Merge pull request #4910 from nulano/anchor-part1

Tests/test_imagefont.py

@@ -35,9 +35,24 @@ class TestImageFont:
     # Freetype has different metrics depending on the version.
     # (and, other things, but first things first)
     METRICS = {
-        (">=2.3", "<2.4"): {"multiline": 30, "textsize": 12, "getters": (13, 16)},
-        (">=2.7",): {"multiline": 6.2, "textsize": 2.5, "getters": (12, 16)},
-        "Default": {"multiline": 0.5, "textsize": 0.5, "getters": (12, 16)},
+        (">=2.3", "<2.4"): {
+            "multiline": 30,
+            "textsize": 12,
+            "getters": (13, 16),
+            "mask": (107, 13),
+        },
+        (">=2.7",): {
+            "multiline": 6.2,
+            "textsize": 2.5,
+            "getters": (12, 16),
+            "mask": (108, 13),
+        },
+        "Default": {
+            "multiline": 0.5,
+            "textsize": 0.5,
+            "getters": (12, 16),
+            "mask": (108, 13),
+        },
     }
 
     @classmethod
@@ -343,7 +358,7 @@ class TestImageFont:
         mask = transposed_font.getmask(text)
 
         # Assert
-        assert mask.size == (13, 108)
+        assert mask.size == self.metrics["mask"][::-1]
 
     def test_unrotated_transposed_font_get_mask(self):
         # Arrange
@@ -356,7 +371,7 @@ class TestImageFont:
         mask = transposed_font.getmask(text)
 
         # Assert
-        assert mask.size == (108, 13)
+        assert mask.size == self.metrics["mask"]
 
     def test_free_type_font_get_name(self):
         # Arrange
@@ -400,7 +415,7 @@ class TestImageFont:
         mask = font.getmask(text)
 
         # Assert
-        assert mask.size == (108, 13)
+        assert mask.size == self.metrics["mask"]
 
     def test_load_path_not_found(self):
         # Arrange
@@ -471,7 +486,8 @@ class TestImageFont:
         d = ImageDraw.Draw(img)
         d.text((10, 10), text, font=ttf)
 
-        assert_image_similar_tofile(img, target, self.metrics["multiline"])
+        # fails with 14.7
+        assert_image_similar_tofile(img, target, 6.2)
 
     def _test_fake_loading_font(self, monkeypatch, path_to_fake, fontname):
         # Make a copy of FreeTypeFont so we can patch the original
@@ -728,7 +744,7 @@ class TestImageFont:
 
         font = ImageFont.truetype("Tests/fonts/AdobeVFPrototype.ttf", 36)
         font.set_variation_by_axes([500, 50])
-        self._check_text(font, "Tests/images/variation_adobe_axes.png", 5.1)
+        self._check_text(font, "Tests/images/variation_adobe_axes.png", 11.05)
 
         font = ImageFont.truetype("Tests/fonts/TINY5x3GX.ttf", 36)
         font.set_variation_by_axes([100])

src/PIL/ImageFont.py

@@ -259,9 +259,11 @@ class FreeTypeFont:
 
         :return: (width, height)
         """
+        # vertical offset is added for historical reasons
+        # see https://github.com/python-pillow/Pillow/pull/4910#discussion_r486682929
         size, offset = self.font.getsize(text, False, direction, features, language)
         return (
-            size[0] + stroke_width * 2 + offset[0],
+            size[0] + stroke_width * 2,
             size[1] + stroke_width * 2 + offset[1],
         )
 

src/_imagingft.c

@@ -131,8 +131,8 @@ typedef struct {
 static p_raqm_func p_raqm;
 
 
-/* round a 26.6 pixel coordinate to the nearest larger integer */
-#define PIXEL(x) ((((x)+63) & -64)>>6)
+/* round a 26.6 pixel coordinate to the nearest integer */
+#define PIXEL(x) ((((x)+32) & -64)>>6)
 
 static PyObject*
 geterror(int code)
@@ -585,7 +585,8 @@ text_layout_fallback(PyObject* string, FontObject* self, const char* dir, PyObje
         }
 
