src/core/SkDraw.cpp

/*
 * Copyright 2006 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 "include/core/SkBitmap.h"
#include "include/core/SkColorType.h"
#include "include/core/SkMatrix.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPixmap.h"
#include "include/core/SkPoint.h"
#include "include/core/SkRect.h"
#include "include/core/SkRegion.h"
#include "include/core/SkScalar.h"
#include "include/core/SkTileMode.h"
#include "include/private/base/SkAssert.h"
#include "include/private/base/SkDebug.h"
#include "include/private/base/SkFixed.h"
#include "include/private/base/SkFloatingPoint.h"
#include "include/private/base/SkTemplates.h"
#include "include/private/base/SkTo.h"
#include "src/base/SkArenaAlloc.h"
#include "src/base/SkTLazy.h"
#include "src/core/SkAutoBlitterChoose.h"
#include "src/core/SkBlitter.h"
#include "src/core/SkDraw.h"
#include "src/core/SkImageInfoPriv.h"
#include "src/core/SkImagePriv.h"
#include "src/core/SkMatrixUtils.h"
#include "src/core/SkRasterClip.h"
#include "src/core/SkRectPriv.h"
#include "src/core/SkScan.h"

#if defined(SK_SUPPORT_LEGACY_ALPHA_BITMAP_AS_COVERAGE)
#include "src/core/SkMaskFilterBase.h"
#endif

using namespace skia_private;

static SkPaint make_paint_with_image(const SkPaint& origPaint, const SkBitmap& bitmap,
                                     const SkSamplingOptions& sampling,
                                     SkMatrix* matrix = nullptr) {
    SkPaint paint(origPaint);
    paint.setShader(SkMakeBitmapShaderForPaint(origPaint, bitmap, SkTileMode::kClamp,
                                               SkTileMode::kClamp, sampling, matrix,
                                               kNever_SkCopyPixelsMode));
    return paint;
}

SkDraw::SkDraw() {
    fBlitterChooser = SkBlitter::Choose;
}

struct PtProcRec {
    SkCanvas::PointMode fMode;
    const SkPaint*  fPaint;
    const SkRegion* fClip;
    const SkRasterClip* fRC;

    // computed values
    SkRect   fClipBounds;
    SkScalar fRadius;

    typedef void (*Proc)(const PtProcRec&, const SkPoint devPts[], int count,
                         SkBlitter*);

    bool init(SkCanvas::PointMode, const SkPaint&, const SkMatrix* matrix,
              const SkRasterClip*);
    Proc chooseProc(SkBlitter** blitter);

private:
    SkAAClipBlitterWrapper fWrapper;
};

static void bw_pt_hair_proc(const PtProcRec& rec, const SkPoint devPts[],
                            int count, SkBlitter* blitter) {
    for (int i = 0; i < count; i++) {
        int x = SkScalarFloorToInt(devPts[i].fX);
        int y = SkScalarFloorToInt(devPts[i].fY);
        if (rec.fClip->contains(x, y)) {
            blitter->blitH(x, y, 1);
        }
    }
}

static void bw_line_hair_proc(const PtProcRec& rec, const SkPoint devPts[],
                              int count, SkBlitter* blitter) {
    for (int i = 0; i < count; i += 2) {
        SkScan::HairLine(&devPts[i], 2, *rec.fRC, blitter);
    }
}

static void bw_poly_hair_proc(const PtProcRec& rec, const SkPoint devPts[],
                              int count, SkBlitter* blitter) {
    SkScan::HairLine(devPts, count, *rec.fRC, blitter);
}

// aa versions

static void aa_line_hair_proc(const PtProcRec& rec, const SkPoint devPts[],
                              int count, SkBlitter* blitter) {
    for (int i = 0; i < count; i += 2) {
        SkScan::AntiHairLine(&devPts[i], 2, *rec.fRC, blitter);
    }
}

static void aa_poly_hair_proc(const PtProcRec& rec, const SkPoint devPts[],
                              int count, SkBlitter* blitter) {
    SkScan::AntiHairLine(devPts, count, *rec.fRC, blitter);
}

