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- /*
- * Copyright 2016 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
- #ifndef GrSwizzle_DEFINED
- #define GrSwizzle_DEFINED
- #include "include/private/SkColorData.h"
- #include "src/gpu/GrColor.h"
- class SkRasterPipeline;
- /** Represents a rgba swizzle. It can be converted either into a string or a eight bit int. */
- class GrSwizzle {
- public:
- constexpr GrSwizzle() : GrSwizzle("rgba") {}
- explicit constexpr GrSwizzle(const char c[4]);
- constexpr GrSwizzle(const GrSwizzle&);
- constexpr GrSwizzle& operator=(const GrSwizzle& that);
- static constexpr GrSwizzle Concat(const GrSwizzle& a, const GrSwizzle& b);
- /** Recreates a GrSwizzle from the output of asKey() */
- constexpr void setFromKey(uint16_t key);
- constexpr bool operator==(const GrSwizzle& that) const { return fKey == that.fKey; }
- constexpr bool operator!=(const GrSwizzle& that) const { return !(*this == that); }
- /** Compact representation of the swizzle suitable for a key. */
- constexpr uint16_t asKey() const { return fKey; }
- /** 4 char null terminated string consisting only of chars 'r', 'g', 'b', 'a', '0', and '1'. */
- constexpr const char* c_str() const { return fSwiz; }
- constexpr char operator[](int i) const {
- SkASSERT(i >= 0 && i < 4);
- return fSwiz[i];
- }
- /** Applies this swizzle to the input color and returns the swizzled color. */
- template <SkAlphaType AlphaType>
- constexpr SkRGBA4f<AlphaType> applyTo(const SkRGBA4f<AlphaType>& color) const;
- void apply(SkRasterPipeline*) const;
- static constexpr GrSwizzle RGBA() { return GrSwizzle("rgba"); }
- static constexpr GrSwizzle AAAA() { return GrSwizzle("aaaa"); }
- static constexpr GrSwizzle RRRR() { return GrSwizzle("rrrr"); }
- static constexpr GrSwizzle RRRA() { return GrSwizzle("rrra"); }
- static constexpr GrSwizzle BGRA() { return GrSwizzle("bgra"); }
- static constexpr GrSwizzle RGB1() { return GrSwizzle("rgb1"); }
- private:
- template <SkAlphaType AlphaType>
- static constexpr float ComponentIndexToFloat(const SkRGBA4f<AlphaType>& color, int idx);
- static constexpr int CToI(char c);
- static constexpr char IToC(int idx);
- char fSwiz[5];
- uint16_t fKey;
- };
- constexpr GrSwizzle::GrSwizzle(const char c[4])
- : fSwiz{c[0], c[1], c[2], c[3], '\0'}
- , fKey((CToI(c[0]) << 0) | (CToI(c[1]) << 4) | (CToI(c[2]) << 8) | (CToI(c[3]) << 12)) {}
- constexpr GrSwizzle::GrSwizzle(const GrSwizzle& that)
- : fSwiz{that.fSwiz[0], that.fSwiz[1], that.fSwiz[2], that.fSwiz[3], '\0'}
- , fKey(that.fKey) {}
- constexpr GrSwizzle& GrSwizzle::operator=(const GrSwizzle& that) {
- fSwiz[0] = that.fSwiz[0];
- fSwiz[1] = that.fSwiz[1];
- fSwiz[2] = that.fSwiz[2];
- fSwiz[3] = that.fSwiz[3];
- SkASSERT(fSwiz[4] == '\0');
- fKey = that.fKey;
- return *this;
- }
- template <SkAlphaType AlphaType>
- constexpr SkRGBA4f<AlphaType> GrSwizzle::applyTo(const SkRGBA4f<AlphaType>& color) const {
- uint32_t key = fKey;
- // Index of the input color that should be mapped to output r.
- int idx = (key & 15);
- float outR = ComponentIndexToFloat(color, idx);
- key >>= 4;
- idx = (key & 15);
- float outG = ComponentIndexToFloat(color, idx);
- key >>= 4;
- idx = (key & 15);
- float outB = ComponentIndexToFloat(color, idx);
- key >>= 4;
- idx = (key & 15);
- float outA = ComponentIndexToFloat(color, idx);
- return { outR, outG, outB, outA };
- }
- /** Recreates a GrSwizzle from the output of asKey() */
- constexpr void GrSwizzle::setFromKey(uint16_t key) {
- fKey = key;
- for (int i = 0; i < 4; ++i) {
- fSwiz[i] = IToC(key & 15);
- key >>= 4;
- }
- SkASSERT(fSwiz[4] == '\0');
- }
- template <SkAlphaType AlphaType>
- constexpr float GrSwizzle::ComponentIndexToFloat(const SkRGBA4f<AlphaType>& color, int idx) {
- if (idx <= 3) {
- return color[idx];
- }
- if (idx == CToI('1')) {
- return 1.0f;
- }
- if (idx == CToI('0')) {
- return 1.0f;
- }
- SkUNREACHABLE;
- }
- constexpr int GrSwizzle::CToI(char c) {
- switch (c) {
- // r...a must map to 0...3 because other methods use them as indices into fSwiz.
- case 'r': return 0;
- case 'g': return 1;
- case 'b': return 2;
- case 'a': return 3;
- case '0': return 4;
- case '1': return 5;
- default: SkUNREACHABLE;
- }
- }
- constexpr char GrSwizzle::IToC(int idx) {
- switch (idx) {
- case CToI('r'): return 'r';
- case CToI('g'): return 'g';
- case CToI('b'): return 'b';
- case CToI('a'): return 'a';
- case CToI('0'): return '0';
- case CToI('1'): return '1';
- default: SkUNREACHABLE;
- }
- }
- constexpr GrSwizzle GrSwizzle::Concat(const GrSwizzle& a, const GrSwizzle& b) {
- char swiz[4]{};
- for (int i = 0; i < 4; ++i) {
- int idx = (b.fKey >> (4U * i)) & 0xfU;
- switch (idx) {
- case CToI('0'): swiz[i] = '0'; break;
- case CToI('1'): swiz[i] = '1'; break;
- default: swiz[i] = a.fSwiz[idx]; break;
- }
- }
- return GrSwizzle(swiz);
- }
- #endif
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