         (*glyph_info)[i].x_advance = glyph->metrics.horiAdvance;
-        (*glyph_info)[i].y_advance = glyph->metrics.vertAdvance;
+        // y_advance is only used in ttb, which is not supported by basic layout
+        (*glyph_info)[i].y_advance = 0;
         last_index = (*glyph_info)[i].index;
         (*glyph_info)[i].cluster = ch;
     }
@@ -609,116 +610,103 @@ text_layout(PyObject* string, FontObject* self, const char* dir, PyObject *featu
 static PyObject*
 font_getsize(FontObject* self, PyObject* args)
 {
-    int x_position, x_max, x_min, y_max, y_min;
+    int position; /* pen position along primary axis, in 26.6 precision */
+    int advanced; /* pen position along primary axis, in pixels */
+    int px, py; /* position of current glyph, in pixels */
+    int x_min, x_max, y_min, y_max; /* text bounding box, in pixels */
+    int x_anchor, y_anchor; /* offset of point drawn at (0, 0), in pixels */
+    int load_flags; /* FreeType load_flags parameter */
+    int error;
     FT_Face face;
-    int xoffset, yoffset;
-    int horizontal_dir;
-    int mask = 0;
-    int load_flags;
+    FT_Glyph glyph;
+    FT_BBox bbox; /* glyph bounding box */
+    GlyphInfo *glyph_info = NULL; /* computed text layout */
+    size_t i, count; /* glyph_info index and length */
+    int horizontal_dir; /* is primary axis horizontal? */
+    int mask = 0; /* is FT_LOAD_TARGET_MONO enabled? */
     const char *dir = NULL;
     const char *lang = NULL;
-    size_t i, count;
-    GlyphInfo *glyph_info = NULL;
     PyObject *features = Py_None;
+    PyObject *string;
 
     /* calculate size and bearing for a given string */
 
-    PyObject* string;
     if (!PyArg_ParseTuple(args, "O|izOz:getsize", &string, &mask, &dir, &features, &lang)) {
         return NULL;
     }
 
+    horizontal_dir = dir && strcmp(dir, "ttb") == 0 ? 0 : 1;
+
     count = text_layout(string, self, dir, features, lang, &glyph_info, mask);
     if (PyErr_Occurred()) {
         return NULL;
     }
 
-    face = NULL;
-    xoffset = yoffset = 0;
-    x_position = x_max = x_min = y_max = y_min = 0;
+    /* Note: bitmap fonts within ttf fonts do not work, see #891/pr#960
+     *   Yifu Yu<root@jackyyf.com>, 2014-10-15
+     */
+    load_flags = FT_LOAD_NO_BITMAP;
+    if (mask) {
+        load_flags |= FT_LOAD_TARGET_MONO;
+    }
 
-    horizontal_dir = dir && strcmp(dir, "ttb") == 0 ? 0 : 1;
+    /*
+     * text bounds are given by:
+     *   - bounding boxes of individual glyphs
+     *   - pen line, i.e. 0 to `advanced` along primary axis
+     *     this means point (0, 0) is part of the text bounding box
+     */
+    face = NULL;
+    position = x_min = x_max = y_min = y_max = 0;
     for (i = 0; i < count; i++) {
-        int index, error, offset, x_advanced;
-        FT_BBox bbox;
-        FT_Glyph glyph;
         face = self->face;
-        index = glyph_info[i].index;
-        /* Note: bitmap fonts within ttf fonts do not work, see #891/pr#960
-         *   Yifu Yu<root@jackyyf.com>, 2014-10-15
-         */
-        load_flags = FT_LOAD_NO_BITMAP;
-        if (mask) {
-            load_flags |= FT_LOAD_TARGET_MONO;
+
+        if (horizontal_dir) {
+            px = PIXEL(position + glyph_info[i].x_offset);
+            py = PIXEL(glyph_info[i].y_offset);
+
+            position += glyph_info[i].x_advance;
+            advanced = PIXEL(position);
+            if (advanced > x_max) {
+                x_max = advanced;
+            }
+        } else {
+            px = PIXEL(glyph_info[i].x_offset);
+            py = PIXEL(position + glyph_info[i].y_offset);
+
+            position += glyph_info[i].y_advance;
+            advanced = PIXEL(position);
+            if (advanced < y_min) {
+                y_min = advanced;
+            }
         }
-        error = FT_Load_Glyph(face, index, load_flags);
+
+        error = FT_Load_Glyph(face, glyph_info[i].index, load_flags);
         if (error) {
             return geterror(error);
         }
 
