gtktextview.c

/* -*- Mode: C; c-file-style: "gnu"; tab-width: 8 -*- */
/* GTK - The GIMP Toolkit
 * gtktextview.c Copyright (C) 2000 Red Hat, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library. If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * Modified by the GTK+ Team and others 1997-2000.  See the AUTHORS
 * file for a list of people on the GTK+ Team.  See the ChangeLog
 * files for a list of changes.  These files are distributed with
 * GTK+ at ftp://ftp.gtk.org/pub/gtk/.
 */

#include "config.h"

#include "gtktextviewprivate.h"

#include <string.h>

#include "gtkadjustmentprivate.h"
#include "gtkcsscolorvalueprivate.h"
#include "gtkdebug.h"
#include "gtkdragsourceprivate.h"
#include "gtkdropcontrollermotion.h"
#include "gtkintl.h"
#include "gtkmain.h"
#include "gtkmarshalers.h"
#include "gtkrenderbackgroundprivate.h"
#include "gtksettings.h"
#include "gtktextiterprivate.h"
#include "gtkimmulticontext.h"
#include "gtkprivate.h"
#include "gtktextutil.h"
#include "gtkwidgetprivate.h"
#include "gtkwindow.h"
#include "gtkscrollable.h"
#include "gtktypebuiltins.h"
#include "gtktextviewchildprivate.h"
#include "gtktexthandleprivate.h"
#include "gtkstylecontextprivate.h"
#include "gtkpopover.h"
#include "gtkmagnifierprivate.h"
#include "gtkemojichooser.h"
#include "gtkpango.h"
#include "gtknative.h"
#include "gtkwidgetprivate.h"
#include "gtkjoinedmenuprivate.h"
#include "gtkcsslineheightvalueprivate.h"
#include "gtkcssenumvalueprivate.h"


/**
 * GtkTextView:
 *
 * A widget that displays the contents of a [class@Gtk.TextBuffer].
 *
 * ![An example GtkTextview](multiline-text.png)
 *
 * You may wish to begin by reading the [conceptual overview](section-text-widget.html),
 * which gives an overview of all the objects and data types related to the
 * text widget and how they work together.
 *
 * ## CSS nodes
 *
 * ```
 * textview.view
 * ├── border.top
 * ├── border.left
 * ├── text
 * │   ╰── [selection]
 * ├── border.right
 * ├── border.bottom
 * ╰── [window.popup]
 * ```
 *
 * `GtkTextView` has a main css node with name textview and style class .view,
 * and subnodes for each of the border windows, and the main text area,
 * with names border and text, respectively. The border nodes each get
 * one of the style classes .left, .right, .top or .bottom.
 *
 * A node representing the selection will appear below the text node.
 *
 * If a context menu is opened, the window node will appear as a subnode
 * of the main node.
 *
 * ## Accessibility
 *
 * `GtkTextView` uses the %GTK_ACCESSIBLE_ROLE_TEXT_BOX role.
 */

/* How scrolling, validation, exposes, etc. work.
 *
 * The expose_event handler has the invariant that the onscreen lines
 * have been validated.
 *
 * There are two ways that onscreen lines can become invalid. The first
 * is to change which lines are onscreen. This happens when the value
 * of a scroll adjustment changes. So the code path begins in
 * gtk_text_view_value_changed() and goes like this:
 *   - gdk_surface_scroll() to reflect the new adjustment value
 *   - validate the lines that were moved onscreen
 *   - gdk_surface_process_updates() to handle the exposes immediately
 *
 * The second way is that you get the “invalidated” signal from the layout,
 * indicating that lines have become invalid. This code path begins in
 * invalidated_handler() and goes like this:
 *   - install high-priority idle which does the rest of the steps
 *   - if a scroll is pending from scroll_to_mark(), do the scroll,
 *     jumping to the gtk_text_view_value_changed() code path
 *   - otherwise, validate the onscreen lines
 *   - DO NOT process updates
 *
 * In both cases, validating the onscreen lines can trigger a scroll
 * due to maintaining the first_para on the top of the screen.
 * If validation triggers a scroll, we jump to the top of the code path
 * for value_changed, and bail out of the current code path.
 *
 * Also, in size_allocate, if we invalidate some lines from changing
 * the layout width, we need to go ahead and run the high-priority idle,
 * because GTK sends exposes right after doing the size allocates without
 * returning to the main loop. This is also why the high-priority idle
 * is at a higher priority than resizing.
 *
 */

#if 0
#define DEBUG_VALIDATION_AND_SCROLLING
#endif

#ifdef DEBUG_VALIDATION_AND_SCROLLING
#define DV(x) (x)
#else
#define DV(x)
#endif

