[pango/visible-things: 21/32] Add an attribute for showing invisible chars

[Matthias Clasen <matthiasc src gnome org>]

commit 3c1a325fca4867cdc7fabfab3a804c0798ce8cb2
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Jul 13 15:49:25 2019 -0400

    Add an attribute for showing invisible chars
    
    Allow to opt-in to showing spaces, line breaks,
    and default-ignorable chars, separately.

 docs/pango-sections.txt  |  2 ++
 pango/pango-attributes.c | 25 +++++++++++++++++++++++++
 pango/pango-attributes.h | 25 ++++++++++++++++++++++++-
 3 files changed, 51 insertions(+), 1 deletion(-)
---
diff --git a/docs/pango-sections.txt b/docs/pango-sections.txt
index 5050a1f3..51e85095 100644
--- a/docs/pango-sections.txt
+++ b/docs/pango-sections.txt
@@ -415,6 +415,8 @@ pango_color_parse
 pango_color_copy
 pango_color_free
 pango_color_to_string
+PangoShowFlags
+pango_attr_show_new
 <SUBSECTION>
 PangoAttrList
 PANGO_TYPE_ATTR_LIST
diff --git a/pango/pango-attributes.c b/pango/pango-attributes.c
index 4db959fd..9acd6cf8 100644
--- a/pango/pango-attributes.c
+++ b/pango/pango-attributes.c
@@ -1206,6 +1206,31 @@ pango_attr_allow_breaks_new (gboolean allow_breaks)
   return pango_attr_int_new (&klass, (int)allow_breaks);
 }
 
+/**
+ * pango_attr_show_new:
+ * @show: #PangoShowFlags to apply
+ *
+ * Create a new attribute that influences how invisible
+ * characters are rendered.
+ *
+ * Return value: (transfer full): the newly allocated #PangoAttribute,
+ *               which should be freed with pango_attribute_destroy().
+ *
+ * Since: 1.44
+ **/
+PangoAttribute *
+pango_attr_show_new (PangoShowFlags flags)
+{
+  static const PangoAttrClass klass = {
+    PANGO_ATTR_SHOW,
+    pango_attr_int_copy,
+    pango_attr_int_destroy,
+    pango_attr_int_equal,
+  };
+
+  return pango_attr_int_new (&klass, (int)flags);
+}
+
 /*
  * Attribute List
  */
diff --git a/pango/pango-attributes.h b/pango/pango-attributes.h
index f7a0c1cb..d46ce6f0 100644
--- a/pango/pango-attributes.h
+++ b/pango/pango-attributes.h
@@ -148,6 +148,7 @@ typedef struct _PangoAttrIterator PangoAttrIterator;
  * @PANGO_ATTR_FOREGROUND_ALPHA: foreground alpha (#PangoAttrInt). Since 1.38
  * @PANGO_ATTR_BACKGROUND_ALPHA: background alpha (#PangoAttrInt). Since 1.38
  * @PANGO_ATTR_ALLOW_BREAKS: whether breaks are allowed (#PangoAttrInt). Since 1.44
+ * @PANGO_ATTR_SHOW: how to render invisible characters (#PangoAttrInt). Since 1.44
  *
  * The #PangoAttrType
  * distinguishes between different types of attributes. Along with the
@@ -184,7 +185,8 @@ typedef enum
   PANGO_ATTR_FONT_FEATURES,    /* PangoAttrString */
   PANGO_ATTR_FOREGROUND_ALPHA, /* PangoAttrInt */
   PANGO_ATTR_BACKGROUND_ALPHA, /* PangoAttrInt */
-  PANGO_ATTR_ALLOW_BREAKS      /* PangoAttrInt */
+  PANGO_ATTR_ALLOW_BREAKS,     /* PangoAttrInt */
+  PANGO_ATTR_SHOW,             /* PangoAttrInt */
 } PangoAttrType;
 
 /**
@@ -527,6 +529,27 @@ PangoAttribute *pango_attr_background_alpha_new (guint16 alpha);
 PANGO_AVAILABLE_IN_1_44
 PangoAttribute *pango_attr_allow_breaks_new     (gboolean allow_breaks);
 
+/**
+ * PangoShowFlags:
+ * @PANGO_SHOW_NONE: No special treatment for invisible characters
+ * @PANGO_SHOW_SPACES: Render spaces, tabs and newlines visibly
+ * @PANGO_SHOW_LINE_BREAKS: Render line breaks visibly
+ * @PANGO_SHOW_IGNORABLES: Render default-ignorable Unicode
+ *      characters visibly
+ *
+ * These flags affect how Pango treats characters that are normally
+ * not visible in the output.
+ */
+typedef enum {
+  PANGO_SHOW_NONE        = 0,
+  PANGO_SHOW_SPACES      = 1 << 0,
+  PANGO_SHOW_LINE_BREAKS = 1 << 1,
+  PANGO_SHOW_IGNORABLES  = 1 << 2
+} PangoShowFlags;
+
+PANGO_AVAILABLE_IN_1_44
+PangoAttribute *pango_attr_show_new              (PangoShowFlags flags);
+
 PANGO_AVAILABLE_IN_ALL
 GType              pango_attr_list_get_type      (void) G_GNUC_CONST;
 PANGO_AVAILABLE_IN_ALL