Merge branch 'line-height-attribute' into 'main'

Implement css-like line-height

See merge request GNOME/pango!390

6 files changed, 214 insertions, 17 deletions

diff --git a/docs/pango_markup.md b/docs/pango_markup.md
index 16359777..03718907 100644
--- a/docs/pango_markup.md
+++ b/docs/pango_markup.md
@@ -190,6 +190,12 @@ allow_breaks
 : 'true' or 'false' to indicate whether breaking lines is allowed. Available
   since Pango 1.44.
 
+line_height
+: Overrides the line height. The value can be either a factor (< 1024) that is
+  used to scale up the logical extents of runs or an absolute value (in 1024th
+  of a point).
+  Available since Pango 1.50.
+
 ## Convenience Tags
 
 `<b>`
diff --git a/pango/pango-attributes.c b/pango/pango-attributes.c
index 1a4a9443..fdb37f56 100644
--- a/pango/pango-attributes.c
+++ b/pango/pango-attributes.c
@@ -1341,6 +1341,58 @@ pango_attr_overline_color_new (guint16 red,
   return pango_attr_color_new (&klass, red, green, blue);
 }
 
+/**
+ * pango_attr_line_height_new:
+ * @factor: the scaling factor to apply to the logical height
+ *
+ * Modify the height of logical line extents by a factor.
+ *
+ * This affects the values returned by
+ * [method@Pango.LayoutLine.get_extents],
+ * [method@Pango.LayoutLine.get_pixel_extents] and
+ * [method@Pango.LayoutIter.get_line_extents].
+ *
+ *
+ * Since: 1.50
+ */
+PangoAttribute *
+pango_attr_line_height_new (double factor)
+{
+  static const PangoAttrClass klass = {
+    PANGO_ATTR_LINE_HEIGHT,
+    pango_attr_float_copy,
+    pango_attr_float_destroy,
+    pango_attr_float_equal
+  };
+
+  return pango_attr_float_new (&klass, factor);
+}
+
+/**
+ * pango_attr_line_height_new_absolute:
+ * @height: the line height, in %PANGO_SCALE-ths of a point
+ *
+ * Override the height of logical line extents to be @height.
+ *
+ * This affects the values returned by
+ * [method@Pango.LayoutLine.get_extents],
+ * [method@Pango.LayoutLine.get_pixel_extents] and
+ * [method@Pango.LayoutIter.get_line_extents].
+ *
+ * Since: 1.50
+ */
+PangoAttribute *
+pango_attr_line_height_new_absolute (int height)
+{
+  static const PangoAttrClass klass = {
+    PANGO_ATTR_ABSOLUTE_LINE_HEIGHT,
+    pango_attr_int_copy,
+    pango_attr_int_destroy,
+    pango_attr_int_equal
+  };
+
+  return pango_attr_int_new (&klass, height);
+}
 /*
  * Attribute List
  */
@@ -2559,6 +2611,7 @@ pango_attribute_as_float (PangoAttribute *attr)
   switch (attr->klass->type)
     {
     case PANGO_ATTR_SCALE:
+    case PANGO_ATTR_LINE_HEIGHT:
       return (PangoAttrFloat *)attr;
 
     default:
diff --git a/pango/pango-attributes.h b/pango/pango-attributes.h
index 6f18718e..c28623fb 100644
--- a/pango/pango-attributes.h
+++ b/pango/pango-attributes.h
@@ -160,6 +160,7 @@ typedef struct _PangoAttrIterator PangoAttrIterator;
  * @PANGO_ATTR_INSERT_HYPHENS: whether to insert hyphens at intra-word line breaks ([struct@Pango.AttrInt]). Since 1.44
  * @PANGO_ATTR_OVERLINE: whether the text has an overline ([struct@Pango.AttrInt]). Since 1.46
  * @PANGO_ATTR_OVERLINE_COLOR: overline color ([struct@Pango.AttrColor]). Since 1.46
+ * @PANGO_ATTR_LINE_HEIGHT: line height factor ([struct@Pango.AttrFloat]). Since: 1.50
  *
  * The `PangoAttrType` distinguishes between different types of attributes.
  *
@@ -201,6 +202,8 @@ typedef enum
   PANGO_ATTR_INSERT_HYPHENS,	/* PangoAttrInt */
   PANGO_ATTR_OVERLINE,		/* PangoAttrInt */
   PANGO_ATTR_OVERLINE_COLOR,	/* PangoAttrColor */
+  PANGO_ATTR_LINE_HEIGHT,	/* PangoAttrFloat */
+  PANGO_ATTR_ABSOLUTE_LINE_HEIGHT, /* PangoAttrInt */
 } PangoAttrType;
 