#define SCREEN_WIDTH(widget) text_window_get_width (GTK_TEXT_VIEW (widget)->priv->text_window)
#define SCREEN_HEIGHT(widget) text_window_get_height (GTK_TEXT_VIEW (widget)->priv->text_window)

#define SPACE_FOR_CURSOR 1

typedef struct _GtkTextWindow GtkTextWindow;
typedef struct _GtkTextPendingScroll GtkTextPendingScroll;

enum
{
  TEXT_HANDLE_CURSOR,
  TEXT_HANDLE_SELECTION_BOUND,
  TEXT_HANDLE_N_HANDLES
};

struct _GtkTextViewPrivate
{
  GtkTextLayout *layout;
  GtkTextBuffer *buffer;

  guint blink_time;  /* time in msec the cursor has blinked since last user event */
  guint im_spot_idle;
  char *im_module;

  int dnd_x;
  int dnd_y;

  GtkTextHandle *text_handles[TEXT_HANDLE_N_HANDLES];
  GtkWidget *selection_bubble;
  guint selection_bubble_timeout_id;

  GtkWidget *magnifier_popover;
  GtkWidget *magnifier;

  GtkBorder border_window_size;
  GtkTextWindow *text_window;

  GQueue anchored_children;

  GtkTextViewChild *left_child;
  GtkTextViewChild *right_child;
  GtkTextViewChild *top_child;
  GtkTextViewChild *bottom_child;
  GtkTextViewChild *center_child;

  GtkAdjustment *hadjustment;
  GtkAdjustment *vadjustment;

  /* X offset between widget coordinates and buffer coordinates
   * taking left_padding in account
   */
  int xoffset;

  /* Y offset between widget coordinates and buffer coordinates
   * taking top_padding and top_margin in account
   */
  int yoffset;

  /* Width and height of the buffer */
  int width;
  int height;

  /* The virtual cursor position is normally the same as the
   * actual (strong) cursor position, except in two circumstances:
   *
   * a) When the cursor is moved vertically with the keyboard
   * b) When the text view is scrolled with the keyboard
   *
   * In case a), virtual_cursor_x is preserved, but not virtual_cursor_y
   * In case b), both virtual_cursor_x and virtual_cursor_y are preserved.
   */
  int virtual_cursor_x;   /* -1 means use actual cursor position */
  int virtual_cursor_y;   /* -1 means use actual cursor position */

  GtkTextMark *first_para_mark; /* Mark at the beginning of the first onscreen paragraph */
  int first_para_pixels;       /* Offset of top of screen in the first onscreen paragraph */

  guint64 blink_start_time;
  guint blink_tick;
  float cursor_alpha;

  guint scroll_timeout;

  guint first_validate_idle;        /* Idle to revalidate onscreen portion, runs before resize */
  guint incremental_validate_idle;  /* Idle to revalidate offscreen portions, runs after redraw */

  /* Mark for drop target */
  GtkTextMark *dnd_mark;

  /* Mark for selection of drag source */
  GtkTextMark *dnd_drag_begin_mark;
  GtkTextMark *dnd_drag_end_mark;

  GtkIMContext *im_context;
  GtkWidget *popup_menu;
  GMenuModel *extra_menu;

  GtkTextPendingScroll *pending_scroll;

  GtkGesture *drag_gesture;
  GtkEventController *key_controller;

  GtkCssNode *selection_node;

  GdkDrag *drag;

  /* Default style settings */
  int pixels_above_lines;
  int pixels_below_lines;
  int pixels_inside_wrap;
  GtkWrapMode wrap_mode;
  GtkJustification justify;

  int left_margin;
  int right_margin;
  int top_margin;
  int bottom_margin;
  int left_padding;
  int right_padding;
  int top_padding;
  int bottom_padding;

  int indent;

  guint32 obscured_cursor_timestamp;

  gint64 handle_place_time;
  PangoTabArray *tabs;

  guint editable : 1;

  guint overwrite_mode : 1;
  guint cursor_visible : 1;

  /* if we have reset the IM since the last character entered */
  guint need_im_reset : 1;

  guint accepts_tab : 1;

  /* debug flag - means that we've validated onscreen since the
   * last "invalidate" signal from the layout
   */
  guint onscreen_validated : 1;

  guint mouse_cursor_obscured : 1;

  guint scroll_after_paste : 1;

  guint text_handles_enabled : 1;

