libs/hwui/VectorDrawable.cpp

/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "VectorDrawable.h"

#include "PathParser.h"
#include "SkImageInfo.h"
#include <utils/Log.h>
#include "utils/Macros.h"
#include "utils/VectorDrawableUtils.h"

#include <math.h>
#include <string.h>

namespace android {
namespace uirenderer {
namespace VectorDrawable {

const int Tree::MAX_CACHED_BITMAP_SIZE = 2048;

void Path::draw(Canvas* outCanvas, const SkMatrix& groupStackedMatrix, float scaleX, float scaleY) {
    float matrixScale = getMatrixScale(groupStackedMatrix);
    if (matrixScale == 0) {
        // When either x or y is scaled to 0, we don't need to draw anything.
        return;
    }

    const SkPath updatedPath = getUpdatedPath();
    SkMatrix pathMatrix(groupStackedMatrix);
    pathMatrix.postScale(scaleX, scaleY);

    //TODO: try apply the path matrix to the canvas instead of creating a new path.
    SkPath renderPath;
    renderPath.reset();
    renderPath.addPath(updatedPath, pathMatrix);

    float minScale = fmin(scaleX, scaleY);
    float strokeScale = minScale * matrixScale;
    drawPath(outCanvas, renderPath, strokeScale);
}

void Path::setPathData(const Data& data) {
    if (mData == data) {
        return;
    }
    // Updates the path data. Note that we don't generate a new Skia path right away
    // because there are cases where the animation is changing the path data, but the view
    // that hosts the VD has gone off screen, in which case we won't even draw. So we
    // postpone the Skia path generation to the draw time.
    mData = data;
    mSkPathDirty = true;
}

void Path::dump() {
    ALOGD("Path: %s has %zu points", mName.c_str(), mData.points.size());
}

float Path::getMatrixScale(const SkMatrix& groupStackedMatrix) {
    // Given unit vectors A = (0, 1) and B = (1, 0).
    // After matrix mapping, we got A' and B'. Let theta = the angel b/t A' and B'.
    // Therefore, the final scale we want is min(|A'| * sin(theta), |B'| * sin(theta)),
    // which is (|A'| * |B'| * sin(theta)) / max (|A'|, |B'|);
    // If  max (|A'|, |B'|) = 0, that means either x or y has a scale of 0.
    //
    // For non-skew case, which is most of the cases, matrix scale is computing exactly the
    // scale on x and y axis, and take the minimal of these two.
    // For skew case, an unit square will mapped to a parallelogram. And this function will
    // return the minimal height of the 2 bases.
    SkVector skVectors[2];
    skVectors[0].set(0, 1);
    skVectors[1].set(1, 0);
    groupStackedMatrix.mapVectors(skVectors, 2);
    float scaleX = hypotf(skVectors[0].fX, skVectors[0].fY);
    float scaleY = hypotf(skVectors[1].fX, skVectors[1].fY);
    float crossProduct = skVectors[0].cross(skVectors[1]);
    float maxScale = fmax(scaleX, scaleY);

    float matrixScale = 0;
    if (maxScale > 0) {
        matrixScale = fabs(crossProduct) / maxScale;
    }
    return matrixScale;
}
Path::Path(const char* pathStr, size_t strLength) {
    PathParser::ParseResult result;
    PathParser::getPathDataFromString(&mData, &result, pathStr, strLength);
    if (!result.failureOccurred) {
        VectorDrawableUtils::verbsToPath(&mSkPath, mData);
    }
}

Path::Path(const Data& data) {
    mData = data;
    // Now we need to construct a path
    VectorDrawableUtils::verbsToPath(&mSkPath, data);
}

Path::Path(const Path& path) : Node(path) {
    mData = path.mData;
    VectorDrawableUtils::verbsToPath(&mSkPath, mData);
}

bool Path::canMorph(const Data& morphTo) {
    return VectorDrawableUtils::canMorph(mData, morphTo);
}

bool Path::canMorph(const Path& path) {
    return canMorph(path.mData);
}

const SkPath& Path::getUpdatedPath() {
    if (mSkPathDirty) {
        mSkPath.reset();
        VectorDrawableUtils::verbsToPath(&mSkPath, mData);
        mSkPathDirty = false;
    }
    return mSkPath;
}

void Path::setPath(const char* pathStr, size_t strLength) {
    PathParser::ParseResult result;
    mSkPathDirty = true;
    PathParser::getPathDataFromString(&mData, &result, pathStr, strLength);
}

