Add complex text support.

This pull request adds support for languages that require complex text layout.

We are using the Raqm library, that wraps FriBidi (for bidirectional
text support) and HarfBuzz (for text shaping), and does proper BiDi and script
itemization:
https://github.com/HOST-Oman/libraqm

This should fix #1089.

.travis/install.sh

@@ -2,9 +2,12 @@
 
 set -e
 
+sudo add-apt-repository -y ppa:as-bahanta/raqm
 sudo apt-get update
-sudo apt-get -qq install libfreetype6-dev liblcms2-dev python-tk \
-			 python-qt4 ghostscript libffi-dev libjpeg-turbo-progs cmake imagemagick
+sudo apt-get -qq install libfreetype6-dev liblcms2-dev python-tk\
+			 python-qt4 ghostscript libffi-dev libjpeg-turbo-progs cmake imagemagick\
+             libharfbuzz-dev libfribidi-dev libraqm-dev
+
 pip install cffi
 pip install nose
 pip install check-manifest

PIL/ImageDraw.py

@@ -203,10 +203,10 @@ class ImageDraw(object):
         return text.split(split_character)
 
     def text(self, xy, text, fill=None, font=None, anchor=None,
-             *args, **kwargs):
+             *args, **kwargs, direction=None, features=[]):
         if self._multiline_check(text):
             return self.multiline_text(xy, text, fill, font, anchor,
-                                       *args, **kwargs)
+                                       *args, **kwargs, direction=direction, features=features)
 
         ink, fill = self._getink(fill)
         if font is None:
@@ -215,17 +215,17 @@ class ImageDraw(object):
             ink = fill
         if ink is not None:
             try:
-                mask, offset = font.getmask2(text, self.fontmode)
+                mask, offset = font.getmask2(text, self.fontmode, direction=direction, features=features)
                 xy = xy[0] + offset[0], xy[1] + offset[1]
             except AttributeError:
                 try:
-                    mask = font.getmask(text, self.fontmode)
+                    mask = font.getmask(text, self.fontmode, direction, features)
                 except TypeError:
                     mask = font.getmask(text)
             self.draw.draw_bitmap(xy, mask, ink)
 
     def multiline_text(self, xy, text, fill=None, font=None, anchor=None,
-                       spacing=4, align="left"):
+                       spacing=4, align="left", direction=None, features=[]):
         widths = []
         max_width = 0
         lines = self._multiline_split(text)
@@ -244,7 +244,7 @@ class ImageDraw(object):
                 left += (max_width - widths[idx])
             else:
                 assert False, 'align must be "left", "center" or "right"'
-            self.text((left, top), line, fill, font, anchor)
+            self.text((left, top), line, fill, font, anchor, direction=direction, features=features)
             top += line_spacing
             left = xy[0]
 

PIL/ImageFont.py

@@ -143,13 +143,13 @@ class FreeTypeFont(object):
     def getoffset(self, text):
         return self.font.getsize(text)[1]
 
-    def getmask(self, text, mode=""):
-        return self.getmask2(text, mode)[0]
+    def getmask(self, text, mode="", direction=None, features=[]):
+        return self.getmask2(text, mode, direction, features)[0]
 
-    def getmask2(self, text, mode="", fill=Image.core.fill):
+    def getmask2(self, text, mode="", fill=Image.core.fill, direction=None, features=[]):
         size, offset = self.font.getsize(text)
         im = fill("L", size, 0)
-        self.font.render(text, im.id, mode == "1")
+        self.font.render(text, im.id, mode == "1", direction, features)
         return im, offset
 
     def font_variant(self, font=None, size=None, index=None, encoding=None):

_imagingft.c

@@ -48,6 +48,7 @@ struct {
 } ft_errors[] =
 
 #include FT_ERRORS_H
+#include "raqm.h"
 
 /* -------------------------------------------------------------------- */
 /* font objects */
@@ -329,11 +330,7 @@ font_render(FontObject* self, PyObject* args)
     int index, error, ascender;
     int load_flags;
     unsigned char *source;
-    FT_ULong ch;
     FT_GlyphSlot glyph;
-    FT_Bool kerning = FT_HAS_KERNING(self->face);
-    FT_UInt last_index = 0;
-
     /* render string into given buffer (the buffer *must* have
        the right size, or this will crash) */
     PyObject* string;
@@ -341,16 +338,127 @@ font_render(FontObject* self, PyObject* args)
     int mask = 0;
     int temp;
     int xx, x0, x1;
-    if (!PyArg_ParseTuple(args, "On|i:render", &string, &id, &mask))
+    const char *dir = NULL;
+    raqm_direction_t direction;
+    raqm_t *rq;
+    size_t count;
+    raqm_glyph_t *glyph_info;
+    PyObject *features = NULL;
+
+    if (!PyArg_ParseTuple(args, "On|izO:render", &string,  &id, &mask, &dir, &features))
         return NULL;
 
