C++ SkMatrix::getMaxScale方法代码示例

bool GrAADistanceFieldPathRenderer::canDrawPath(const GrDrawTarget* target,
                                                const GrPipelineBuilder* pipelineBuilder,
                                                const SkMatrix& viewMatrix,
                                                const SkPath& path,
                                                const GrStrokeInfo& stroke,
                                                bool antiAlias) const {
    
    // TODO: Support inverse fill
    // TODO: Support strokes
    if (!target->caps()->shaderCaps()->shaderDerivativeSupport() || !antiAlias 
        || path.isInverseFillType() || path.isVolatile() || !stroke.isFillStyle()) {
        return false;
    }

    // currently don't support perspective
    if (viewMatrix.hasPerspective()) {
        return false;
    }
    
    // only support paths smaller than 64x64, scaled to less than 256x256
    // the goal is to accelerate rendering of lots of small paths that may be scaling
    SkScalar maxScale = viewMatrix.getMaxScale();
    const SkRect& bounds = path.getBounds();
    SkScalar maxDim = SkMaxScalar(bounds.width(), bounds.height());
    return maxDim < 64.f && maxDim * maxScale < 256.f;
}

bool GrDistanceFieldTextContext::canDraw(const SkPaint& paint, const SkMatrix& viewMatrix) {
    // TODO: support perspective (need getMaxScale replacement)
    if (viewMatrix.hasPerspective()) {
        return false;
    }

    SkScalar maxScale = viewMatrix.getMaxScale();
    SkScalar scaledTextSize = maxScale*paint.getTextSize();
    // Scaling up beyond 2x yields undesireable artifacts
    if (scaledTextSize > 2*kLargeDFFontSize) {
        return false;
    }

    if (!fEnableDFRendering && !paint.isDistanceFieldTextTEMP() &&
        scaledTextSize < kLargeDFFontSize) {
        return false;
    }

    // rasterizers and mask filters modify alpha, which doesn't
    // translate well to distance
    if (paint.getRasterizer() || paint.getMaskFilter() ||
        !fContext->getTextTarget()->caps()->shaderDerivativeSupport()) {
        return false;
    }

    // TODO: add some stroking support
    if (paint.getStyle() != SkPaint::kFill_Style) {
        return false;
    }

    return true;
}

void GrTextUtils::InitDistanceFieldPaint(GrAtlasTextBlob* blob,
                                         SkPaint* skPaint,
                                         SkScalar* textRatio,
                                         const SkMatrix& viewMatrix) {
    // getMaxScale doesn't support perspective, so neither do we at the moment
    SkASSERT(!viewMatrix.hasPerspective());
    SkScalar maxScale = viewMatrix.getMaxScale();
    SkScalar textSize = skPaint->getTextSize();
    SkScalar scaledTextSize = textSize;
    // if we have non-unity scale, we need to choose our base text size
    // based on the SkPaint's text size multiplied by the max scale factor
    // TODO: do we need to do this if we're scaling down (i.e. maxScale < 1)?
    if (maxScale > 0 && !SkScalarNearlyEqual(maxScale, SK_Scalar1)) {
        scaledTextSize *= maxScale;
    }

    // We have three sizes of distance field text, and within each size 'bucket' there is a floor
    // and ceiling.  A scale outside of this range would require regenerating the distance fields
    SkScalar dfMaskScaleFloor;
    SkScalar dfMaskScaleCeil;
    if (scaledTextSize <= kSmallDFFontLimit) {
        dfMaskScaleFloor = kMinDFFontSize;
        dfMaskScaleCeil = kSmallDFFontLimit;
        *textRatio = textSize / kSmallDFFontSize;
        skPaint->setTextSize(SkIntToScalar(kSmallDFFontSize));
    } else if (scaledTextSize <= kMediumDFFontLimit) {
        dfMaskScaleFloor = kSmallDFFontLimit;
        dfMaskScaleCeil = kMediumDFFontLimit;
        *textRatio = textSize / kMediumDFFontSize;
        skPaint->setTextSize(SkIntToScalar(kMediumDFFontSize));
    } else {
        dfMaskScaleFloor = kMediumDFFontLimit;
        dfMaskScaleCeil = kLargeDFFontLimit;
        *textRatio = textSize / kLargeDFFontSize;
        skPaint->setTextSize(SkIntToScalar(kLargeDFFontSize));
    }

