Improvements to layout

Author: mdboom

docstrings/bbox.py

@@ -54,8 +54,13 @@
     x_min, y_min, x_max, y_max = bbox
 """
 
+BBox_ascent = """
+The height of the bounding box above the baseline.  This is an alias
+for `y_max`.
+"""
+
 BBox_depth = """
-The depth of the bounding box beneath the baseline.  This is an alias
+The depth of the bounding box below the baseline.  This is an alias
 for `y_min`.
 """
 

docstrings/layout.py

@@ -49,8 +49,15 @@
     The size of the text, in pixels.
 """
 
-Layout_bbox = """
-Get the bounding box of the layout.
+Layout_ink_bbox = """
+Get the tight bounding box (`BBox`) of the physical characters in the
+layout.  The origin is at (0, 0).  The result is in pixels.
+"""
+
+Layout_layout_bbox = """
+Get the logical bounding box (`BBox`) of the layout.  This should be
+used to manage the layout of the text against other text.  The result
+is in pixels.
 """
 
 Layout_glyph_indices = """

lib/freetypy/tests/test_layout.py

@@ -41,11 +41,12 @@ def test_layout():
     layout = ft.Layout(
         face, "The quick brown fox jumped over the lazy dog")
 
-    assert layout.bbox.width == 553.984375
-    assert layout.bbox.height == 23.0
-    assert layout.bbox.y_min == -5.0
+    assert layout.ink_bbox.width == 553.984375
+    assert layout.ink_bbox.ascent == 18.0
+    assert layout.ink_bbox.depth == -5.0
+
+    assert tuple(layout.layout_bbox) == (0.0, -6.0, 555.984375, 22.0)
 
-    print(layout.glyph_indices.to_list())
     assert layout.glyph_indices.to_list() == [
         55, 75, 72, 3, 84, 88, 76, 70, 78, 3, 69, 85, 82, 90, 81, 3,
         73, 82, 91, 3, 77, 88, 80, 83, 72, 71, 3, 82, 89, 72, 85, 3,

src/bbox.c

@@ -101,6 +101,12 @@ Py_BBox_init(Py_BBox *self, PyObject *args, PyObject *kwds)
 */
 
 
+static PyObject *ascent_get(Py_BBox *self, PyObject *closure)
+{
+    return PyFloat_FromDouble(self->yMax);
+}
+
+
 static PyObject *depth_get(Py_BBox *self, PyObject *closure)
 {
     return PyFloat_FromDouble(self->yMin);
@@ -109,7 +115,7 @@ static PyObject *depth_get(Py_BBox *self, PyObject *closure)
 
 static PyObject *height_get(Py_BBox *self, PyObject *closure)
 {
-    return PyFloat_FromDouble(self->yMax);
+    return PyFloat_FromDouble(self->yMax - self->yMin);
 }
 
 
@@ -120,9 +126,11 @@ static PyObject *width_get(Py_BBox *self, PyObject *closure)
 
 
 static PyGetSetDef Py_BBox_getset[] = {
+    DEF_BBOX_GETTER(ascent),
     DEF_BBOX_GETTER(depth),
     DEF_BBOX_GETTER(height),
     DEF_BBOX_GETTER(width),
+    {NULL}
 };
 
 

src/layout.c

@@ -139,9 +139,14 @@ Py_Layout_init(Py_Layout *self, PyObject *args, PyObject *kwds)
 */
 
 
-static PyObject *bbox_get(Py_Layout *self, PyObject *closure)
+static PyObject *ink_bbox_get(Py_Layout *self, PyObject *closure)
 {
-    return Py_BBox_cnew(&self->x.bbox, 1.0 / (double)(1 << 6));
+    return Py_BBox_cnew(&self->x.ink_bbox, 1.0 / (double)(1 << 6));
+}
+
+static PyObject *layout_bbox_get(Py_Layout *self, PyObject *closure)
+{
+    return Py_BBox_cnew(&self->x.layout_bbox, 1.0 / (double)(1 << 6));
 }
 
