[pango/pango2: 41/135] Tweak PangoAlignment

[Matthias Clasen <matthiasc src gnome org>]

commit 5ec2dbd34a9c8fa62537e59f61745b1fe819f908
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Jan 23 22:06:28 2022 -0500

    Tweak PangoAlignment
    
    Remove the justify-all value, and drop the justify-last-line
    feature from PangoLayout. This can be done better using
    PangoLineBreaker now.
    
    On the flip side, add a 'natural' value, since that is what
    we want to fall back to for the last line in a justified
    paragraph. And CoreText has this value too.
    
    Make PANGO_ALIGN_NATURAL the default.

 pango/pango-layout.c  | 41 +++++++++++++++++++++++++++++------------
 pango/pango-types.h   | 11 +++++------
 pango/serializer.c    |  4 ++--
 tests/testserialize.c |  2 +-
 4 files changed, 37 insertions(+), 21 deletions(-)
---
diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index 9671ab61..4d33bb83 100644
--- a/pango/pango-layout.c
+++ b/pango/pango-layout.c
@@ -72,7 +72,7 @@ pango_layout_init (PangoLayout *layout)
   layout->height = -1;
   layout->indent = 0;
   layout->wrap = PANGO_WRAP_WORD;
-  layout->alignment = PANGO_ALIGN_LEFT;
+  layout->alignment = PANGO_ALIGN_NATURAL;
   layout->ellipsize = PANGO_ELLIPSIZE_NONE;
   layout->line_spacing = 0.0;
   layout->auto_dir = TRUE;
@@ -409,11 +409,11 @@ pango_layout_class_init (PangoLayoutClass *class)
    *
    * The alignment mode of this `PangoLayout.
    *
-   * The default value is `PANGO_ALIGNMENT_LEFT`.
+   * The default value is `PANGO_ALIGN_NATURAL`.
    */
   props[PROP_ALIGNMENT] = g_param_spec_enum ("alignment", "alignment", "alignment",
                                              PANGO_TYPE_ALIGNMENT,
-                                             PANGO_ALIGN_LEFT,
+                                             PANGO_ALIGN_NATURAL,
                                              G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);
 
   /**
@@ -603,23 +603,40 @@ retry:
       offset = 0;
       switch (layout->alignment)
         {
+
         case PANGO_ALIGN_LEFT:
           break;
+
         case PANGO_ALIGN_CENTER:
           if (ext.width < width)
             offset = (width - ext.width) / 2;
           break;
+
+        case PANGO_ALIGN_JUSTIFY:
+          if (!pango_layout_line_ends_paragraph (line))
+            {
+              line = pango_layout_line_justify (line, width);
+              break;
+            }
+          G_GNUC_FALLTHROUGH;
+
+        case PANGO_ALIGN_NATURAL:
+          {
+            PangoLayoutLine *first_line;
+            if (pango_lines_get_line_count (layout->lines) > 0)
+              first_line = pango_lines_get_line (layout->lines, 0, NULL, NULL);
+            else
+              first_line = line;
+            if (pango_layout_line_get_resolved_direction (first_line) == PANGO_DIRECTION_LTR)
+              break;
+          }
+          G_GNUC_FALLTHROUGH;
+
         case PANGO_ALIGN_RIGHT:
           if (ext.width < width)
             offset = width - ext.width;
           break;
-        case PANGO_ALIGN_JUSTIFY:
-          if (!pango_layout_line_ends_paragraph (line))
-            line = pango_layout_line_justify (line, width);
-          break;
-        case PANGO_ALIGN_JUSTIFY_ALL:
-          line = pango_layout_line_justify (line, width);
-          break;
+
         default: g_assert_not_reached ();
         }
 