-        if (i == 0) {
-            if (horizontal_dir) {
-                if (face->glyph->metrics.horiBearingX < 0) {
-                    xoffset = face->glyph->metrics.horiBearingX;
-                    x_position -= xoffset;
-                }
-            } else {
-                if (face->glyph->metrics.vertBearingY < 0) {
-                    yoffset = face->glyph->metrics.vertBearingY;
-                    y_max -= yoffset;
-                }
-            }
+        error = FT_Get_Glyph(face->glyph, &glyph);
+        if (error) {
+            return geterror(error);
         }
 
-        FT_Get_Glyph(face->glyph, &glyph);
-        FT_Glyph_Get_CBox(glyph, FT_GLYPH_BBOX_SUBPIXELS, &bbox);
-        if (horizontal_dir) {
-            x_position += glyph_info[i].x_advance;
-
-            x_advanced = x_position;
-            offset = glyph_info[i].x_advance -
-                    face->glyph->metrics.width -
-                    face->glyph->metrics.horiBearingX;
-            if (offset < 0) {
-                x_advanced -= offset;
-            }
-            if (x_advanced > x_max) {
-                x_max = x_advanced;
-            }
-
-            bbox.yMax += glyph_info[i].y_offset;
-            bbox.yMin += glyph_info[i].y_offset;
-            if (bbox.yMax > y_max) {
-                y_max = bbox.yMax;
-            }
-            if (bbox.yMin < y_min) {
-                y_min = bbox.yMin;
-            }
-
-            // find max distance of baseline from top
-            if (face->glyph->metrics.horiBearingY > yoffset) {
-                yoffset = face->glyph->metrics.horiBearingY;
-            }
-        } else {
-            y_max -= glyph_info[i].y_advance;
-
-            if (i == count - 1) {
-                // trim end gap from final glyph
-                int offset;
-                offset = -glyph_info[i].y_advance -
-                        face->glyph->metrics.height -
-                        face->glyph->metrics.vertBearingY;
-                if (offset < 0) {
-                    y_max -= offset;
-                }
-            }
-
-            if (bbox.xMax > x_max) {
-                x_max = bbox.xMax;
-            }
-            if (i == 0 || bbox.xMin < x_min) {
-                x_min = bbox.xMin;
-            }
+        FT_Glyph_Get_CBox(glyph, FT_GLYPH_BBOX_PIXELS, &bbox);
+        bbox.xMax += px;
+        if (bbox.xMax > x_max) {
+            x_max = bbox.xMax;
+        }
+        bbox.xMin += px;
+        if (bbox.xMin < x_min) {
+            x_min = bbox.xMin;
+        }
+        bbox.yMax += py;
+        if (bbox.yMax > y_max) {
+            y_max = bbox.yMax;
+        }
+        bbox.yMin += py;
+        if (bbox.yMin < y_min) {
+            y_min = bbox.yMin;
         }
 
         FT_Done_Glyph(glyph);
@@ -729,72 +717,63 @@ font_getsize(FontObject* self, PyObject* args)
         glyph_info = NULL;
     }
 