    // Because there can be multiple runs in the blob, we want the overall maxMinScale, and
    // minMaxScale to make regeneration decisions.  Specifically, we want the maximum minimum scale
    // we can tolerate before we'd drop to a lower mip size, and the minimum maximum scale we can
    // tolerate before we'd have to move to a large mip size.  When we actually test these values
    // we look at the delta in scale between the new viewmatrix and the old viewmatrix, and test
    // against these values to decide if we can reuse or not(ie, will a given scale change our mip
    // level)
    SkASSERT(dfMaskScaleFloor <= scaledTextSize && scaledTextSize <= dfMaskScaleCeil);
    blob->setMinAndMaxScale(dfMaskScaleFloor / scaledTextSize, dfMaskScaleCeil / scaledTextSize);

    skPaint->setLCDRenderText(false);
    skPaint->setAutohinted(false);
    skPaint->setHinting(SkPaint::kNormal_Hinting);
    skPaint->setSubpixelText(true);
}

// The general idea here is to, conceptually, start with the original polygon and slide
// the vertices along the bisectors until the first intersection. At that
// point two of the edges collapse and the process repeats on the new polygon.
// The polygon state is captured in the Ring class while the GrAAConvexTessellator
// controls the iteration. The CandidateVerts holds the formative points for the
// next ring.
bool GrAAConvexTessellator::tessellate(const SkMatrix& m, const SkPath& path) {
    if (!this->extractFromPath(m, path)) {
        return false;
    }

    SkScalar coverage = 1.0f;
    SkScalar scaleFactor = 0.0f;
    if (fStrokeWidth >= 0.0f) {
        SkASSERT(m.isSimilarity()); 
        scaleFactor = m.getMaxScale(); // x and y scale are the same
        SkScalar effectiveStrokeWidth = scaleFactor * fStrokeWidth;
        Ring outerStrokeRing;
        this->createOuterRing(fInitialRing, effectiveStrokeWidth / 2 - kAntialiasingRadius, 
                              coverage, &outerStrokeRing);
        outerStrokeRing.init(*this);
        Ring outerAARing;
        this->createOuterRing(outerStrokeRing, kAntialiasingRadius * 2, 0.0f, &outerAARing);
    } else {
        Ring outerAARing;
        this->createOuterRing(fInitialRing, kAntialiasingRadius, 0.0f, &outerAARing);
    }

    // the bisectors are only needed for the computation of the outer ring
    fBisectors.rewind();
    if (fStrokeWidth >= 0.0f && fInitialRing.numPts() > 2) {
        SkScalar effectiveStrokeWidth = scaleFactor * fStrokeWidth;
        Ring* insetStrokeRing;
        SkScalar strokeDepth = effectiveStrokeWidth / 2 - kAntialiasingRadius;
        if (this->createInsetRings(fInitialRing, 0.0f, coverage, strokeDepth, coverage, 
                             &insetStrokeRing)) {
            Ring* insetAARing;
            this->createInsetRings(*insetStrokeRing, strokeDepth, coverage, strokeDepth + 
                             kAntialiasingRadius * 2, 0.0f, &insetAARing);
        }
    } else {
        Ring* insetAARing;
        this->createInsetRings(fInitialRing, 0.0f, 0.5f, kAntialiasingRadius, 1.0f, &insetAARing);
    }

    SkDEBUGCODE(this->validate();)
    return true;

SkScalar GrPathUtils::scaleToleranceToSrc(SkScalar devTol,
                                          const SkMatrix& viewM,
                                          const SkRect& pathBounds) {
    // In order to tesselate the path we get a bound on how much the matrix can
    // scale when mapping to screen coordinates.
    SkScalar stretch = viewM.getMaxScale();
    SkScalar srcTol = devTol;

    if (stretch < 0) {
        // take worst case mapRadius amoung four corners.
        // (less than perfect)
        for (int i = 0; i < 4; ++i) {
            SkMatrix mat;
            mat.setTranslate((i % 2) ? pathBounds.fLeft : pathBounds.fRight,
                             (i < 2) ? pathBounds.fTop : pathBounds.fBottom);
            mat.postConcat(viewM);
            stretch = SkMaxScalar(stretch, mat.mapRadius(SK_Scalar1));
        }
    }
    return srcTol / stretch;
}

bool GrTextUtils::CanDrawAsDistanceFields(const SkPaint& skPaint, const SkMatrix& viewMatrix,
                                          const SkSurfaceProps& props, const GrShaderCaps& caps) {
    // TODO: support perspective (need getMaxScale replacement)
    if (viewMatrix.hasPerspective()) {
        return false;
    }

