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tesseract/training/pango_font_info.cpp
Ray Smith 941d87057e Fixed training build
2015-05-13 17:46:58 -07:00

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/**********************************************************************
* File: pango_font_info.cpp
* Description: Font-related objects and helper functions
* Author: Ranjith Unnikrishnan
* Created: Mon Nov 18 2013
*
* (C) Copyright 2013, Google Inc.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
**********************************************************************/
// Include automatically generated configuration file if running autoconf.
#ifdef HAVE_CONFIG_H
#include "config_auto.h"
#endif
#ifdef MINGW
// workaround for stdlib.h and putenv
#undef __STRICT_ANSI__
#include "strcasestr.h"
#endif // MINGW
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/param.h>
#include <algorithm>
#include "pango_font_info.h"
#include "commandlineflags.h"
#include "fileio.h"
#include "normstrngs.h"
#include "tlog.h"
#include "unichar.h"
#include "util.h"
#include "pango/pango.h"
#include "pango/pangocairo.h"
#include "pango/pangofc-font.h"
STRING_PARAM_FLAG(fonts_dir, "/auto/ocr-data/tesstraining/fonts",
"Overrides system default font location");
STRING_PARAM_FLAG(fontconfig_tmpdir, "/tmp",
"Overrides fontconfig default temporary dir");
BOOL_PARAM_FLAG(fontconfig_refresh_cache, false,
"Does a one-time deletion of cache files from the "
"fontconfig_tmpdir before initializing fontconfig.");
BOOL_PARAM_FLAG(fontconfig_refresh_config_file, true,
"Does a one-time reset of the fontconfig config file to point"
" to fonts_dir before initializing fontconfig. Set to true"
" if fontconfig_refresh_cache is true. Set it to false to use"
" multiple instances in separate processes without having to"
" rescan the fonts_dir, using a previously setup font cache");
#ifndef USE_STD_NAMESPACE
#include "ocr/trainingdata/typesetting/legacy_fonts.h"
BOOL_PARAM_FLAG(use_only_legacy_fonts, false,
"Overrides --fonts_dir and sets the known universe of fonts to"
"the list in legacy_fonts.h");
#else
using std::pair;
#endif
namespace tesseract {
// Default assumed output resolution. Required only for providing font metrics
// in pixels.
const int kDefaultResolution = 300;
bool PangoFontInfo::fontconfig_initialized_ = false;
PangoFontInfo::PangoFontInfo() : desc_(NULL), resolution_(kDefaultResolution) {
Clear();
}
PangoFontInfo::PangoFontInfo(const string& desc)
: desc_(NULL), resolution_(kDefaultResolution) {
if (!ParseFontDescriptionName(desc)) {
tprintf("ERROR: Could not parse %s\n", desc.c_str());
Clear();
}
}
void PangoFontInfo::Clear() {
font_size_ = 0;
is_bold_ = false;
is_italic_ = false;
is_smallcaps_ = false;
is_monospace_ = false;
family_name_.clear();
font_type_ = UNKNOWN;
if (desc_) {
pango_font_description_free(desc_);
desc_ = NULL;
}
}
string PangoFontInfo::DescriptionName() const {
if (!desc_) return "";
char* desc_str = pango_font_description_to_string(desc_);
string desc_name(desc_str);
g_free(desc_str);
return desc_name;
}
// Initializes Fontconfig for use by writing a fake fonts.conf file into the
// FLAGS_fontconfigs_tmpdir directory, that points to the supplied
// fonts_dir, and then overrides the FONTCONFIG_PATH environment variable
// to point to this fonts.conf file. If force_clear, the cache is refreshed
// even if it has already been initialized.
