src/effects/SkMagnifierImageFilter.cpp

/*
 * Copyright 2012 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.
 */

#include "SkMagnifierImageFilter.h"

#include "SkBitmap.h"
#include "SkColorData.h"
#include "SkColorSpaceXformer.h"
#include "SkImageFilterPriv.h"
#include "SkReadBuffer.h"
#include "SkSpecialImage.h"
#include "SkWriteBuffer.h"
#include "SkValidationUtils.h"

////////////////////////////////////////////////////////////////////////////////
#if SK_SUPPORT_GPU
#include "../private/GrGLSL.h"
#include "GrColorSpaceXform.h"
#include "GrContext.h"
#include "GrCoordTransform.h"
#include "GrTexture.h"
#include "effects/GrMagnifierEffect.h"
#include "glsl/GrGLSLFragmentProcessor.h"
#include "glsl/GrGLSLFragmentShaderBuilder.h"
#include "glsl/GrGLSLProgramDataManager.h"
#include "glsl/GrGLSLUniformHandler.h"
#endif

sk_sp<SkImageFilter> SkMagnifierImageFilter::Make(const SkRect& srcRect, SkScalar inset,
                                                  sk_sp<SkImageFilter> input,
                                                  const CropRect* cropRect) {
    if (!SkScalarIsFinite(inset) || !SkIsValidRect(srcRect)) {
        return nullptr;
    }
    if (inset < 0) {
        return nullptr;
    }
    // Negative numbers in src rect are not supported
    if (srcRect.fLeft < 0 || srcRect.fTop < 0) {
        return nullptr;
    }
    return sk_sp<SkImageFilter>(new SkMagnifierImageFilter(srcRect, inset,
                                                           std::move(input),
                                                           cropRect));
}

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

SkMagnifierImageFilter::SkMagnifierImageFilter(const SkRect& srcRect,
                                               SkScalar inset,
                                               sk_sp<SkImageFilter> input,
                                               const CropRect* cropRect)
    : INHERITED(&input, 1, cropRect)
    , fSrcRect(srcRect)
    , fInset(inset) {
    SkASSERT(srcRect.left() >= 0 && srcRect.top() >= 0 && inset >= 0);
}

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

void SkMagnifierImageFilter::flatten(SkWriteBuffer& buffer) const {
    this->INHERITED::flatten(buffer);
    buffer.writeRect(fSrcRect);
    buffer.writeScalar(fInset);
}

sk_sp<SkSpecialImage> SkMagnifierImageFilter::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;
    }

    const SkIRect inputBounds = SkIRect::MakeXYWH(inputOffset.x(), inputOffset.y(),
                                                  input->width(), input->height());

    SkIRect bounds;
    if (!this->applyCropRect(ctx, inputBounds, &bounds)) {
        return nullptr;
    }

    SkScalar invInset = fInset > 0 ? SkScalarInvert(fInset) : SK_Scalar1;

    SkScalar invXZoom = fSrcRect.width() / bounds.width();
    SkScalar invYZoom = fSrcRect.height() / bounds.height();


#if SK_SUPPORT_GPU
    if (source->isTextureBacked()) {
        GrContext* context = source->getContext();

        sk_sp<GrTextureProxy> inputProxy(input->asTextureProxyRef(context));
        SkASSERT(inputProxy);

        offset->fX = bounds.left();
        offset->fY = bounds.top();
        bounds.offset(-inputOffset);

        GrPixelConfig inputConfig = inputProxy->config();
        auto fp = GrMagnifierEffect::Make(std::move(inputProxy),
                                          bounds,
                                          fSrcRect,
                                          invXZoom,
                                          invYZoom,
                                          bounds.width() * invInset,
                                          bounds.height() * invInset);
        fp = GrColorSpaceXformEffect::Make(std::move(fp), input->getColorSpace(),
                                           inputConfig, ctx.outputProperties().colorSpace());
        if (!fp) {
            return nullptr;
        }

        return DrawWithFP(context, std::move(fp), bounds, ctx.outputProperties());
    }
#endif

    SkBitmap inputBM;

    if (!input->getROPixels(&inputBM)) {
        return nullptr;
    }

    if ((inputBM.colorType() != kN32_SkColorType) ||
        (fSrcRect.width() >= inputBM.width()) || (fSrcRect.height() >= inputBM.height())) {
        return nullptr;
    }

    SkASSERT(inputBM.getPixels());
    if (!inputBM.getPixels() || inputBM.width() <= 0 || inputBM.height() <= 0) {
        return nullptr;
    }

    const SkImageInfo info = SkImageInfo::MakeN32Premul(bounds.width(), bounds.height());

    SkBitmap dst;
    if (!dst.tryAllocPixels(info)) {
        return nullptr;
    }

    SkColor* dptr = dst.getAddr32(0, 0);
    int dstWidth = dst.width(), dstHeight = dst.height();
    for (int y = 0; y < dstHeight; ++y) {
        for (int x = 0; x < dstWidth; ++x) {
            SkScalar x_dist = SkMin32(x, dstWidth - x - 1) * invInset;
            SkScalar y_dist = SkMin32(y, dstHeight - y - 1) * invInset;
            SkScalar weight = 0;

            static const SkScalar kScalar2 = SkScalar(2);

            // To create a smooth curve at the corners, we need to work on
            // a square twice the size of the inset.
            if (x_dist < kScalar2 && y_dist < kScalar2) {
                x_dist = kScalar2 - x_dist;
                y_dist = kScalar2 - y_dist;

                SkScalar dist = SkScalarSqrt(SkScalarSquare(x_dist) +
                                             SkScalarSquare(y_dist));
                dist = SkMaxScalar(kScalar2 - dist, 0);
                weight = SkMinScalar(SkScalarSquare(dist), SK_Scalar1);
            } else {
                SkScalar sqDist = SkMinScalar(SkScalarSquare(x_dist),
                                              SkScalarSquare(y_dist));
                weight = SkMinScalar(sqDist, SK_Scalar1);
            }

            SkScalar x_interp = weight * (fSrcRect.x() + x * invXZoom) + (1 - weight) * x;
            SkScalar y_interp = weight * (fSrcRect.y() + y * invYZoom) + (1 - weight) * y;

            int x_val = SkTPin(bounds.x() + SkScalarFloorToInt(x_interp), 0, inputBM.width() - 1);
            int y_val = SkTPin(bounds.y() + SkScalarFloorToInt(y_interp), 0, inputBM.height() - 1);

            *dptr = *inputBM.getAddr32(x_val, y_val);
            dptr++;
        }
    }

    offset->fX = bounds.left();
    offset->fY = bounds.top();
    return SkSpecialImage::MakeFromRaster(SkIRect::MakeWH(bounds.width(), bounds.height()),
                                          dst);
}

sk_sp<SkImageFilter> SkMagnifierImageFilter::onMakeColorSpace(SkColorSpaceXformer* xformer) const {
    SkASSERT(1 == this->countInputs());
    auto input = xformer->apply(this->getInput(0));
    if (input.get() != this->getInput(0)) {
        return SkMagnifierImageFilter::Make(fSrcRect, fInset, std::move(input),
                                            this->getCropRectIfSet());
    }
    return this->refMe();
}

void SkMagnifierImageFilter::toString(SkString* str) const {
    str->appendf("SkMagnifierImageFilter: (");
    str->appendf("src: (%f,%f,%f,%f) ",
                 fSrcRect.fLeft, fSrcRect.fTop, fSrcRect.fRight, fSrcRect.fBottom);
    str->appendf("inset: %f", fInset);
    str->append(")");
}