    SkScalar maxScale = viewMatrix.getMaxScale();
    SkScalar scaledTextSize = maxScale*skPaint.getTextSize();
    // Hinted text looks far better at small resolutions
    // Scaling up beyond 2x yields undesireable artifacts
    if (scaledTextSize < kMinDFFontSize ||
        scaledTextSize > kLargeDFFontLimit) {
        return false;
    }

    bool useDFT = props.isUseDeviceIndependentFonts();
#if SK_FORCE_DISTANCE_FIELD_TEXT
    useDFT = true;
#endif

    if (!useDFT && scaledTextSize < kLargeDFFontSize) {
        return false;
    }

    // rasterizers and mask filters modify alpha, which doesn't
    // translate well to distance
    if (skPaint.getRasterizer() || skPaint.getMaskFilter() || !caps.shaderDerivativeSupport()) {
        return false;
    }

    // TODO: add some stroking support
    if (skPaint.getStyle() != SkPaint::kFill_Style) {
        return false;
    }

    return true;
}

static void test_matrix_min_max_scale(skiatest::Reporter* reporter) {
    SkScalar scales[2];
    bool success;

    SkMatrix identity;
    identity.reset();
    REPORTER_ASSERT(reporter, SK_Scalar1 == identity.getMinScale());
    REPORTER_ASSERT(reporter, SK_Scalar1 == identity.getMaxScale());
    success = identity.getMinMaxScales(scales);
    REPORTER_ASSERT(reporter, success && SK_Scalar1 == scales[0] && SK_Scalar1 == scales[1]);

    SkMatrix scale;
    scale.setScale(SK_Scalar1 * 2, SK_Scalar1 * 4);
    REPORTER_ASSERT(reporter, SK_Scalar1 * 2 == scale.getMinScale());
    REPORTER_ASSERT(reporter, SK_Scalar1 * 4 == scale.getMaxScale());
    success = scale.getMinMaxScales(scales);
    REPORTER_ASSERT(reporter, success && SK_Scalar1 * 2 == scales[0] && SK_Scalar1 * 4 == scales[1]);

    SkMatrix rot90Scale;
    rot90Scale.setRotate(90 * SK_Scalar1);
    rot90Scale.postScale(SK_Scalar1 / 4, SK_Scalar1 / 2);
    REPORTER_ASSERT(reporter, SK_Scalar1 / 4 == rot90Scale.getMinScale());
    REPORTER_ASSERT(reporter, SK_Scalar1 / 2 == rot90Scale.getMaxScale());
    success = rot90Scale.getMinMaxScales(scales);
    REPORTER_ASSERT(reporter, success && SK_Scalar1 / 4  == scales[0] && SK_Scalar1 / 2 == scales[1]);

    SkMatrix rotate;
    rotate.setRotate(128 * SK_Scalar1);
    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SK_Scalar1, rotate.getMinScale(), SK_ScalarNearlyZero));
    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SK_Scalar1, rotate.getMaxScale(), SK_ScalarNearlyZero));
    success = rotate.getMinMaxScales(scales);
    REPORTER_ASSERT(reporter, success);
    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SK_Scalar1, scales[0], SK_ScalarNearlyZero));
    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SK_Scalar1, scales[1], SK_ScalarNearlyZero));

    SkMatrix translate;
    translate.setTranslate(10 * SK_Scalar1, -5 * SK_Scalar1);
    REPORTER_ASSERT(reporter, SK_Scalar1 == translate.getMinScale());
    REPORTER_ASSERT(reporter, SK_Scalar1 == translate.getMaxScale());
    success = translate.getMinMaxScales(scales);
    REPORTER_ASSERT(reporter, success && SK_Scalar1 == scales[0] && SK_Scalar1 == scales[1]);

    SkMatrix perspX;
    perspX.reset();
    perspX.setPerspX(SkScalarToPersp(SK_Scalar1 / 1000));
    REPORTER_ASSERT(reporter, -SK_Scalar1 == perspX.getMinScale());
    REPORTER_ASSERT(reporter, -SK_Scalar1 == perspX.getMaxScale());
    // Verify that getMinMaxScales() doesn't update the scales array on failure.
    scales[0] = -5;
    scales[1] = -5;
    success = perspX.getMinMaxScales(scales);
    REPORTER_ASSERT(reporter, !success && -5 * SK_Scalar1 == scales[0] && -5 * SK_Scalar1  == scales[1]);

    SkMatrix perspY;
    perspY.reset();
    perspY.setPerspY(SkScalarToPersp(-SK_Scalar1 / 500));
    REPORTER_ASSERT(reporter, -SK_Scalar1 == perspY.getMinScale());
    REPORTER_ASSERT(reporter, -SK_Scalar1 == perspY.getMaxScale());
    scales[0] = -5;
    scales[1] = -5;
    success = perspY.getMinMaxScales(scales);
    REPORTER_ASSERT(reporter, !success && -5 * SK_Scalar1 == scales[0] && -5 * SK_Scalar1  == scales[1]);