 /**
@@ -611,6 +614,11 @@ typedef enum {
 PANGO_AVAILABLE_IN_1_44
 PangoAttribute *pango_attr_show_new              (PangoShowFlags flags);
 
+PANGO_AVAILABLE_IN_1_50
+PangoAttribute *pango_attr_line_height_new (double factor);
+PANGO_AVAILABLE_IN_1_50
+PangoAttribute *pango_attr_line_height_new_absolute (int height);
+
 PANGO_AVAILABLE_IN_ALL
 GType              pango_attr_list_get_type      (void) G_GNUC_CONST;
 PANGO_AVAILABLE_IN_ALL
diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index e0475a5e..2a3cb5a2 100644
--- a/pango/pango-layout.c
+++ b/pango/pango-layout.c
@@ -78,6 +78,7 @@
 #include "pango-impl-utils.h"
 #include "pango-glyph-item.h"
 #include <string.h>
+#include <math.h>
 
 #include "pango-layout-private.h"
 #include "pango-attributes-private.h"
@@ -107,6 +108,8 @@ struct _ItemProperties
   gboolean        shape_set;
   PangoRectangle *shape_ink_rect;
   PangoRectangle *shape_logical_rect;
+  double line_height;
+  int    absolute_line_height;
 };
 
 typedef struct _PangoLayoutLinePrivate PangoLayoutLinePrivate;
@@ -177,7 +180,8 @@ static void              pango_layout_line_postprocess (PangoLayoutLine *line,
 static void pango_layout_line_leaked (PangoLayoutLine *line);
 
 /* doesn't leak line */
-static PangoLayoutLine* _pango_layout_iter_get_line (PangoLayoutIter *iter);
+static PangoLayoutLine * _pango_layout_iter_get_line (PangoLayoutIter *iter);
+static PangoLayoutRun *  _pango_layout_iter_get_run  (PangoLayoutIter *iter);
 
 static void pango_layout_get_item_properties (PangoItem      *item,
                                               ItemProperties *properties);
@@ -587,9 +591,12 @@ pango_layout_get_indent (PangoLayout *layout)
  * The default value is 0.
  *
  * Note: Since 1.44, Pango is using the line height (as determined
- * by the font) for placing lines when the line height factor is set
+ * by the font) for placing lines when the line spacing factor is set
  * to a non-zero value with [method@Pango.Layout.set_line_spacing].
  * In that case, the @spacing set with this function is ignored.
+ *
+ * Note: for semantics that are closer to the CSS line-height
+ * property, see [func@Pango.attr_line_height_new].
  */
 void
 pango_layout_set_spacing (PangoLayout *layout,
@@ -638,6 +645,9 @@ pango_layout_get_spacing (PangoLayout *layout)
  *
  * If @factor is zero (the default), spacing is applied as before.
  *
+ * Note: for semantics that are closer to the CSS line-height
+ * property, see [func@Pango.attr_line_height_new].
+ *
  * Since: 1.44
  */
 void
@@ -1793,7 +1803,8 @@ pango_layout_index_to_line (PangoLayout      *layout,
 static PangoLayoutLine *
 pango_layout_index_to_line_and_extents (PangoLayout     *layout,
                                         int              index,
-                                        PangoRectangle  *line_rect)
+                                        PangoRectangle  *line_rect,
+                                        PangoRectangle  *run_rect)
 {
   PangoLayoutIter iter;
   PangoLayoutLine *line = NULL;
@@ -1813,7 +1824,26 @@ pango_layout_index_to_line_and_extents (PangoLayout     *layout,
         pango_layout_iter_get_line_extents (&iter, NULL, line_rect);
 