+    rq = raqm_create();
+    if (rq == NULL) {
+        PyErr_SetString(PyExc_ValueError, "raqm_create() failed.");
+        goto failed;
+    }
+
 #if PY_VERSION_HEX >= 0x03000000
-    if (!PyUnicode_Check(string)) {
+    if (PyUnicode_Check(string)) {
+        Py_ssize_t size = PyUnicode_GET_LENGTH(string);
+        Py_UCS4 text[size];
+        PyUnicode_READY(string);
+        if (!PyUnicode_AsUCS4(string, text, size, 0))
+            goto failed;
+        if (!raqm_set_text(rq, text, size)) {
+            PyErr_SetString(PyExc_ValueError, "raqm_set_text() failed");
+            goto failed;
+        }
+    }
 #else
-    if (!PyUnicode_Check(string) && !PyString_Check(string)) {
+    if (PyUnicode_Check(string)) {
+        Py_UNICODE *text = PyUnicode_AS_UNICODE(string);
+        Py_ssize_t size = PyUnicode_GET_SIZE(string);
+        if (!raqm_set_text(rq, text, size)) {
+            PyErr_SetString(PyExc_ValueError, "raqm_set_text() failed");
+            goto failed;
+        }
+    }
+    else if (PyString_Check(string)) {
+        char *text = PyString_AS_STRING(string);
+        int size = PyString_GET_SIZE(string);
+        if (!raqm_set_text_utf8(rq, text, size)) {
+            PyErr_SetString(PyExc_ValueError, "raqm_set_text_utf8() failed");
+            goto failed;
+        }
+    }
 #endif
+    else {
         PyErr_SetString(PyExc_TypeError, "expected string");
-        return NULL;
+        goto failed;
+    }
+
+    direction = RAQM_DIRECTION_DEFAULT;
+    if (dir) {
+        if (strcmp(dir, "rtl") == 0)
+            direction = RAQM_DIRECTION_RTL;
+        else if (strcmp(dir, "ltr") == 0)
+            direction = RAQM_DIRECTION_LTR;
+        else if (strcmp(dir, "ttb") == 0)
+            direction = RAQM_DIRECTION_TTB;
+        else {
+            PyErr_SetString(PyExc_ValueError, "direction must be either 'rtl', 'ltr' or 'ttb'");
+            goto failed;
+        }
+    }
+
+    if (!raqm_set_par_direction(rq, direction)) {
+        PyErr_SetString(PyExc_ValueError, "raqm_set_par_direction() failed");
+        goto failed;
+    }
+
+    if (features) {
+        int len;
+        PyObject *seq = PySequence_Fast(features, "expected a sequence");
+        if (!seq) {
+            goto failed;
+        }
+
+        len = PySequence_Size(seq);
+        for (i = 0; i < len; i++) {
+            PyObject *item = PySequence_Fast_GET_ITEM(seq, i);
+            char *feature = NULL;
+            Py_ssize_t size = 0;
+#if PY_VERSION_HEX >= 0x03000000
+            if (!PyUnicode_Check(item) ||
+                PyUnicode_READY(string) != 0 ||
+                PyUnicode_KIND(item) != PyUnicode_1BYTE_KIND) {
+                PyErr_SetString(PyExc_TypeError, "expected an ASCII string");
+                goto failed;
+            }
+
+            feature = PyUnicode_1BYTE_DATA(item);
+            size = PyUnicode_GET_LENGTH(item);
+#else
+            if (!PyString_Check(item)) {
+                PyErr_SetString(PyExc_TypeError, "expected a string");
+                goto failed;
+            }
+            feature = PyString_AsString(item);
+            size = PyString_GET_SIZE(item);
+#endif
+            if (!raqm_add_font_feature(rq, feature, size)) {
+                PyErr_SetString(PyExc_ValueError, "raqm_add_font_feature() failed");
+                goto failed;
+            }
+        }
+    }
+
+    if (!raqm_set_freetype_face(rq, self->face)) {
+      PyErr_SetString(PyExc_RuntimeError, "raqm_set_freetype_face() failed.");
+      goto failed;
+    }
+
+    if (!raqm_layout (rq)) {
+      PyErr_SetString(PyExc_RuntimeError, "raqm_layout() failed.");
+      goto failed;
+    }
+
+    glyph_info = raqm_get_glyphs(rq, &count);
+    if (glyph_info == NULL) {
+        PyErr_SetString(PyExc_ValueError, "raqm_get_glyphs() failed.");
+        goto failed;
     }
 
     im = (Imaging) id;
@@ -360,36 +468,36 @@ font_render(FontObject* self, PyObject* args)
         load_flags |= FT_LOAD_TARGET_MONO;
 
     ascender = 0;
-    for (i = 0; font_getchar(string, i, &ch); i++) {
-        index = FT_Get_Char_Index(self->face, ch);
+    for (i = 0; i < count; i++) {
+        index = glyph_info[i].index;
         error = FT_Load_Glyph(self->face, index, load_flags);
-        if (error)
-            return geterror(error);
+        if (error) {
+            geterror(error);
+            goto failed;
+        }
         glyph = self->face->glyph;
         temp = (glyph->bitmap.rows - glyph->bitmap_top);
+        temp -= PIXEL(glyph_info[i].y_offset);
         if (temp > ascender)
             ascender = temp;
     }
 
