[evince] libview: Implement support for moving text annotations.

[Carlos Garcia Campos <carlosgc src gnome org>]

commit 3439819eb1ac4b50ee10e92c4fb09e4fd696f01e
Author: Philipp Reinkemeier <philipp reinkemeier offis de>
Date:   Tue Jun 9 10:00:10 2015 +0200

    libview: Implement support for moving text annotations.
    
    This adds support for moving text annotations by simply
    dragging them to a new location.
    The call to ev_view_handle_annotation has been moved from callback
    ev_view_button_press_event to ev_view_button_release_event.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=649043

 libview/ev-view-private.h |    9 +++
 libview/ev-view.c         |  121 ++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 129 insertions(+), 1 deletions(-)
---
diff --git a/libview/ev-view-private.h b/libview/ev-view-private.h
index 5d4537d..a6862b1 100644
--- a/libview/ev-view-private.h
+++ b/libview/ev-view-private.h
@@ -122,6 +122,14 @@ typedef struct {
        EvAnnotation    *annot;
 } AddingAnnotInfo;
 
+typedef struct {
+       GdkPoint      start;
+       EvPoint       cursor_offset;
+       gboolean      annot_clicked;
+       gboolean      moving_annot;
+       EvAnnotation *annot;
+} MovingAnnotInfo;
+
 struct _EvView {
        GtkContainer layout;
 
@@ -217,6 +225,7 @@ struct _EvView {
        GList             *window_children;
        EvViewWindowChild *window_child_focus;
        AddingAnnotInfo    adding_annot_info;
+       MovingAnnotInfo    moving_annot_info;
 
        /* Focus */
        EvMapping *focused_element;
diff --git a/libview/ev-view.c b/libview/ev-view.c
index 9e5e0e0..6f2876d 100644
--- a/libview/ev-view.c
+++ b/libview/ev-view.c
@@ -5006,7 +5006,42 @@ ev_view_button_press_event (GtkWidget      *widget,
                        } else if ((media = ev_view_get_media_at_location (view, event->x, event->y))) {
                                ev_view_handle_media (view, media);
                        } else if ((annot = ev_view_get_annotation_at_location (view, event->x, event->y))) {
-                               ev_view_handle_annotation (view, annot, event->x, event->y, event->time);
+                               if (EV_IS_ANNOTATION_TEXT (annot)) {
+                                       EvRectangle  current_area;
+                                       GdkPoint     view_point;
+                                       EvPoint      doc_point;
+                                       GdkRectangle page_area;
+                                       GtkBorder    border;
+                                       guint        annot_page;
+
+                                       /* annot_clicked remembers that we clicked
+                                        * on an annotation. We need moving_annot
+                                        * to distinguish moving an annotation from
+                                        * showing its popup upon button release. */
+                                       view->moving_annot_info.annot_clicked = TRUE;
+                                       view->moving_annot_info.moving_annot = FALSE;
+                                       view->moving_annot_info.annot = annot;
+                                       ev_annotation_get_area (annot, &current_area);
+
+                                       view_point.x = event->x + view->scroll_x;
+                                       view_point.y = event->y + view->scroll_y;
+
+                                       /* Remember the coordinates of the button press event
+                                        * in order to implement a minimum threshold for moving
+                                        * annotations. */
+                                       view->moving_annot_info.start = view_point;
+                                       annot_page = ev_annotation_get_page_index (annot);
+                                       ev_view_get_page_extents (view, annot_page, &page_area, &border);
+                                       _ev_view_transform_view_point_to_doc_point (view, &view_point,
+                                                                                   &page_area, &border,
+                                                                                   &doc_point.x, 
&doc_point.y);
+
+                                       /* Remember the offset of the cursor with respect to
+                                        * the annotation area in order to prevent the annotation from
+                                        * jumping under the cursor while moving it. */
+                                       view->moving_annot_info.cursor_offset.x = doc_point.x - 
current_area.x1;
+                                       view->moving_annot_info.cursor_offset.y = doc_point.y - 
current_area.y1;
+                               }
                        } else if ((field = ev_view_get_form_field_at_location (view, event->x, event->y))) {
                                ev_view_remove_all_form_fields (view);
                                ev_view_handle_form_field (view, field);
@@ -5406,6 +5441,69 @@ ev_view_motion_notify_event (GtkWidget      *widget,
 
