From ac41bac40f5a80d2bc5ccec584c23478a6900179 Mon Sep 17 00:00:00 2001 From: mtklein Date: Fri, 8 Jul 2016 06:33:16 -0700 Subject: Move sRGB <-> linear conversion components to their own files. This makes them a little easier to use outside SkColorXform code. I've added some notes about how best to use them and their eccentricities, and added a test. Ultimately any software sRGB <-> linear conversion should funnel somehow through here. BUG=skia: GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2128893002 CQ_EXTRA_TRYBOTS=client.skia.android:Test-Android-GCC-Nexus5-CPU-NEON-Arm7-Release-Trybot;client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot Committed: https://skia.googlesource.com/skia/+/45e58c8807179638980aae8503573b950b844e4c Review-Url: https://codereview.chromium.org/2128893002 --- tests/SRGBTest.cpp | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) create mode 100644 tests/SRGBTest.cpp (limited to 'tests/SRGBTest.cpp') diff --git a/tests/SRGBTest.cpp b/tests/SRGBTest.cpp new file mode 100644 index 0000000000..95d2866fdc --- /dev/null +++ b/tests/SRGBTest.cpp @@ -0,0 +1,41 @@ +/* + * Copyright 2016 Google Inc. + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +#include "SkSRGB.h" +#include "SkTypes.h" +#include "Test.h" +#include + +static uint8_t linear_to_srgb(float l) { + return (uint8_t)roundf(sk_linear_to_srgb(Sk4f{l})[0]); +} + +DEF_TEST(sk_linear_to_srgb, r) { + // Should map 0 -> 0 and 1 -> 1. + REPORTER_ASSERT(r, 0 == linear_to_srgb(0.0f)); + REPORTER_ASSERT(r, 255 == linear_to_srgb(1.0f)); + + // Should be monotonic between 0 and 1. + // We don't bother checking denorm values. + int tolerated_regressions = 0; +#if defined(SK_ARM_HAS_NEON) + // Values around 0.166016 are usually 72 but drop briefly (41 floats) down to 71. + tolerated_regressions = 1; +#endif + uint8_t prev = 0; + for (float f = FLT_MIN; f <= 1.0f; ) { + uint8_t srgb = linear_to_srgb(f); + + REPORTER_ASSERT(r, srgb >= prev || tolerated_regressions > 0); + if (srgb < prev) { tolerated_regressions--; } + prev = srgb; + + union { float flt; uint32_t bits; } pun = { f }; + pun.bits++; + f = pun.flt; + } +} -- cgit v1.2.3