// square procs (strokeWidth > 0 but matrix is square-scale (sx == sy)

static SkRect make_square_rad(SkPoint center, SkScalar radius) {
    return {
        center.fX - radius, center.fY - radius,
        center.fX + radius, center.fY + radius
    };
}

static SkXRect make_xrect(const SkRect& r) {
    SkASSERT(SkRectPriv::FitsInFixed(r));
    return {
        SkScalarToFixed(r.fLeft), SkScalarToFixed(r.fTop),
        SkScalarToFixed(r.fRight), SkScalarToFixed(r.fBottom)
    };
}

static void bw_square_proc(const PtProcRec& rec, const SkPoint devPts[],
                           int count, SkBlitter* blitter) {
    for (int i = 0; i < count; i++) {
        SkRect r = make_square_rad(devPts[i], rec.fRadius);
        if (r.intersect(rec.fClipBounds)) {
            SkScan::FillXRect(make_xrect(r), *rec.fRC, blitter);
        }
    }
}

static void aa_square_proc(const PtProcRec& rec, const SkPoint devPts[],
                           int count, SkBlitter* blitter) {
    for (int i = 0; i < count; i++) {
        SkRect r = make_square_rad(devPts[i], rec.fRadius);
        if (r.intersect(rec.fClipBounds)) {
            SkScan::AntiFillXRect(make_xrect(r), *rec.fRC, blitter);
        }
    }
}

// If this returns true, then chooseProc() must return a valid proc
bool PtProcRec::init(SkCanvas::PointMode mode, const SkPaint& paint,
                     const SkMatrix* matrix, const SkRasterClip* rc) {
    if ((unsigned)mode > (unsigned)SkCanvas::kPolygon_PointMode) {
        return false;
    }
    if (paint.getPathEffect() || paint.getMaskFilter()) {
        return false;
    }
    SkScalar width = paint.getStrokeWidth();
    SkScalar radius = -1;   // sentinel value, a "valid" value must be > 0

    if (0 == width) {
        radius = 0.5f;
    } else if (paint.getStrokeCap() != SkPaint::kRound_Cap &&
               matrix->isScaleTranslate() && SkCanvas::kPoints_PointMode == mode) {
        SkScalar sx = matrix->get(SkMatrix::kMScaleX);
        SkScalar sy = matrix->get(SkMatrix::kMScaleY);
        if (SkScalarNearlyZero(sx - sy)) {
            radius = SkScalarHalf(width * SkScalarAbs(sx));
        }
    }
    if (radius > 0) {
        SkRect clipBounds = SkRect::Make(rc->getBounds());
        // if we return true, the caller may assume that the constructed shapes can be represented
        // using SkFixed (after clipping), so we preflight that here.
        if (!SkRectPriv::FitsInFixed(clipBounds)) {
            return false;
        }
        fMode = mode;
        fPaint = &paint;
        fClip = nullptr;
        fRC = rc;
        fClipBounds = clipBounds;
        fRadius = radius;
        return true;
    }
    return false;
}

PtProcRec::Proc PtProcRec::chooseProc(SkBlitter** blitterPtr) {
    Proc proc = nullptr;

    SkBlitter* blitter = *blitterPtr;
    if (fRC->isBW()) {
        fClip = &fRC->bwRgn();
    } else {
        fWrapper.init(*fRC, blitter);
        fClip = &fWrapper.getRgn();
        blitter = fWrapper.getBlitter();
        *blitterPtr = blitter;
    }

