/*
|
* Copyright 2018 Google Inc.
|
*
|
* Use of this source code is governed by a BSD-style license that can be
|
* found in the LICENSE file.
|
*/
|
|
#ifndef SkYUVAIndex_DEFINED
|
#define SkYUVAIndex_DEFINED
|
|
#include "SkTypes.h"
|
|
/** \enum SkColorChannel
|
Describes different color channels one can manipulate
|
*/
|
enum class SkColorChannel {
|
kR, // the red channel
|
kG, // the green channel
|
kB, // the blue channel
|
kA, // the alpha channel
|
|
kLastEnum = kA,
|
};
|
|
/** \struct SkYUVAIndex
|
Describes from which image source and which channel to read each individual YUVA plane.
|
|
SkYUVAIndex contains a index for which image source to read from and a enum for which channel
|
to read from.
|
*/
|
struct SK_API SkYUVAIndex {
|
bool operator==(const SkYUVAIndex& that) const {
|
return this->fIndex == that.fIndex && this->fChannel == that.fChannel;
|
}
|
|
bool operator!=(const SkYUVAIndex& that) const {
|
return !(*this == that);
|
}
|
|
// Index in the array of SkYUVAIndex
|
// TODO: rename as Component
|
enum Index {
|
kY_Index = 0,
|
kU_Index = 1,
|
kV_Index = 2,
|
kA_Index = 3,
|
|
kLast_Index = kA_Index
|
};
|
static constexpr int kIndexCount = kLast_Index + 1;
|
|
/** The index is a number between -1..3 which definies which image source to read from, where -1
|
* means the image source doesn't exist. The assumption is we will always have image sources for
|
* each of YUV planes, but optionally have image source for A plane. */
|
int fIndex;
|
/** The channel describes from which channel to read the info from. Currently we only deal with
|
* YUV and NV12 and channel info is ignored. */
|
SkColorChannel fChannel;
|
|
static bool AreValidIndices(const SkYUVAIndex yuvaIndices[4], int* numPlanes) {
|
// Note that 'numPlanes' is always filled in even if the indices are not valid.
|
// This means it can always be used to process the backing resources (but be careful
|
// of empty intervening slots).
|
int maxSlotUsed = -1;
|
bool used[4] = { false, false, false, false };
|
bool valid = true;
|
for (int i = 0; i < 4; ++i) {
|
if (yuvaIndices[i].fIndex < 0) {
|
if (SkYUVAIndex::kA_Index != i) {
|
valid = false; // only the 'A' plane can be omitted
|
}
|
} else if (yuvaIndices[i].fIndex > 3) {
|
valid = false; // A maximum of four input textures is allowed
|
} else {
|
maxSlotUsed = SkTMax(yuvaIndices[i].fIndex, maxSlotUsed);
|
used[i] = true;
|
}
|
}
|
|
// All the used slots should be packed starting at 0 with no gaps
|
for (int i = 0; i <= maxSlotUsed; ++i) {
|
if (!used[i]) {
|
valid = false;
|
}
|
}
|
|
*numPlanes = maxSlotUsed + 1;
|
return valid;
|
}
|
};
|
|
#endif
|