 
@@ -158,9 +163,11 @@ static PyObject *points_get(Py_Layout *self, PyObject *closure)
 
 
 static PyGetSetDef Py_Layout_getset[] = {
-    DEF_LAYOUT_GETTER(bbox),
+    DEF_LAYOUT_GETTER(ink_bbox),
+    DEF_LAYOUT_GETTER(layout_bbox),
     DEF_LAYOUT_GETTER(glyph_indices),
     DEF_LAYOUT_GETTER(points),
+    {NULL}
 };
 
 

src/simple_layout.c

@@ -27,6 +27,8 @@ of the authors and should not be interpreted as representing official policies,
 either expressed or implied, of the FreeBSD Project.
 */
 
+#include <limits.h>
+
 #include "simple_layout.h"
 
 #define FROM_FT_FIXED(v) (((double)(v) / (double)(1 << 16)))
@@ -61,8 +63,13 @@ FT_Error ftpy_calculate_simple_layout(
 
     layout->size = text_length;
 
-    layout->bbox.xMin = layout->bbox.yMin = 0;
-    layout->bbox.xMax = layout->bbox.yMax = 0;
+    layout->layout_bbox.xMin = 0;
+    layout->layout_bbox.xMax = 0;
+    layout->layout_bbox.yMax = face->size->metrics.ascender;
+    layout->layout_bbox.yMin = face->size->metrics.descender;
+
+    layout->ink_bbox.xMin = layout->ink_bbox.yMin = LONG_MAX;
+    layout->ink_bbox.xMax = layout->ink_bbox.yMax = LONG_MIN;
 
     use_kerning = FT_HAS_KERNING(face);
     pen.x = 0;
@@ -98,22 +105,33 @@ FT_Error ftpy_calculate_simple_layout(
         layout->xys[i].x = FROM_FT_FIXED(pen.x);
         layout->xys[i].y = FROM_FT_FIXED(pen.y);
 
-        /* TODO: Bounding box should be calculated from advance width */
         FT_Outline_Get_BBox(&((FT_OutlineGlyph)glyph)->outline, &glyph_bbox);
         glyph_bbox.xMin += pen.x >> 10;
         glyph_bbox.yMin += pen.y >> 10;
         glyph_bbox.xMax += pen.x >> 10;
         glyph_bbox.yMax += pen.y >> 10;
-        if (glyph_bbox.xMin < layout->bbox.xMin) layout->bbox.xMin = glyph_bbox.xMin;
-        if (glyph_bbox.yMin < layout->bbox.yMin) layout->bbox.yMin = glyph_bbox.yMin;
-        if (glyph_bbox.xMax > layout->bbox.xMax) layout->bbox.xMax = glyph_bbox.xMax;
-        if (glyph_bbox.yMax > layout->bbox.yMax) layout->bbox.yMax = glyph_bbox.yMax;
+        if (glyph_bbox.xMin < layout->ink_bbox.xMin)
+            layout->ink_bbox.xMin = glyph_bbox.xMin;
+        if (glyph_bbox.yMin < layout->ink_bbox.yMin)
+            layout->ink_bbox.yMin = glyph_bbox.yMin;
+        if (glyph_bbox.xMax > layout->ink_bbox.xMax)
+            layout->ink_bbox.xMax = glyph_bbox.xMax;
+        if (glyph_bbox.yMax > layout->ink_bbox.yMax)
+            layout->ink_bbox.yMax = glyph_bbox.yMax;
 
         pen.x += glyph->advance.x;
+        layout->layout_bbox.xMax = pen.x >> 10;
 
         previous_glyph_index = glyph_index;
     }
 
+    /* layout->ink_bbox.xMin &= 0xffffffc0; */
+    /* layout->ink_bbox.yMin &= 0xffffffc0; */
+    /* layout->ink_bbox.xMax += 1 << 6; */
+    /* layout->ink_bbox.xMax &= 0xffffffc0; */
+    /* layout->ink_bbox.yMax += 1 << 6; */
+    /* layout->ink_bbox.yMax &= 0xffffffc0; */
+
     status = 0;
 
  exit:

src/simple_layout.h

@@ -49,7 +49,8 @@ typedef struct {
     size_t size;
     FT_ULong *glyph_indices;
     ftpy_Layout_Vector *xys;
-    FT_BBox bbox;
+    FT_BBox layout_bbox;
+    FT_BBox ink_bbox;
 } ftpy_Layout;