    // for our arrays
    SkASSERT(0 == SkCanvas::kPoints_PointMode);
    SkASSERT(1 == SkCanvas::kLines_PointMode);
    SkASSERT(2 == SkCanvas::kPolygon_PointMode);
    SkASSERT((unsigned)fMode <= (unsigned)SkCanvas::kPolygon_PointMode);

    if (fPaint->isAntiAlias()) {
        if (0 == fPaint->getStrokeWidth()) {
            static const Proc gAAProcs[] = {
                aa_square_proc, aa_line_hair_proc, aa_poly_hair_proc
            };
            proc = gAAProcs[fMode];
        } else if (fPaint->getStrokeCap() != SkPaint::kRound_Cap) {
            SkASSERT(SkCanvas::kPoints_PointMode == fMode);
            proc = aa_square_proc;
        }
    } else {    // BW
        if (fRadius <= 0.5f) {    // small radii and hairline
            static const Proc gBWProcs[] = {
                bw_pt_hair_proc, bw_line_hair_proc, bw_poly_hair_proc
            };
            proc = gBWProcs[fMode];
        } else {
            proc = bw_square_proc;
        }
    }
    return proc;
}

// each of these costs 8-bytes of stack space, so don't make it too large
// must be even for lines/polygon to work
#define MAX_DEV_PTS     32

void SkDraw::drawPoints(SkCanvas::PointMode mode, size_t count,
                        const SkPoint pts[], const SkPaint& paint,
                        SkDevice* device) const {
    // if we're in lines mode, force count to be even
    if (SkCanvas::kLines_PointMode == mode) {
        count &= ~(size_t)1;
    }

    SkASSERT(pts != nullptr);
    SkDEBUGCODE(this->validate();)

     // nothing to draw
    if (!count || fRC->isEmpty()) {
        return;
    }

    PtProcRec rec;
    if (!device && rec.init(mode, paint, fCTM, fRC)) {
        SkAutoBlitterChoose blitter(*this, nullptr, paint);

        SkPoint             devPts[MAX_DEV_PTS];
        SkBlitter*          bltr = blitter.get();
        PtProcRec::Proc     proc = rec.chooseProc(&bltr);
        // we have to back up subsequent passes if we're in polygon mode
        const size_t backup = (SkCanvas::kPolygon_PointMode == mode);

        do {
            int n = SkToInt(count);
            if (n > MAX_DEV_PTS) {
                n = MAX_DEV_PTS;
            }
            fCTM->mapPoints(devPts, pts, n);
            if (!SkIsFinite(&devPts[0].fX, n * 2)) {
                return;
            }
            proc(rec, devPts, n, bltr);
            pts += n - backup;
            SkASSERT(SkToInt(count) >= n);
            count -= n;
            if (count > 0) {
                count += backup;
            }
        } while (count != 0);
    } else {
        this->drawDevicePoints(mode, count, pts, paint, device);
    }
}

static bool clipped_out(const SkMatrix& m, const SkRasterClip& c,
                        const SkRect& srcR) {
    SkRect  dstR;
    m.mapRect(&dstR, srcR);
    return c.quickReject(dstR.roundOut());
}

static bool clipped_out(const SkMatrix& matrix, const SkRasterClip& clip,
                        int width, int height) {
    SkRect  r;
    r.setIWH(width, height);
    return clipped_out(matrix, clip, r);
}

static bool clipHandlesSprite(const SkRasterClip& clip, int x, int y, const SkPixmap& pmap) {
    return clip.isBW() || clip.quickContains(SkIRect::MakeXYWH(x, y, pmap.width(), pmap.height()));
}

void SkDraw::drawBitmap(const SkBitmap& bitmap, const SkMatrix& prematrix,
                        const SkRect* dstBounds, const SkSamplingOptions& sampling,
                        const SkPaint& origPaint) const {
    SkDEBUGCODE(this->validate();)

    // nothing to draw
    if (fRC->isEmpty() ||
            bitmap.width() == 0 || bitmap.height() == 0 ||
            bitmap.colorType() == kUnknown_SkColorType) {
        return;
    }

    SkTCopyOnFirstWrite<SkPaint> paint(origPaint);
    if (origPaint.getStyle() != SkPaint::kFill_Style) {
        paint.writable()->setStyle(SkPaint::kFill_Style);
    }

