src/core/SkBitmapProcShader.cpp

/*
 * Copyright 2011 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkBitmapProcShader.h"
#include "SkBitmapProcState.h"
#include "SkColorPriv.h"
#include "SkErrorInternals.h"
#include "SkPixelRef.h"
#include "SkReadBuffer.h"
#include "SkWriteBuffer.h"

#if SK_SUPPORT_GPU
#include "effects/GrBicubicEffect.h"
#include "effects/GrExtractAlphaFragmentProcessor.h"
#include "effects/GrSimpleTextureEffect.h"
#endif

size_t SkBitmapProcShader::ContextSize() {
    // The SkBitmapProcState is stored outside of the context object, with the context holding
    // a pointer to it.
    return sizeof(BitmapProcShaderContext) + sizeof(SkBitmapProcState);
}

SkBitmapProcShader::SkBitmapProcShader(const SkBitmap& src, TileMode tmx, TileMode tmy,
                                       const SkMatrix* localMatrix)
        : INHERITED(localMatrix) {
    fRawBitmap = src;
    fTileModeX = (uint8_t)tmx;
    fTileModeY = (uint8_t)tmy;
}

bool SkBitmapProcShader::onIsABitmap(SkBitmap* texture, SkMatrix* texM, TileMode xy[]) const {
    if (texture) {
        *texture = fRawBitmap;
    }
    if (texM) {
        texM->reset();
    }
    if (xy) {
        xy[0] = (TileMode)fTileModeX;
        xy[1] = (TileMode)fTileModeY;
    }
    return true;
}

SkFlattenable* SkBitmapProcShader::CreateProc(SkReadBuffer& buffer) {
    SkMatrix lm;
    buffer.readMatrix(&lm);
    SkBitmap bm;
    if (!buffer.readBitmap(&bm)) {
        return nullptr;
    }
    bm.setImmutable();
    TileMode mx = (TileMode)buffer.readUInt();
    TileMode my = (TileMode)buffer.readUInt();
    return SkShader::CreateBitmapShader(bm, mx, my, &lm);
}

void SkBitmapProcShader::flatten(SkWriteBuffer& buffer) const {
    buffer.writeMatrix(this->getLocalMatrix());
    buffer.writeBitmap(fRawBitmap);
    buffer.writeUInt(fTileModeX);
    buffer.writeUInt(fTileModeY);
}

static bool only_scale_and_translate(const SkMatrix& matrix) {
    unsigned mask = SkMatrix::kTranslate_Mask | SkMatrix::kScale_Mask;
    return (matrix.getType() & ~mask) == 0;
}

bool SkBitmapProcShader::isOpaque() const {
    return fRawBitmap.isOpaque();
}

SkShader::Context* SkBitmapProcShader::MakeContext(const SkShader& shader,
                                                   TileMode tmx, TileMode tmy,
                                                   const SkBitmap& bitmap,
                                                   const ContextRec& rec, void* storage) {
    SkMatrix totalInverse;
    // Do this first, so we know the matrix can be inverted.
    if (!shader.computeTotalInverse(rec, &totalInverse)) {
        return nullptr;
    }

    void* stateStorage = (char*)storage + sizeof(BitmapProcShaderContext);
    SkBitmapProcState* state = new (stateStorage) SkBitmapProcState(SkBitmapProvider(bitmap),
                                                                    tmx, tmy);

    SkASSERT(state);
    if (!state->chooseProcs(totalInverse, *rec.fPaint)) {
        state->~SkBitmapProcState();
        return nullptr;
    }

    return new (storage) BitmapProcShaderContext(shader, rec, state);
}

SkShader::Context* SkBitmapProcShader::onCreateContext(const ContextRec& rec, void* storage) const {
    return MakeContext(*this, (TileMode)fTileModeX, (TileMode)fTileModeY, fRawBitmap, rec, storage);
}

SkBitmapProcShader::BitmapProcShaderContext::BitmapProcShaderContext(const SkShader& shader,
                                                                     const ContextRec& rec,
                                                                     SkBitmapProcState* state)
    : INHERITED(shader, rec)
    , fState(state)
{
    const SkPixmap& pixmap = fState->fPixmap;
    bool isOpaque = pixmap.isOpaque();

    // update fFlags
    uint32_t flags = 0;
    if (isOpaque && (255 == this->getPaintAlpha())) {
        flags |= kOpaqueAlpha_Flag;
    }

    switch (pixmap.colorType()) {
        case kRGB_565_SkColorType:
            flags |= (kHasSpan16_Flag | kIntrinsicly16_Flag);
            break;
        case kIndex_8_SkColorType:
        case kN32_SkColorType:
            if (isOpaque) {
                flags |= kHasSpan16_Flag;
            }
            break;
        case kAlpha_8_SkColorType:
            break;  // never set kHasSpan16_Flag
        default:
            break;
    }

    if (rec.fPaint->isDither() && pixmap.colorType() != kRGB_565_SkColorType) {
        // gradients can auto-dither in their 16bit sampler, but we don't so
        // we clear the flag here.
        flags &= ~kHasSpan16_Flag;
    }

