[pango/line-height: 2/5] Add line heights to layout lines

[Matthias Clasen <matthiasc src gnome org>]

commit fe9e971cf5d49d561d917db78a55143fc10d420d
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Jul 4 23:14:54 2019 +0000

    Add line heights to layout lines
    
    Add a getter for the line height of a layout line.

 pango/pango-layout.c | 144 +++++++++++++++++++++++++++++++++++++--------------
 pango/pango-layout.h |   4 ++
 2 files changed, 109 insertions(+), 39 deletions(-)
---
diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index a3850843..0934e6c7 100644
--- a/pango/pango-layout.c
+++ b/pango/pango-layout.c
@@ -113,6 +113,7 @@ struct _PangoLayoutLinePrivate
   } cache_status;
   PangoRectangle ink_rect;
   PangoRectangle logical_rect;
+  int height;
 };
 
 struct _PangoLayoutClass
@@ -2480,12 +2481,18 @@ get_x_offset (PangoLayout     *layout,
     }
 }
 
+static void
+pango_layout_line_get_extents_and_height (PangoLayoutLine *line,
+                                          PangoRectangle *ink,
+                                          PangoRectangle *logical,
+                                          int            *height);
 static void
 get_line_extents_layout_coords (PangoLayout     *layout,
                                PangoLayoutLine *line,
                                int              layout_width,
                                int              y_offset,
                                int             *baseline,
+                               int             *height,
                                PangoRectangle  *line_ink_layout,
                                PangoRectangle  *line_logical_layout)
 {
@@ -2494,8 +2501,9 @@ get_line_extents_layout_coords (PangoLayout     *layout,
   PangoRectangle line_ink;
   PangoRectangle line_logical;
 
-  pango_layout_line_get_extents (line, line_ink_layout ? &line_ink : NULL,
-                                &line_logical);
+  pango_layout_line_get_extents_and_height (line, line_ink_layout ? &line_ink : NULL,
+                                            &line_logical,
+                                            height);
 
   get_x_offset (layout, line, layout_width, line_logical.width, &x_offset);
 
@@ -2611,10 +2619,12 @@ pango_layout_get_extents_internal (PangoLayout    *layout,
       /* This block gets the line extents in layout coords */
       {
        int baseline;
+        int height;
 
        get_line_extents_layout_coords (layout, line,
                                        width, y_offset,
                                        &baseline,
+                                        &height,
                                        ink_rect ? &line_ink_layout : NULL,
                                        &line_logical_layout);
 
@@ -4544,12 +4554,14 @@ pango_layout_line_get_empty_extents (PangoLayoutLine *line,
 }
 
 static void
-pango_layout_run_get_extents (PangoLayoutRun *run,
-                             PangoRectangle *run_ink,
-                             PangoRectangle *run_logical)
+pango_layout_run_get_extents_and_height (PangoLayoutRun *run,
+                                         PangoRectangle *run_ink,
+                                         PangoRectangle *run_logical,
+                                         int            *height)
 {
   PangoRectangle logical;
   ItemProperties properties;
+  PangoFontMetrics *metrics = NULL;
 
   if (G_UNLIKELY (!run_ink && !run_logical))
     return;
@@ -4573,15 +4585,21 @@ pango_layout_run_get_extents (PangoLayoutRun *run,
 
   if (run_ink && (properties.uline != PANGO_UNDERLINE_NONE || properties.strikethrough))
     {
-      PangoFontMetrics *metrics = pango_font_get_metrics (run->item->analysis.font,
-                                                         run->item->analysis.language);
-      int underline_thickness = pango_font_metrics_get_underline_thickness (metrics);
-      int underline_position = pango_font_metrics_get_underline_position (metrics);
-      int strikethrough_thickness = pango_font_metrics_get_strikethrough_thickness (metrics);
-      int strikethrough_position = pango_font_metrics_get_strikethrough_position (metrics);
-
+      int underline_thickness;
+      int underline_position;
+      int strikethrough_thickness;
+      int strikethrough_position;
       int new_pos;
 