    SkMatrix matrix = *fCTM * prematrix;

    if (clipped_out(matrix, *fRC, bitmap.width(), bitmap.height())) {
        return;
    }

    if (!SkColorTypeIsAlphaOnly(bitmap.colorType()) &&
        SkTreatAsSprite(matrix, bitmap.dimensions(), sampling, paint->isAntiAlias())) {
        //
        // It is safe to call lock pixels now, since we know the matrix is
        // (more or less) identity.
        //
        SkPixmap pmap;
        if (!bitmap.peekPixels(&pmap)) {
            return;
        }
        int ix = SkScalarRoundToInt(matrix.getTranslateX());
        int iy = SkScalarRoundToInt(matrix.getTranslateY());
        if (clipHandlesSprite(*fRC, ix, iy, pmap)) {
            SkSTArenaAlloc<kSkBlitterContextSize> allocator;
            // blitter will be owned by the allocator.
            SkBlitter* blitter = SkBlitter::ChooseSprite(fDst, *paint, pmap, ix, iy, &allocator,
                                                         fRC->clipShader());
            if (blitter) {
                SkScan::FillIRect(SkIRect::MakeXYWH(ix, iy, pmap.width(), pmap.height()),
                                  *fRC, blitter);
                return;
            }
            // if !blitter, then we fall-through to the slower case
        }
    }

    // now make a temp draw on the stack, and use it
    //
    SkDraw draw(*this);
    draw.fCTM = &matrix;

    // For a long time, the CPU backend treated A8 bitmaps as coverage, rather than alpha. This was
    // inconsistent with the GPU backend (skbug.com/9692). When this was fixed, it altered behavior
    // for some Android apps (b/231400686). Thus: keep the old behavior in the framework.
#if defined(SK_SUPPORT_LEGACY_ALPHA_BITMAP_AS_COVERAGE)
    if (bitmap.colorType() == kAlpha_8_SkColorType && !paint->getColorFilter()) {
        draw.drawBitmapAsMask(bitmap, sampling, *paint);
        return;
    }
#endif

    SkPaint paintWithShader = make_paint_with_image(*paint, bitmap, sampling);
    const SkRect srcBounds = SkRect::MakeIWH(bitmap.width(), bitmap.height());
    if (dstBounds) {
        this->drawRect(srcBounds, paintWithShader, &prematrix, dstBounds);
    } else {
        draw.drawRect(srcBounds, paintWithShader);
    }
}

void SkDraw::drawSprite(const SkBitmap& bitmap, int x, int y, const SkPaint& origPaint) const {
    SkDEBUGCODE(this->validate();)

    // nothing to draw
    if (fRC->isEmpty() ||
            bitmap.width() == 0 || bitmap.height() == 0 ||
            bitmap.colorType() == kUnknown_SkColorType) {
        return;
    }

    const SkIRect bounds = SkIRect::MakeXYWH(x, y, bitmap.width(), bitmap.height());

    if (fRC->quickReject(bounds)) {
        return; // nothing to draw
    }

    SkPaint paint(origPaint);
    paint.setStyle(SkPaint::kFill_Style);

    SkPixmap pmap;
    if (!bitmap.peekPixels(&pmap)) {
        return;
    }

    if (nullptr == paint.getColorFilter() && clipHandlesSprite(*fRC, x, y, pmap)) {
        // blitter will be owned by the allocator.
        SkSTArenaAlloc<kSkBlitterContextSize> allocator;
        SkBlitter* blitter = SkBlitter::ChooseSprite(fDst, paint, pmap, x, y, &allocator,
                                                     fRC->clipShader());
        if (blitter) {
            SkScan::FillIRect(bounds, *fRC, blitter);
            return;
        }
    }

    SkMatrix matrix;
    SkRect   r;

    // get a scalar version of our rect
    r.set(bounds);

    // create shader with offset
    matrix.setTranslate(r.fLeft, r.fTop);
    SkPaint paintWithShader = make_paint_with_image(paint, bitmap, SkSamplingOptions(), &matrix);
    SkDraw draw(*this);
    draw.fCTM = &SkMatrix::I();
    // call ourself with a rect
    draw.drawRect(r, paintWithShader);
}