void PangoFontInfo::InitFontConfig(bool force_clear, const string& fonts_dir) {
if ((fontconfig_initialized_ && !force_clear) || fonts_dir.empty()) {
fontconfig_initialized_ = true;
return;
}
if (FLAGS_fontconfig_refresh_cache || force_clear) {
File::DeleteMatchingFiles(File::JoinPath(
FLAGS_fontconfig_tmpdir.c_str(), "*cache-?").c_str());
}
if (FLAGS_fontconfig_refresh_config_file || FLAGS_fontconfig_refresh_cache ||
force_clear) {
const int MAX_FONTCONF_FILESIZE = 1024;
char fonts_conf_template[MAX_FONTCONF_FILESIZE];
snprintf(fonts_conf_template, MAX_FONTCONF_FILESIZE,
"<?xml version=\"1.0\"?>\n"
"<!DOCTYPE fontconfig SYSTEM \"fonts.dtd\">\n"
"<fontconfig>\n"
"<dir>%s</dir>\n"
"<cachedir>%s</cachedir>\n"
"<config></config>\n"
"</fontconfig>", fonts_dir.c_str(),
FLAGS_fontconfig_tmpdir.c_str());
string fonts_conf_file = File::JoinPath(FLAGS_fontconfig_tmpdir.c_str(),
"fonts.conf");
File::WriteStringToFileOrDie(fonts_conf_template, fonts_conf_file);
}
#ifdef _WIN32
std::string env("FONTCONFIG_PATH=");
env.append(FLAGS_fontconfig_tmpdir.c_str());
putenv(env.c_str());
putenv("LANG=en_US.utf8");
#else
setenv("FONTCONFIG_PATH", FLAGS_fontconfig_tmpdir.c_str(), true);
// Fix the locale so that the reported font names are consistent.
setenv("LANG", "en_US.utf8", true);
#endif // _WIN32
if (!fontconfig_initialized_ || force_clear) {
if (FcInitReinitialize() != FcTrue) {
tprintf("FcInitiReinitialize failed!!\n");
}
}
fontconfig_initialized_ = true;
FontUtils::ReInit();
}
static void ListFontFamilies(PangoFontFamily*** families,
int* n_families) {
PangoFontInfo::InitFontConfig(false, FLAGS_fonts_dir.c_str());
PangoFontMap* font_map = pango_cairo_font_map_get_default();
DISABLE_HEAP_LEAK_CHECK;
pango_font_map_list_families(font_map, families, n_families);
}
// Inspects whether a given font family is monospace. If the font is not
// available, it cannot make a decision and returns false by default.
static bool IsMonospaceFontFamily(const char* family_name) {
PangoFontFamily** families = 0;
int n_families = 0;
bool is_monospace = false;
ListFontFamilies(&families, &n_families);
ASSERT_HOST(n_families > 0);
bool found = false;
for (int i = 0; i < n_families; ++i) {
if (!strcasecmp(family_name, pango_font_family_get_name(families[i]))) {
is_monospace = pango_font_family_is_monospace(families[i]);
found = true;
break;
}
}
if (!found) {
tlog(1, "Could not find monospace property of family %s\n", family_name);
}
g_free(families);
return is_monospace;
}
bool PangoFontInfo::ParseFontDescription(const PangoFontDescription *desc) {
Clear();
const char* family = pango_font_description_get_family(desc);
if (!family) {
char* desc_str = pango_font_description_to_string(desc);
tprintf("WARNING: Could not parse family name from description: '%s'\n",
desc_str);
g_free(desc_str);
return false;
}
family_name_ = string(family);
desc_ = pango_font_description_copy(desc);
is_monospace_ = IsMonospaceFontFamily(family);
// Set font size in points
font_size_ = pango_font_description_get_size(desc);
if (!pango_font_description_get_size_is_absolute(desc)) {
font_size_ /= PANGO_SCALE;
}
PangoStyle style = pango_font_description_get_style(desc);
is_italic_ = (PANGO_STYLE_ITALIC == style ||
PANGO_STYLE_OBLIQUE == style);
is_smallcaps_ = (pango_font_description_get_variant(desc)
== PANGO_VARIANT_SMALL_CAPS);
is_bold_ = (pango_font_description_get_weight(desc) >= PANGO_WEIGHT_BOLD);
// We dont have a way to detect whether a font is of type Fraktur. The fonts
// we currently use all have "Fraktur" in their family name, so we do a
// fragile but functional check for that here.
is_fraktur_ = (strcasestr(family, "Fraktur") != NULL);
return true;
}
bool PangoFontInfo::ParseFontDescriptionName(const string& name) {
PangoFontDescription *desc = pango_font_description_from_string(name.c_str());
bool success = ParseFontDescription(desc);
pango_font_description_free(desc);
return success;
}
// Returns the PangoFont structure corresponding to the closest available font
// in the font map. Note that if the font is wholly missing, this could
// correspond to a completely different font family and face.