  /* GtkScrollablePolicy needs to be checked when
   * driving the scrollable adjustment values */
  guint hscroll_policy : 1;
  guint vscroll_policy : 1;
  guint cursor_handle_dragged : 1;
  guint selection_handle_dragged : 1;
};

struct _GtkTextPendingScroll
{
  GtkTextMark   *mark;
  double         within_margin;
  gboolean       use_align;
  double         xalign;
  double         yalign;
};

typedef enum
{
  SELECT_CHARACTERS,
  SELECT_WORDS,
  SELECT_LINES
} SelectionGranularity;

enum
{
  MOVE_CURSOR,
  PAGE_HORIZONTALLY,
  SET_ANCHOR,
  INSERT_AT_CURSOR,
  DELETE_FROM_CURSOR,
  BACKSPACE,
  CUT_CLIPBOARD,
  COPY_CLIPBOARD,
  PASTE_CLIPBOARD,
  TOGGLE_OVERWRITE,
  MOVE_VIEWPORT,
  SELECT_ALL,
  TOGGLE_CURSOR_VISIBLE,
  PREEDIT_CHANGED,
  EXTEND_SELECTION,
  INSERT_EMOJI,
  LAST_SIGNAL
};

enum
{
  PROP_0,
  PROP_PIXELS_ABOVE_LINES,
  PROP_PIXELS_BELOW_LINES,
  PROP_PIXELS_INSIDE_WRAP,
  PROP_EDITABLE,
  PROP_WRAP_MODE,
  PROP_JUSTIFICATION,
  PROP_LEFT_MARGIN,
  PROP_RIGHT_MARGIN,
  PROP_TOP_MARGIN,
  PROP_BOTTOM_MARGIN,
  PROP_INDENT,
  PROP_TABS,
  PROP_CURSOR_VISIBLE,
  PROP_BUFFER,
  PROP_OVERWRITE,
  PROP_ACCEPTS_TAB,
  PROP_IM_MODULE,
  PROP_HADJUSTMENT,
  PROP_VADJUSTMENT,
  PROP_HSCROLL_POLICY,
  PROP_VSCROLL_POLICY,
  PROP_INPUT_PURPOSE,
  PROP_INPUT_HINTS,
  PROP_MONOSPACE,
  PROP_EXTRA_MENU
};

static GQuark quark_text_selection_data = 0;
static GQuark quark_gtk_signal = 0;
static GQuark quark_text_view_child = 0;

static void gtk_text_view_finalize             (GObject         *object);
static void gtk_text_view_set_property         (GObject         *object,
						guint            prop_id,
						const GValue    *value,
						GParamSpec      *pspec);
static void gtk_text_view_get_property         (GObject         *object,
						guint            prop_id,
						GValue          *value,
						GParamSpec      *pspec);
static void gtk_text_view_dispose              (GObject         *object);
static void gtk_text_view_measure (GtkWidget      *widget,
                                   GtkOrientation  orientation,
                                   int             for_size,
                                   int            *minimum,
                                   int            *natural,
                                   int            *minimum_baseline,
                                   int            *natural_baseline);
static void gtk_text_view_size_allocate        (GtkWidget           *widget,
                                                int                  width,
                                                int                  height,
                                                int                  baseline);
static void gtk_text_view_realize              (GtkWidget           *widget);
static void gtk_text_view_unrealize            (GtkWidget           *widget);
static void gtk_text_view_map                  (GtkWidget           *widget);
static void gtk_text_view_css_changed          (GtkWidget           *widget,
                                                GtkCssStyleChange   *change);
static void gtk_text_view_direction_changed    (GtkWidget        *widget,
                                                GtkTextDirection  previous_direction);
static void gtk_text_view_system_setting_changed (GtkWidget           *widget,
                                                  GtkSystemSetting     setting);
static void gtk_text_view_state_flags_changed  (GtkWidget        *widget,
					        GtkStateFlags     previous_state);

static void gtk_text_view_click_gesture_pressed (GtkGestureClick *gesture,
                                                      int                   n_press,
                                                      double                x,
                                                      double                y,
                                                      GtkTextView          *text_view);
static void gtk_text_view_drag_gesture_update        (GtkGestureDrag *gesture,
                                                      double          offset_x,
                                                      double          offset_y,
                                                      GtkTextView    *text_view);
static void gtk_text_view_drag_gesture_end           (GtkGestureDrag *gesture,
                                                      double          offset_x,
                                                      double          offset_y,
                                                      GtkTextView    *text_view);

static gboolean gtk_text_view_key_controller_key_pressed  (GtkEventControllerKey *controller,
                                                           guint                  keyval,
                                                           guint                  keycode,
                                                           GdkModifierType        state,
                                                           GtkTextView           *text_view);
static void     gtk_text_view_key_controller_im_update    (GtkEventControllerKey *controller,
                                                           GtkTextView           *text_view);

static void gtk_text_view_focus_in             (GtkWidget            *widget);
static void gtk_text_view_focus_out            (GtkWidget            *widget);
static void gtk_text_view_motion               (GtkEventController *controller,
                                                double              x,
                                                double              y,
                                                gpointer            user_data);
static void gtk_text_view_snapshot             (GtkWidget        *widget,
                                                GtkSnapshot      *snapshot);
static void gtk_text_view_select_all           (GtkWidget        *widget,
                                                gboolean          select);
static gboolean get_middle_click_paste         (GtkTextView      *text_view);

static GtkTextBuffer* gtk_text_view_create_buffer (GtkTextView   *text_view);