+      if (!metrics)
+        metrics = pango_font_get_metrics (run->item->analysis.font,
+                                         run->item->analysis.language);
+
+      underline_thickness = pango_font_metrics_get_underline_thickness (metrics);
+      underline_position = pango_font_metrics_get_underline_position (metrics);
+      strikethrough_thickness = pango_font_metrics_get_strikethrough_thickness (metrics);
+      strikethrough_position = pango_font_metrics_get_strikethrough_position (metrics);
+
       /* the underline/strikethrough takes x,width of logical_rect.  reflect
        * that into ink_rect.
        */
@@ -4625,8 +4643,14 @@ pango_layout_run_get_extents (PangoLayoutRun *run,
          g_critical ("unknown underline mode");
          break;
        }
+    }
 
-      pango_font_metrics_unref (metrics);
+  if (height)
+    {
+      if (!metrics)
+        metrics = pango_font_get_metrics (run->item->analysis.font,
+                                         run->item->analysis.language);
+      *height = pango_font_metrics_get_height (metrics);
     }
 
   if (run->item->analysis.flags & PANGO_ANALYSIS_FLAG_CENTERED_BASELINE)
@@ -4648,24 +4672,16 @@ pango_layout_run_get_extents (PangoLayoutRun *run,
       if (run_logical)
        run_logical->y -= properties.rise;
     }
+
+  if (metrics)
+    pango_font_metrics_unref (metrics);
 }
 
-/**
- * pango_layout_line_get_extents:
- * @line:     a #PangoLayoutLine
- * @ink_rect: (out) (allow-none): rectangle used to store the extents of
- *            the glyph string as drawn, or %NULL
- * @logical_rect: (out) (allow-none):rectangle used to store the logical
- *                extents of the glyph string, or %NULL
- *
- * Computes the logical and ink extents of a layout line. See
- * pango_font_get_glyph_extents() for details about the interpretation
- * of the rectangles.
- */
-void
-pango_layout_line_get_extents (PangoLayoutLine *line,
-                              PangoRectangle  *ink_rect,
-                              PangoRectangle  *logical_rect)
+static void
+pango_layout_line_get_extents_and_height (PangoLayoutLine *line,
+                                          PangoRectangle  *ink_rect,
+                                          PangoRectangle  *logical_rect,
+                                          int             *height)
 {
   PangoLayoutLinePrivate *private = (PangoLayoutLinePrivate *)line;
   GSList *tmp_list;
@@ -4685,6 +4701,8 @@ pango_layout_line_get_extents (PangoLayoutLine *line,
          *ink_rect = private->ink_rect;
        if (logical_rect)
          *logical_rect = private->logical_rect;
+        if (height)
+          *height = private->height;
        return;
       }
     case NOT_CACHED:
@@ -4694,6 +4712,8 @@ pango_layout_line_get_extents (PangoLayoutLine *line,
          ink_rect = &private->ink_rect;
        if (!logical_rect)
          logical_rect = &private->logical_rect;
+        if (!height)
+          height = &private->height;
        break;
       }
     case LEAKED:
@@ -4718,6 +4738,9 @@ pango_layout_line_get_extents (PangoLayoutLine *line,
       logical_rect->height = 0;
     }
 
+  if (height)
+    height = 0;
+
   tmp_list = line->runs;
   while (tmp_list)
     {
@@ -4725,10 +4748,12 @@ pango_layout_line_get_extents (PangoLayoutLine *line,
       int new_pos;
       PangoRectangle run_ink;
       PangoRectangle run_logical;
+      int run_height;
 
-      pango_layout_run_get_extents (run,
-                                   ink_rect ? &run_ink : NULL,
-                                   &run_logical);
+      pango_layout_run_get_extents_and_height (run,
+                                               ink_rect ? &run_ink : NULL,
+                                               &run_logical,
+                                               height ? &run_height : NULL);
 
       if (ink_rect)
        {
@@ -4752,9 +4777,9 @@ pango_layout_line_get_extents (PangoLayoutLine *line,
        }
 
       if (logical_rect)
-       {
-         new_pos = MIN (logical_rect->x, x_pos + run_logical.x);
-         logical_rect->width = MAX (logical_rect->x + logical_rect->width,
+        {
+          new_pos = MIN (logical_rect->x, x_pos + run_logical.x);
+          logical_rect->width = MAX (logical_rect->x + logical_rect->width,
                                     x_pos + run_logical.x + run_logical.width) - new_pos;
          logical_rect->x = new_pos;
 