    SkMatrix baseMats[] = {scale, rot90Scale, rotate,
                           translate, perspX, perspY};
    SkMatrix mats[2*SK_ARRAY_COUNT(baseMats)];
    for (size_t i = 0; i < SK_ARRAY_COUNT(baseMats); ++i) {
        mats[i] = baseMats[i];
        bool invertable = mats[i].invert(&mats[i + SK_ARRAY_COUNT(baseMats)]);
        REPORTER_ASSERT(reporter, invertable);
    }
    SkRandom rand;
    for (int m = 0; m < 1000; ++m) {
        SkMatrix mat;
        mat.reset();
        for (int i = 0; i < 4; ++i) {
            int x = rand.nextU() % SK_ARRAY_COUNT(mats);
            mat.postConcat(mats[x]);
        }

        SkScalar minScale = mat.getMinScale();
        SkScalar maxScale = mat.getMaxScale();
        REPORTER_ASSERT(reporter, (minScale < 0) == (maxScale < 0));
        REPORTER_ASSERT(reporter, (maxScale < 0) == mat.hasPerspective());

        SkScalar scales[2];
        bool success = mat.getMinMaxScales(scales);
        REPORTER_ASSERT(reporter, success == !mat.hasPerspective());
        REPORTER_ASSERT(reporter, !success || (scales[0] == minScale && scales[1] == maxScale));

        if (mat.hasPerspective()) {
            m -= 1; // try another non-persp matrix
            continue;
        }

        // test a bunch of vectors. All should be scaled by between minScale and maxScale
        // (modulo some error) and we should find a vector that is scaled by almost each.
        static const SkScalar gVectorScaleTol = (105 * SK_Scalar1) / 100;
        static const SkScalar gCloseScaleTol = (97 * SK_Scalar1) / 100;
        SkScalar max = 0, min = SK_ScalarMax;
//.........这里部分代码省略.........

bool GrStencilAndCoverPathRenderer::onDrawPath(GrDrawTarget* target,
                                               GrPipelineBuilder* pipelineBuilder,
                                               GrColor color,
                                               const SkMatrix& viewMatrix,
                                               const SkPath& path,
                                               const GrStrokeInfo& stroke,
                                               bool antiAlias) {
    SkASSERT(!antiAlias);
    SkASSERT(!stroke.getStrokeRec().isHairlineStyle());
    SkASSERT(!stroke.isDashed());
    SkASSERT(pipelineBuilder->getStencil().isDisabled());

    SkAutoTUnref<GrPath> p(get_gr_path(fGpu, path, stroke.getStrokeRec()));

    if (path.isInverseFillType()) {
        GR_STATIC_CONST_SAME_STENCIL(kInvertedStencilPass,
            kZero_StencilOp,
            kZero_StencilOp,
            // We know our rect will hit pixels outside the clip and the user bits will be 0
            // outside the clip. So we can't just fill where the user bits are 0. We also need to
            // check that the clip bit is set.
            kEqualIfInClip_StencilFunc,
            0xffff,
            0x0000,
            0xffff);

        pipelineBuilder->setStencil(kInvertedStencilPass);

        // fake inverse with a stencil and cover
        SkAutoTUnref<GrPathProcessor> pp(GrPathProcessor::Create(GrColor_WHITE, viewMatrix));
        target->stencilPath(pipelineBuilder, pp, p, convert_skpath_filltype(path.getFillType()));

        SkMatrix invert = SkMatrix::I();
        SkRect bounds =
            SkRect::MakeLTRB(0, 0, SkIntToScalar(pipelineBuilder->getRenderTarget()->width()),
                             SkIntToScalar(pipelineBuilder->getRenderTarget()->height()));
        SkMatrix vmi;
        // mapRect through persp matrix may not be correct
        if (!viewMatrix.hasPerspective() && viewMatrix.invert(&vmi)) {
            vmi.mapRect(&bounds);
            // theoretically could set bloat = 0, instead leave it because of matrix inversion
            // precision.
            SkScalar bloat = viewMatrix.getMaxScale() * SK_ScalarHalf;
            bounds.outset(bloat, bloat);
        } else {
            if (!viewMatrix.invert(&invert)) {
                return false;
            }
        }
        const SkMatrix& viewM = viewMatrix.hasPerspective() ? SkMatrix::I() : viewMatrix;
        target->drawRect(pipelineBuilder, color, viewM, bounds, NULL, &invert);
    } else {
        GR_STATIC_CONST_SAME_STENCIL(kStencilPass,
            kZero_StencilOp,
            kZero_StencilOp,
            kNotEqual_StencilFunc,
            0xffff,
            0x0000,
            0xffff);