                        /* FIXME: reload only annotation area */
                        ev_view_reload_page (view, annot_page, NULL);
+               } else if (view->moving_annot_info.annot_clicked) {
+                       EvRectangle  rect;
+                       EvRectangle  current_area;
+                       GdkPoint     view_point;
+                       EvPoint      doc_point;
+                       GdkRectangle page_area;
+                       GtkBorder    border;
+                       guint        annot_page;
+                       double       page_width;
+                       double       page_height;
+
+                       if (!view->moving_annot_info.annot)
+                               return TRUE;
+
+                       view_point.x = event->x + view->scroll_x;
+                       view_point.y = event->y + view->scroll_y;
+
+                       if (!view->moving_annot_info.moving_annot) {
+                               /* Only move the annotation if the threshold is exceeded */
+                               if (!gtk_drag_check_threshold (widget,
+                                                              view->moving_annot_info.start.x,
+                                                              view->moving_annot_info.start.y,
+                                                              view_point.x,
+                                                              view_point.y))
+                                       return TRUE;
+                               view->moving_annot_info.moving_annot = TRUE;
+                       }
+
+                       ev_annotation_get_area (view->moving_annot_info.annot, &current_area);
+                       annot_page = ev_annotation_get_page_index (view->moving_annot_info.annot);
+                       ev_view_get_page_extents (view, annot_page, &page_area, &border);
+                       _ev_view_transform_view_point_to_doc_point (view, &view_point, &page_area, &border,
+                                                                   &doc_point.x, &doc_point.y);
+
+                       ev_document_get_page_size (view->document, annot_page, &page_width, &page_height);
+
+                       rect.x1 = MAX (0, doc_point.x - view->moving_annot_info.cursor_offset.x);
+                       rect.y1 = MAX (0, doc_point.y - view->moving_annot_info.cursor_offset.y);
+                       rect.x2 = rect.x1 + current_area.x2 - current_area.x1;
+                       rect.y2 = rect.y1 + current_area.y2 - current_area.y1;
+
+                       /* Prevent the annotation from being moved off the page */
+                       if (rect.x2 > page_width) {
+                               rect.x2 = page_width;
+                               rect.x1 = page_width - current_area.x2 + current_area.x1;
+                       }
+                       if (rect.y2 > page_height) {
+                               rect.y2 = page_height;
+                               rect.y1 = page_height - current_area.y2 + current_area.y1;
+                       }
+
+                       /* Take the mutex before set_area, because the notify signal
+                        * updates the mappings in the backend */
+                       ev_document_doc_mutex_lock ();
+                       if (ev_annotation_set_area (view->moving_annot_info.annot, &rect)) {
+                               ev_document_annotations_save_annotation (EV_DOCUMENT_ANNOTATIONS 
(view->document),
+                                                                        view->moving_annot_info.annot,
+                                                                        EV_ANNOTATIONS_SAVE_AREA);
+                       }
+                       ev_document_doc_mutex_unlock ();
+
+                       /* FIXME: reload only annotation area */
+                       ev_view_reload_page (view, annot_page, NULL);
                } else {
                        /* Schedule timeout to scroll during selection and additionally
                         * scroll once to allow arbitrary speed. */
@@ -5589,6 +5687,27 @@ ev_view_button_release_event (GtkWidget      *widget,
                return FALSE;
        }
 
+       if (view->moving_annot_info.annot_clicked) {
+               if (view->moving_annot_info.moving_annot)
+                       ev_view_handle_cursor_over_xy (view, event->x, event->y);
+               else
+                       ev_view_handle_annotation (view, view->moving_annot_info.annot, event->x, event->y, 
event->time);
+
+               view->moving_annot_info.annot_clicked = FALSE;
+               view->moving_annot_info.moving_annot = FALSE;
+               view->moving_annot_info.annot = NULL;
+               view->pressed_button = -1;
+
+               return FALSE;
+       }
+
+       if (view->pressed_button == 1) {
+               EvAnnotation *annot = ev_view_get_annotation_at_location (view, event->x, event->y);
+
+               if (annot)
+                       ev_view_handle_annotation (view, annot, event->x, event->y, event->time);
+       }
+
        if (view->pressed_button == 2) {
                ev_view_handle_cursor_over_xy (view, event->x, event->y);
        }