gboolean changed;
-       gchar   *alt_ui_name;
 };
 
 struct _EvFormFieldClass
@@ -190,6 +189,9 @@ struct _EvFormFieldSignatureClass
 
 /* EvFormField base class */
 GType        ev_form_field_get_type           (void) G_GNUC_CONST;
+gchar       *ev_form_field_get_alternate_name (EvFormField *field);
+void         ev_form_field_set_alternate_name (EvFormField *field,
+                                              gchar       *alternative_text);
 
 /* EvFormFieldText */
 GType        ev_form_field_text_get_type      (void) G_GNUC_CONST;
diff --git a/libview/ev-view.c b/libview/ev-view.c
index e0171b4d..22ffdad3 100644
--- a/libview/ev-view.c
+++ b/libview/ev-view.c
@@ -2331,7 +2331,7 @@ ev_view_handle_cursor_over_xy (EvView *view, gint x, gint y)
                }
        }
 
-       if (link || annot || (field && field->alt_ui_name))
+       if (link || annot || (field && ev_form_field_get_alternate_name (field)))
                g_object_set (view, "has-tooltip", TRUE, NULL);
 }
 
@@ -5320,14 +5320,18 @@ ev_view_query_tooltip (GtkWidget  *widget,
        }
 
        field = ev_view_get_form_field_at_location (view, x, y);
-       if (field && field->alt_ui_name && *(field->alt_ui_name) != '\0') {
-               GdkRectangle field_area;
+       if (field != NULL) {
+               gchar *alt_ui_name = ev_form_field_get_alternate_name (field);
 
-               get_field_area (view, x, y, field, &field_area);
-               gtk_tooltip_set_text (tooltip, field->alt_ui_name);
-               gtk_tooltip_set_tip_area (tooltip, &field_area);
+               if (alt_ui_name && *(alt_ui_name) != '\0') {
+                       GdkRectangle field_area;
 
-               return TRUE;
+                       get_field_area (view, x, y, field, &field_area);
+                       gtk_tooltip_set_text (tooltip, alt_ui_name);
+                       gtk_tooltip_set_tip_area (tooltip, &field_area);
+
+                       return TRUE;
+               }
        }
 
        link = ev_view_get_link_at_location (view, x, y);