        pipelineBuilder->setStencil(kStencilPass);
        SkAutoTUnref<GrPathProcessor> pp(GrPathProcessor::Create(color, viewMatrix));
        target->drawPath(pipelineBuilder, pp, p, convert_skpath_filltype(path.getFillType()));
    }

    pipelineBuilder->stencil()->setDisabled();
    return true;
}

bool GrAtlasTextBlob::mustRegenerate(const SkPaint& paint,
                                     GrColor color, const SkMaskFilter::BlurRec& blurRec,
                                     const SkMatrix& viewMatrix, SkScalar x, SkScalar y) {
    // If we have LCD text then our canonical color will be set to transparent, in this case we have
    // to regenerate the blob on any color change
    // We use the grPaint to get any color filter effects
    if (fKey.fCanonicalColor == SK_ColorTRANSPARENT &&
        fPaintColor != color) {
        return true;
    }

    if (fInitialViewMatrix.hasPerspective() != viewMatrix.hasPerspective()) {
        return true;
    }

    if (fInitialViewMatrix.hasPerspective() && !fInitialViewMatrix.cheapEqualTo(viewMatrix)) {
        return true;
    }

    // We only cache one masked version
    if (fKey.fHasBlur &&
        (fBlurRec.fSigma != blurRec.fSigma ||
         fBlurRec.fStyle != blurRec.fStyle ||
         fBlurRec.fQuality != blurRec.fQuality)) {
        return true;
    }

    // Similarly, we only cache one version for each style
    if (fKey.fStyle != SkPaint::kFill_Style &&
        (fStrokeInfo.fFrameWidth != paint.getStrokeWidth() ||
         fStrokeInfo.fMiterLimit != paint.getStrokeMiter() ||
         fStrokeInfo.fJoin != paint.getStrokeJoin())) {
        return true;
    }

    // Mixed blobs must be regenerated.  We could probably figure out a way to do integer scrolls
    // for mixed blobs if this becomes an issue.
    if (this->hasBitmap() && this->hasDistanceField()) {
        // Identical viewmatrices and we can reuse in all cases
        if (fInitialViewMatrix.cheapEqualTo(viewMatrix) && x == fInitialX && y == fInitialY) {
            return false;
        }
        return true;
    }

    if (this->hasBitmap()) {
        if (fInitialViewMatrix.getScaleX() != viewMatrix.getScaleX() ||
            fInitialViewMatrix.getScaleY() != viewMatrix.getScaleY() ||
            fInitialViewMatrix.getSkewX() != viewMatrix.getSkewX() ||
            fInitialViewMatrix.getSkewY() != viewMatrix.getSkewY()) {
            return true;
        }

        // We can update the positions in the cachedtextblobs without regenerating the whole blob,
        // but only for integer translations.
        // This cool bit of math will determine the necessary translation to apply to the already
        // generated vertex coordinates to move them to the correct position
        SkScalar transX = viewMatrix.getTranslateX() +
                          viewMatrix.getScaleX() * (x - fInitialX) +
                          viewMatrix.getSkewX() * (y - fInitialY) -
                          fInitialViewMatrix.getTranslateX();
        SkScalar transY = viewMatrix.getTranslateY() +
                          viewMatrix.getSkewY() * (x - fInitialX) +
                          viewMatrix.getScaleY() * (y - fInitialY) -
                          fInitialViewMatrix.getTranslateY();
        if (!SkScalarIsInt(transX) || !SkScalarIsInt(transY)) {
            return true;
        }
    } else if (this->hasDistanceField()) {
        // A scale outside of [blob.fMaxMinScale, blob.fMinMaxScale] would result in a different
        // distance field being generated, so we have to regenerate in those cases
        SkScalar newMaxScale = viewMatrix.getMaxScale();
        SkScalar oldMaxScale = fInitialViewMatrix.getMaxScale();
        SkScalar scaleAdjust = newMaxScale / oldMaxScale;
        if (scaleAdjust < fMaxMinScale || scaleAdjust > fMinMaxScale) {
            return true;
        }
    }

    // It is possible that a blob has neither distanceField nor bitmaptext.  This is in the case
    // when all of the runs inside the blob are drawn as paths.  In this case, we always regenerate
    // the blob anyways at flush time, so no need to regenerate explicitly
    return false;
}