[gnome-text-editor] sourceview: add plumbing to draw search bubbles

[Christian Hergert <chergert src gnome org>]

commit ae89fd62c06a7a8cad7287d645830d3120cddb81
Author: Christian Hergert <chergert redhat com>
Date:   Thu Jan 6 15:42:53 2022 -0800

    sourceview: add plumbing to draw search bubbles
    
    Currently, the gtk_text_view_get_iter_location() API does not take into
    account the line-height, so this code ported from Builder is not fully
    accurate as the line-height grows.
    
    However, it's nice to have a port here so that we can handle that later
    once the API is fixed.

 src/editor-source-view.c | 181 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 181 insertions(+)
---
diff --git a/src/editor-source-view.c b/src/editor-source-view.c
index 4ed5f4c..e397fc0 100644
--- a/src/editor-source-view.c
+++ b/src/editor-source-view.c
@@ -29,6 +29,9 @@
 #include "editor-spell-menu.h"
 #include "editor-utils-private.h"
 
+#define X_PAD 3
+#define Y_PAD 3
+
 struct _EditorSourceView
 {
   GtkSourceView parent_instance;
@@ -473,6 +476,181 @@ editor_source_view_action_delete_line (GtkWidget  *widget,
   gdk_clipboard_set_text (gtk_widget_get_primary_clipboard (widget), text);
 }
 
