Merge "Apply texture matrix to the layer canvas"

bool LayerDrawable::DrawLayer(GrContext* context, SkCanvas* canvas, Layer* layer) {

    // transform the matrix based on the layer

    int saveCount = -1;

    if (!layer->getTransform().isIdentity()) {

        saveCount = canvas->save();

        SkMatrix transform;

        layer->getTransform().copyTo(transform);

        canvas->concat(transform);

    }

    SkMatrix layerTransform;

    layer->getTransform().copyTo(layerTransform);

    sk_sp<SkImage> layerImage;

    int layerWidth = layer->getWidth();

    int layerHeight = layer->getHeight();

    if (layer->getApi() == Layer::Api::OpenGL) {

        GlLayer* glLayer = static_cast<GlLayer*>(layer);

        GrGLTextureInfo externalTexture;

        externalTexture.fTarget = glLayer->getRenderTarget();

        externalTexture.fID = glLayer->getTextureId();

        GrBackendTexture backendTexture(glLayer->getWidth(), glLayer->getHeight(),

                kRGBA_8888_GrPixelConfig, externalTexture);

        GrBackendTexture backendTexture(layerWidth, layerHeight, kRGBA_8888_GrPixelConfig,

                externalTexture);

        layerImage = SkImage::MakeFromTexture(context, backendTexture, kTopLeft_GrSurfaceOrigin,

                kPremul_SkAlphaType, nullptr);

    } else {

    }

    if (layerImage) {

        SkMatrix textureMatrix;

        layer->getTexTransform().copyTo(textureMatrix);

        //TODO: after skia bug https://bugs.chromium.org/p/skia/issues/detail?id=7075 is fixed

        // use bottom left origin and remove flipV and invert transformations.

        SkMatrix flipV;

        flipV.setAll(1, 0, 0, 0, -1, 1, 0, 0, 1);

        textureMatrix.preConcat(flipV);

        textureMatrix.preScale(1.0f/layerWidth, 1.0f/layerHeight);

        textureMatrix.postScale(layerWidth, layerHeight);

        SkMatrix textureMatrixInv;

        if (!textureMatrix.invert(&textureMatrixInv)) {

            textureMatrixInv = textureMatrix;

        }

        SkMatrix matrix = SkMatrix::Concat(textureMatrixInv, layerTransform);

        SkPaint paint;

        paint.setAlpha(layer->getAlpha());

        paint.setBlendMode(layer->getMode());

        paint.setColorFilter(sk_ref_sp(layer->getColorFilter()));

        canvas->drawImage(layerImage, 0, 0, &paint);

    }

    // restore the original matrix

    if (saveCount >= 0) {

        canvas->restoreToCount(saveCount);

        // draw image with a shader to avoid save/restore of the matrix

        paint.setShader(layerImage->makeShader(&matrix));

        canvas->drawRect(SkRect::MakeWH(layerWidth, layerHeight), paint);

    }

    return layerImage;