/* * Copyright 2006 The Android Open Source Project * * Use of this source code is governed by a BSD-style license that can be * found in the LICENSE file. */ #ifndef SkColorPriv_DEFINED #define SkColorPriv_DEFINED #include "include/core/SkColor.h" #include "include/core/SkMath.h" #include "include/private/SkTo.h" /** Turn 0..255 into 0..256 by adding 1 at the half-way point. Used to turn a byte into a scale value, so that we can say scale * value >> 8 instead of alpha * value / 255. In debugging, asserts that alpha is 0..255 */ static inline unsigned SkAlpha255To256(U8CPU alpha) { SkASSERT(SkToU8(alpha) == alpha); // this one assues that blending on top of an opaque dst keeps it that way // even though it is less accurate than a+(a>>7) for non-opaque dsts return alpha + 1; } /** Multiplify value by 0..256, and shift the result down 8 (i.e. return (value * alpha256) >> 8) */ #define SkAlphaMul(value, alpha256) (((value) * (alpha256)) >> 8) static inline U8CPU SkUnitScalarClampToByte(SkScalar x) { return static_cast(SkScalarPin(x, 0, 1) * 255 + 0.5); } #define SK_A32_BITS 8 #define SK_R32_BITS 8 #define SK_G32_BITS 8 #define SK_B32_BITS 8 #define SK_A32_MASK ((1 << SK_A32_BITS) - 1) #define SK_R32_MASK ((1 << SK_R32_BITS) - 1) #define SK_G32_MASK ((1 << SK_G32_BITS) - 1) #define SK_B32_MASK ((1 << SK_B32_BITS) - 1) /* * Skia's 32bit backend only supports 1 swizzle order at a time (compile-time). * This is specified by SK_R32_SHIFT=0 or SK_R32_SHIFT=16. * * For easier compatibility with Skia's GPU backend, we further restrict these * to either (in memory-byte-order) RGBA or BGRA. Note that this "order" does * not directly correspond to the same shift-order, since we have to take endianess * into account. * * Here we enforce this constraint. */ #define SK_RGBA_R32_SHIFT 0 #define SK_RGBA_G32_SHIFT 8 #define SK_RGBA_B32_SHIFT 16 #define SK_RGBA_A32_SHIFT 24 #define SK_BGRA_B32_SHIFT 0 #define SK_BGRA_G32_SHIFT 8 #define SK_BGRA_R32_SHIFT 16 #define SK_BGRA_A32_SHIFT 24 #if defined(SK_PMCOLOR_IS_RGBA) || defined(SK_PMCOLOR_IS_BGRA) #error "Configure PMCOLOR by setting SK_R32_SHIFT." #endif // Deduce which SK_PMCOLOR_IS_ to define from the _SHIFT defines #if (SK_A32_SHIFT == SK_RGBA_A32_SHIFT && \ SK_R32_SHIFT == SK_RGBA_R32_SHIFT && \ SK_G32_SHIFT == SK_RGBA_G32_SHIFT && \ SK_B32_SHIFT == SK_RGBA_B32_SHIFT) #define SK_PMCOLOR_IS_RGBA #elif (SK_A32_SHIFT == SK_BGRA_A32_SHIFT && \ SK_R32_SHIFT == SK_BGRA_R32_SHIFT && \ SK_G32_SHIFT == SK_BGRA_G32_SHIFT && \ SK_B32_SHIFT == SK_BGRA_B32_SHIFT) #define SK_PMCOLOR_IS_BGRA #else #error "need 32bit packing to be either RGBA or BGRA" #endif #define SkGetPackedA32(packed) ((uint32_t)((packed) << (24 - SK_A32_SHIFT)) >> 24) #define SkGetPackedR32(packed) ((uint32_t)((packed) << (24 - SK_R32_SHIFT)) >> 24) #define SkGetPackedG32(packed) ((uint32_t)((packed) << (24 - SK_G32_SHIFT)) >> 24) #define SkGetPackedB32(packed) ((uint32_t)((packed) << (24 - SK_B32_SHIFT)) >> 24) #define SkA32Assert(a) SkASSERT((unsigned)(a) <= SK_A32_MASK) #define SkR32Assert(r) SkASSERT((unsigned)(r) <= SK_R32_MASK) #define SkG32Assert(g) SkASSERT((unsigned)(g) <= SK_G32_MASK) #define SkB32Assert(b) SkASSERT((unsigned)(b) <= SK_B32_MASK) /** * Pack the components into a SkPMColor, checking (in the debug version) that * the components are 0..255, and are already premultiplied (i.e. alpha >= color) */ static inline SkPMColor SkPackARGB32(U8CPU a, U8CPU r, U8CPU g, U8CPU b) { SkA32Assert(a); SkASSERT(r <= a); SkASSERT(g <= a); SkASSERT(b <= a); return (a << SK_A32_SHIFT) | (r << SK_R32_SHIFT) | (g << SK_G32_SHIFT) | (b << SK_B32_SHIFT); } /** * Same as SkPackARGB32, but this version guarantees to not check that the * values are premultiplied in the debug version. */ static inline SkPMColor SkPackARGB32NoCheck(U8CPU a, U8CPU r, U8CPU g, U8CPU b) { return (a << SK_A32_SHIFT) | (r << SK_R32_SHIFT) | (g << SK_G32_SHIFT) | (b << SK_B32_SHIFT); } static inline SkPMColor SkPremultiplyARGBInline(U8CPU a, U8CPU r, U8CPU g, U8CPU b) { SkA32Assert(a); SkR32Assert(r); SkG32Assert(g); SkB32Assert(b); if (a != 255) { r = SkMulDiv255Round(r, a); g = SkMulDiv255Round(g, a); b = SkMulDiv255Round(b, a); } return SkPackARGB32(a, r, g, b); } // When Android is compiled optimizing for size, SkAlphaMulQ doesn't get // inlined; forcing inlining significantly improves performance. static SK_ALWAYS_INLINE uint32_t SkAlphaMulQ(uint32_t c, unsigned scale) { uint32_t mask = 0xFF00FF; uint32_t rb = ((c & mask) * scale) >> 8; uint32_t ag = ((c >> 8) & mask) * scale; return (rb & mask) | (ag & ~mask); } static inline SkPMColor SkPMSrcOver(SkPMColor src, SkPMColor dst) { return src + SkAlphaMulQ(dst, SkAlpha255To256(255 - SkGetPackedA32(src))); } #endif