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SkFloatToDecimal moved to src/utils

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This change stages SkFloatToDecimal() for possible re-use by pdfium.

Change-Id: Iedc0c78c8a633f0b0973365d2d8b540b5443590d
Reviewed-on: https://skia-review.googlesource.com/90400
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Cary Clark <caryclark@google.com>
This commit is contained in:
Hal Canary 2018-01-02 16:25:53 -05:00 committed by Skia Commit-Bot
parent 0d825666f7
commit 3c36ef6be9
7 changed files with 238 additions and 188 deletions
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39
bench/PDFBench.cpp
View File

@ -10,6 +10,7 @@
#include "Resources.h"
#include "SkAutoPixmapStorage.h"
#include "SkData.h"
#include "SkFloatToDecimal.h"
#include "SkGradientShader.h"
#include "SkImage.h"
#include "SkPixmap.h"
@ -36,12 +37,30 @@ struct WStreamWriteTextBenchmark : public Benchmark {
DEF_BENCH(return new WStreamWriteTextBenchmark;)
// Test speed of SkFloatToDecimal for typical floats that
// might be found in a PDF document.
struct PDFScalarBench : public Benchmark {
bool isSuitableFor(Backend b) override {
return b == kNonRendering_Backend;
}
const char* onGetName() override { return "PDFScalar"; }
void onDraw(int loops, SkCanvas*) override {
SkRandom random;
char dst[kMaximumSkFloatToDecimalLength];
while (loops-- > 0) {
auto f = random.nextRangeF(-500.0f, 1500.0f);
(void)SkFloatToDecimal(f, dst);
}
}
};
DEF_BENCH(return new PDFScalarBench;)
#ifdef SK_SUPPORT_PDF
#include "SkPDFBitmap.h"
#include "SkPDFDocument.h"
#include "SkPDFShader.h"
#include "SkPDFUtils.h"
namespace {
static void test_pdf_object_serialization(const sk_sp<SkPDFObject> object) {
@ -164,23 +183,6 @@ private:
std::unique_ptr<SkStreamAsset> fAsset;
};
// Test speed of SkPDFUtils::FloatToDecimal for typical floats that
// might be found in a PDF document.
struct PDFScalarBench : public Benchmark {
bool isSuitableFor(Backend b) override {
return b == kNonRendering_Backend;
}
const char* onGetName() override { return "PDFScalar"; }
void onDraw(int loops, SkCanvas*) override {
SkRandom random;
char dst[SkPDFUtils::kMaximumFloatDecimalLength];
while (loops-- > 0) {
auto f = random.nextRangeF(-500.0f, 1500.0f);
(void)SkPDFUtils::FloatToDecimal(f, dst);
}
}
};
struct PDFColorComponentBench : public Benchmark {
bool isSuitableFor(Backend b) override {
return b == kNonRendering_Backend;
@ -244,7 +246,6 @@ struct WritePDFTextBenchmark : public Benchmark {
DEF_BENCH(return new PDFImageBench;)
DEF_BENCH(return new PDFJpegImageBench;)
DEF_BENCH(return new PDFCompressionBench;)
DEF_BENCH(return new PDFScalarBench;)
DEF_BENCH(return new PDFColorComponentBench;)
DEF_BENCH(return new PDFShaderBench;)
DEF_BENCH(return new WritePDFTextBenchmark;)

2
gn/utils.gni
View File

@ -38,6 +38,8 @@ skia_utils_sources = [
"$_src/utils/SkDashPathPriv.h",
"$_src/utils/SkDumpCanvas.cpp",
"$_src/utils/SkEventTracer.cpp",
"$_src/utils/SkFloatToDecimal.cpp",
"$_src/utils/SkFloatToDecimal.h",
"$_src/utils/SkFloatUtils.h",
"$_src/utils/SkInsetConvexPolygon.cpp",
"$_src/utils/SkInsetConvexPolygon.h",

