[gtk/wip/otte/wrapping-is-natural] label: Add gtk_label_set_natural_wrap_mode()

[Benjamin Otte <otte src gnome org>]

commit b44744fcb6776fac74c0cce16a55323218300cea
Author: Benjamin Otte <otte redhat com>
Date:   Sun Dec 19 19:22:31 2021 +0100

    label: Add gtk_label_set_natural_wrap_mode()
    
    Allows influencing natural size requests so that labels can request more
    width than necessary for a given height.
    
    Related: !4245
    Related: #4535

 gtk/gtkenums.h                                     |  25 ++++++
 gtk/gtklabel.c                                     | 100 +++++++++++++++++++--
 gtk/gtklabel.h                                     |   5 ++
 .../label-wrap-word-char-natural-size.ref.ui       |  14 ++-
 .../reftests/label-wrap-word-char-natural-size.ui  |  17 +++-
 5 files changed, 146 insertions(+), 15 deletions(-)
---
diff --git a/gtk/gtkenums.h b/gtk/gtkenums.h
index d356a9154e..69faa56db8 100644
--- a/gtk/gtkenums.h
+++ b/gtk/gtkenums.h
@@ -285,6 +285,31 @@ typedef enum
   GTK_MOVEMENT_HORIZONTAL_PAGES
 } GtkMovementStep;
 
+/**
+ * GtkNaturalWrapMode:
+ * @GTK_NATURAL_WRAP_INHERIT: Inherit the minimum size request.
+ *   In particular, this should be used with %PANGO_WRAP_CHAR.
+ * @GTK_NATURAL_WRAP_NONE: Try not to wrap the text. This mode is the
+ *   closest to GTK3's behavior but can lead to a wide label leaving
+ *   lots of empty space below the text.
+ * @GTK_NATURAL_WRAP_WORD: Attempt to wrap at word boundaries. This
+ *   is useful in particular when using %PANGO_WRAP_WORD_CHAR as the
+ *   wrap mode.
+ *
+ * Options for selecting a different wrap mode for natural size
+ * requests.
+ *
+ * See for example the [property@Gtk.Label:natural-wrap-mode] property.
+ *
+ * Since: 4.6
+ */
+typedef enum
+{
+  GTK_NATURAL_WRAP_INHERIT,
+  GTK_NATURAL_WRAP_NONE,
+  GTK_NATURAL_WRAP_WORD
+} GtkNaturalWrapMode;
+
 /**
  * GtkScrollStep:
  * @GTK_SCROLL_STEPS: Scroll in steps.
diff --git a/gtk/gtklabel.c b/gtk/gtklabel.c
index 9af80f43a9..7f05a29dad 100644
--- a/gtk/gtklabel.c
+++ b/gtk/gtklabel.c
@@ -272,6 +272,7 @@ struct _GtkLabel
   guint    ellipsize          : 3;
   guint    use_markup         : 1;
   guint    wrap_mode          : 3;
+  guint    natural_wrap_mode  : 3;
   guint    single_line_mode   : 1;
   guint    in_click           : 1;
   guint    track_links        : 1;
@@ -380,6 +381,7 @@ enum {
   PROP_JUSTIFY,
   PROP_WRAP,
   PROP_WRAP_MODE,
+  PROP_NATURAL_WRAP_MODE,
   PROP_SELECTABLE,
   PROP_MNEMONIC_KEYVAL,
   PROP_MNEMONIC_WIDGET,
@@ -484,6 +486,9 @@ gtk_label_set_property (GObject      *object,
     case PROP_WRAP_MODE:
       gtk_label_set_wrap_mode (self, g_value_get_enum (value));
       break;
+    case PROP_NATURAL_WRAP_MODE:
+      gtk_label_set_natural_wrap_mode (self, g_value_get_enum (value));
+      break;
     case PROP_SELECTABLE:
       gtk_label_set_selectable (self, g_value_get_boolean (value));
       break;
@@ -551,6 +556,9 @@ gtk_label_get_property (GObject     *object,
     case PROP_WRAP_MODE:
       g_value_set_enum (value, self->wrap_mode);
       break;
+    case PROP_NATURAL_WRAP_MODE:
+      g_value_set_enum (value, self->natural_wrap_mode);
+      break;
     case PROP_SELECTABLE:
       g_value_set_boolean (value, gtk_label_get_selectable (self));
       break;
@@ -604,6 +612,7 @@ gtk_label_init (GtkLabel *self)
   self->jtype = GTK_JUSTIFY_LEFT;
   self->wrap = FALSE;
   self->wrap_mode = PANGO_WRAP_WORD;
+  self->natural_wrap_mode = GTK_NATURAL_WRAP_INHERIT;
   self->ellipsize = PANGO_ELLIPSIZE_NONE;
 
   self->use_underline = FALSE;
@@ -1218,8 +1227,6 @@ get_width_for_height (GtkLabel *self,
       gtk_label_ensure_layout (self);
       layout = pango_layout_copy (self->layout);
       pango_layout_set_ellipsize (layout, PANGO_ELLIPSIZE_NONE);
-      if (self->wrap_mode == PANGO_WRAP_WORD_CHAR)
-        pango_layout_set_wrap (layout, PANGO_WRAP_WORD);
 