FullPath::FullPath(const FullPath& path) : Path(path) {
    mStrokeWidth = path.mStrokeWidth;
    mStrokeColor = path.mStrokeColor;
    mStrokeAlpha = path.mStrokeAlpha;
    mFillColor = path.mFillColor;
    mFillAlpha = path.mFillAlpha;
    mTrimPathStart = path.mTrimPathStart;
    mTrimPathEnd = path.mTrimPathEnd;
    mTrimPathOffset = path.mTrimPathOffset;
    mStrokeMiterLimit = path.mStrokeMiterLimit;
    mStrokeLineCap = path.mStrokeLineCap;
    mStrokeLineJoin = path.mStrokeLineJoin;
}

const SkPath& FullPath::getUpdatedPath() {
    if (!mSkPathDirty && !mTrimDirty) {
        return mTrimmedSkPath;
    }
    Path::getUpdatedPath();
    if (mTrimPathStart != 0.0f || mTrimPathEnd != 1.0f) {
        applyTrim();
        return mTrimmedSkPath;
    } else {
        return mSkPath;
    }
}

void FullPath::updateProperties(float strokeWidth, SkColor strokeColor, float strokeAlpha,
        SkColor fillColor, float fillAlpha, float trimPathStart, float trimPathEnd,
        float trimPathOffset, float strokeMiterLimit, int strokeLineCap, int strokeLineJoin) {
    mStrokeWidth = strokeWidth;
    mStrokeColor = strokeColor;
    mStrokeAlpha = strokeAlpha;
    mFillColor = fillColor;
    mFillAlpha = fillAlpha;
    mStrokeMiterLimit = strokeMiterLimit;
    mStrokeLineCap = SkPaint::Cap(strokeLineCap);
    mStrokeLineJoin = SkPaint::Join(strokeLineJoin);

    // If any trim property changes, mark trim dirty and update the trim path
    setTrimPathStart(trimPathStart);
    setTrimPathEnd(trimPathEnd);
    setTrimPathOffset(trimPathOffset);
}

inline SkColor applyAlpha(SkColor color, float alpha) {
    int alphaBytes = SkColorGetA(color);
    return SkColorSetA(color, alphaBytes * alpha);
}

void FullPath::drawPath(Canvas* outCanvas, const SkPath& renderPath, float strokeScale){
    // Draw path's fill, if fill color isn't transparent.
    if (mFillColor != SK_ColorTRANSPARENT) {
        mPaint.setStyle(SkPaint::Style::kFill_Style);
        mPaint.setAntiAlias(true);
        mPaint.setColor(applyAlpha(mFillColor, mFillAlpha));
        outCanvas->drawPath(renderPath, mPaint);
    }
    // Draw path's stroke, if stroke color isn't transparent
    if (mStrokeColor != SK_ColorTRANSPARENT) {
        mPaint.setStyle(SkPaint::Style::kStroke_Style);
        mPaint.setAntiAlias(true);
        mPaint.setStrokeJoin(mStrokeLineJoin);
        mPaint.setStrokeCap(mStrokeLineCap);
        mPaint.setStrokeMiter(mStrokeMiterLimit);
        mPaint.setColor(applyAlpha(mStrokeColor, mStrokeAlpha));
        mPaint.setStrokeWidth(mStrokeWidth * strokeScale);
        outCanvas->drawPath(renderPath, mPaint);
    }
}

/**
 * Applies trimming to the specified path.
 */
void FullPath::applyTrim() {
    if (mTrimPathStart == 0.0f && mTrimPathEnd == 1.0f) {
        // No trimming necessary.
        return;
    }
    SkPathMeasure measure(mSkPath, false);
    float len = SkScalarToFloat(measure.getLength());
    float start = len * fmod((mTrimPathStart + mTrimPathOffset), 1.0f);
    float end = len * fmod((mTrimPathEnd + mTrimPathOffset), 1.0f);

    mTrimmedSkPath.reset();
    if (start > end) {
        measure.getSegment(start, len, &mTrimmedSkPath, true);
        measure.getSegment(0, end, &mTrimmedSkPath, true);
    } else {
        measure.getSegment(start, end, &mTrimmedSkPath, true);
    }
    mTrimDirty = false;
}

inline int putData(int8_t* outBytes, int startIndex, float value) {
    int size = sizeof(float);
    memcpy(&outBytes[startIndex], &value, size);
    return size;
}

inline int putData(int8_t* outBytes, int startIndex, int value) {
    int size = sizeof(int);
    memcpy(&outBytes[startIndex], &value, size);
    return size;
}

struct FullPathProperties {
    // TODO: Consider storing full path properties in this struct instead of the fields.
    float strokeWidth;
    SkColor strokeColor;
    float strokeAlpha;
    SkColor fillColor;
    float fillAlpha;
    float trimPathStart;
    float trimPathEnd;
    float trimPathOffset;
    int32_t strokeLineCap;
    int32_t strokeLineJoin;
    float strokeMiterLimit;
};