159
src/pdf/SkPDFUtils.cpp
View File

@ -287,165 +287,6 @@ size_t SkPDFUtils::ColorToDecimal(uint8_t value, char result[5]) {
return j + 1;
}
void SkPDFUtils::AppendScalar(SkScalar value, SkWStream* stream) {
char result[kMaximumFloatDecimalLength];
size_t len = SkPDFUtils::FloatToDecimal(SkScalarToFloat(value), result);
SkASSERT(len < kMaximumFloatDecimalLength);
stream->write(result, len);
}
// Return pow(10.0, e), optimized for common cases.
inline double pow10(int e) {
switch (e) {
case 0: return 1.0; // common cases
case 1: return 10.0;
case 2: return 100.0;
case 3: return 1e+03;
case 4: return 1e+04;
case 5: return 1e+05;
case 6: return 1e+06;
case 7: return 1e+07;
case 8: return 1e+08;
case 9: return 1e+09;
case 10: return 1e+10;
case 11: return 1e+11;
case 12: return 1e+12;
case 13: return 1e+13;
case 14: return 1e+14;
case 15: return 1e+15;
default:
if (e > 15) {
double value = 1e+15;
while (e-- > 15) { value *= 10.0; }
return value;
} else {
SkASSERT(e < 0);
double value = 1.0;
while (e++ < 0) { value /= 10.0; }
return value;
}
}
}
/** Write a string into result, includeing a terminating '\0' (for
unit testing). Return strlen(result) (for SkWStream::write) The
resulting string will be in the form /[-]?([0-9]*.)?[0-9]+/ and
sscanf(result, "%f", &x) will return the original value iff the
value is finite. This function accepts all possible input values.
Motivation: "PDF does not support [numbers] in exponential format
(such as 6.02e23)." Otherwise, this function would rely on a
sprintf-type function from the standard library. */
size_t SkPDFUtils::FloatToDecimal(float value,
char result[kMaximumFloatDecimalLength]) {
/* The longest result is -FLT_MIN.
We serialize it as "-.0000000000000000000000000000000000000117549435"
which has 48 characters plus a terminating '\0'. */
/* section C.1 of the PDF1.4 spec (http://goo.gl/0SCswJ) says that
most PDF rasterizers will use fixed-point scalars that lack the
dynamic range of floats. Even if this is the case, I want to
serialize these (uncommon) very small and very large scalar
values with enough precision to allow a floating-point
rasterizer to read them in with perfect accuracy.
Experimentally, rasterizers such as pdfium do seem to benefit
from this. Rasterizers that rely on fixed-point scalars should
gracefully ignore these values that they can not parse. */
char* output = &result[0];
const char* const end = &result[kMaximumFloatDecimalLength - 1];
// subtract one to leave space for '\0'.
/* This function is written to accept any possible input value,
including non-finite values such as INF and NAN. In that case,
we ignore value-correctness and and output a syntacticly-valid
number. */
if (value == SK_FloatInfinity) {
value = FLT_MAX; // nearest finite float.
}
if (value == SK_FloatNegativeInfinity) {
value = -FLT_MAX; // nearest finite float.
}
if (!std::isfinite(value) || value == 0.0f) {
// NAN is unsupported in PDF. Always output a valid number.
// Also catch zero here, as a special case.
*output++ = '0';
*output = '\0';
return output - result;
}
if (value < 0.0) {
*output++ = '-';
value = -value;
}
SkASSERT(value >= 0.0f);
int binaryExponent;
(void)std::frexp(value, &binaryExponent);
static const double kLog2 = 0.3010299956639812; // log10(2.0);
int decimalExponent = static_cast<int>(std::floor(kLog2 * binaryExponent));
int decimalShift = decimalExponent - 8;
double power = pow10(-decimalShift);
int32_t d = static_cast<int32_t>(value * power + 0.5);
// SkASSERT(value == (float)(d * pow(10.0, decimalShift)));
SkASSERT(d <= 999999999);
if (d > 167772159) { // floor(pow(10,1+log10(1<<24)))
// need one fewer decimal digits for 24-bit precision.
decimalShift = decimalExponent - 7;
// SkASSERT(power * 0.1 = pow10(-decimalShift));
// recalculate to get rounding right.
d = static_cast<int32_t>(value * (power * 0.1) + 0.5);
SkASSERT(d <= 99999999);
}
while (d % 10 == 0) {
d /= 10;
++decimalShift;
}
SkASSERT(d > 0);
// SkASSERT(value == (float)(d * pow(10.0, decimalShift)));
uint8_t buffer[9]; // decimal value buffer.
int bufferIndex = 0;
do {
buffer[bufferIndex++] = d % 10;
d /= 10;
} while (d != 0);
SkASSERT(bufferIndex <= (int)sizeof(buffer) && bufferIndex > 0);
if (decimalShift >= 0) {
do {
--bufferIndex;
*output++ = '0' + buffer[bufferIndex];
} while (bufferIndex);
for (int i = 0; i < decimalShift; ++i) {
*output++ = '0';
}
} else {
int placesBeforeDecimal = bufferIndex + decimalShift;
if (placesBeforeDecimal > 0) {
while (placesBeforeDecimal-- > 0) {
--bufferIndex;
*output++ = '0' + buffer[bufferIndex];
}
*output++ = '.';
} else {
*output++ = '.';
int placesAfterDecimal = -placesBeforeDecimal;
while (placesAfterDecimal-- > 0) {
*output++ = '0';
}
}
while (bufferIndex > 0) {
--bufferIndex;
*output++ = '0' + buffer[bufferIndex];
if (output == end) {
break; // denormalized: don't need extra precision.
// Note: denormalized numbers will not have the same number of
// significantDigits, but do not need them to round-trip.
}
}
}
SkASSERT(output <= end);
*output = '\0';
return output - result;
}
void SkPDFUtils::WriteString(SkWStream* wStream, const char* cin, size_t len) {
SkDEBUGCODE(static const size_t kMaxLen = 65535;)
SkASSERT(len <= kMaxLen);