    // if we're only 1-pixel high, and we don't rotate, then we can claim this
    if (1 == pixmap.height() &&
            only_scale_and_translate(this->getTotalInverse())) {
        flags |= kConstInY32_Flag;
        if (flags & kHasSpan16_Flag) {
            flags |= kConstInY16_Flag;
        }
    }

    fFlags = flags;
}

SkBitmapProcShader::BitmapProcShaderContext::~BitmapProcShaderContext() {
    // The bitmap proc state has been created outside of the context on memory that will be freed
    // elsewhere. Only call the destructor but leave the freeing of the memory to the caller.
    fState->~SkBitmapProcState();
}

#define BUF_MAX     128

#define TEST_BUFFER_OVERRITEx

#ifdef TEST_BUFFER_OVERRITE
    #define TEST_BUFFER_EXTRA   32
    #define TEST_PATTERN    0x88888888
#else
    #define TEST_BUFFER_EXTRA   0
#endif

void SkBitmapProcShader::BitmapProcShaderContext::shadeSpan(int x, int y, SkPMColor dstC[],
                                                            int count) {
    const SkBitmapProcState& state = *fState;
    if (state.getShaderProc32()) {
        state.getShaderProc32()(state, x, y, dstC, count);
        return;
    }

    uint32_t buffer[BUF_MAX + TEST_BUFFER_EXTRA];
    SkBitmapProcState::MatrixProc   mproc = state.getMatrixProc();
    SkBitmapProcState::SampleProc32 sproc = state.getSampleProc32();
    int max = state.maxCountForBufferSize(sizeof(buffer[0]) * BUF_MAX);

    SkASSERT(state.fPixmap.addr());

    for (;;) {
        int n = count;
        if (n > max) {
            n = max;
        }
        SkASSERT(n > 0 && n < BUF_MAX*2);
#ifdef TEST_BUFFER_OVERRITE
        for (int i = 0; i < TEST_BUFFER_EXTRA; i++) {
            buffer[BUF_MAX + i] = TEST_PATTERN;
        }
#endif
        mproc(state, buffer, n, x, y);
#ifdef TEST_BUFFER_OVERRITE
        for (int j = 0; j < TEST_BUFFER_EXTRA; j++) {
            SkASSERT(buffer[BUF_MAX + j] == TEST_PATTERN);
        }
#endif
        sproc(state, buffer, n, dstC);

        if ((count -= n) == 0) {
            break;
        }
        SkASSERT(count > 0);
        x += n;
        dstC += n;
    }
}

SkShader::Context::ShadeProc SkBitmapProcShader::BitmapProcShaderContext::asAShadeProc(void** ctx) {
    if (fState->getShaderProc32()) {
        *ctx = fState;
        return (ShadeProc)fState->getShaderProc32();
    }
    return nullptr;
}

void SkBitmapProcShader::BitmapProcShaderContext::shadeSpan16(int x, int y, uint16_t dstC[],
                                                              int count) {
    const SkBitmapProcState& state = *fState;
    if (state.getShaderProc16()) {
        state.getShaderProc16()(state, x, y, dstC, count);
        return;
    }

    uint32_t buffer[BUF_MAX];
    SkBitmapProcState::MatrixProc   mproc = state.getMatrixProc();
    SkBitmapProcState::SampleProc16 sproc = state.getSampleProc16();
    int max = state.maxCountForBufferSize(sizeof(buffer));

    SkASSERT(state.fPixmap.addr());

    for (;;) {
        int n = count;
        if (n > max) {
            n = max;
        }
        mproc(state, buffer, n, x, y);
        sproc(state, buffer, n, dstC);

        if ((count -= n) == 0) {
            break;
        }
        x += n;
        dstC += n;
    }
}

///////////////////////////////////////////////////////////////////////////////

#include "SkUnPreMultiply.h"
#include "SkColorShader.h"
#include "SkEmptyShader.h"