       /* binary search for the smallest width where the height doesn't
        * eclipse the given height */
@@ -1228,8 +1235,19 @@ get_width_for_height (GtkLabel *self,
       pango_layout_set_width (layout, -1);
       pango_layout_get_size (layout, &max, NULL);
 
-      *natural_width = my_pango_layout_get_width_for_height (layout, height, min, max);
+      /* first, do natural width */
+      if (self->natural_wrap_mode == GTK_NATURAL_WRAP_NONE)
+        {
+          *natural_width = max;
+        }
+      else
+        {
+          if (self->natural_wrap_mode == GTK_NATURAL_WRAP_WORD)
+            pango_layout_set_wrap (layout, PANGO_WRAP_WORD);
+          *natural_width = my_pango_layout_get_width_for_height (layout, height, min, max);
+        }
 
+      /* then, do minimum width */
       if (self->ellipsize != PANGO_ELLIPSIZE_NONE)
         {
           g_object_unref (layout);
@@ -1237,14 +1255,14 @@ get_width_for_height (GtkLabel *self,
           pango_layout_get_size (layout, minimum_width, NULL);
           *minimum_width = MAX (*minimum_width, minimum_default);
         }
-      else if (self->wrap_mode == PANGO_WRAP_WORD_CHAR)
+      else if (self->natural_wrap_mode == GTK_NATURAL_WRAP_INHERIT)
         {
-          pango_layout_set_wrap (layout, PANGO_WRAP_WORD_CHAR);
-          *minimum_width = my_pango_layout_get_width_for_height (layout, height, min, *natural_width);
+          *minimum_width = *natural_width;
         }
       else
         {
-          *minimum_width = *natural_width;
+          pango_layout_set_wrap (layout, self->wrap_mode);
+          *minimum_width = my_pango_layout_get_width_for_height (layout, height, min, *natural_width);
         }
     }
 
@@ -2384,6 +2402,27 @@ gtk_label_class_init (GtkLabelClass *class)
                          PANGO_WRAP_WORD,
                          GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY);
 
+  /**
+   * GtkLabel:natural-wrap-mode: (attributes org.gtk.Property.get=gtk_label_get_natural_wrap_mode 
org.gtk.Property.set=gtk_label_set_natural_wrap_mode)
+   *
+   * Select the line wrapping for the natural size request.
+   *
+   * This only affects the natural size requested. For the actual wrapping used,
+   * see the [property@Gtk.Label:wrap-mode] property.
+   *
+   * The default is %GTK_NATURAL_WRAP_INHERIT, which inherits the behavior of the
+   * [property@Gtk.Label:wrap-mode] property.
+   *
+   * Since: 4.6
+   */
+  label_props[PROP_NATURAL_WRAP_MODE] =
+      g_param_spec_enum ("natural-wrap-mode",
+                         P_("Natrural wrap mode"),
+                         P_("If wrap is set, controls linewrapping for natural size requests"),
+                         GTK_TYPE_NATURAL_WRAP_MODE,
+                         GTK_NATURAL_WRAP_INHERIT,
+                         GTK_PARAM_READWRITE|G_PARAM_EXPLICIT_NOTIFY);
+
   /**
    * GtkLabel:selectable: (attributes org.gtk.Property.get=gtk_label_get_selectable 
og.gtk.Property.set=gtk_label_set_selectable)
    *
@@ -4032,6 +4071,53 @@ gtk_label_get_wrap_mode (GtkLabel *self)
   return self->wrap_mode;
 }
 