REQUIRE_COMPATIBLE_LAYOUT(FullPathProperties);

static_assert(sizeof(float) == sizeof(int32_t), "float is not the same size as int32_t");
static_assert(sizeof(SkColor) == sizeof(int32_t), "SkColor is not the same size as int32_t");

bool FullPath::getProperties(int8_t* outProperties, int length) {
    int propertyDataSize = sizeof(FullPathProperties);
    if (length != propertyDataSize) {
        LOG_ALWAYS_FATAL("Properties needs exactly %d bytes, a byte array of size %d is provided",
                propertyDataSize, length);
        return false;
    }
    // TODO: consider replacing the property fields with a FullPathProperties struct.
    FullPathProperties properties;
    properties.strokeWidth = mStrokeWidth;
    properties.strokeColor = mStrokeColor;
    properties.strokeAlpha = mStrokeAlpha;
    properties.fillColor = mFillColor;
    properties.fillAlpha = mFillAlpha;
    properties.trimPathStart = mTrimPathStart;
    properties.trimPathEnd = mTrimPathEnd;
    properties.trimPathOffset = mTrimPathOffset;
    properties.strokeLineCap = mStrokeLineCap;
    properties.strokeLineJoin = mStrokeLineJoin;
    properties.strokeMiterLimit = mStrokeMiterLimit;

    memcpy(outProperties, &properties, length);
    return true;
}

void ClipPath::drawPath(Canvas* outCanvas, const SkPath& renderPath,
        float strokeScale){
    outCanvas->clipPath(&renderPath, SkRegion::kIntersect_Op);
}

Group::Group(const Group& group) : Node(group) {
    mRotate = group.mRotate;
    mPivotX = group.mPivotX;
    mPivotY = group.mPivotY;
    mScaleX = group.mScaleX;
    mScaleY = group.mScaleY;
    mTranslateX = group.mTranslateX;
    mTranslateY = group.mTranslateY;
}

void Group::draw(Canvas* outCanvas, const SkMatrix& currentMatrix, float scaleX,
        float scaleY) {
    // TODO: Try apply the matrix to the canvas instead of passing it down the tree

    // Calculate current group's matrix by preConcat the parent's and
    // and the current one on the top of the stack.
    // Basically the Mfinal = Mviewport * M0 * M1 * M2;
    // Mi the local matrix at level i of the group tree.
    SkMatrix stackedMatrix;
    getLocalMatrix(&stackedMatrix);
    stackedMatrix.postConcat(currentMatrix);

    // Save the current clip information, which is local to this group.
    outCanvas->save(SkCanvas::kMatrixClip_SaveFlag);
    // Draw the group tree in the same order as the XML file.
    for (Node* child : mChildren) {
        child->draw(outCanvas, stackedMatrix, scaleX, scaleY);
    }
    // Restore the previous clip information.
    outCanvas->restore();
}

void Group::dump() {
    ALOGD("Group %s has %zu children: ", mName.c_str(), mChildren.size());
    for (size_t i = 0; i < mChildren.size(); i++) {
        mChildren[i]->dump();
    }
}

void Group::updateLocalMatrix(float rotate, float pivotX, float pivotY,
        float scaleX, float scaleY, float translateX, float translateY) {
    setRotation(rotate);
    setPivotX(pivotX);
    setPivotY(pivotY);
    setScaleX(scaleX);
    setScaleY(scaleY);
    setTranslateX(translateX);
    setTranslateY(translateY);
}

void Group::getLocalMatrix(SkMatrix* outMatrix) {
    outMatrix->reset();
    // TODO: use rotate(mRotate, mPivotX, mPivotY) and scale with pivot point, instead of
    // translating to pivot for rotating and scaling, then translating back.
    outMatrix->postTranslate(-mPivotX, -mPivotY);
    outMatrix->postScale(mScaleX, mScaleY);
    outMatrix->postRotate(mRotate, 0, 0);
    outMatrix->postTranslate(mTranslateX + mPivotX, mTranslateY + mPivotY);
}

