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- /*
- * 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<U8CPU>(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
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