-    for (x = i = 0; font_getchar(string, i, &ch); i++) {
+    for (x = i = 0; i < count; i++) {
         if (i == 0 && self->face->glyph->metrics.horiBearingX < 0)
             x = -PIXEL(self->face->glyph->metrics.horiBearingX);
-        index = FT_Get_Char_Index(self->face, ch);
-        if (kerning && last_index && index) {
-            FT_Vector delta;
-            FT_Get_Kerning(self->face, last_index, index, ft_kerning_default,
-                           &delta);
-            x += delta.x >> 6;
-        }
+        index = glyph_info[i].index;
 
         error = FT_Load_Glyph(self->face, index, load_flags);
-        if (error)
-            return geterror(error);
+        if (error){
+            geterror(error);
+            goto failed;
+        }
 
         glyph = self->face->glyph;
 
         source = (unsigned char*) glyph->bitmap.buffer;
         xx = x + glyph->bitmap_left;
+        xx += PIXEL(glyph_info[i].x_offset);
         x0 = 0;
         x1 = glyph->bitmap.width;
         if (xx < 0)
@@ -401,6 +509,7 @@ font_render(FontObject* self, PyObject* args)
             /* use monochrome mask (on palette images, etc) */
             for (y = 0; y < glyph->bitmap.rows; y++) {
                 int yy = y + im->ysize - (PIXEL(glyph->metrics.horiBearingY) + ascender);
+                yy -= PIXEL(glyph_info[i].y_offset);
                 if (yy >= 0 && yy < im->ysize) {
                     /* blend this glyph into the buffer */
                     unsigned char *target = im->image8[yy] + xx;
@@ -420,6 +529,7 @@ font_render(FontObject* self, PyObject* args)
             /* use antialiased rendering */
             for (y = 0; y < glyph->bitmap.rows; y++) {
                 int yy = y + im->ysize - (PIXEL(glyph->metrics.horiBearingY) + ascender);
+                yy -= PIXEL(glyph_info[i].y_offset);
                 if (yy >= 0 && yy < im->ysize) {
                     /* blend this glyph into the buffer */
                     int i;
@@ -432,11 +542,14 @@ font_render(FontObject* self, PyObject* args)
                 source += glyph->bitmap.pitch;
             }
         }
-        x += PIXEL(glyph->metrics.horiAdvance);
-        last_index = index;
+        x += PIXEL(glyph_info[i].x_advance);
     }
 
     Py_RETURN_NONE;
+
+failed:
+    raqm_destroy(rq);
+    return NULL;
 }
 
 static void

setup.py

@@ -114,6 +114,7 @@ TIFF_ROOT = None
 FREETYPE_ROOT = None
 LCMS_ROOT = None
 
+RAQM_ROOT = None
 
 def _pkg_config(name):
     try:
@@ -131,7 +132,7 @@ def _pkg_config(name):
 
 class pil_build_ext(build_ext):
     class feature:
-        features = ['zlib', 'jpeg', 'tiff', 'freetype', 'lcms', 'webp',
+        features = ['zlib', 'jpeg', 'tiff', 'freetype', 'raqm', 'lcms', 'webp',
                     'webpmux', 'jpeg2000', 'imagequant']
 
         required = {'jpeg', 'zlib'}
@@ -516,6 +517,11 @@ class pil_build_ext(build_ext):
                     if subdir:
                         _add_directory(self.compiler.include_dirs, subdir, 0)
 
+        if feature.want('raqm'):
+            if _find_include_file(self, "raqm.h"):
+                if _find_library_file(self, "raqm"):
+                    feature.raqm = "raqm"
+
         if feature.want('lcms'):
             _dbg('Looking for lcms')
             if _find_include_file(self, "lcms2.h"):
@@ -597,6 +603,9 @@ class pil_build_ext(build_ext):
             exts.append(Extension("PIL._imagingft",
                                   ["_imagingft.c"],
                                   libraries=["freetype"]))
+        if feature.freetype and feature.raqm:
+            exts.append(Extension(
+                "PIL._imagingft", ["_imagingft.c"], libraries=["freetype", "fribidi" , "harfbuzz", "raqm"]))
 
         if feature.lcms:
             extra = []
@@ -658,6 +667,7 @@ class pil_build_ext(build_ext):
             (feature.imagequant, "LIBIMAGEQUANT"),
             (feature.tiff, "LIBTIFF"),
             (feature.freetype, "FREETYPE2"),
+            (feature.raqm, "RAQM"),
             (feature.lcms, "LITTLECMS2"),
             (feature.webp, "WEBP"),
             (feature.webpmux, "WEBPMUX"),