PangoFont* PangoFontInfo::ToPangoFont() const {
InitFontConfig(false, FLAGS_fonts_dir.c_str());
PangoFontMap* font_map = pango_cairo_font_map_get_default();
PangoContext* context = pango_context_new();
pango_cairo_context_set_resolution(context, resolution_);
pango_context_set_font_map(context, font_map);
PangoFont* font = NULL;
{
DISABLE_HEAP_LEAK_CHECK;
font = pango_font_map_load_font(font_map, context, desc_);
}
g_object_unref(context);
return font;
}
bool PangoFontInfo::CoversUTF8Text(const char* utf8_text, int byte_length) const {
PangoFont* font = ToPangoFont();
PangoCoverage* coverage = pango_font_get_coverage(font, NULL);
for (UNICHAR::const_iterator it = UNICHAR::begin(utf8_text, byte_length);
it != UNICHAR::end(utf8_text, byte_length);
++it) {
if (IsWhitespace(*it) || pango_is_zero_width(*it))
continue;
if (pango_coverage_get(coverage, *it) != PANGO_COVERAGE_EXACT) {
char tmp[5];
int len = it.get_utf8(tmp);
tmp[len] = '\0';
tlog(2, "'%s' (U+%x) not covered by font\n", tmp, *it);
return false;
}
}
return true;
}
// This variant of strncpy permits src and dest to overlap. It will copy the
// first byte first.
static char* my_strnmove(char* dest, const char* src, size_t n) {
char* ret = dest;
// Copy characters until n reaches zero or the src byte is a nul.
do {
*dest = *src;
--n;
++dest;
++src;
} while (n && src[0]);
// If we reached a nul byte and there are more 'n' left, zero them out.
while (n) {
*dest = '\0';
--n;
++dest;
}
return ret;
}
int PangoFontInfo::DropUncoveredChars(string* utf8_text) const {
PangoFont* font = ToPangoFont();
PangoCoverage* coverage = pango_font_get_coverage(font, NULL);
int num_dropped_chars = 0;
// Maintain two iterators that point into the string. For space efficiency, we
// will repeatedly copy one covered UTF8 character from one to the other, and
// at the end resize the string to the right length.
char* out = const_cast<char*>(utf8_text->c_str());
const UNICHAR::const_iterator it_begin =
UNICHAR::begin(utf8_text->c_str(), utf8_text->length());
const UNICHAR::const_iterator it_end =
UNICHAR::end(utf8_text->c_str(), utf8_text->length());
for (UNICHAR::const_iterator it = it_begin; it != it_end;) {
// Skip bad utf-8.
if (!it.is_legal()) {
++it; // One suitable error message will still be issued.
continue;
}
int unicode = *it;
int utf8_len = it.utf8_len();
const char* utf8_char = it.utf8_data();
// Move it forward before the data gets modified.
++it;
if (!IsWhitespace(unicode) && !pango_is_zero_width(unicode) &&
pango_coverage_get(coverage, unicode) != PANGO_COVERAGE_EXACT) {
if (TLOG_IS_ON(2)) {
UNICHAR unichar(unicode);
char* str = unichar.utf8_str();
tlog(2, "'%s' (U+%x) not covered by font\n", str, unicode);
delete[] str;
}
++num_dropped_chars;
continue;
}
my_strnmove(out, utf8_char, utf8_len);
out += utf8_len;
}
utf8_text->resize(out - utf8_text->c_str());
return num_dropped_chars;
}
bool PangoFontInfo::GetSpacingProperties(const string& utf8_char,
int* x_bearing, int* x_advance) const {
// Convert to equivalent PangoFont structure
PangoFont* font = ToPangoFont();
// Find the glyph index in the font for the supplied utf8 character.
int total_advance = 0;
int min_bearing = 0;
// Handle multi-unicode strings by reporting the left-most position of the
// x-bearing, and right-most position of the x-advance if the string were to
// be rendered.
const UNICHAR::const_iterator it_begin = UNICHAR::begin(utf8_char.c_str(),
utf8_char.length());
const UNICHAR::const_iterator it_end = UNICHAR::end(utf8_char.c_str(),
utf8_char.length());
for (UNICHAR::const_iterator it = it_begin; it != it_end; ++it) {
PangoGlyph glyph_index = pango_fc_font_get_glyph(
reinterpret_cast<PangoFcFont*>(font), *it);
if (!glyph_index) {
// Glyph for given unicode character doesn't exist in font.