+    x_anchor = y_anchor = 0;
     if (face) {
         if (horizontal_dir) {
-            // left bearing
-            if (xoffset < 0) {
-                x_max -= xoffset;
-            } else {
-                xoffset = 0;
-            }
-
-            /* difference between the font ascender and the distance of
-             * the baseline from the top */
-            yoffset = PIXEL(self->face->size->metrics.ascender - yoffset);
+            x_anchor = 0;
+            y_anchor = PIXEL(self->face->size->metrics.ascender);
         } else {
-            // top bearing
-            if (yoffset < 0) {
-                y_max -= yoffset;
-            } else {
-                yoffset = 0;
-            }
+            x_anchor = x_min;
+            y_anchor = 0;
         }
     }
 
     return Py_BuildValue(
         "(ii)(ii)",
-        PIXEL(x_max - x_min), PIXEL(y_max - y_min),
-        PIXEL(xoffset), yoffset
-        );
+        (x_max - x_min), (y_max - y_min),
+        (-x_anchor + x_min), -(-y_anchor + y_max)
+    );
 }
 
 static PyObject*
 font_render(FontObject* self, PyObject* args)
 {
-    int x;
-    unsigned int y;
-    Imaging im;
-    int index, error, ascender, horizontal_dir;
-    int load_flags;
-    unsigned char *source;
+    int x, y; /* pen position, in 26.6 precision */
+    int px, py; /* position of current glyph, in pixels */
+    int x_min, y_max; /* text offset in 26.6 precision */
+    int load_flags; /* FreeType load_flags parameter */
+    int error;
     FT_Glyph glyph;
     FT_GlyphSlot glyph_slot;
     FT_Bitmap bitmap;
     FT_BitmapGlyph bitmap_glyph;
-    int stroke_width = 0;
     FT_Stroker stroker = NULL;
-    FT_Int left;
-    /* render string into given buffer (the buffer *must* have
-       the right size, or this will crash) */
-    PyObject* string;
+    GlyphInfo *glyph_info = NULL; /* computed text layout */
+    size_t i, count; /* glyph_info index and length */
+    int xx, yy; /* pixel offset of current glyph bitmap */
+    int x0, x1; /* horizontal bounds of glyph bitmap to copy */
+    unsigned int bitmap_y; /* glyph bitmap y index */
+    unsigned char *source; /* glyph bitmap source buffer */
+    Imaging im;
     Py_ssize_t id;
-    int mask = 0;
-    int temp;
-    int xx, x0, x1;
-    int yy;
-    unsigned int bitmap_y;
+    int horizontal_dir; /* is primary axis horizontal? */
+    int mask = 0; /* is FT_LOAD_TARGET_MONO enabled? */
+    int stroke_width = 0;
     const char *dir = NULL;
     const char *lang = NULL;
-    size_t i, count;
-    GlyphInfo *glyph_info;
-    PyObject *features = NULL;
+    PyObject *features = Py_None;
+    PyObject* string;
+
+    /* render string into given buffer (the buffer *must* have
+       the right size, or this will crash) */
 
     if (!PyArg_ParseTuple(args, "On|izOzi:render", &string,  &id, &mask, &dir, &features, &lang,
                                                    &stroke_width)) {
         return NULL;
     }
 
-    glyph_info = NULL;
+    horizontal_dir = dir && strcmp(dir, "ttb") == 0 ? 0 : 1;
+
     count = text_layout(string, self, dir, features, lang, &glyph_info, mask);
     if (PyErr_Occurred()) {
         return NULL;
@@ -813,16 +792,23 @@ font_render(FontObject* self, PyObject* args)
     }
 
     im = (Imaging) id;
+
     /* Note: bitmap fonts within ttf fonts do not work, see #891/pr#960 */
     load_flags = FT_LOAD_NO_BITMAP;
     if (mask) {
         load_flags |= FT_LOAD_TARGET_MONO;
     }
 
-    ascender = 0;
+    /*
+     * calculate x_min and y_max
+     * must match font_getsize or there may be clipping!
+     */
+    x = y = x_min = y_max = 0;
     for (i = 0; i < count; i++) {
-        index = glyph_info[i].index;
-        error = FT_Load_Glyph(self->face, index, load_flags | FT_LOAD_RENDER);
+        px = PIXEL(x + glyph_info[i].x_offset);
+        py = PIXEL(y + glyph_info[i].y_offset);
+
+        error = FT_Load_Glyph(self->face, glyph_info[i].index, load_flags | FT_LOAD_RENDER);
         if (error) {
             return geterror(error);
         }
@@ -830,22 +816,30 @@ font_render(FontObject* self, PyObject* args)
         glyph_slot = self->face->glyph;
         bitmap = glyph_slot->bitmap;
 
