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Feb 19, 2015
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Font advance width #4031

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c6d0183
Fix #253: Use advance width to calculate text bounding box
mdboom Jan 27, 2015
3afdaf0
Update baseline images with text
mdboom Jan 27, 2015
f8dc710
Update docstring
mdboom Jan 27, 2015
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Fix #253: Use advance width to calculate text bounding box
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@mdboom
mdboom committed Jan 27, 2015
commit c6d01835816ace3204212d072da1ac3af2b54997
3 changes: 3 additions & 0 deletions CHANGELOG
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@@ -1,3 +1,6 @@
2015-01-23 Text bounding boxes are now computed with advance width rather than
ink area. This may result in slightly different placement of text.

2014-10-27 Allowed selection of the backend using the `MPLBACKEND` environment
variable. Added documentation on backend selection methods.

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5 changes: 4 additions & 1 deletion lib/matplotlib/backends/backend_agg.py
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Expand Up @@ -202,12 +202,15 @@ def draw_text(self, gc, x, y, s, prop, angle, ismath=False, mtext=None):
font.draw_glyphs_to_bitmap(antialiased=rcParams['text.antialiased'])
d = font.get_descent() / 64.0
# The descent needs to be adjusted for the angle
xo, yo = font.get_bitmap_offset()
xo /= 64.0
yo /= 64.0
xd = -d * np.sin(np.deg2rad(angle))
yd = d * np.cos(np.deg2rad(angle))

#print x, y, int(x), int(y), s
self._renderer.draw_text_image(
font, np.round(x - xd), np.round(y + yd) + 1, angle, gc)
font, np.round(x - xd + xo), np.round(y + yd + yo) + 1, angle, gc)

def get_text_width_height_descent(self, s, prop, ismath):
"""
Expand Down
101 changes: 36 additions & 65 deletions src/ft2font.cpp
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Expand Up @@ -569,46 +569,6 @@ void FT2Font::select_charmap(unsigned long i)
}
}

FT_BBox FT2Font::compute_string_bbox()
{
FT_BBox bbox;
/* initialize string bbox to "empty" values */
bbox.xMin = bbox.yMin = 32000;
bbox.xMax = bbox.yMax = -32000;

int right_side = 0;
for (size_t n = 0; n < glyphs.size(); n++) {
FT_BBox glyph_bbox;
FT_Glyph_Get_CBox(glyphs[n], ft_glyph_bbox_subpixels, &glyph_bbox);
if (glyph_bbox.xMin < bbox.xMin) {
bbox.xMin = glyph_bbox.xMin;
}
if (glyph_bbox.yMin < bbox.yMin) {
bbox.yMin = glyph_bbox.yMin;
}
if (glyph_bbox.xMin == glyph_bbox.xMax) {
right_side += glyphs[n]->advance.x >> 10;
if (right_side > bbox.xMax) {
bbox.xMax = right_side;
}
} else {
if (glyph_bbox.xMax > bbox.xMax) {
bbox.xMax = glyph_bbox.xMax;
}
}
if (glyph_bbox.yMax > bbox.yMax)
bbox.yMax = glyph_bbox.yMax;
}
/* check that we really grew the string bbox */
if (bbox.xMin > bbox.xMax) {
bbox.xMin = 0;
bbox.yMin = 0;
bbox.xMax = 0;
bbox.yMax = 0;
}
return bbox;
}

int FT2Font::get_kerning(int left, int right, int mode)
{
if (!FT_HAS_KERNING(face)) {
Expand All @@ -617,7 +577,7 @@ int FT2Font::get_kerning(int left, int right, int mode)
FT_Vector delta;

if (!FT_Get_Kerning(face, left, right, mode, &delta)) {
return (int)(delta.x / hinting_factor);
return (int)(delta.x) / (hinting_factor << 6);
} else {
return 0;
}
Expand All @@ -641,17 +601,22 @@ void FT2Font::set_text(
pen.x = 0;
pen.y = 0;

bbox.xMin = bbox.yMin = 32000;
bbox.xMax = bbox.yMax = -32000;

for (unsigned int n = 0; n < N; n++) {
std::string thischar("?");
FT_UInt glyph_index;
FT_BBox glyph_bbox;
FT_Pos last_advance;

glyph_index = FT_Get_Char_Index(face, codepoints[n]);