/* Target side drag signals */
static void     gtk_text_view_drag_leave         (GtkDropTarget    *dest,
                                                  GtkTextView      *text_view);
static GdkDragAction
                gtk_text_view_drag_motion        (GtkDropTarget    *dest,
                                                  double            x,
                                                  double            y,
                                                  GtkTextView      *text_view);
static gboolean gtk_text_view_drag_drop          (GtkDropTarget    *dest,
                                                  const GValue     *value,
                                                  double            x,
                                                  double            y,
                                                  GtkTextView      *text_view);

static void gtk_text_view_popup_menu        (GtkWidget  *widget,
                                             const char *action_name,
                                             GVariant   *parameters);
static void gtk_text_view_move_cursor       (GtkTextView           *text_view,
                                             GtkMovementStep        step,
                                             int                    count,
                                             gboolean               extend_selection);
static void gtk_text_view_move_viewport     (GtkTextView           *text_view,
                                             GtkScrollStep          step,
                                             int                    count);
static void gtk_text_view_set_anchor       (GtkTextView           *text_view);
static gboolean gtk_text_view_scroll_pages (GtkTextView           *text_view,
                                            int                    count,
                                            gboolean               extend_selection);
static gboolean gtk_text_view_scroll_hpages(GtkTextView           *text_view,
                                            int                    count,
                                            gboolean               extend_selection);
static void gtk_text_view_insert_at_cursor (GtkTextView           *text_view,
                                            const char            *str);
static void gtk_text_view_delete_from_cursor (GtkTextView           *text_view,
                                              GtkDeleteType          type,
                                              int                    count);
static void gtk_text_view_backspace        (GtkTextView           *text_view);
static void gtk_text_view_cut_clipboard    (GtkTextView           *text_view);
static void gtk_text_view_copy_clipboard   (GtkTextView           *text_view);
static void gtk_text_view_paste_clipboard  (GtkTextView           *text_view);
static void gtk_text_view_toggle_overwrite (GtkTextView           *text_view);
static void gtk_text_view_toggle_cursor_visible (GtkTextView      *text_view);

static void gtk_text_view_unselect         (GtkTextView           *text_view);

static void     gtk_text_view_validate_onscreen     (GtkTextView        *text_view);
static void     gtk_text_view_get_first_para_iter   (GtkTextView        *text_view,
                                                     GtkTextIter        *iter);
static void     gtk_text_view_update_layout_width       (GtkTextView        *text_view);
static void     gtk_text_view_set_attributes_from_style (GtkTextView        *text_view,
                                                         GtkTextAttributes  *values);
static void     gtk_text_view_ensure_layout          (GtkTextView        *text_view);
static void     gtk_text_view_destroy_layout         (GtkTextView        *text_view);
static void     gtk_text_view_check_keymap_direction (GtkTextView        *text_view);
static void     gtk_text_view_start_selection_drag   (GtkTextView          *text_view,
                                                      const GtkTextIter    *iter,
                                                      SelectionGranularity  granularity,
                                                      gboolean              extends);
static gboolean gtk_text_view_end_selection_drag     (GtkTextView        *text_view);
static void     gtk_text_view_start_selection_dnd    (GtkTextView        *text_view,
                                                      const GtkTextIter  *iter,
                                                      GdkEvent           *event,
                                                      int                 x,
                                                      int                 y);
static void     gtk_text_view_check_cursor_blink     (GtkTextView        *text_view);
static void     gtk_text_view_pend_cursor_blink      (GtkTextView        *text_view);
static void     gtk_text_view_stop_cursor_blink      (GtkTextView        *text_view);
static void     gtk_text_view_reset_blink_time       (GtkTextView        *text_view);

static void     gtk_text_view_value_changed                (GtkAdjustment *adjustment,
							    GtkTextView   *view);
static void     gtk_text_view_commit_handler               (GtkIMContext  *context,
							    const char    *str,
							    GtkTextView   *text_view);
static void     gtk_text_view_commit_text                  (GtkTextView   *text_view,
                                                            const char    *text);
static void     gtk_text_view_preedit_start_handler        (GtkIMContext  *context,
                                                            GtkTextView   *text_view);
static void     gtk_text_view_preedit_changed_handler      (GtkIMContext  *context,
                                                            GtkTextView   *text_view);
static gboolean gtk_text_view_retrieve_surrounding_handler (GtkIMContext  *context,
							    GtkTextView   *text_view);
static gboolean gtk_text_view_delete_surrounding_handler   (GtkIMContext  *context,
							    int            offset,
							    int            n_chars,
							    GtkTextView   *text_view);