16
src/pdf/SkPDFUtils.h
View File

@ -7,6 +7,7 @@
#ifndef SkPDFUtils_DEFINED
#define SkPDFUtils_DEFINED
#include "SkFloatToDecimal.h"
#include "SkPDFTypes.h"
#include "SkPaint.h"
#include "SkPath.h"
@ -76,14 +77,13 @@ inline void AppendColorComponent(uint8_t value, SkWStream* wStream) {
wStream->write(buffer, len);
}
// 3 = '-', '.', and '\0' characters.
// 9 = number of significant digits
// abs(FLT_MIN_10_EXP) = number of zeros in FLT_MIN
const size_t kMaximumFloatDecimalLength = 3 + 9 - FLT_MIN_10_EXP;
// FloatToDecimal is exposed for unit tests.
size_t FloatToDecimal(float value,
char output[kMaximumFloatDecimalLength]);
void AppendScalar(SkScalar value, SkWStream* stream);
inline void AppendScalar(SkScalar value, SkWStream* stream) {
char result[kMaximumSkFloatToDecimalLength];
size_t len = SkFloatToDecimal(SkScalarToFloat(value), result);
SkASSERT(len < kMaximumSkFloatToDecimalLength);
stream->write(result, len);
}
void WriteString(SkWStream* wStream, const char* input, size_t len);
inline void WriteUInt16BE(SkDynamicMemoryWStream* wStream, uint16_t value) {