+/**
+ * gtk_label_set_natural_wrap_mode: (attributes org.gtk.Method.set_property=natural-wrap-mode)
+ * @self: a `GtkLabel`
+ * @wrap_mode: the line wrapping mode
+ *
+ * Select the line wrapping for the natural size request.
+ *
+ * This only affects the natural size requested, for the actual wrapping used,
+ * see the [property@Gtk.Label:wrap-mode] property.
+ *
+ * Since: 4.6
+ */
+void
+gtk_label_set_natural_wrap_mode (GtkLabel           *self,
+                                 GtkNaturalWrapMode  wrap_mode)
+{
+  g_return_if_fail (GTK_IS_LABEL (self));
+
+  if (self->natural_wrap_mode != wrap_mode)
+    {
+      self->natural_wrap_mode = wrap_mode;
+      g_object_notify_by_pspec (G_OBJECT (self), label_props[PROP_NATURAL_WRAP_MODE]);
+
+      gtk_widget_queue_resize (GTK_WIDGET (self));
+    }
+}
+
+/**
+ * gtk_label_get_natural_wrap_mode: (attributes org.gtk.Method.get_property=natural-wrap-mode)
+ * @self: a `GtkLabel`
+ *
+ * Returns line wrap mode used by the label.
+ *
+ * See [method@Gtk.Label.set_natural_wrap_mode].
+ *
+ * Returns: the natural line wrap mode
+ *
+ * Since: 4.6
+ */
+GtkNaturalWrapMode
+gtk_label_get_natural_wrap_mode (GtkLabel *self)
+{
+  g_return_val_if_fail (GTK_IS_LABEL (self), PANGO_WRAP_CHAR);
+
+  return self->natural_wrap_mode;
+}
+
 static void
 gtk_label_clear_layout (GtkLabel *self)
 {
diff --git a/gtk/gtklabel.h b/gtk/gtklabel.h
index 36441a5fe9..4a42a4ba32 100644
--- a/gtk/gtklabel.h
+++ b/gtk/gtklabel.h
@@ -122,6 +122,11 @@ void     gtk_label_set_wrap_mode                  (GtkLabel         *self,
                                                    PangoWrapMode     wrap_mode);
 GDK_AVAILABLE_IN_ALL
 PangoWrapMode gtk_label_get_wrap_mode             (GtkLabel         *self);
+GDK_AVAILABLE_IN_4_6
+void          gtk_label_set_natural_wrap_mode     (GtkLabel         *self,
+                                                   GtkNaturalWrapMode wrap_mode);
+GDK_AVAILABLE_IN_4_6
+GtkNaturalWrapMode gtk_label_get_natural_wrap_mode(GtkLabel         *self);
 GDK_AVAILABLE_IN_ALL
 void     gtk_label_set_selectable                 (GtkLabel         *self,
                                                   gboolean          setting);
diff --git a/testsuite/reftests/label-wrap-word-char-natural-size.ref.ui 
b/testsuite/reftests/label-wrap-word-char-natural-size.ref.ui
index b8a08efc62..405064420c 100644
--- a/testsuite/reftests/label-wrap-word-char-natural-size.ref.ui
+++ b/testsuite/reftests/label-wrap-word-char-natural-size.ref.ui
@@ -1,21 +1,27 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <interface>
   <object class="GtkWindow">
-    <property name="default-width">300</property>
+    <property name="default-width">600</property>
     <property name="default-height">300</property>
     <child>
       <object class="GtkBox">
         <property name="halign">center</property>
-        <property name="valign">center</property>
         <child>
           <object class="GtkLabel">
-            <property name="label">two
+            <property name="label">lots
+of
 lines</property>
           </object>
         </child>
         <child>
           <object class="GtkLabel">
-            <property name="label">unwrapped</property>
+            <property name="label">unwrappable
+words</property>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">single line of text</property>
           </object>
         </child>
       </object>
diff --git a/testsuite/reftests/label-wrap-word-char-natural-size.ui 
b/testsuite/reftests/label-wrap-word-char-natural-size.ui
index 929e5a3089..f70099651e 100644
--- a/testsuite/reftests/label-wrap-word-char-natural-size.ui
+++ b/testsuite/reftests/label-wrap-word-char-natural-size.ui
@@ -1,23 +1,32 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <interface>
   <object class="GtkWindow">
-    <property name="default-width">300</property>
+    <property name="default-width">600</property>
     <property name="default-height">300</property>
     <child>
       <object class="GtkBox">
         <property name="halign">center</property>
-        <property name="valign">center</property>
         <child>
           <object class="GtkLabel">
-            <property name="label">two
+            <property name="label">lots
+of
 lines</property>
           </object>
         </child>
         <child>
           <object class="GtkLabel">
-            <property name="label">unwrapped</property>
+            <property name="label">unwrappable words</property>
             <property name="wrap">1</property>
             <property name="wrap-mode">word-char</property>
+            <property name="natural-wrap-mode">word</property>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">single line of text</property>
+            <property name="wrap">1</property>
+            <property name="wrap-mode">word-char</property>
+            <property name="natural-wrap-mode">none</property>
           </object>
         </child>
       </object>