// retrieve kerning distance and move pen position
if (use_kerning && previous && glyph_index) {
FT_Vector delta;
FT_Get_Kerning(face, previous, glyph_index, FT_KERNING_DEFAULT, &delta);
pen.x += delta.x / hinting_factor;
pen.x += (delta.x << 10) / (hinting_factor << 16);
}
error = FT_Load_Glyph(face, glyph_index, flags);
if (error) {
Expand All @@ -669,18 +634,30 @@ void FT2Font::set_text(
}
// ignore errors, jump to next glyph

last_advance = face->glyph->advance.x;
FT_Glyph_Transform(thisGlyph, 0, &pen);
FT_Glyph_Transform(thisGlyph, &matrix, 0);
xys.push_back(pen.x);
xys.push_back(pen.y);
pen.x += face->glyph->advance.x;

FT_Glyph_Get_CBox(thisGlyph, ft_glyph_bbox_subpixels, &glyph_bbox);

bbox.xMin = std::min(bbox.xMin, glyph_bbox.xMin);
bbox.xMax = std::max(bbox.xMax, glyph_bbox.xMax);
bbox.yMin = std::min(bbox.yMin, glyph_bbox.yMin);
bbox.yMax = std::max(bbox.yMax, glyph_bbox.yMax);

pen.x += last_advance;

previous = glyph_index;
glyphs.push_back(thisGlyph);
}

// now apply the rotation
for (unsigned int n = 0; n < glyphs.size(); n++) {
FT_Glyph_Transform(glyphs[n], &matrix, 0);
FT_Vector_Transform(&pen, &matrix);
advance = pen.x;

if (bbox.xMin > bbox.xMax) {
bbox.xMin = bbox.yMin = bbox.xMax = bbox.yMax = 0;
}
}

Expand Down Expand Up @@ -722,30 +699,29 @@ void FT2Font::load_glyph(FT_UInt glyph_index, FT_UInt32 flags)

void FT2Font::get_width_height(long *width, long *height)
{
FT_BBox bbox = compute_string_bbox();

*width = bbox.xMax - bbox.xMin;
*width = advance;
*height = bbox.yMax - bbox.yMin;
}

long FT2Font::get_descent()
{
FT_BBox bbox = compute_string_bbox();
return -bbox.yMin;
}

void FT2Font::get_bitmap_offset(long *x, long *y)
{
*x = bbox.xMin;
*y = 0;
}

void FT2Font::draw_glyphs_to_bitmap(bool antialiased)
{
FT_BBox string_bbox = compute_string_bbox();
size_t width = (string_bbox.xMax - string_bbox.xMin) / 64 + 2;
size_t height = (string_bbox.yMax - string_bbox.yMin) / 64 + 2;
size_t width = (bbox.xMax - bbox.xMin) / 64 + 2;
size_t height = (bbox.yMax - bbox.yMin) / 64 + 2;

image.resize(width, height);

for (size_t n = 0; n < glyphs.size(); n++) {
FT_BBox bbox;
FT_Glyph_Get_CBox(glyphs[n], ft_glyph_bbox_pixels, &bbox);

error = FT_Glyph_To_Bitmap(
&glyphs[n], antialiased ? FT_RENDER_MODE_NORMAL : FT_RENDER_MODE_MONO, 0, 1);
if (error) {
Expand All @@ -756,22 +732,17 @@ void FT2Font::draw_glyphs_to_bitmap(bool antialiased)
// now, draw to our target surface (convert position)

// bitmap left and top in pixel, string bbox in subpixel
FT_Int x = (FT_Int)(bitmap->left - (string_bbox.xMin / 64.));
FT_Int y = (FT_Int)((string_bbox.yMax / 64.) - bitmap->top + 1);
FT_Int x = (FT_Int)(bitmap->left - (bbox.xMin / 64.));
FT_Int y = (FT_Int)((bbox.yMax / 64.) - bitmap->top + 1);

image.draw_bitmap(&bitmap->bitmap, x, y);
}
}

void FT2Font::get_xys(bool antialiased, std::vector<double> &xys)
{
FT_BBox string_bbox = compute_string_bbox();

for (size_t n = 0; n < glyphs.size(); n++) {

FT_BBox bbox;
FT_Glyph_Get_CBox(glyphs[n], ft_glyph_bbox_pixels, &bbox);

error = FT_Glyph_To_Bitmap(
&glyphs[n], antialiased ? FT_RENDER_MODE_NORMAL : FT_RENDER_MODE_MONO, 0, 1);
if (error) {
Expand All @@ -781,8 +752,8 @@ void FT2Font::get_xys(bool antialiased, std::vector<double> &xys)
FT_BitmapGlyph bitmap = (FT_BitmapGlyph)glyphs[n];