@@ -1278,7 +1295,7 @@ pango_layout_get_indent (PangoLayout *layout)
  * Sets the alignment for the layout: how short lines are
  * positioned within the horizontal space available.
  *
- * The default alignment is `PANGO_ALIGN_LEFT`.
+ * The default alignment is `PANGO_ALIGN_NATURAL`.
  */
 void
 pango_layout_set_alignment (PangoLayout    *layout,
@@ -1307,7 +1324,7 @@ pango_layout_set_alignment (PangoLayout    *layout,
 PangoAlignment
 pango_layout_get_alignment (PangoLayout *layout)
 {
-  g_return_val_if_fail (PANGO_IS_LAYOUT (layout), PANGO_ALIGN_LEFT);
+  g_return_val_if_fail (PANGO_IS_LAYOUT (layout), PANGO_ALIGN_NATURAL);
 
   return layout->alignment;
 }
diff --git a/pango/pango-types.h b/pango/pango-types.h
index 78a43931..44dd2e62 100644
--- a/pango/pango-types.h
+++ b/pango/pango-types.h
@@ -245,10 +245,9 @@ void pango_extents_to_pixels (PangoRectangle *inclusive,
  * @PANGO_ALIGN_LEFT: Put all available space on the right
  * @PANGO_ALIGN_CENTER: Center the line within the available space
  * @PANGO_ALIGN_RIGHT: Put all available space on the left
- * @PANGO_ALIGN_JUSTIFY: Justify the content to fill the available
- *   space, unless the line ends the paragraph
- * @PANGO_ALIGN_JUSTIFY_ALL: Justify the content to fill the available
- *   space, even if the line ends the paragraph
+ * @PANGO_ALIGN_NATURAL: Use left or right alignment, depending
+ *   on the text direction of the paragraph
+ * @PANGO_ALIGN_JUSTIFY: Justify the content to fill the available space
  *
  * `PangoAlignment` describes how to align the lines of a `PangoLayout`
  * within the available space.
@@ -258,8 +257,8 @@ typedef enum
   PANGO_ALIGN_LEFT,
   PANGO_ALIGN_CENTER,
   PANGO_ALIGN_RIGHT,
-  PANGO_ALIGN_JUSTIFY,
-  PANGO_ALIGN_JUSTIFY_ALL,
+  PANGO_ALIGN_NATURAL,
+  PANGO_ALIGN_JUSTIFY
 } PangoAlignment;
 
 /**
diff --git a/pango/serializer.c b/pango/serializer.c
index c666e149..3b54e80f 100644
--- a/pango/serializer.c
+++ b/pango/serializer.c
@@ -244,8 +244,8 @@ static const char *alignment_names[] = {
   "left",
   "center",
   "right",
+  "natural",
   "justify",
-  "justify-all",
   NULL
 };
 
@@ -806,7 +806,7 @@ layout_to_json (GtkJsonPrinter            *printer,
   if (!pango_layout_get_auto_dir (layout))
     gtk_json_printer_add_boolean (printer, "auto-dir", FALSE);
 
-  if (pango_layout_get_alignment (layout) != PANGO_ALIGN_LEFT)
+  if (pango_layout_get_alignment (layout) != PANGO_ALIGN_NATURAL)
     gtk_json_printer_add_string (printer, "alignment", alignment_names[pango_layout_get_alignment (layout)]);
 
   if (pango_layout_get_wrap (layout) != PANGO_WRAP_WORD)
diff --git a/tests/testserialize.c b/tests/testserialize.c
index dabcf798..0219d91a 100644
--- a/tests/testserialize.c
+++ b/tests/testserialize.c
@@ -205,7 +205,7 @@ test_serialize_layout_minimal (void)
   g_assert_null (pango_layout_get_attributes (layout));
   g_assert_null (pango_layout_get_tabs (layout));
   g_assert_null (pango_layout_get_font_description (layout));
-  g_assert_cmpint (pango_layout_get_alignment (layout), ==, PANGO_ALIGN_LEFT);
+  g_assert_cmpint (pango_layout_get_alignment (layout), ==, PANGO_ALIGN_NATURAL);
   g_assert_cmpint (pango_layout_get_width (layout), ==, -1);
 
   out_bytes = pango_layout_serialize (layout, PANGO_LAYOUT_SERIALIZE_DEFAULT);