return false;
}
// Find the ink glyph extents for the glyph
PangoRectangle ink_rect, logical_rect;
pango_font_get_glyph_extents(font, glyph_index, &ink_rect, &logical_rect);
pango_extents_to_pixels(&ink_rect, NULL);
pango_extents_to_pixels(&logical_rect, NULL);
int bearing = total_advance + PANGO_LBEARING(ink_rect);
if (it == it_begin || bearing < min_bearing) {
min_bearing = bearing;
}
total_advance += PANGO_RBEARING(logical_rect);
}
*x_bearing = min_bearing;
*x_advance = total_advance;
return true;
}
bool PangoFontInfo::CanRenderString(const char* utf8_word, int len) const {
vector<string> graphemes;
return CanRenderString(utf8_word, len, &graphemes);
}
bool PangoFontInfo::CanRenderString(const char* utf8_word, int len,
vector<string>* graphemes) const {
if (graphemes) graphemes->clear();
// We check for font coverage of the text first, as otherwise Pango could
// (undesirably) fall back to another font that does have the required
// coverage.
if (!CoversUTF8Text(utf8_word, len)) {
return false;
}
// U+25CC dotted circle character that often (but not always) gets rendered
// when there is an illegal grapheme sequence.
const char32 kDottedCircleGlyph = 9676;
bool bad_glyph = false;
PangoFontMap* font_map = pango_cairo_font_map_get_default();
PangoContext* context = pango_context_new();
pango_context_set_font_map(context, font_map);
PangoLayout* layout;
{
// Pango is not relasing the cached layout.
DISABLE_HEAP_LEAK_CHECK;
layout = pango_layout_new(context);
}
if (desc_) {
pango_layout_set_font_description(layout, desc_);
} else {
PangoFontDescription *desc = pango_font_description_from_string(
DescriptionName().c_str());
pango_layout_set_font_description(layout, desc);
pango_font_description_free(desc);
}
pango_layout_set_text(layout, utf8_word, len);
PangoLayoutIter* run_iter = NULL;
{ // Fontconfig caches some information here that is not freed before exit.
DISABLE_HEAP_LEAK_CHECK;
run_iter = pango_layout_get_iter(layout);
}
do {
PangoLayoutRun* run = pango_layout_iter_get_run_readonly(run_iter);
if (!run) {
tlog(2, "Found end of line NULL run marker\n");
continue;
}
PangoGlyph dotted_circle_glyph;
PangoFont* font = run->item->analysis.font;
dotted_circle_glyph = pango_fc_font_get_glyph(
reinterpret_cast<PangoFcFont*>(font), kDottedCircleGlyph);
if (TLOG_IS_ON(2)) {
PangoFontDescription* desc = pango_font_describe(font);
char* desc_str = pango_font_description_to_string(desc);
tlog(2, "Desc of font in run: %s\n", desc_str);
g_free(desc_str);
pango_font_description_free(desc);
}
PangoGlyphItemIter cluster_iter;
gboolean have_cluster;
for (have_cluster = pango_glyph_item_iter_init_start(&cluster_iter,
run, utf8_word);
have_cluster && !bad_glyph;
have_cluster = pango_glyph_item_iter_next_cluster(&cluster_iter)) {
const int start_byte_index = cluster_iter.start_index;
const int end_byte_index = cluster_iter.end_index;
int start_glyph_index = cluster_iter.start_glyph;
int end_glyph_index = cluster_iter.end_glyph;
string cluster_text = string(utf8_word + start_byte_index,
end_byte_index - start_byte_index);
if (graphemes) graphemes->push_back(cluster_text);
if (IsUTF8Whitespace(cluster_text.c_str())) {
tlog(2, "Skipping whitespace\n");
continue;
}
if (TLOG_IS_ON(2)) {
printf("start_byte=%d end_byte=%d start_glyph=%d end_glyph=%d ",
start_byte_index, end_byte_index,
start_glyph_index, end_glyph_index);
}
for (int i = start_glyph_index,
step = (end_glyph_index > start_glyph_index) ? 1 : -1;
!bad_glyph && i != end_glyph_index; i+= step) {
const bool unknown_glyph =
(cluster_iter.glyph_item->glyphs->glyphs[i].glyph &
PANGO_GLYPH_UNKNOWN_FLAG);