         if (line->start_index + line->length > index)
-          break;
+          {
+            if (run_rect)
+              {
+                while (TRUE)
+                  {
+                    PangoLayoutRun *run = _pango_layout_iter_get_run (&iter);
+
+                    if (run->item->offset <= index && index < run->item->offset + run->item->length)
+                      {
+                        pango_layout_iter_get_run_extents (&iter, NULL, run_rect);
+                        break;
+                      }
+
+                    if (!pango_layout_iter_next_run (&iter))
+                      break;
+                  }
+              }
+
+            break;
+          }
 
         if (!pango_layout_iter_next_line (&iter))
           break; /* Use end of last line */
@@ -2291,10 +2321,24 @@ pango_layout_index_to_pos (PangoLayout    *layout,
 
           layout_line = tmp_line;
 
-          pango_layout_iter_get_line_extents (&iter, NULL, &logical_rect);
-
           if (layout_line->start_index + layout_line->length > index)
-            break;
+            {
+              while (TRUE)
+                {
+                  PangoLayoutRun *run = _pango_layout_iter_get_run (&iter);
+
+                  if (run->item->offset <= index && index < run->item->offset + run->item->length)
+                    {
+                      pango_layout_iter_get_run_extents (&iter, NULL, &logical_rect);
+                      break;
+                    }
+
+                  if (!pango_layout_iter_next_run (&iter))
+                    break;
+                }
+
+              break;
+            }
 
           if (!pango_layout_iter_next_line (&iter))
             {
@@ -2367,7 +2411,7 @@ pango_layout_get_direction (PangoLayout *layout,
 {
   PangoLayoutLine *line;
 
-  line = pango_layout_index_to_line_and_extents (layout, index, NULL);
+  line = pango_layout_index_to_line_and_extents (layout, index, NULL, NULL);
 
   if (line)
     return pango_layout_line_get_char_direction (line, index);
@@ -2400,6 +2444,7 @@ pango_layout_get_cursor_pos (PangoLayout    *layout,
   PangoDirection dir1, dir2;
   int level1, level2;
   PangoRectangle line_rect;
+  PangoRectangle run_rect;
   PangoLayoutLine *layout_line = NULL; /* Quiet GCC */
   int x1_trailing;
   int x2;
@@ -2408,7 +2453,7 @@ pango_layout_get_cursor_pos (PangoLayout    *layout,
   g_return_if_fail (index >= 0 && index <= layout->length);
 
   layout_line = pango_layout_index_to_line_and_extents (layout, index,
-                                                        &line_rect);
+                                                        &line_rect, &run_rect);
 
   g_assert (index >= layout_line->start_index);
 
@@ -2457,9 +2502,9 @@ pango_layout_get_cursor_pos (PangoLayout    *layout,
       else
         strong_pos->x += x2;
 
-      strong_pos->y = line_rect.y;
+      strong_pos->y = run_rect.y;
       strong_pos->width = 0;
-      strong_pos->height = line_rect.height;
+      strong_pos->height = run_rect.height;
     }
 
   if (weak_pos)
@@ -2472,9 +2517,9 @@ pango_layout_get_cursor_pos (PangoLayout    *layout,
       else
         weak_pos->x += x1_trailing;
 
-      weak_pos->y = line_rect.y;
+      weak_pos->y = run_rect.y;
       weak_pos->width = 0;
-      weak_pos->height = line_rect.height;
+      weak_pos->height = run_rect.height;
     }
 }
 