// returns true and set color if the bitmap can be drawn as a single color
// (for efficiency)
static bool can_use_color_shader(const SkBitmap& bm, SkColor* color) {
#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
    // HWUI does not support color shaders (see b/22390304)
    return false;
#endif

    if (1 != bm.width() || 1 != bm.height()) {
        return false;
    }

    SkAutoLockPixels alp(bm);
    if (!bm.readyToDraw()) {
        return false;
    }

    switch (bm.colorType()) {
        case kN32_SkColorType:
            *color = SkUnPreMultiply::PMColorToColor(*bm.getAddr32(0, 0));
            return true;
        case kRGB_565_SkColorType:
            *color = SkPixel16ToColor(*bm.getAddr16(0, 0));
            return true;
        case kIndex_8_SkColorType:
            *color = SkUnPreMultiply::PMColorToColor(bm.getIndex8Color(0, 0));
            return true;
        default: // just skip the other configs for now
            break;
    }
    return false;
}

static bool bitmap_is_too_big(const SkBitmap& bm) {
    // SkBitmapProcShader stores bitmap coordinates in a 16bit buffer, as it
    // communicates between its matrix-proc and its sampler-proc. Until we can
    // widen that, we have to reject bitmaps that are larger.
    //
    static const int kMaxSize = 65535;

    return bm.width() > kMaxSize || bm.height() > kMaxSize;
}

SkShader* SkCreateBitmapShader(const SkBitmap& src, SkShader::TileMode tmx,
                               SkShader::TileMode tmy, const SkMatrix* localMatrix,
                               SkTBlitterAllocator* allocator) {
    SkShader* shader;
    SkColor color;
    if (src.isNull() || bitmap_is_too_big(src)) {
        if (nullptr == allocator) {
            shader = new SkEmptyShader;
        } else {
            shader = allocator->createT<SkEmptyShader>();
        }
    } else if (can_use_color_shader(src, &color)) {
        if (nullptr == allocator) {
            shader = new SkColorShader(color);
        } else {
            shader = allocator->createT<SkColorShader>(color);
        }
    } else {
        if (nullptr == allocator) {
            shader = new SkBitmapProcShader(src, tmx, tmy, localMatrix);
        } else {
            shader = allocator->createT<SkBitmapProcShader>(src, tmx, tmy, localMatrix);
        }
    }
    return shader;
}

///////////////////////////////////////////////////////////////////////////////

#ifndef SK_IGNORE_TO_STRING
void SkBitmapProcShader::toString(SkString* str) const {
    static const char* gTileModeName[SkShader::kTileModeCount] = {
        "clamp", "repeat", "mirror"
    };

    str->append("BitmapShader: (");

    str->appendf("(%s, %s)",
                 gTileModeName[fTileModeX],
                 gTileModeName[fTileModeY]);

    str->append(" ");
    fRawBitmap.toString(str);

    this->INHERITED::toString(str);

    str->append(")");
}
#endif

///////////////////////////////////////////////////////////////////////////////

#if SK_SUPPORT_GPU

#include "GrTextureAccess.h"
#include "SkGr.h"
#include "effects/GrSimpleTextureEffect.h"

const GrFragmentProcessor* SkBitmapProcShader::asFragmentProcessor(GrContext* context,
                                             const SkMatrix& viewM, const SkMatrix* localMatrix,
                                             SkFilterQuality filterQuality,
                                             GrProcessorDataManager* procDataManager) const {
    SkMatrix matrix;
    matrix.setIDiv(fRawBitmap.width(), fRawBitmap.height());

    SkMatrix lmInverse;
    if (!this->getLocalMatrix().invert(&lmInverse)) {
        return nullptr;
    }
    if (localMatrix) {
        SkMatrix inv;
        if (!localMatrix->invert(&inv)) {
            return nullptr;
        }
        lmInverse.postConcat(inv);
    }
    matrix.preConcat(lmInverse);

    SkShader::TileMode tm[] = {
        (TileMode)fTileModeX,
        (TileMode)fTileModeY,
    };

    // Must set wrap and filter on the sampler before requesting a texture. In two places below
    // we check the matrix scale factors to determine how to interpret the filter quality setting.
    // This completely ignores the complexity of the drawVertices case where explicit local coords
    // are provided by the caller.
    bool doBicubic;
    GrTextureParams::FilterMode textureFilterMode =
            GrSkFilterQualityToGrFilterMode(filterQuality, viewM, this->getLocalMatrix(),
                                            &doBicubic);
    GrTextureParams params(tm, textureFilterMode);
    SkAutoTUnref<GrTexture> texture(GrRefCachedBitmapTexture(context, fRawBitmap, &params));

    if (!texture) {
        SkErrorInternals::SetError( kInternalError_SkError,
                                    "Couldn't convert bitmap to texture.");
        return nullptr;
    }

    SkAutoTUnref<GrFragmentProcessor> inner;
    if (doBicubic) {
        inner.reset(GrBicubicEffect::Create(procDataManager, texture, matrix, tm));
    } else {
        inner.reset(GrSimpleTextureEffect::Create(procDataManager, texture, matrix, params));
    }

    if (kAlpha_8_SkColorType == fRawBitmap.colorType()) {
        return SkRef(inner.get());
    }
    return GrExtractAlphaFragmentProcessor::Create(inner);
}

#endif