const bool illegal_glyph =
(cluster_iter.glyph_item->glyphs->glyphs[i].glyph ==
dotted_circle_glyph);
bad_glyph = unknown_glyph || illegal_glyph;
if (TLOG_IS_ON(2)) {
printf("(%d=%d)", cluster_iter.glyph_item->glyphs->glyphs[i].glyph,
bad_glyph ? 1 : 0);
}
}
if (TLOG_IS_ON(2)) {
printf(" '%s'\n", cluster_text.c_str());
}
if (bad_glyph)
tlog(1, "Found illegal glyph!\n");
}
} while (!bad_glyph && pango_layout_iter_next_run(run_iter));
pango_layout_iter_free(run_iter);
g_object_unref(context);
g_object_unref(layout);
if (bad_glyph && graphemes) graphemes->clear();
return !bad_glyph;
}
// ------------------------ FontUtils ------------------------------------
vector<string> FontUtils::available_fonts_; // cache list
// Returns whether the specified font description is available in the fonts
// directory.
//
// The generated list of font families and faces includes "synthesized" font
// faces that are not truly loadable. Pango versions >=1.18 have a
// pango_font_face_is_synthesized method that can be used to prune the list.
// Until then, we are restricted to using a hack where we try to load the font
// from the font_map, and then check what we loaded to see if it has the
// description we expected. If it is not, then the font is deemed unavailable.
/* static */
bool FontUtils::IsAvailableFont(const char* input_query_desc,
string* best_match) {
string query_desc(input_query_desc);
if (PANGO_VERSION <= 12005) {
// Strip commas and any ' Medium' substring in the name.
query_desc.erase(std::remove(query_desc.begin(), query_desc.end(), ','),
query_desc.end());
const string kMediumStr = " Medium";
std::size_t found = query_desc.find(kMediumStr);
if (found != std::string::npos) {
query_desc.erase(found, kMediumStr.length());
}
}
PangoFontDescription *desc = pango_font_description_from_string(
query_desc.c_str());
PangoFont* selected_font = NULL;
{
PangoFontInfo::InitFontConfig(false, FLAGS_fonts_dir.c_str());
PangoFontMap* font_map = pango_cairo_font_map_get_default();
PangoContext* context = pango_context_new();
pango_context_set_font_map(context, font_map);
{
DISABLE_HEAP_LEAK_CHECK;
selected_font = pango_font_map_load_font(font_map, context, desc);
}
g_object_unref(context);
}
if (selected_font == NULL) {
pango_font_description_free(desc);
return false;
}
PangoFontDescription* selected_desc = pango_font_describe(selected_font);
bool equal = pango_font_description_equal(desc, selected_desc);
tlog(3, "query weight = %d \t selected weight =%d\n",
pango_font_description_get_weight(desc),
pango_font_description_get_weight(selected_desc));
char* selected_desc_str = pango_font_description_to_string(selected_desc);
tlog(2, "query_desc: '%s' Selected: 's'\n", query_desc.c_str(),
selected_desc_str);
if (!equal && best_match != NULL) {
*best_match = selected_desc_str;
// Clip the ending ' 0' if there is one. It seems that, if there is no
// point size on the end of the fontname, then Pango always appends ' 0'.
int len = best_match->size();
if (len > 2 && best_match->at(len - 1) == '0' &&
best_match->at(len - 2) == ' ') {
*best_match = best_match->substr(0, len - 2);
}
}
g_free(selected_desc_str);
pango_font_description_free(selected_desc);
g_object_unref(selected_font);
pango_font_description_free(desc);
return equal;
}
static bool ShouldIgnoreFontFamilyName(const char* query) {
static const char* kIgnoredFamilyNames[]
= { "Sans", "Serif", "Monospace", NULL };
const char** list = kIgnoredFamilyNames;
for (; *list != NULL; ++list) {
if (!strcmp(*list, query))
return true;
}
return false;
}
// Outputs description names of available fonts.