static void gtk_text_view_mark_set_handler       (GtkTextBuffer     *buffer,
                                                  const GtkTextIter *location,
                                                  GtkTextMark       *mark,
                                                  gpointer           data);
static void gtk_text_view_paste_done_handler     (GtkTextBuffer     *buffer,
                                                  GdkClipboard      *clipboard,
                                                  gpointer           data);
static void gtk_text_view_buffer_changed_handler (GtkTextBuffer     *buffer,
                                                  gpointer           data);
static void gtk_text_view_buffer_notify_redo     (GtkTextBuffer     *buffer,
                                                  GParamSpec        *pspec,
                                                  GtkTextView       *view);
static void gtk_text_view_buffer_notify_undo     (GtkTextBuffer     *buffer,
                                                  GParamSpec        *pspec,
                                                  GtkTextView       *view);
static void gtk_text_view_get_virtual_cursor_pos (GtkTextView       *text_view,
                                                  GtkTextIter       *cursor,
                                                  int               *x,
                                                  int               *y);
static void gtk_text_view_set_virtual_cursor_pos (GtkTextView       *text_view,
                                                  int                x,
                                                  int                y);

static void gtk_text_view_do_popup               (GtkTextView       *text_view,
						  GdkEvent          *event);

static void cancel_pending_scroll                (GtkTextView   *text_view);
static void gtk_text_view_queue_scroll           (GtkTextView   *text_view,
                                                  GtkTextMark   *mark,
                                                  double         within_margin,
                                                  gboolean       use_align,
                                                  double         xalign,
                                                  double         yalign);

static gboolean gtk_text_view_flush_scroll         (GtkTextView *text_view);
static void     gtk_text_view_update_adjustments   (GtkTextView *text_view);
static void     gtk_text_view_invalidate           (GtkTextView *text_view);
static void     gtk_text_view_flush_first_validate (GtkTextView *text_view);

static void     gtk_text_view_set_hadjustment        (GtkTextView   *text_view,
                                                      GtkAdjustment *adjustment);
static void     gtk_text_view_set_vadjustment        (GtkTextView   *text_view,
                                                      GtkAdjustment *adjustment);
static void     gtk_text_view_set_hadjustment_values (GtkTextView   *text_view);
static void     gtk_text_view_set_vadjustment_values (GtkTextView   *text_view);

static void gtk_text_view_update_im_spot_location (GtkTextView *text_view);
static void gtk_text_view_insert_emoji (GtkTextView *text_view);

static void update_node_ordering (GtkWidget    *widget);
static void gtk_text_view_update_pango_contexts (GtkTextView *text_view);

/* GtkTextHandle handlers */
static void gtk_text_view_handle_drag_started  (GtkTextHandle         *handle,
                                                GtkTextView           *text_view);
static void gtk_text_view_handle_dragged       (GtkTextHandle         *handle,
                                                int                    x,
                                                int                    y,
                                                GtkTextView           *text_view);
static void gtk_text_view_handle_drag_finished (GtkTextHandle         *handle,
                                                GtkTextView           *text_view);
static void gtk_text_view_update_handles       (GtkTextView           *text_view);

static void gtk_text_view_selection_bubble_popup_unset (GtkTextView *text_view);
static void gtk_text_view_selection_bubble_popup_set   (GtkTextView *text_view);

static gboolean gtk_text_view_extend_selection (GtkTextView            *text_view,
                                                GtkTextExtendSelection  granularity,
                                                const GtkTextIter      *location,
                                                GtkTextIter            *start,
                                                GtkTextIter            *end);
static void extend_selection (GtkTextView          *text_view,
                              SelectionGranularity  granularity,
                              const GtkTextIter    *location,
                              GtkTextIter          *start,
                              GtkTextIter          *end);


static void gtk_text_view_update_clipboard_actions (GtkTextView *text_view);
static void gtk_text_view_update_emoji_action      (GtkTextView *text_view);