-        temp = bitmap.rows - glyph_slot->bitmap_top;
-        temp -= PIXEL(glyph_info[i].y_offset);
-        if (temp > ascender) {
-            ascender = temp;
+        if (glyph_slot->bitmap_top + py > y_max) {
+            y_max = glyph_slot->bitmap_top + py;
         }
+        if (glyph_slot->bitmap_left + px < x_min) {
+            x_min = glyph_slot->bitmap_left + px;
+        }
+
+        x += glyph_info[i].x_advance;
+        y += glyph_info[i].y_advance;
     }
 
+    /* set pen position to text origin */
+    x = (-x_min + stroke_width) << 6;
+    y = (-y_max + (-stroke_width)) << 6;
+
     if (stroker == NULL) {
         load_flags |= FT_LOAD_RENDER;
     }
 
-    x = y = 0;
-    horizontal_dir = dir && strcmp(dir, "ttb") == 0 ? 0 : 1;
     for (i = 0; i < count; i++) {
-        index = glyph_info[i].index;
-        error = FT_Load_Glyph(self->face, index, load_flags);
+        px = PIXEL(x + glyph_info[i].x_offset);
+        py = PIXEL(y + glyph_info[i].y_offset);
+
+        error = FT_Load_Glyph(self->face, glyph_info[i].index, load_flags);
         if (error) {
             return geterror(error);
         }
@@ -867,25 +861,15 @@ font_render(FontObject* self, PyObject* args)
             bitmap_glyph = (FT_BitmapGlyph)glyph;
 
             bitmap = bitmap_glyph->bitmap;
-            left = bitmap_glyph->left;
+            xx = px + bitmap_glyph->left;
+            yy = -(py + bitmap_glyph->top);
         } else {
             bitmap = glyph_slot->bitmap;
-            left = glyph_slot->bitmap_left;
-        }
-
-        if (horizontal_dir) {
-            if (i == 0 && glyph_slot->metrics.horiBearingX < 0) {
-                x = -glyph_slot->metrics.horiBearingX;
-            }
-            xx = PIXEL(x) + left;
-            xx += PIXEL(glyph_info[i].x_offset) + stroke_width;
-        } else {
-            if (glyph_slot->metrics.vertBearingX < 0) {
-                x = -glyph_slot->metrics.vertBearingX;
-            }
-            xx = im->xsize / 2 - bitmap.width / 2;
+            xx = px + glyph_slot->bitmap_left;
+            yy = -(py + glyph_slot->bitmap_top);
         }
 
+        /* clip glyph bitmap width to target image bounds */
         x0 = 0;
         x1 = bitmap.width;
         if (xx < 0) {
@@ -896,14 +880,8 @@ font_render(FontObject* self, PyObject* args)
         }
 
         source = (unsigned char*) bitmap.buffer;
-        for (bitmap_y = 0; bitmap_y < bitmap.rows; bitmap_y++) {
-            if (horizontal_dir) {
-                yy = bitmap_y + im->ysize - (PIXEL(glyph_slot->metrics.horiBearingY) + ascender);
-                yy -= PIXEL(glyph_info[i].y_offset) + stroke_width * 2;
-            } else {
-                yy = bitmap_y + PIXEL(y + glyph_slot->metrics.vertBearingY) + ascender;
-                yy += PIXEL(glyph_info[i].y_offset);
-            }
+        for (bitmap_y = 0; bitmap_y < bitmap.rows; bitmap_y++, yy++) {
+            /* clip glyph bitmap height to target image bounds */
             if (yy >= 0 && yy < im->ysize) {
                 // blend this glyph into the buffer
                 unsigned char *target = im->image8[yy] + xx;
@@ -932,7 +910,7 @@ font_render(FontObject* self, PyObject* args)
             source += bitmap.pitch;
         }
         x += glyph_info[i].x_advance;
-        y -= glyph_info[i].y_advance;
+        y += glyph_info[i].y_advance;
         if (stroker != NULL) {
             FT_Done_Glyph(glyph);
         }