@@ -4149,6 +4194,8 @@ affects_itemization (PangoAttribute *attr,
     case PANGO_ATTR_LETTER_SPACING:
     case PANGO_ATTR_SHAPE:
     case PANGO_ATTR_RISE:
+    case PANGO_ATTR_LINE_HEIGHT:
+    case PANGO_ATTR_ABSOLUTE_LINE_HEIGHT:
       return TRUE;
     default:
       return FALSE;
@@ -5011,6 +5058,7 @@ static void
 pango_layout_run_get_extents_and_height (PangoLayoutRun *run,
                                          PangoRectangle *run_ink,
                                          PangoRectangle *run_logical,
+                                         PangoRectangle *line_logical,
                                          int            *height)
 {
   PangoRectangle logical;
@@ -5019,7 +5067,7 @@ pango_layout_run_get_extents_and_height (PangoLayoutRun *run,
   gboolean has_underline;
   gboolean has_overline;
 
-  if (G_UNLIKELY (!run_ink && !run_logical && !height))
+  if (G_UNLIKELY (!run_ink && !run_logical && !line_logical && !height))
     return;
 
   pango_layout_get_item_properties (run->item, &properties);
@@ -5034,6 +5082,9 @@ pango_layout_run_get_extents_and_height (PangoLayoutRun *run,
   if (!run_logical && (has_underline || has_overline || properties.strikethrough))
     run_logical = &logical;
 
+  if (!run_logical && line_logical)
+    run_logical = &logical;
+
   if (properties.shape_set)
     _pango_shape_get_extents (run->item->num_chars,
                               properties.shape_ink_rect,
@@ -5104,6 +5155,7 @@ pango_layout_run_get_extents_and_height (PangoLayoutRun *run,
       if (!metrics)
         metrics = pango_font_get_metrics (run->item->analysis.font,
                                           run->item->analysis.language);
+
       *height = pango_font_metrics_get_height (metrics);
     }
 
@@ -5127,6 +5179,21 @@ pango_layout_run_get_extents_and_height (PangoLayoutRun *run,
         run_logical->y -= properties.rise;
     }
 
+  if (line_logical)
+    {
+      *line_logical = *run_logical;
+
+      if (properties.absolute_line_height != 0 || properties.line_height != 0.0)
+        {
+          int line_height, leading;
+
+          line_height = MAX (properties.absolute_line_height, ceilf (properties.line_height * line_logical->height));
+          leading = line_height - line_logical->height;
+          line_logical->y -= leading / 2;
+          line_logical->height += leading;
+        }
+    }
+
   if (metrics)
     pango_font_metrics_unref (metrics);
 }
@@ -5206,6 +5273,7 @@ pango_layout_line_get_extents_and_height (PangoLayoutLine *line,
 
       pango_layout_run_get_extents_and_height (run,
                                                ink_rect ? &run_ink : NULL,
+                                               NULL,
                                                &run_logical,
                                                height ? &run_height : NULL);
 
@@ -5985,6 +6053,8 @@ pango_layout_get_item_properties (PangoItem      *item,
   properties->shape_set = FALSE;
   properties->shape_ink_rect = NULL;
   properties->shape_logical_rect = NULL;
+  properties->line_height = 0.0;
+  properties->absolute_line_height = 0;
 
   while (tmp_list)
     {
@@ -6048,6 +6118,14 @@ pango_layout_get_item_properties (PangoItem      *item,
           properties->shape_ink_rect = &((PangoAttrShape *)attr)->ink_rect;
           break;
 
+        case PANGO_ATTR_LINE_HEIGHT:
+          properties->line_height = ((PangoAttrFloat *)attr)->value;
+          break;
+
+        case PANGO_ATTR_ABSOLUTE_LINE_HEIGHT:
+          properties->absolute_line_height = ((PangoAttrInt *)attr)->value;
+          break;
+
         default:
           break;
         }
@@ -6446,6 +6524,12 @@ _pango_layout_iter_get_line (PangoLayoutIter *iter)
   return iter->line;
 }
 