static void gtk_text_view_activate_clipboard_cut        (GtkWidget  *widget,
                                                         const char *action_name,
                                                         GVariant   *parameter);
static void gtk_text_view_activate_clipboard_copy       (GtkWidget  *widget,
                                                         const char *action_name,
                                                         GVariant   *parameter);
static void gtk_text_view_activate_clipboard_paste      (GtkWidget  *widget,
                                                         const char *action_name,
                                                         GVariant   *parameter);
static void gtk_text_view_activate_selection_delete     (GtkWidget  *widget,
                                                         const char *action_name,
                                                         GVariant   *parameter);
static void gtk_text_view_activate_selection_select_all (GtkWidget  *widget,
                                                         const char *action_name,
                                                         GVariant   *parameter);
static void gtk_text_view_activate_misc_insert_emoji    (GtkWidget  *widget,
                                                         const char *action_name,
                                                         GVariant   *parameter);

static void gtk_text_view_real_undo (GtkWidget   *widget,
                                     const char *action_name,
                                     GVariant    *parameter);
static void gtk_text_view_real_redo (GtkWidget   *widget,
                                     const char *action_name,
                                     GVariant    *parameter);


/* FIXME probably need the focus methods. */

typedef struct
{
  GList               link;
  GtkWidget          *widget;
  GtkTextChildAnchor *anchor;
  int                 from_top_of_line;
  int                 from_left_of_buffer;
} AnchoredChild;

static AnchoredChild *anchored_child_new  (GtkWidget          *child,
                                           GtkTextChildAnchor *anchor,
                                           GtkTextLayout      *layout);
static void           anchored_child_free (AnchoredChild      *child);

struct _GtkTextWindow
{
  GtkTextWindowType type;
  GtkWidget *widget;
  GtkCssNode *css_node;
  GdkRectangle allocation;
};

static GtkTextWindow *text_window_new             (GtkWidget         *widget);
static void           text_window_free            (GtkTextWindow     *win);
static void           text_window_size_allocate   (GtkTextWindow     *win,
                                                   GdkRectangle      *rect);
static int            text_window_get_width       (GtkTextWindow     *win);
static int            text_window_get_height      (GtkTextWindow     *win);


static guint signals[LAST_SIGNAL] = { 0 };

G_DEFINE_TYPE_WITH_CODE (GtkTextView, gtk_text_view, GTK_TYPE_WIDGET,
                         G_ADD_PRIVATE (GtkTextView)
                         G_IMPLEMENT_INTERFACE (GTK_TYPE_SCROLLABLE, NULL))

static GtkTextBuffer*
get_buffer (GtkTextView *text_view)
{
  if (text_view->priv->buffer == NULL)
    {
      GtkTextBuffer *b;
      b = GTK_TEXT_VIEW_GET_CLASS (text_view)->create_buffer (text_view);
      gtk_text_view_set_buffer (text_view, b);
      g_object_unref (b);
    }

  return text_view->priv->buffer;
}

#define UPPER_OFFSET_ANCHOR 0.8
#define LOWER_OFFSET_ANCHOR 0.2

static gboolean
check_scroll (double offset, GtkAdjustment *adjustment)
{
  if ((offset > UPPER_OFFSET_ANCHOR &&
       gtk_adjustment_get_value (adjustment) + gtk_adjustment_get_page_size (adjustment) < gtk_adjustment_get_upper (adjustment)) ||
      (offset < LOWER_OFFSET_ANCHOR &&
       gtk_adjustment_get_value (adjustment) > gtk_adjustment_get_lower (adjustment)))
    return TRUE;

  return FALSE;
}

static int
gtk_text_view_drop_motion_scroll_timeout (gpointer data)
{
  GtkTextView *text_view;
  GtkTextViewPrivate *priv;
  GtkTextIter newplace;
  double pointer_xoffset, pointer_yoffset;

  text_view = GTK_TEXT_VIEW (data);
  priv = text_view->priv;

  gtk_text_layout_get_iter_at_pixel (priv->layout,
                                     &newplace,
                                     priv->dnd_x + priv->xoffset,
                                     priv->dnd_y + priv->yoffset);

  gtk_text_buffer_move_mark (get_buffer (text_view), priv->dnd_mark, &newplace);

  pointer_xoffset = (double) priv->dnd_x / text_window_get_width (priv->text_window);
  pointer_yoffset = (double) priv->dnd_y / text_window_get_height (priv->text_window);

  if (check_scroll (pointer_xoffset, priv->hadjustment) ||
      check_scroll (pointer_yoffset, priv->vadjustment))
    {
      /* do not make offsets surpass lower nor upper anchors, this makes
       * scrolling speed relative to the distance of the pointer to the
       * anchors when it moves beyond them.
       */
      pointer_xoffset = CLAMP (pointer_xoffset, LOWER_OFFSET_ANCHOR, UPPER_OFFSET_ANCHOR);
      pointer_yoffset = CLAMP (pointer_yoffset, LOWER_OFFSET_ANCHOR, UPPER_OFFSET_ANCHOR);

