Font variations.

src/ports/SkFontConfigParser_android.cpp

 /*
  * Copyright 2011 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkFontConfigParser_android.h"
 #include "SkFontMgr_android.h"
 #include "SkStream.h"
 #include "SkTDArray.h"
 #include "SkTSearch.h"
 #include "SkTypeface.h"
 
 #include <expat.h>
 #include <dirent.h>
 #include <stdio.h>
 
+#include <climits>
 #include <limits>
 #include <stdlib.h>
 
 // From Android version LMP onwards, all font files collapse into
 // /system/etc/fonts.xml. Instead of trying to detect which version
 // we're on, try to open fonts.xml; if that fails, fall back to the
 // older filename.
 #define LMP_SYSTEM_FONTS_FILE "/system/etc/fonts.xml"
 #define OLD_SYSTEM_FONTS_FILE "/system/etc/system_fonts.xml"
 #define FALLBACK_FONTS_FILE "/system/etc/fallback_fonts.xml"
@@ skipping 61 matching lines @@
 template <typename T> static bool parse_non_negative_integer(const char* s, T* value) {
     SK_COMPILE_ASSERT(std::numeric_limits<T>::is_integer, T_must_be_integer);
     const T nMax = std::numeric_limits<T>::max() / 10;
     const T dMax = std::numeric_limits<T>::max() - (nMax * 10);
     T n = 0;
     for (; *s; ++s) {
         // Check if digit
         if (*s < '0' || '9' < *s) {
             return false;
         }
-        int d = *s - '0';
+        T d = *s - '0';
         // Check for overflow
         if (n > nMax || (n == nMax && d > dMax)) {
             return false;
         }
         n = (n * 10) + d;
     }
     *value = n;
     return true;
 }
 
+/** Parses a null terminated string into a signed fixed point value with bias N.
+ *
+ *  Like http://www.w3.org/TR/html-markup/datatypes.html#common.data.float-def ,
+ *  but may start with '.' and does not support 'e'. '-?:digit:*(.:digit:+)?'
+ *
+ *  Checks for overflow.
+ *  Low bit rounding is not defined (is currently truncate).
+ *  Bias (N) required to allow for the sign bit and 4 bits of integer.
+ *
+ *  If the string cannot be parsed into 'value', returns false and does not change 'value'.
+ */

[reed1, 2015/04/29 15:36:46]

why not cal sscanf and convert the double to a fixed?

[bungeman-skia, 2015/04/29 22:12:44]

Because it's evil and should never be used.

https://www.securecoding.cert.org/confluence/display/c/INT05-C.+Do+not+use+in...

even the alternatives get mired in the current locale setting, which is
impossible to get right (and cannot be used correctly in threaded environments).
Also, I explicitly don't want all the double stuff (exponentiation and the
like), mostly so this in the future this can be reliably done more automatically
with a more full featured xml parser which supports xml types.

+template <int N, typename T> static bool parse_fixed(const char* s, T* value) {
+    SK_COMPILE_ASSERT(std::numeric_limits<T>::is_integer, T_must_be_integer);
+    SK_COMPILE_ASSERT(std::numeric_limits<T>::is_signed, T_must_be_signed);
+    SK_COMPILE_ASSERT(sizeof(T) * CHAR_BIT - N >= 5, N_must_leave_four_bits_plus_sign);
+
+    bool negate = false;
+    if (*s == '-') { ++s; negate = true; }
+
+    const T nMax = (std::numeric_limits<T>::max() >> N) / 10;
+    const T dMax = (std::numeric_limits<T>::max() >> N) - (nMax * 10);
+
+    T n = 0;
+    T frac = 0;
+    for (; *s; ++s) {
+        // Check if digit
+        if (*s < '0' || '9' < *s) {
+            // If it wasn't a digit, check if it is a '.' followed by a digit.
+            if (*s == '.' && '0' <= s[1] && s[1] <= '9') {
+                // Find the end, verify digits.
+                for (++s; *s; ++s) {
+                    if (*s < '0' || '9' < *s) {
+                        return false;
+                    }
+                }
+                // Read back toward the '.'.
+                for (--s; *s != '.'; --s) {
+                    T d = *s - '0';
+                    frac = (frac + (d << N)) / 10; // This requires four bits overhead.
+                }
+                break;
+            }
+            return false;
+        }
+        T d = *s - '0';
+        // Check for overflow
+        if (n > nMax || (n == nMax && d > dMax)) {
+            return false;
+        }
+        n = (n * 10) + d;
+    }
+    if (negate) { n = -n; frac = -frac; }
+    *value = (n << N) + frac;
+    return true;
+}
+
+#if 0
+#include "math.h"
+template <int N, typename T> static void test_parse_fixed_r(double low, double high, double inc) {
+    SkDEBUGCODE(double SK_FixedMax_double = nextafter(1 << (sizeof(T) * CHAR_BIT - N - 1), 0.0);)
+    double SK_FixedEpsilon_double = (1.0 / (1 << N));
+    double maxError = 0;
+    char buffer[64];
+    for (double f = low; f < high; f += inc) {
+        SkString s;
+        sprintf(buffer, "%.20f", f);
+        T fix;
+        bool b = parse_fixed<N>(buffer, &fix);
+        if (b) {
+            double f2 = fix * SK_FixedEpsilon_double;
+            SkASSERT(fabs(f - f2) <= SK_FixedEpsilon_double);
+            maxError = SkTMax(maxError, fabs(f - f2));
+        } else {
+            SkASSERT(f > SK_FixedMax_double || f < -SK_FixedMax_double);
+        }
+    }
+
+    SkDebugf("maxError: %.20f\n", maxError);
+}
+
+static void test_parse_fixed() {
+    test_parse_fixed_r<27, int32_t>(-17.1, 17.1, 0.000001);
+    test_parse_fixed_r<16, int32_t>(-1.125, 1.125, 1.0 / (1 << 19));
+    test_parse_fixed_r<16, int32_t>(-32769.0, -32766.0, 1.0 / (1 << 19));
+    test_parse_fixed_r<16, int32_t>(32766.0, 32769.0, 1.0 / (1 << 19));
+    test_parse_fixed_r<16, int32_t>(-40000.0, 40000.0, 1.0 / (1 << 4));
+    test_parse_fixed_r<16, int32_t>(-1.1, 1.1, 0.0001);
+
+    SkFixed fix;
+    SkASSERT(!parse_fixed<16>("123.", &fix));
+    SkASSERT(!parse_fixed<16>("a", &fix));
+    SkASSERT(!parse_fixed<16>(".123a", &fix));
+}
+#endif
+
 static bool memeq(const char* s1, const char* s2, size_t n1, size_t n2) {
     return n1 == n2 && 0 == memcmp(s1, s2, n1);
 }
 #define MEMEQ(c, s, n) memeq(c, s, sizeof(c) - 1, n)
 