// bitmap left and top in pixel, string bbox in subpixel
FT_Int x = (FT_Int)(bitmap->left - string_bbox.xMin / 64.);
FT_Int y = (FT_Int)(string_bbox.yMax / 64. - bitmap->top + 1);
FT_Int x = (FT_Int)(bitmap->left - bbox.xMin / 64.);
FT_Int y = (FT_Int)(bbox.yMax / 64. - bitmap->top + 1);
// make sure the index is non-neg
x = x < 0 ? 0 : x;
y = y < 0 ? 0 : y;
Expand Down
4 changes: 3 additions & 1 deletion src/ft2font.h
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Expand Up @@ -77,6 +77,7 @@ class FT2Font
void load_char(long charcode, FT_UInt32 flags);
void load_glyph(FT_UInt glyph_index, FT_UInt32 flags);
void get_width_height(long *width, long *height);
void get_bitmap_offset(long *x, long *y);
long get_descent();
// TODO: Since we know the size of the array upfront, we probably don't
// need to dynamically allocate like this
Expand Down Expand Up @@ -121,12 +122,13 @@ class FT2Font
FT_Error error;
std::vector<FT_Glyph> glyphs;
std::vector<FT_Vector> pos;
FT_BBox bbox;
FT_Pos advance;
double angle;
double ptsize;
double dpi;
long hinting_factor;

FT_BBox compute_string_bbox();
void set_scalable_attributes();

// prevent copying
Expand Down
15 changes: 15 additions & 0 deletions src/ft2font_wrapper.cpp
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Expand Up @@ -765,6 +765,20 @@ static PyObject *PyFT2Font_get_width_height(PyFT2Font *self, PyObject *args, PyO
return Py_BuildValue("ll", width, height);
}

const char *PyFT2Font_get_bitmap_offset__doc__ =
"w, h = get_bitmap_offset()\n"
"\n"
"Get the offset in 26.6 subpixels for the bitmap if ink hangs left or below (0, 0)\n";

static PyObject *PyFT2Font_get_bitmap_offset(PyFT2Font *self, PyObject *args, PyObject *kwds)
{
long x, y;

CALL_CPP("get_bitmap_offset", (self->x->get_bitmap_offset(&x, &y)));

return Py_BuildValue("ll", x, y);
}

const char *PyFT2Font_get_descent__doc__ =
"d = get_descent()\n"
"\n"
Expand Down Expand Up @@ -1572,6 +1586,7 @@ static PyTypeObject *PyFT2Font_init_type(PyObject *m, PyTypeObject *type)
{"load_char", (PyCFunction)PyFT2Font_load_char, METH_VARARGS|METH_KEYWORDS, PyFT2Font_load_char__doc__},
{"load_glyph", (PyCFunction)PyFT2Font_load_glyph, METH_VARARGS|METH_KEYWORDS, PyFT2Font_load_glyph__doc__},
{"get_width_height", (PyCFunction)PyFT2Font_get_width_height, METH_NOARGS, PyFT2Font_get_width_height__doc__},
{"get_bitmap_offset", (PyCFunction)PyFT2Font_get_bitmap_offset, METH_NOARGS, PyFT2Font_get_bitmap_offset__doc__},
{"get_descent", (PyCFunction)PyFT2Font_get_descent, METH_NOARGS, PyFT2Font_get_descent__doc__},
{"draw_glyphs_to_bitmap", (PyCFunction)PyFT2Font_draw_glyphs_to_bitmap, METH_VARARGS|METH_KEYWORDS, PyFT2Font_draw_glyphs_to_bitmap__doc__},
{"get_xys", (PyCFunction)PyFT2Font_get_xys, METH_VARARGS|METH_KEYWORDS, PyFT2Font_get_xys__doc__},
Expand Down