      gtk_text_view_scroll_to_mark (text_view,
                                    priv->dnd_mark,
                                    0., TRUE, pointer_xoffset, pointer_yoffset);
    }

  return G_SOURCE_CONTINUE;
}

static void
gtk_text_view_drop_scroll_motion (GtkDropControllerMotion *motion,
                                  double                   x,
                                  double                   y,
                                  GtkTextView             *self)
{
  GtkTextViewPrivate *priv = self->priv;
  GdkRectangle target_rect;

  target_rect = priv->text_window->allocation;

  if (x < target_rect.x ||
      y < target_rect.y ||
      x > (target_rect.x + target_rect.width) ||
      y > (target_rect.y + target_rect.height))
    {
      priv->dnd_x = priv->dnd_y = -1;
      g_clear_handle_id (&priv->scroll_timeout, g_source_remove);
      return;
    }

  /* DnD uses text window coords, so subtract extra widget
   * coords that happen e.g. when displaying line numbers.
   */
  priv->dnd_x = x - target_rect.x;
  priv->dnd_y = y - target_rect.y;

  if (!priv->scroll_timeout)
  {
    priv->scroll_timeout = g_timeout_add (100, gtk_text_view_drop_motion_scroll_timeout, self);
    gdk_source_set_static_name_by_id (priv->scroll_timeout, "[gtk] gtk_text_view_drop_motion_scroll_timeout");
  }
}

static void
gtk_text_view_drop_scroll_leave (GtkDropControllerMotion *motion,
                                 GtkTextView             *self)
{
  GtkTextViewPrivate *priv = self->priv;

  priv->dnd_x = priv->dnd_y = -1;
  g_clear_handle_id (&priv->scroll_timeout, g_source_remove);
}

static void
add_move_binding (GtkWidgetClass *widget_class,
                  guint           keyval,
                  guint           modmask,
                  GtkMovementStep step,
                  int             count)
{
  g_assert ((modmask & GDK_SHIFT_MASK) == 0);

  gtk_widget_class_add_binding_signal (widget_class,
                                       keyval, modmask,
                                       "move-cursor",
                                       "(iib)", step, count, FALSE);

  /* Selection-extending version */
  gtk_widget_class_add_binding_signal (widget_class,
                                       keyval, modmask | GDK_SHIFT_MASK,
                                       "move-cursor",
                                       "(iib)", step, count, TRUE);
}

static void
gtk_text_view_class_init (GtkTextViewClass *klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);

  /* Default handlers and virtual methods
   */
  gobject_class->set_property = gtk_text_view_set_property;
  gobject_class->get_property = gtk_text_view_get_property;
  gobject_class->finalize = gtk_text_view_finalize;
  gobject_class->dispose = gtk_text_view_dispose;

  widget_class->realize = gtk_text_view_realize;
  widget_class->unrealize = gtk_text_view_unrealize;
  widget_class->map = gtk_text_view_map;
  widget_class->css_changed = gtk_text_view_css_changed;
  widget_class->direction_changed = gtk_text_view_direction_changed;
  widget_class->system_setting_changed = gtk_text_view_system_setting_changed;
  widget_class->state_flags_changed = gtk_text_view_state_flags_changed;
  widget_class->measure = gtk_text_view_measure;
  widget_class->size_allocate = gtk_text_view_size_allocate;
  widget_class->snapshot = gtk_text_view_snapshot;

  klass->move_cursor = gtk_text_view_move_cursor;
  klass->set_anchor = gtk_text_view_set_anchor;
  klass->insert_at_cursor = gtk_text_view_insert_at_cursor;
  klass->delete_from_cursor = gtk_text_view_delete_from_cursor;
  klass->backspace = gtk_text_view_backspace;
  klass->cut_clipboard = gtk_text_view_cut_clipboard;
  klass->copy_clipboard = gtk_text_view_copy_clipboard;
  klass->paste_clipboard = gtk_text_view_paste_clipboard;
  klass->toggle_overwrite = gtk_text_view_toggle_overwrite;
  klass->create_buffer = gtk_text_view_create_buffer;
  klass->extend_selection = gtk_text_view_extend_selection;
  klass->insert_emoji = gtk_text_view_insert_emoji;

  /*
   * Properties
   */

  /**
   * GtkTextview:pixels-above-lines: (attributes org.gtk.Property.get=gtk_text_view_get_pixels_above_lines org.gtk.Property.set=gtk_text_view_set_pixels_above_lines)
   *
   * Pixels of blank space above paragraphs.
   */
  g_object_class_install_property (gobject_class,
                                   PROP_PIXELS_ABOVE_LINES,
                                   g_param_spec_int ("pixels-above-lines", NULL, NULL,
                                                     0, G_MAXINT, 0,
                                                     GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY));