 #define ATTS_NON_NULL(a, i) (a[i] != NULL && a[i+1] != NULL)
 
 #define SK_FONTCONFIGPARSER_PREFIX "[SkFontConfigParser] "
 
 #define SK_FONTCONFIGPARSER_WARNING(message, ...) SkDebugf( \
@@ skipping 30 matching lines @@
             }
         }
     }
 }
 
 static void XMLCALL font_file_name_handler(void* data, const char* s, int len) {
     FamilyData* self = static_cast<FamilyData*>(data);
     self->fCurrentFontInfo->fFileName.append(s, len);
 }
 
+static void axis_element_handler(FamilyData* self, const char** attributes) {
+    FontFileInfo& file = *self->fCurrentFontInfo;
+    FontFileInfo::Axis& axis = file.fAxes.push_back();
+    for (size_t i = 0; ATTS_NON_NULL(attributes, i); i += 2) {
+        const char* name = attributes[i];
+        const char* value = attributes[i+1];
+        size_t nameLen = strlen(name);
+        if (MEMEQ("tag", name, nameLen)) {
+            size_t valueLen = strlen(value);
+            if (valueLen == 4) {
+                SkFourByteTag tag = SkSetFourByteTag(value[0], value[1], value[2], value[3]);
+                for (int j = 0; j < file.fAxes.count() - 1; ++j) {
+                    if (file.fAxes[j].fTag == tag) {
+                        SK_FONTCONFIGPARSER_WARNING("'%c%c%c%c' axis specified more than once",
+                                                    (tag >> 24) & 0xFF,
+                                                    (tag >> 16) & 0xFF,
+                                                    (tag >>  8) & 0xFF,
+                                                    (tag      ) & 0xFF);
+                    }
+                }
+                axis.fTag = SkSetFourByteTag(value[0], value[1], value[2], value[3]);
+            } else {
+                SK_FONTCONFIGPARSER_WARNING("'%s' is an invalid axis tag", value);
+            }
+        } else if (MEMEQ("stylevalue", name, nameLen)) {
+            if (!parse_fixed<16>(value, &axis.fValue)) {
+                SK_FONTCONFIGPARSER_WARNING("'%s' is an invalid axis stylevalue", value);
+            }
+        }
+    }
+}
+
 static void font_element_handler(FamilyData* self, const char** attributes) {
     // A <font> element should be contained in a <family> element.
     // The element may have 'weight' (non-negative integer), 'style' ("normal", "italic"),
     // and 'index' (non-negative integer) attributes.
     // The element should contain a filename.
     FontFileInfo& file = self->fCurrentFamily->fFonts.push_back();
     self->fCurrentFontInfo = &file;
     for (size_t i = 0; ATTS_NON_NULL(attributes, i); i += 2) {
         const char* name = attributes[i];
         const char* value = attributes[i+1];
@@ skipping 82 matching lines @@
 
 static void XMLCALL start_element_handler(void* data, const char* tag, const char** attributes) {
     FamilyData* self = static_cast<FamilyData*>(data);
     size_t len = strlen(tag);
     if (MEMEQ("family", tag, len)) {
         family_element_handler(self, attributes);
     } else if (MEMEQ("font", tag, len)) {
         font_element_handler(self, attributes);
     } else if (MEMEQ("alias", tag, len)) {
         alias_element_handler(self, attributes);
+    } else if (MEMEQ("axis", tag, len)) {
+        axis_element_handler(self, attributes);
     }
 }
 
 static void XMLCALL end_element_handler(void* data, const char* tag) {
     FamilyData* self = static_cast<FamilyData*>(data);
     size_t len = strlen(tag);
     if (MEMEQ("family", tag, len)) {
         *self->fFamilies.append() = self->fCurrentFamily.detach();
     } else if (MEMEQ("font", tag, len)) {
         XML_SetCharacterDataHandler(self->fParser, NULL);
@@ skipping 377 matching lines @@
     const char* tag = fTag.c_str();
 
     // strip off the rightmost "-.*"
     const char* parentTagEnd = strrchr(tag, '-');
     if (parentTagEnd == NULL) {
         return SkLanguage();
     }
     size_t parentTagLen = parentTagEnd - tag;
     return SkLanguage(tag, parentTagLen);
 }