/* static */
const vector<string>& FontUtils::ListAvailableFonts() {
if (available_fonts_.size()) {
return available_fonts_;
}
#ifndef USE_STD_NAMESPACE
if (FLAGS_use_only_legacy_fonts) {
// Restrict view to list of fonts in legacy_fonts.h
tprintf("Using list of legacy fonts only\n");
const int kNumFontLists = 4;
for (int i = 0; i < kNumFontLists; ++i) {
for (int j = 0; kFontlists[i][j] != NULL; ++j) {
available_fonts_.push_back(kFontlists[i][j]);
}
}
return available_fonts_;
}
#endif
PangoFontFamily** families = 0;
int n_families = 0;
ListFontFamilies(&families, &n_families);
for (int i = 0; i < n_families; ++i) {
const char* family_name = pango_font_family_get_name(families[i]);
tlog(2, "Listing family %s\n", family_name);
if (ShouldIgnoreFontFamilyName(family_name)) {
continue;
}
int n_faces;
PangoFontFace** faces = NULL;
pango_font_family_list_faces(families[i], &faces, &n_faces);
for (int j = 0; j < n_faces; ++j) {
PangoFontDescription* desc = pango_font_face_describe(faces[j]);
char* desc_str = pango_font_description_to_string(desc);
if (IsAvailableFont(desc_str)) {
available_fonts_.push_back(desc_str);
}
pango_font_description_free(desc);
g_free(desc_str);
}
g_free(faces);
}
g_free(families);
sort(available_fonts_.begin(), available_fonts_.end());
return available_fonts_;
}
static void CharCoverageMapToBitmap(PangoCoverage* coverage,
vector<bool>* unichar_bitmap) {
const int kMinUnicodeValue = 33;
const int kMaxUnicodeValue = 0x10FFFF;
unichar_bitmap->resize(kMaxUnicodeValue + 1, false);
// Mark off characters that the font can render.
for (int i = kMinUnicodeValue; i <= kMaxUnicodeValue; ++i) {
if (IsInterchangeValid(i)) {
(*unichar_bitmap)[i]
= (pango_coverage_get(coverage, i) == PANGO_COVERAGE_EXACT);
}
}
}
/* static */
void FontUtils::GetAllRenderableCharacters(vector<bool>* unichar_bitmap) {
const vector<string>& all_fonts = ListAvailableFonts();
return GetAllRenderableCharacters(all_fonts, unichar_bitmap);
}
/* static */
void FontUtils::GetAllRenderableCharacters(const string& font_name,
vector<bool>* unichar_bitmap) {
PangoFontInfo font_info(font_name);
PangoCoverage* coverage = pango_font_get_coverage(
font_info.ToPangoFont(), NULL);
CharCoverageMapToBitmap(coverage, unichar_bitmap);
}
/* static */
void FontUtils::GetAllRenderableCharacters(const vector<string>& fonts,
vector<bool>* unichar_bitmap) {
// Form the union of coverage maps from the fonts
PangoCoverage* all_coverage = pango_coverage_new();
tlog(1, "Processing %d fonts\n", fonts.size());
for (int i = 0; i < fonts.size(); ++i) {
PangoFontInfo font_info(fonts[i]);
PangoCoverage* coverage = pango_font_get_coverage(
font_info.ToPangoFont(), NULL);
// Mark off characters that any font can render.
pango_coverage_max(all_coverage, coverage);
}
CharCoverageMapToBitmap(all_coverage, unichar_bitmap);
pango_coverage_unref(all_coverage);
}
// Utilities written to be backward compatible with StringRender
/* static */
int FontUtils::FontScore(const unordered_map<char32, inT64>& ch_map,
const string& fontname,
int* raw_score,
vector<bool>* ch_flags) {
PangoFontInfo font_info;
if (!font_info.ParseFontDescriptionName(fontname)) {
tprintf("ERROR: Could not parse %s\n", fontname.c_str());
}
PangoFont* font = font_info.ToPangoFont();
PangoCoverage* coverage = pango_font_get_coverage(font, NULL);
if (ch_flags) {
ch_flags->clear();
ch_flags->reserve(ch_map.size());
}
*raw_score = 0;
int ok_chars = 0;
for (unordered_map<char32, inT64>::const_iterator it = ch_map.begin();
it != ch_map.end(); ++it) {
bool covered = (IsWhitespace(it->first) ||
(pango_coverage_get(coverage, it->first)
== PANGO_COVERAGE_EXACT));
if (covered) {
++(*raw_score);
ok_chars += it->second;
}
if (ch_flags) {
ch_flags->push_back(covered);
}
}
return ok_chars;
}
/* static */
string FontUtils::BestFonts(const unordered_map<char32, inT64>& ch_map,
vector<pair<const char*, vector<bool> > >* fonts) {
const double kMinOKFraction = 0.99;
// Weighted fraction of characters that must be renderable in a font to make
// it OK even if the raw count is not good.
