textlayout: introduce caching for GtkTextLineDisplay

This adds a GtkTextLineDisplayCache which can be used to cache a number
of GtkTextLineDisplay (and thus, PangoLayout) while displaying a view.

It uses a GSequence to track the position of the GtkTextLineDisplay
relative to each other, a MRU to cull the least recently used display,
and and a direct hashtable to lookup display by GtkTextLine.

We only cache lines that are to be displayed (!size_only). We may want to
either create a second collection of "size_only" lines to speed that up,
or determine that it is unnecessary (which is likely the case).

1 files changed, 59 insertions, 0 deletions

diff --git a/gtk/gtktextlinedisplaycacheprivate.h b/gtk/gtktextlinedisplaycacheprivate.h
new file mode 100644
index 0000000000..5639ec2070
--- /dev/null
+++ b/gtk/gtktextlinedisplaycacheprivate.h
@@ -0,0 +1,59 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
+ * Copyright (C) 2019 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/>.
+ */
+
+#ifndef __GTK_TEXT_LINE_DISPLAY_CACHE_PRIVATE_H__
+#define __GTK_TEXT_LINE_DISPLAY_CACHE_PRIVATE_H__
+
+#include "gtktextlayoutprivate.h"
+
+G_BEGIN_DECLS
+
+typedef struct _GtkTextLineDisplayCache GtkTextLineDisplayCache;
+
+GtkTextLineDisplayCache *gtk_text_line_display_cache_new                (void);
+void                     gtk_text_line_display_cache_free               (GtkTextLineDisplayCache *cache);
+GtkTextLineDisplay      *gtk_text_line_display_cache_get                (GtkTextLineDisplayCache *cache,
+                                                                         GtkTextLayout           *layout,
+                                                                         GtkTextLine             *line,
+                                                                         gboolean                 size_only);
+void                     gtk_text_line_display_cache_delay_eviction     (GtkTextLineDisplayCache *cache);
+void                     gtk_text_line_display_cache_set_cursor_line    (GtkTextLineDisplayCache *cache,
+                                                                         GtkTextLine             *line);
+void                     gtk_text_line_display_cache_invalidate         (GtkTextLineDisplayCache *cache);
+void                     gtk_text_line_display_cache_invalidate_cursors (GtkTextLineDisplayCache *cache,
+                                                                         GtkTextLine             *line);
+void                     gtk_text_line_display_cache_invalidate_display (GtkTextLineDisplayCache *cache,
+                                                                         GtkTextLineDisplay      *display,
+                                                                         gboolean                 cursors_only);
+void                     gtk_text_line_display_cache_invalidate_line    (GtkTextLineDisplayCache *cache,
+                                                                         GtkTextLine             *line);
+void                     gtk_text_line_display_cache_invalidate_range   (GtkTextLineDisplayCache *cache,
+                                                                         GtkTextLayout           *layout,
+                                                                         const GtkTextIter       *begin,
+                                                                         const GtkTextIter       *end,
+                                                                         gboolean                 cursors_only);
+void                     gtk_text_line_display_cache_invalidate_y_range (GtkTextLineDisplayCache *cache,
+                                                                         GtkTextLayout           *layout,
+                                                                         gint                     y,
+                                                                         gint                     height,
+                                                                         gboolean                 cursors_only);
+
+G_END_DECLS
+
+#endif /* __GTK_TEXT_LINE_DISPLAY_CACHE_PRIVATE_H__ */