172
src/utils/SkFloatToDecimal.cpp Normal file
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@ -0,0 +1,172 @@
/*
* Copyright 2017 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkFloatToDecimal.h"
#include <cfloat>
#include <climits>
#include <cmath>
#include "SkTypes.h"
// Return pow(10.0, e), optimized for common cases.
static double pow10(int e) {
switch (e) {
case 0: return 1.0; // common cases
case 1: return 10.0;
case 2: return 100.0;
case 3: return 1e+03;
case 4: return 1e+04;
case 5: return 1e+05;
case 6: return 1e+06;
case 7: return 1e+07;
case 8: return 1e+08;
case 9: return 1e+09;
case 10: return 1e+10;
case 11: return 1e+11;
case 12: return 1e+12;
case 13: return 1e+13;
case 14: return 1e+14;
case 15: return 1e+15;
default:
if (e > 15) {
double value = 1e+15;
while (e-- > 15) { value *= 10.0; }
return value;
} else {
SkASSERT(e < 0);
double value = 1.0;
while (e++ < 0) { value /= 10.0; }
return value;
}
}
}
/** Write a string into result, includeing a terminating '\0' (for
unit testing). Return strlen(result) (for SkWStream::write) The
resulting string will be in the form /[-]?([0-9]*.)?[0-9]+/ and
sscanf(result, "%f", &x) will return the original value iff the
value is finite. This function accepts all possible input values.
Motivation: "PDF does not support [numbers] in exponential format
(such as 6.02e23)." Otherwise, this function would rely on a
sprintf-type function from the standard library. */
unsigned SkFloatToDecimal(float value, char result[kMaximumSkFloatToDecimalLength]) {
/* The longest result is -FLT_MIN.
We serialize it as "-.0000000000000000000000000000000000000117549435"
which has 48 characters plus a terminating '\0'. */
static_assert(kMaximumSkFloatToDecimalLength == 49, "");
// 3 = '-', '.', and '\0' characters.
// 9 = number of significant digits
// abs(FLT_MIN_10_EXP) = number of zeros in FLT_MIN
static_assert(kMaximumSkFloatToDecimalLength == 3 + 9 - FLT_MIN_10_EXP, "");
/* section C.1 of the PDF1.4 spec (http://goo.gl/0SCswJ) says that
most PDF rasterizers will use fixed-point scalars that lack the
dynamic range of floats. Even if this is the case, I want to
serialize these (uncommon) very small and very large scalar
values with enough precision to allow a floating-point
rasterizer to read them in with perfect accuracy.
Experimentally, rasterizers such as pdfium do seem to benefit
from this. Rasterizers that rely on fixed-point scalars should
gracefully ignore these values that they can not parse. */
char* output = &result[0];
const char* const end = &result[kMaximumSkFloatToDecimalLength - 1];
// subtract one to leave space for '\0'.
/* This function is written to accept any possible input value,
including non-finite values such as INF and NAN. In that case,
we ignore value-correctness and and output a syntacticly-valid
number. */
if (value == INFINITY) {
value = FLT_MAX; // nearest finite float.
}
if (value == -INFINITY) {
value = -FLT_MAX; // nearest finite float.
}
if (!std::isfinite(value) || value == 0.0f) {
// NAN is unsupported in PDF. Always output a valid number.
// Also catch zero here, as a special case.
*output++ = '0';
*output = '\0';
return static_cast<unsigned>(output - result);
}
if (value < 0.0) {
*output++ = '-';
value = -value;
}
SkASSERT(value >= 0.0f);
int binaryExponent;
(void)std::frexp(value, &binaryExponent);
static const double kLog2 = 0.3010299956639812; // log10(2.0);
int decimalExponent = static_cast<int>(std::floor(kLog2 * binaryExponent));
int decimalShift = decimalExponent - 8;
double power = pow10(-decimalShift);
SkASSERT(value * power <= (double)INT_MAX);
int d = static_cast<int>(value * power + 0.5);
// SkASSERT(value == (float)(d * pow(10.0, decimalShift)));
SkASSERT(d <= 999999999);
if (d > 167772159) { // floor(pow(10,1+log10(1<<24)))
// need one fewer decimal digits for 24-bit precision.
decimalShift = decimalExponent - 7;
// SkASSERT(power * 0.1 = pow10(-decimalShift));
// recalculate to get rounding right.
d = static_cast<int>(value * (power * 0.1) + 0.5);
SkASSERT(d <= 99999999);
}
while (d % 10 == 0) {
d /= 10;
++decimalShift;
}
SkASSERT(d > 0);
// SkASSERT(value == (float)(d * pow(10.0, decimalShift)));
unsigned char buffer[9]; // decimal value buffer.
int bufferIndex = 0;
do {
buffer[bufferIndex++] = d % 10;
d /= 10;
} while (d != 0);
SkASSERT(bufferIndex <= (int)sizeof(buffer) && bufferIndex > 0);
if (decimalShift >= 0) {
do {
--bufferIndex;
*output++ = '0' + buffer[bufferIndex];
} while (bufferIndex);
for (int i = 0; i < decimalShift; ++i) {
*output++ = '0';
}
} else {
int placesBeforeDecimal = bufferIndex + decimalShift;
if (placesBeforeDecimal > 0) {
while (placesBeforeDecimal-- > 0) {
--bufferIndex;
*output++ = '0' + buffer[bufferIndex];
}
*output++ = '.';
} else {
*output++ = '.';
int placesAfterDecimal = -placesBeforeDecimal;
while (placesAfterDecimal-- > 0) {
*output++ = '0';
}
}
while (bufferIndex > 0) {
--bufferIndex;
*output++ = '0' + buffer[bufferIndex];
if (output == end) {
break; // denormalized: don't need extra precision.
// Note: denormalized numbers will not have the same number of
// significantDigits, but do not need them to round-trip.
}
}
}
SkASSERT(output <= end);
*output = '\0';
return static_cast<unsigned>(output - result);
}

34
src/utils/SkFloatToDecimal.h Normal file
View File

@ -0,0 +1,34 @@
/*
* Copyright 2017 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkFloatToDecimal_DEFINED
#define SkFloatToDecimal_DEFINED
constexpr unsigned kMaximumSkFloatToDecimalLength = 49;
/** \fn SkFloatToDecimal
Convert a float into a decimal string.
The resulting string will be in the form `[-]?([0-9]*\.)?[0-9]+` (It does
not use scientific notation.) and `sscanf(output, "%f", &x)` will return
the original value if the value is finite. This function accepts all
possible input values.
INFINITY and -INFINITY are rounded to FLT_MAX and -FLT_MAX.
NAN values are converted to 0.
This function will always add a terminating '\0' to the output.
@param value Any floating-point number
@param output The buffer to write the string into. Must be non-null.
@return strlen(output)
*/
unsigned SkFloatToDecimal(float value, char output[kMaximumSkFloatToDecimalLength]);
#endif // SkFloatToDecimal_DEFINED

4
tests/PDFPrimitivesTest.cpp
View File

@ -436,8 +436,8 @@ DEF_TEST(SkPDF_FontCanEmbedTypeface, reporter) {
// test to see that all finite scalars round trip via scanf().
static void check_pdf_scalar_serialization(
skiatest::Reporter* reporter, float inputFloat) {
char floatString[SkPDFUtils::kMaximumFloatDecimalLength];
size_t len = SkPDFUtils::FloatToDecimal(inputFloat, floatString);
char floatString[kMaximumSkFloatToDecimalLength];
size_t len = SkFloatToDecimal(inputFloat, floatString);
if (len >= sizeof(floatString)) {
ERRORF(reporter, "string too long: %u", (unsigned)len);
return;