src/effects/SkTileImageFilter.cpp

/*
 * Copyright 2013 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkTileImageFilter.h"

#include "SkCanvas.h"
#include "SkImage.h"
#include "SkMatrix.h"
#include "SkOffsetImageFilter.h"
#include "SkPaint.h"
#include "SkReadBuffer.h"
#include "SkShader.h"
#include "SkSpecialImage.h"
#include "SkSpecialSurface.h"
#include "SkSurface.h"
#include "SkValidationUtils.h"
#include "SkWriteBuffer.h"

sk_sp<SkImageFilter> SkTileImageFilter::Make(const SkRect& srcRect, const SkRect& dstRect,
                                             sk_sp<SkImageFilter> input) {
    if (!SkIsValidRect(srcRect) || !SkIsValidRect(dstRect)) {
        return nullptr;
    }
    if (srcRect.width() == dstRect.width() && srcRect.height() == dstRect.height()) {
        SkRect ir = dstRect;
        if (!ir.intersect(srcRect)) {
            return input;
        }
        CropRect cropRect(ir);
        return SkOffsetImageFilter::Make(dstRect.x() - srcRect.x(),
                                         dstRect.y() - srcRect.y(),
                                         std::move(input),
                                         &cropRect);
    }
    return sk_sp<SkImageFilter>(new SkTileImageFilter(srcRect, dstRect, std::move(input)));
}

sk_sp<SkSpecialImage> SkTileImageFilter::onFilterImage(SkSpecialImage* source,
                                                       const Context& ctx,
                                                       SkIPoint* offset) const {
    SkIPoint inputOffset = SkIPoint::Make(0, 0);
    sk_sp<SkSpecialImage> input(this->filterInput(0, source, ctx, &inputOffset));
    if (!input) {
        return nullptr;
    }

    SkRect dstRect;
    ctx.ctm().mapRect(&dstRect, fDstRect);
    if (!dstRect.intersect(SkRect::Make(ctx.clipBounds()))) {
        return nullptr;
    }

    const SkIRect dstIRect = dstRect.roundOut();
    if (!fSrcRect.width() || !fSrcRect.height() || !dstIRect.width() || !dstIRect.height()) {
        return nullptr;
    }

    SkRect srcRect;
    ctx.ctm().mapRect(&srcRect, fSrcRect);
    SkIRect srcIRect;
    srcRect.roundOut(&srcIRect);
    srcIRect.offset(-inputOffset);
    const SkIRect inputBounds = SkIRect::MakeWH(input->width(), input->height());

    if (!SkIRect::Intersects(srcIRect, inputBounds)) {
        return nullptr;
    }

    // We create an SkImage here b.c. it needs to be a tight fit for the tiling
    sk_sp<SkImage> subset;
    if (inputBounds.contains(srcIRect)) {
        subset = input->asImage(&srcIRect);
        if (!subset) {
            return nullptr;
        }
    } else {
        sk_sp<SkSurface> surf(input->makeTightSurface(ctx.outputProperties(), srcIRect.size()));
        if (!surf) {
            return nullptr;
        }

        SkCanvas* canvas = surf->getCanvas();
        SkASSERT(canvas);

        SkPaint paint;
        paint.setBlendMode(SkBlendMode::kSrc);

        input->draw(canvas, 
                    SkIntToScalar(inputOffset.x()), SkIntToScalar(inputOffset.y()),
                    &paint);

        subset = surf->makeImageSnapshot();
    }
    SkASSERT(subset->width() == srcIRect.width());
    SkASSERT(subset->height() == srcIRect.height());

    sk_sp<SkSpecialSurface> surf(source->makeSurface(ctx.outputProperties(), dstIRect.size()));
    if (!surf) {
        return nullptr;
    }

    SkCanvas* canvas = surf->getCanvas();
    SkASSERT(canvas);

    SkPaint paint;
    paint.setBlendMode(SkBlendMode::kSrc);
    paint.setShader(subset->makeShader(SkShader::kRepeat_TileMode, SkShader::kRepeat_TileMode));
    canvas->translate(-dstRect.fLeft, -dstRect.fTop);
    canvas->drawRect(dstRect, paint);
    offset->fX = dstIRect.fLeft;
    offset->fY = dstIRect.fTop;
    return surf->makeImageSnapshot();
}

sk_sp<SkImageFilter> SkTileImageFilter::onMakeColorSpace(SkColorSpaceXformer* xformer) const {
    SkASSERT(1 == this->countInputs());
    if (!this->getInput(0)) {
        return sk_ref_sp(const_cast<SkTileImageFilter*>(this));
    }

    sk_sp<SkImageFilter> input = this->getInput(0)->makeColorSpace(xformer);
    return SkTileImageFilter::Make(fSrcRect, fDstRect, std::move(input));
}

SkIRect SkTileImageFilter::onFilterNodeBounds(const SkIRect& src, const SkMatrix& ctm,
                                              MapDirection direction) const {
    SkRect rect = kReverse_MapDirection == direction ? fSrcRect : fDstRect;
    ctm.mapRect(&rect);
    return rect.roundOut();
}

SkIRect SkTileImageFilter::onFilterBounds(const SkIRect& src, const SkMatrix&, MapDirection) const {
    // Don't recurse into inputs.
    return src;
}

SkRect SkTileImageFilter::computeFastBounds(const SkRect& src) const {
    return fDstRect;
}

sk_sp<SkFlattenable> SkTileImageFilter::CreateProc(SkReadBuffer& buffer) {
    SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 1);
    SkRect src, dst;
    buffer.readRect(&src);
    buffer.readRect(&dst);
    return Make(src, dst, common.getInput(0));
}

void SkTileImageFilter::flatten(SkWriteBuffer& buffer) const {
    this->INHERITED::flatten(buffer);
    buffer.writeRect(fSrcRect);
    buffer.writeRect(fDstRect);
}

#ifndef SK_IGNORE_TO_STRING
void SkTileImageFilter::toString(SkString* str) const {
    str->appendf("SkTileImageFilter: (");
    str->appendf("src: %.2f %.2f %.2f %.2f",
                 fSrcRect.fLeft, fSrcRect.fTop, fSrcRect.fRight, fSrcRect.fBottom);
    str->appendf(" dst: %.2f %.2f %.2f %.2f",
                 fDstRect.fLeft, fDstRect.fTop, fDstRect.fRight, fDstRect.fBottom);
    if (this->getInput(0)) {
        str->appendf("input: (");
        this->getInput(0)->toString(str);
        str->appendf(")");
    }
    str->append(")");
}
#endif