@@ -4762,10 +4787,13 @@ pango_layout_line_get_extents (PangoLayoutLine *line,
          logical_rect->height = MAX (logical_rect->y + logical_rect->height,
                                      run_logical.y + run_logical.height) - new_pos;
          logical_rect->y = new_pos;
-       }
+        }
 
-     x_pos += run_logical.width;
-     tmp_list = tmp_list->next;
+      if (height)
+        *height = MAX (*height, run_height);
+
+      x_pos += run_logical.width;
+      tmp_list = tmp_list->next;
     }
 
   if (logical_rect && !line->runs)
@@ -4781,6 +4809,43 @@ pango_layout_line_get_extents (PangoLayoutLine *line,
     }
 }
 
+/**
+ * pango_layout_line_get_extents:
+ * @line:     a #PangoLayoutLine
+ * @ink_rect: (out) (allow-none): rectangle used to store the extents of
+ *            the glyph string as drawn, or %NULL
+ * @logical_rect: (out) (allow-none):rectangle used to store the logical
+ *                extents of the glyph string, or %NULL
+ *
+ * Computes the logical and ink extents of a layout line. See
+ * pango_font_get_glyph_extents() for details about the interpretation
+ * of the rectangles.
+ */
+void
+pango_layout_line_get_extents (PangoLayoutLine *line,
+                              PangoRectangle  *ink_rect,
+                              PangoRectangle  *logical_rect)
+{
+  pango_layout_line_get_extents_and_height (line, ink_rect, logical_rect, NULL);
+}
+
+/**
+ * pango_layout_line_get_height:
+ * @line:     a #PangoLayoutLine
+ * @height: (out) (allow-none): return location for the line height
+ *
+ * Computes the height of the line, ie the distance between
+ * this and the previous lines baseline.
+ *
+ * Since: 1.44
+ */
+void
+pango_layout_line_get_height (PangoLayoutLine *line,
+                             int             *height)
+{
+  pango_layout_line_get_extents_and_height (line, NULL, NULL, height);
+}
+
 static PangoLayoutLine *
 pango_layout_line_new (PangoLayout *layout)
 {
@@ -6307,7 +6372,7 @@ pango_layout_iter_get_run_extents (PangoLayoutIter *iter,
 
   if (iter->run)
     {
-      pango_layout_run_get_extents (iter->run, ink_rect, logical_rect);
+      pango_layout_run_get_extents_and_height (iter->run, ink_rect, logical_rect, NULL);
 
       if (ink_rect)
        {
@@ -6373,6 +6438,7 @@ pango_layout_iter_get_line_extents (PangoLayoutIter *iter,
                                      iter->layout_width,
                                      ext->logical_rect.y,
                                      NULL,
+                                      NULL,
                                      ink_rect,
                                      NULL);
     }
diff --git a/pango/pango-layout.h b/pango/pango-layout.h
index b095a303..2019a7b5 100644
--- a/pango/pango-layout.h
+++ b/pango/pango-layout.h
@@ -352,6 +352,10 @@ PANGO_AVAILABLE_IN_ALL
 void     pango_layout_line_get_extents  (PangoLayoutLine  *line,
                                         PangoRectangle   *ink_rect,
                                         PangoRectangle   *logical_rect);
+PANGO_AVAILABLE_IN_1_44
+void     pango_layout_line_get_height   (PangoLayoutLine  *line,
+                                        int              *height);
+
 PANGO_AVAILABLE_IN_ALL
 void     pango_layout_line_get_pixel_extents (PangoLayoutLine *layout_line,
                                              PangoRectangle  *ink_rect,