commit-bot@chromium.org | 3339ac5 | 2014-05-22 02:55:59 +0000 | [diff] [blame^] | 1 | |
| 2 | /* |
| 3 | * Copyright 2011 Google Inc. |
| 4 | * |
| 5 | * Use of this source code is governed by a BSD-style license that can be |
| 6 | * found in the LICENSE file. |
| 7 | */ |
| 8 | #include "SkUnitMappers.h" |
| 9 | #include "SkReadBuffer.h" |
| 10 | #include "SkWriteBuffer.h" |
| 11 | |
| 12 | |
| 13 | SkDiscreteMapper::SkDiscreteMapper(int segments) { |
| 14 | if (segments < 2) { |
| 15 | fSegments = 0; |
| 16 | fScale = 0; |
| 17 | } else { |
| 18 | if (segments > 0xFFFF) { |
| 19 | segments = 0xFFFF; |
| 20 | } |
| 21 | fSegments = segments; |
| 22 | fScale = (1 << 30) / (segments - 1); |
| 23 | } |
| 24 | } |
| 25 | |
| 26 | uint16_t SkDiscreteMapper::mapUnit16(uint16_t input) { |
| 27 | SkFixed x = input * fSegments >> 16; |
| 28 | x = x * fScale >> 14; |
| 29 | x += x << 15 >> 31; // map 0x10000 to 0xFFFF |
| 30 | return SkToU16(x); |
| 31 | } |
| 32 | |
| 33 | SkDiscreteMapper::SkDiscreteMapper(SkReadBuffer& rb) |
| 34 | : SkUnitMapper(rb) { |
| 35 | fSegments = rb.readInt(); |
| 36 | fScale = rb.read32(); |
| 37 | } |
| 38 | |
| 39 | void SkDiscreteMapper::flatten(SkWriteBuffer& wb) const { |
| 40 | this->INHERITED::flatten(wb); |
| 41 | |
| 42 | wb.writeInt(fSegments); |
| 43 | wb.write32(fScale); |
| 44 | } |
| 45 | |
| 46 | /////////////////////////////////////////////////////////////////////////////// |
| 47 | |
| 48 | uint16_t SkCosineMapper::mapUnit16(uint16_t input) |
| 49 | { |
| 50 | /* we want to call cosine(input * pi/2) treating input as [0...1) |
| 51 | however, the straight multitply would overflow 32bits since input is |
| 52 | 16bits and pi/2 is 17bits, so we shift down our pi const before we mul |
| 53 | */ |
| 54 | SkFixed rads = (unsigned)(input * (SK_FixedPI >> 2)) >> 15; |
| 55 | SkFixed x = SkFixedCos(rads); |
| 56 | x += x << 15 >> 31; // map 0x10000 to 0xFFFF |
| 57 | return SkToU16(x); |
| 58 | } |
| 59 | |
| 60 | SkCosineMapper::SkCosineMapper(SkReadBuffer& rb) |
| 61 | : SkUnitMapper(rb) {} |