Merge "Improve comparison of fractions" am: 0517cd14

    if (!matrix.rectStaysRect()) return true;

    SkRect dstDevRect = matrix.mapRect(dstRect);

    float dstW, dstH;

    bool requiresIntegerTranslate = false;

    if (MathUtils::isZero(matrix.getScaleX()) && MathUtils::isZero(matrix.getScaleY())) {

        // Has a 90 or 270 degree rotation, although total matrix may also have scale factors

        // in m10 and m01. Those scalings are automatically handled by mapRect so comparing

        // dimensions is sufficient, but swap width and height comparison.

        dstW = dstDevRect.height();

        dstH = dstDevRect.width();

        requiresIntegerTranslate = true;

    } else {

        // Handle H/V flips or 180 rotation matrices. Axes may have been mirrored, but

        // dimensions are still safe to compare directly.

        dstW = dstDevRect.width();

        dstH = dstDevRect.height();

        requiresIntegerTranslate =

                matrix.getScaleX() < -NON_ZERO_EPSILON || matrix.getScaleY() < -NON_ZERO_EPSILON;

    }

    if (!(MathUtils::areEqual(dstW, srcRect.width()) &&

          MathUtils::areEqual(dstH, srcRect.height()))) {

        return true;

    }

    if (requiresIntegerTranslate) {

    // Device rect and source rect should be integer aligned to ensure there's no difference

    // in how nearest-neighbor sampling is resolved.

    return !(isIntegerAligned(srcRect.x()) &&

             isIntegerAligned(srcRect.y()) &&

             isIntegerAligned(dstDevRect.x()) &&

             isIntegerAligned(dstDevRect.y()));

    } else {

        // As long as src and device rects are translated by the same fractional amount,

        // filtering won't be needed

        return !(MathUtils::areEqual(SkScalarFraction(srcRect.x()),

                                     SkScalarFraction(dstDevRect.x())) &&

                 MathUtils::areEqual(SkScalarFraction(srcRect.y()),

                                     SkScalarFraction(dstDevRect.y())));

    }

}

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