src/gpu/GrSWMaskHelper.cpp

/*
 * Copyright 2012 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "GrSWMaskHelper.h"

#include "GrContext.h"
#include "GrContextPriv.h"
#include "GrProxyProvider.h"
#include "GrShape.h"
#include "GrSurfaceContext.h"
#include "GrTextureProxy.h"

/*
 * Convert a boolean operation into a transfer mode code
 */
static SkBlendMode op_to_mode(SkRegion::Op op) {

    static const SkBlendMode modeMap[] = {
        SkBlendMode::kDstOut,   // kDifference_Op
        SkBlendMode::kModulate, // kIntersect_Op
        SkBlendMode::kSrcOver,  // kUnion_Op
        SkBlendMode::kXor,      // kXOR_Op
        SkBlendMode::kClear,    // kReverseDifference_Op
        SkBlendMode::kSrc,      // kReplace_Op
    };

    return modeMap[op];
}

/**
 * Draw a single rect element of the clip stack into the accumulation bitmap
 */
void GrSWMaskHelper::drawRect(const SkRect& rect, const SkMatrix& matrix, SkRegion::Op op, GrAA aa,
                              uint8_t alpha) {
    SkPaint paint;
    paint.setBlendMode(op_to_mode(op));
    paint.setAntiAlias(GrAA::kYes == aa);
    paint.setColor(SkColorSetARGB(alpha, alpha, alpha, alpha));

    SkMatrix translatedMatrix = matrix;
    translatedMatrix.postTranslate(fTranslate.fX, fTranslate.fY);
    fDraw.fMatrix = &translatedMatrix;

    fDraw.drawRect(rect, paint);
}

/**
 * Draw a single path element of the clip stack into the accumulation bitmap
 */
void GrSWMaskHelper::drawShape(const GrShape& shape, const SkMatrix& matrix, SkRegion::Op op,
                               GrAA aa, uint8_t alpha) {
    SkPaint paint;
    paint.setPathEffect(shape.style().refPathEffect());
    shape.style().strokeRec().applyToPaint(&paint);
    paint.setAntiAlias(GrAA::kYes == aa);

    SkMatrix translatedMatrix = matrix;
    translatedMatrix.postTranslate(fTranslate.fX, fTranslate.fY);
    fDraw.fMatrix = &translatedMatrix;

    SkPath path;
    shape.asPath(&path);
    if (SkRegion::kReplace_Op == op && 0xFF == alpha) {
        SkASSERT(0xFF == paint.getAlpha());
        fDraw.drawPathCoverage(path, paint);
    } else {
        paint.setBlendMode(op_to_mode(op));
        paint.setColor(SkColorSetARGB(alpha, alpha, alpha, alpha));
        fDraw.drawPath(path, paint);
    }
};

bool GrSWMaskHelper::init(const SkIRect& resultBounds) {
    // We will need to translate draws so the bound's UL corner is at the origin
    fTranslate = {-SkIntToScalar(resultBounds.fLeft), -SkIntToScalar(resultBounds.fTop)};
    SkIRect bounds = SkIRect::MakeWH(resultBounds.width(), resultBounds.height());

    const SkImageInfo bmImageInfo = SkImageInfo::MakeA8(bounds.width(), bounds.height());
    if (!fPixels->tryAlloc(bmImageInfo)) {
        return false;
    }
    fPixels->erase(0);

    fDraw.fDst      = *fPixels;
    fRasterClip.setRect(bounds);
    fDraw.fRC       = &fRasterClip;
    return true;
}

sk_sp<GrTextureProxy> GrSWMaskHelper::toTextureProxy(GrContext* context, SkBackingFit fit) {
    SkImageInfo ii = SkImageInfo::MakeA8(fPixels->width(), fPixels->height());
    size_t rowBytes = fPixels->rowBytes();

    sk_sp<SkData> data = fPixels->detachPixelsAsData();
    if (!data) {
        return nullptr;
    }

    sk_sp<SkImage> img = SkImage::MakeRasterData(ii, std::move(data), rowBytes);
    if (!img) {
        return nullptr;
    }

    // TODO: http://skbug.com/8422: Although this fixes http://skbug.com/8351, it seems like these
    // should just participate in the normal allocation process and not need the pending IO flag.
    auto surfaceFlags = GrInternalSurfaceFlags::kNone;
    if (!context->priv().resourceProvider()) {
        // In DDL mode, this texture proxy will be instantiated at flush time, therfore it cannot
        // have pending IO.
        surfaceFlags |= GrInternalSurfaceFlags::kNoPendingIO;
    }
    auto clearFlag = kNone_GrSurfaceFlags;
    // In a WASM build on Firefox, we see warnings like
    // WebGL warning: texSubImage2D: This operation requires zeroing texture data. This is slow.
    // WebGL warning: texSubImage2D: Texture has not been initialized prior to a partial upload,
    //                forcing the browser to clear it. This may be slow.
    // Setting the initial clear seems to make those warnings go away and offers a substantial
    // boost in performance in Firefox. Chrome sees a more modest increase.
#if IS_WEBGL==1
    clearFlag = kPerformInitialClear_GrSurfaceFlag;
#endif
    return context->priv().proxyProvider()->createTextureProxy(
            std::move(img), clearFlag, 1, SkBudgeted::kYes, fit, surfaceFlags);
}