Merge pull request #2706 from wiredfool/issue_2666

Fix for crash drawing empty strings

Tests/test_imagefont.py

@@ -394,10 +394,24 @@ class TestImageFont(PillowTestCase):
         self.assert_image_equal(im, target_img)
 
     def test_getsize_empty(self):
+        # issue #2614
         font = self.get_font()
         # should not crash.
         self.assertEqual((0, 0), font.getsize(''))
 
+    def test_render_empty(self):
+        # issue 2666
+        font = self.get_font()
+        im = Image.new(mode='RGB', size=(300, 100))
+        target = im.copy()
+        draw = ImageDraw.Draw(im)
+        #should not crash here. 
+        draw.text((10, 10), '', font=font)
+        self.assert_image_equal(im, target)
+        
+       
+        
+
     def _test_fake_loading_font(self, path_to_fake, fontname):
         # Make a copy of FreeTypeFont so we can patch the original
         free_type_font = copy.deepcopy(ImageFont.FreeTypeFont)

_imagingft.c

@@ -225,6 +225,11 @@ text_layout_raqm(PyObject* string, FontObject* self, const char* dir,
     if (PyUnicode_Check(string)) {
         Py_UNICODE *text = PyUnicode_AS_UNICODE(string);
         Py_ssize_t size = PyUnicode_GET_SIZE(string);
+	if (! size) {
+	    /* return 0 and clean up, no glyphs==no size, 
+	       and raqm fails with empty strings */
+	    goto failed;
+	}
         if (!raqm_set_text(rq, (const uint32_t *)(text), size)) {
             PyErr_SetString(PyExc_ValueError, "raqm_set_text() failed");
             goto failed;
@@ -234,6 +239,9 @@ text_layout_raqm(PyObject* string, FontObject* self, const char* dir,
     else if (PyString_Check(string)) {
         char *text = PyString_AS_STRING(string);
         int size = PyString_GET_SIZE(string);
+	if (! size) {
+	    goto failed;
+	}
         if (!raqm_set_text_utf8(rq, text, size)) {
             PyErr_SetString(PyExc_ValueError, "raqm_set_text_utf8() failed");
             goto failed;
@@ -450,6 +458,10 @@ font_getsize(FontObject* self, PyObject* args)
     y_max = y_min = 0;
 
     count = text_layout(string, self, dir, features, &glyph_info, 0);
+    if (PyErr_Occurred()) {
+        return NULL;
+    }
+
 
     for (x = i = 0; i < count; i++) {
         int index, error;
@@ -589,9 +601,12 @@ font_render(FontObject* self, PyObject* args)
 
     glyph_info = NULL;
     count = text_layout(string, self, dir, features, &glyph_info, mask);
-    if (count == 0) {
+    if (PyErr_Occurred()) {
         return NULL;
     }
+    if (count == 0) {
+        Py_RETURN_NONE;
+    }
 
     im = (Imaging) id;
     /* Note: bitmap fonts within ttf fonts do not work, see #891/pr#960 */