const double kMinWeightedFraction = 0.99995;
fonts->clear();
vector<vector<bool> > font_flags;
vector<int> font_scores;
vector<int> raw_scores;
int most_ok_chars = 0;
int best_raw_score = 0;
const vector<string>& font_names = FontUtils::ListAvailableFonts();
for (int i = 0; i < font_names.size(); ++i) {
vector<bool> ch_flags;
int raw_score = 0;
int ok_chars = FontScore(ch_map, font_names[i], &raw_score, &ch_flags);
most_ok_chars = MAX(ok_chars, most_ok_chars);
best_raw_score = MAX(raw_score, best_raw_score);
font_flags.push_back(ch_flags);
font_scores.push_back(ok_chars);
raw_scores.push_back(raw_score);
}
// Now select the fonts with a score above a threshold fraction
// of both the raw and weighted best scores. To prevent bogus fonts being
// selected for CJK, we require a high fraction (kMinOKFraction = 0.99) of
// BOTH weighted and raw scores.
// In low character-count scripts, the issue is more getting enough fonts,
// when only 1 or 2 might have all those rare dingbats etc in them, so we
// allow a font with a very high weighted (coverage) score
// (kMinWeightedFraction = 0.99995) to be used even if its raw score is poor.
int least_good_enough = static_cast<int>(most_ok_chars * kMinOKFraction);
int least_raw_enough = static_cast<int>(best_raw_score * kMinOKFraction);
int override_enough = static_cast<int>(most_ok_chars * kMinWeightedFraction);
string font_list;
for (int i = 0; i < font_names.size(); ++i) {
int score = font_scores[i];
int raw_score = raw_scores[i];
if ((score >= least_good_enough && raw_score >= least_raw_enough) ||
score >= override_enough) {
fonts->push_back(make_pair(font_names[i].c_str(), font_flags[i]));
tlog(1, "OK font %s = %.4f%%, raw = %d = %.2f%%\n",
font_names[i].c_str(),
100.0 * score / most_ok_chars,
raw_score, 100.0 * raw_score / best_raw_score);
font_list += font_names[i];
font_list += "\n";
} else if (score >= least_good_enough || raw_score >= least_raw_enough) {
tlog(1, "Runner-up font %s = %.4f%%, raw = %d = %.2f%%\n",
font_names[i].c_str(),
100.0 * score / most_ok_chars,
raw_score, 100.0 * raw_score / best_raw_score);
}
}
return font_list;
}
/* static */
bool FontUtils::SelectFont(const char* utf8_word, const int utf8_len,
string* font_name, vector<string>* graphemes) {
return SelectFont(utf8_word, utf8_len, ListAvailableFonts(), font_name,
graphemes);
}
/* static */
bool FontUtils::SelectFont(const char* utf8_word, const int utf8_len,
const vector<string>& all_fonts,
string* font_name, vector<string>* graphemes) {
if (font_name) font_name->clear();
if (graphemes) graphemes->clear();
for (int i = 0; i < all_fonts.size(); ++i) {
PangoFontInfo font;
vector<string> found_graphemes;
ASSERT_HOST_MSG(font.ParseFontDescriptionName(all_fonts[i]),
"Could not parse font desc name %s\n",
all_fonts[i].c_str());
if (font.CanRenderString(utf8_word, utf8_len, &found_graphemes)) {
if (graphemes) graphemes->swap(found_graphemes);
if (font_name) *font_name = all_fonts[i];
return true;
}
}
return false;
}
// PangoFontInfo is reinitialized, so clear the static list of fonts.
/* static */
void FontUtils::ReInit() { available_fonts_.clear(); }
} // namespace tesseract
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