void Group::addChild(Node* child) {
    mChildren.push_back(child);
}

bool Group::getProperties(float* outProperties, int length) {
    int propertyCount = static_cast<int>(Property::Count);
    if (length != propertyCount) {
        LOG_ALWAYS_FATAL("Properties needs exactly %d bytes, a byte array of size %d is provided",
                propertyCount, length);
        return false;
    }
    for (int i = 0; i < propertyCount; i++) {
        Property currentProperty = static_cast<Property>(i);
        switch (currentProperty) {
        case Property::Rotate_Property:
            outProperties[i] = mRotate;
            break;
        case Property::PivotX_Property:
            outProperties[i] = mPivotX;
            break;
        case Property::PivotY_Property:
            outProperties[i] = mPivotY;
            break;
        case Property::ScaleX_Property:
            outProperties[i] = mScaleX;
            break;
        case Property::ScaleY_Property:
            outProperties[i] = mScaleY;
            break;
        case Property::TranslateX_Property:
            outProperties[i] = mTranslateX;
            break;
        case Property::TranslateY_Property:
            outProperties[i] = mTranslateY;
            break;
        default:
            LOG_ALWAYS_FATAL("Invalid input index: %d", i);
            return false;
        }
    }
    return true;
}

void Tree::draw(Canvas* outCanvas, SkColorFilter* colorFilter,
        const SkRect& bounds, bool needsMirroring, bool canReuseCache) {
    // The imageView can scale the canvas in different ways, in order to
    // avoid blurry scaling, we have to draw into a bitmap with exact pixel
    // size first. This bitmap size is determined by the bounds and the
    // canvas scale.
    outCanvas->getMatrix(&mCanvasMatrix);
    mBounds = bounds;
    int scaledWidth = (int) (mBounds.width() * mCanvasMatrix.getScaleX());
    int scaledHeight = (int) (mBounds.height() * mCanvasMatrix.getScaleY());
    scaledWidth = std::min(Tree::MAX_CACHED_BITMAP_SIZE, scaledWidth);
    scaledHeight = std::min(Tree::MAX_CACHED_BITMAP_SIZE, scaledHeight);

    if (scaledWidth <= 0 || scaledHeight <= 0) {
        return;
    }

    int saveCount = outCanvas->save(SkCanvas::SaveFlags::kMatrixClip_SaveFlag);
    outCanvas->translate(mBounds.fLeft, mBounds.fTop);

    // Handle RTL mirroring.
    if (needsMirroring) {
        outCanvas->translate(mBounds.width(), 0);
        outCanvas->scale(-1.0f, 1.0f);
    }

    // At this point, canvas has been translated to the right position.
    // And we use this bound for the destination rect for the drawBitmap, so
    // we offset to (0, 0);
    mBounds.offsetTo(0, 0);

    createCachedBitmapIfNeeded(scaledWidth, scaledHeight);
    if (!mAllowCaching) {
        updateCachedBitmap(scaledWidth, scaledHeight);
    } else {
        if (!canReuseCache || mCacheDirty) {
            updateCachedBitmap(scaledWidth, scaledHeight);
        }
    }
    drawCachedBitmapWithRootAlpha(outCanvas, colorFilter, mBounds);

    outCanvas->restoreToCount(saveCount);
}

void Tree::drawCachedBitmapWithRootAlpha(Canvas* outCanvas, SkColorFilter* filter,
        const SkRect& originalBounds) {
    SkPaint* paint;
    if (mRootAlpha == 1.0f && filter == NULL) {
        paint = NULL;
    } else {
        mPaint.setFilterQuality(kLow_SkFilterQuality);
        mPaint.setAlpha(mRootAlpha * 255);
        mPaint.setColorFilter(filter);
        paint = &mPaint;
    }
    outCanvas->drawBitmap(mCachedBitmap, 0, 0, mCachedBitmap.width(), mCachedBitmap.height(),
            originalBounds.fLeft, originalBounds.fTop, originalBounds.fRight,
            originalBounds.fBottom, paint);
}

void Tree::updateCachedBitmap(int width, int height) {
    mCachedBitmap.eraseColor(SK_ColorTRANSPARENT);
    Canvas* outCanvas = Canvas::create_canvas(mCachedBitmap);
    float scaleX = width / mViewportWidth;
    float scaleY = height / mViewportHeight;
    mRootNode->draw(outCanvas, SkMatrix::I(), scaleX, scaleY);
    mCacheDirty = false;
}

void Tree::createCachedBitmapIfNeeded(int width, int height) {
    if (!canReuseBitmap(width, height)) {
        SkImageInfo info = SkImageInfo::Make(width, height,
                kN32_SkColorType, kPremul_SkAlphaType);
        mCachedBitmap.setInfo(info);
        // TODO: Count the bitmap cache against app's java heap
        mCachedBitmap.allocPixels(info);
        mCacheDirty = true;
    }
}

bool Tree::canReuseBitmap(int width, int height) {
    return width == mCachedBitmap.width() && height == mCachedBitmap.height();
}

}; // namespace VectorDrawable

}; // namespace uirenderer
}; // namespace android