Improve performance of writing path floats.

This CL copies the SkPDF code to convert floats into strings when
writing back to PDF files.

Change-Id: I8f8af3924a07aa67f93b9d951af1eef5d2c705db
Reviewed-on: https://pdfium-review.googlesource.com/21990
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Hal Canary <halcanary@chromium.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/third_party/skia_shared/SkFloatToDecimal.h b/third_party/skia_shared/SkFloatToDecimal.h
new file mode 100644
index 0000000000..ac1042dbfb
--- /dev/null
+++ b/third_party/skia_shared/SkFloatToDecimal.h
@@ -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