  /**
   * GtkTextview:pixels-below-lines: (attributes org.gtk.Property.get=gtk_text_view_get_pixels_below_lines org.gtk.Property.set=gtk_text_view_set_pixels_below_lines)
   *
   * Pixels of blank space below paragraphs.
   */
  g_object_class_install_property (gobject_class,
                                   PROP_PIXELS_BELOW_LINES,
                                   g_param_spec_int ("pixels-below-lines", NULL, NULL,
                                                     0, G_MAXINT, 0,
                                                     GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY));

  /**
   * GtkTextview:pixels-inside-wrap: (attributes org.gtk.Property.get=gtk_text_view_get_pixels_inside_wrap org.gtk.Property.set=gtk_text_view_set_pixels_inside_wrap)
   *
   * Pixels of blank space between wrapped lines in a paragraph.
   */
  g_object_class_install_property (gobject_class,
                                   PROP_PIXELS_INSIDE_WRAP,
                                   g_param_spec_int ("pixels-inside-wrap", NULL, NULL,
                                                     0, G_MAXINT, 0,
                                                     GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY));

  /**
   * GtkTextview:editable: (attributes org.gtk.Property.get=gtk_text_view_get_editable org.gtk.Property.set=gtk_text_view_set_editable)
   *
   * Whether the text can be modified by the user.
   */
  g_object_class_install_property (gobject_class,
                                   PROP_EDITABLE,
                                   g_param_spec_boolean ("editable", NULL, NULL,
                                                         TRUE,
                                                         GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY));

  /**
   * GtkTextview:wrap-mode: (attributes org.gtk.Property.get=gtk_text_view_get_wrap_mode org.gtk.Property.set=gtk_text_view_set_wrap_mode)
   *
   * Whether to wrap lines never, at word boundaries, or at character boundaries.
   */
  g_object_class_install_property (gobject_class,
                                   PROP_WRAP_MODE,
                                   g_param_spec_enum ("wrap-mode", NULL, NULL,
                                                      GTK_TYPE_WRAP_MODE,
                                                      GTK_WRAP_NONE,
                                                      GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY));

  /**
   * GtkTextview:justification: (attributes org.gtk.Property.get=gtk_text_view_get_justification org.gtk.Property.set=gtk_text_view_set_justification)
   *
   * Left, right, or center justification.
   */
  g_object_class_install_property (gobject_class,
                                   PROP_JUSTIFICATION,
                                   g_param_spec_enum ("justification", NULL, NULL,
                                                      GTK_TYPE_JUSTIFICATION,
                                                      GTK_JUSTIFY_LEFT,
                                                      GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY));

  /**
   * GtkTextView:left-margin: (attributes org.gtk.Property.get=gtk_text_view_get_left_margin org.gtk.Property.set=gtk_text_view_set_left_margin)
   *
   * The default left margin for text in the text view.
   *
   * Tags in the buffer may override the default.
   *
   * Note that this property is confusingly named. In CSS terms,
   * the value set here is padding, and it is applied in addition
   * to the padding from the theme.
   */
  g_object_class_install_property (gobject_class,
                                   PROP_LEFT_MARGIN,
                                   g_param_spec_int ("left-margin", NULL, NULL,
                                                     0, G_MAXINT, 0,
                                                     GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY));

  /**
   * GtkTextView:right-margin: (attributes org.gtk.Property.get=gtk_text_view_get_right_margin org.gtk.Property.set=gtk_text_view_set_right_margin)
   *
   * The default right margin for text in the text view.
   *
   * Tags in the buffer may override the default.
   *
   * Note that this property is confusingly named. In CSS terms,
   * the value set here is padding, and it is applied in addition
   * to the padding from the theme.
   */
  g_object_class_install_property (gobject_class,
                                   PROP_RIGHT_MARGIN,
                                   g_param_spec_int ("right-margin", NULL, NULL,
                                                     0, G_MAXINT, 0,
                                                     GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY));

  /**
   * GtkTextView:top-margin: (attributes org.gtk.Property.get=gtk_text_view_get_top_margin org.gtk.Property.set=gtk_text_view_set_top_margin)
   *
   * The top margin for text in the text view.
   *
   * Note that this property is confusingly named. In CSS terms,
   * the value set here is padding, and it is applied in addition
   * to the padding from the theme.
   *
   * Don't confuse this property with [property@Gtk.Widget:margin-top].
   */
  g_object_class_install_property (gobject_class,
                                   PROP_TOP_MARGIN,
                                   g_param_spec_int ("top-margin", NULL, NULL,