+static PangoLayoutRun *
+_pango_layout_iter_get_run (PangoLayoutIter *iter)
+{
+  return iter->run;
+}
+
 /**
  * pango_layout_iter_get_line:
  * @iter: a `PangoLayoutIter`
@@ -6907,7 +6991,7 @@ pango_layout_iter_get_run_extents (PangoLayoutIter *iter,
 
   if (iter->run)
     {
-      pango_layout_run_get_extents_and_height (iter->run, ink_rect, logical_rect, NULL);
+      pango_layout_run_get_extents_and_height (iter->run, ink_rect, logical_rect, NULL, NULL);
 
       if (ink_rect)
         {
diff --git a/pango/pango-markup.c b/pango/pango-markup.c
index 5394c772..00b16943 100644
--- a/pango/pango-markup.c
+++ b/pango/pango-markup.c
@@ -977,6 +977,29 @@ span_parse_int (const char *attr_name,
 }
 
 static gboolean
+span_parse_float (const char  *attr_name,
+                  const char  *attr_val,
+                  double      *val,
+                  int          line_number,
+                  GError     **error)
+{
+  *val = g_ascii_strtod (attr_val, NULL);
+  if (errno != 0)
+    {
+      g_set_error (error,
+                   G_MARKUP_ERROR,
+                   G_MARKUP_ERROR_INVALID_CONTENT,
+                   _("Value of '%s' attribute on <span> tag "
+                     "on line %d could not be parsed; "
+                     "should be a number, not '%s'"),
+                   attr_name, line_number, attr_val);
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
+static gboolean
 span_parse_boolean (const char *attr_name,
 		    const char *attr_val,
 		    gboolean *val,
@@ -1200,6 +1223,7 @@ span_parse_func     (MarkupData            *md G_GNUC_UNUSED,
   const char *allow_breaks = NULL;
   const char *insert_hyphens = NULL;
   const char *show = NULL;
+  const char *line_height = NULL;
 
   g_markup_parse_context_get_position (context,
 				       &line_number, &char_number);
@@ -1278,6 +1302,7 @@ span_parse_func     (MarkupData            *md G_GNUC_UNUSED,
       case 'l':
 	CHECK_ATTRIBUTE (lang);
 	CHECK_ATTRIBUTE (letter_spacing);
+        CHECK_ATTRIBUTE (line_height);
 	break;
       case 'o':
 	CHECK_ATTRIBUTE (overline);
@@ -1639,6 +1664,19 @@ span_parse_func     (MarkupData            *md G_GNUC_UNUSED,
       add_attribute (tag, pango_attr_letter_spacing_new (n));
     }
 
+  if (G_UNLIKELY (line_height))
+    {
+      double f = 0;
+
+      if (!span_parse_float ("line_height", line_height, &f, line_number, error))
+        goto error;
+
+      if (f > 1024.0 && strchr (line_height, ".") == 0)
+        add_attribute (tag, pango_attr_line_height_new_absolute ((int)f));
+      else
+        add_attribute (tag, pango_attr_line_height_new (f));
+    }
+
   if (G_UNLIKELY (lang))
     {
       add_attribute (tag,
diff --git a/tests/test-bidi.c b/tests/test-bidi.c
index 35f2a39d..7a137518 100644
--- a/tests/test-bidi.c
+++ b/tests/test-bidi.c
@@ -352,6 +352,9 @@ test_move_cursor_para (void)
   int index;
   int trailing;
   const char *text;
+  int line_no;
+  PangoLayoutLine *line;
+  PangoRectangle ext;
 
   layout = pango_layout_new (context);
 
@@ -387,9 +390,14 @@ test_move_cursor_para (void)
           if (index >= strlen (tests[i].text) - 1)
             break;
 
+          pango_layout_index_to_line_x (layout, index, FALSE, &line_no, NULL);
+          line = pango_layout_get_line (layout, line_no);
+          pango_layout_line_get_extents (line, NULL, &ext);
+
           pango_layout_get_cursor_pos (layout, index, &pos, NULL);
-          g_assert_true (pos.y > old_pos.y ||
-                         (pos.y == old_pos.y && pos.x > old_pos.x));
+          // assert that we are either moving to the right
+          // or jumping to the next line
+          g_assert_true (pos.y > ext.y + ext.height || pos.x > old_pos.x);
         }
     }