+static GtkSourceSearchContext *
+get_search_context (EditorSourceView *self)
+{
+  EditorPage *page = EDITOR_PAGE (gtk_widget_get_ancestor (GTK_WIDGET (self), EDITOR_TYPE_PAGE));
+
+  if (page->search_bar->context &&
+      gtk_source_search_context_get_highlight (page->search_bar->context))
+    return page->search_bar->context;
+
+  return NULL;
+}
+
+static inline void
+add_match (GtkTextView       *text_view,
+           cairo_region_t    *region,
+           const GtkTextIter *begin,
+           const GtkTextIter *end)
+{
+  GdkRectangle begin_rect;
+  GdkRectangle end_rect;
+  cairo_rectangle_int_t rect;
+
+  /* NOTE: @end is not inclusive of the match. */
+  if (gtk_text_iter_get_line (begin) == gtk_text_iter_get_line (end))
+    {
+      gtk_text_view_get_iter_location (text_view, begin, &begin_rect);
+      gtk_text_view_get_iter_location (text_view, end, &end_rect);
+      rect.x = begin_rect.x;
+      rect.y = begin_rect.y;
+      rect.width = end_rect.x - begin_rect.x;
+      rect.height = MAX (begin_rect.height, end_rect.height);
+
+      cairo_region_union_rectangle (region, &rect);
+
+      return;
+    }
+
+  /*
+   * TODO: Add support for multi-line matches. When @begin and @end are not
+   *       on the same line, we need to add the match region to @region so
+   *       ide_source_view_draw_search_bubbles() can draw search bubbles
+   *       around it.
+   */
+}
+
+static guint
+add_matches (GtkTextView            *text_view,
+             cairo_region_t         *region,
+             GtkSourceSearchContext *search_context,
+             const GtkTextIter      *begin,
+             const GtkTextIter      *end)
+{
+  GtkTextIter first_begin;
+  GtkTextIter new_begin;
+  GtkTextIter match_begin;
+  GtkTextIter match_end;
+  gboolean has_wrapped;
+  guint count = 1;
+
+  g_assert (GTK_IS_TEXT_VIEW (text_view));
+  g_assert (region != NULL);
+  g_assert (GTK_SOURCE_IS_SEARCH_CONTEXT (search_context));
+  g_assert (begin != NULL);
+  g_assert (end != NULL);
+
+  if (!gtk_source_search_context_forward (search_context,
+                                          begin,
+                                          &first_begin,
+                                          &match_end,
+                                          &has_wrapped))
+    return 0;
+
+  add_match (text_view, region, &first_begin, &match_end);
+
+  for (;;)
+    {
+      new_begin = match_end;
+
+      if (gtk_source_search_context_forward (search_context,
+                                             &new_begin,
+                                             &match_begin,
+                                             &match_end,
+                                             &has_wrapped) &&
+          (gtk_text_iter_compare (&match_begin, end) < 0) &&
+          (gtk_text_iter_compare (&first_begin, &match_begin) != 0))
+        {
+          add_match (text_view, region, &match_begin, &match_end);
+          count++;
+          continue;
+        }
+
+      break;
+    }
+
+  return count;
+}
+
+G_GNUC_UNUSED static void
+editor_source_view_draw_search_bubbles (EditorSourceView *self,
+                                        GtkSnapshot      *snapshot)
+{
+  GtkStyleContext *style_context;
+  cairo_region_t *clip_region;
+  cairo_region_t *match_region;
+  GtkSourceSearchContext *context;
+  GdkRectangle area;
+  GtkTextIter begin, end;
+
+  g_assert (EDITOR_IS_SOURCE_VIEW (self));
+  g_assert (GTK_IS_SNAPSHOT (snapshot));
+
+  if (!(context = get_search_context (self)))
+    return;
+
+  style_context = gtk_widget_get_style_context (GTK_WIDGET (self));
+
+  gtk_text_view_get_visible_rect (GTK_TEXT_VIEW (self), &area);
+  gtk_text_view_get_iter_at_location (GTK_TEXT_VIEW (self), &begin,
+                                      area.x, area.y);
+  gtk_text_view_get_iter_at_location (GTK_TEXT_VIEW (self), &end,
+                                      area.x + area.width,
+                                      area.y + area.height);
+
+  clip_region = cairo_region_create_rectangle (&area);
+  match_region = cairo_region_create ();
+
+  if (add_matches (GTK_TEXT_VIEW (self), match_region, context, &begin, &end))
+    {
+      int n_rects;
+
+      cairo_region_subtract (clip_region, match_region);
+
+      n_rects = cairo_region_num_rectangles (match_region);
+
+      gtk_style_context_save (style_context);
+      gtk_style_context_add_class (style_context, "search-match");
+      for (guint i = 0; i < n_rects; i++)
+        {
+          cairo_rectangle_int_t r;
+
+          cairo_region_get_rectangle (match_region, i, &r);
+
+          r.x -= X_PAD;
+          r.width += 2*X_PAD;
+          r.y -= Y_PAD;
+          r.height += 2*Y_PAD;
+
+          gtk_snapshot_render_background (snapshot, style_context, r.x, r.y, r.width, r.height);
+          gtk_snapshot_render_frame (snapshot, style_context, r.x, r.y, r.width, r.height);
+        }
+      gtk_style_context_restore (style_context);
+    }
+
+  cairo_region_destroy (clip_region);
+  cairo_region_destroy (match_region);
+}
+
+static void
+editor_source_view_snapshot_layer (GtkTextView      *text_view,
+                                   GtkTextViewLayer  layer,
+                                   GtkSnapshot      *snapshot)
+{
+  EditorSourceView *self = (EditorSourceView *)text_view;
+
+  g_assert (EDITOR_IS_SOURCE_VIEW (self));
+  g_assert (GTK_IS_SNAPSHOT (snapshot));
+
+  GTK_TEXT_VIEW_CLASS (editor_source_view_parent_class)->snapshot_layer (text_view, layer, snapshot);
+
+#if 0
+  if (layer == GTK_TEXT_VIEW_LAYER_BELOW_TEXT)
+    editor_source_view_draw_search_bubbles (self, snapshot);
+#endif
+}
+
 static void
 editor_source_view_constructed (GObject *object)
 {
@@ -552,12 +730,15 @@ editor_source_view_class_init (EditorSourceViewClass *klass)
 {
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
   GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+  GtkTextViewClass *text_view_class = GTK_TEXT_VIEW_CLASS (klass);
 
   object_class->constructed = editor_source_view_constructed;
   object_class->dispose = editor_source_view_dispose;
   object_class->get_property = editor_source_view_get_property;
   object_class->set_property = editor_source_view_set_property;
 
+  text_view_class->snapshot_layer = editor_source_view_snapshot_layer;
+
   properties [PROP_FONT_DESC] =
     g_param_spec_boxed ("font-desc",
                          "Font Description",