#if defined(SK_SUPPORT_LEGACY_ALPHA_BITMAP_AS_COVERAGE)
void SkDraw::drawDevMask(const SkMask& srcM, const SkPaint& paint) const {
    if (srcM.fBounds.isEmpty()) {
        return;
    }

    const SkMask* mask = &srcM;

    SkMaskBuilder dstM;
    if (paint.getMaskFilter() &&
        as_MFB(paint.getMaskFilter())->filterMask(&dstM, srcM, *fCTM, nullptr)) {
        mask = &dstM;
    }
    SkAutoMaskFreeImage ami(dstM.image());

    SkAutoBlitterChoose blitterChooser(*this, nullptr, paint);
    SkBlitter* blitter = blitterChooser.get();

    SkAAClipBlitterWrapper wrapper;
    const SkRegion* clipRgn;

    if (fRC->isBW()) {
        clipRgn = &fRC->bwRgn();
    } else {
        wrapper.init(*fRC, blitter);
        clipRgn = &wrapper.getRgn();
        blitter = wrapper.getBlitter();
    }
    blitter->blitMaskRegion(*mask, *clipRgn);
}

void SkDraw::drawBitmapAsMask(const SkBitmap& bitmap, const SkSamplingOptions& sampling,
                              const SkPaint& paint) const {
    SkASSERT(bitmap.colorType() == kAlpha_8_SkColorType);

    // nothing to draw
    if (fRC->isEmpty()) {
        return;
    }

    if (SkTreatAsSprite(*fCTM, bitmap.dimensions(), sampling, paint.isAntiAlias()))
    {
        int ix = SkScalarRoundToInt(fCTM->getTranslateX());
        int iy = SkScalarRoundToInt(fCTM->getTranslateY());

        SkPixmap pmap;
        if (!bitmap.peekPixels(&pmap)) {
            return;
        }
        SkMask mask(pmap.addr8(0, 0),
                    SkIRect::MakeXYWH(ix, iy, pmap.width(), pmap.height()),
                    SkToU32(pmap.rowBytes()),
                    SkMask::kA8_Format);

        this->drawDevMask(mask, paint);
    } else {    // need to xform the bitmap first
        SkRect  r;
        SkMaskBuilder mask;

        r.setIWH(bitmap.width(), bitmap.height());
        fCTM->mapRect(&r);
        r.round(&mask.bounds());

        // set the mask's bounds to the transformed bitmap-bounds,
        // clipped to the actual device and further limited by the clip bounds
        {
            SkASSERT(fDst.bounds().contains(fRC->getBounds()));
            SkIRect devBounds = fDst.bounds();
            devBounds.intersect(fRC->getBounds().makeOutset(1, 1));
            // need intersect(l, t, r, b) on irect
            if (!mask.bounds().intersect(devBounds)) {
                return;
            }
        }

        mask.format() = SkMask::kA8_Format;
        mask.rowBytes() = SkAlign4(mask.fBounds.width());
        size_t size = mask.computeImageSize();
        if (0 == size) {
            // the mask is too big to allocated, draw nothing
            return;
        }

        // allocate (and clear) our temp buffer to hold the transformed bitmap
        AutoTMalloc<uint8_t> storage(size);
        mask.image() = storage.get();
        memset(mask.image(), 0, size);

        // now draw our bitmap(src) into mask(dst), transformed by the matrix
        {
            SkBitmap    device;
            device.installPixels(SkImageInfo::MakeA8(mask.fBounds.width(), mask.fBounds.height()),
                                 mask.image(), mask.fRowBytes);

            SkCanvas c(device);
            // need the unclipped top/left for the translate
            c.translate(-SkIntToScalar(mask.fBounds.fLeft),
                        -SkIntToScalar(mask.fBounds.fTop));
            c.concat(*fCTM);

            // We can't call drawBitmap, or we'll infinitely recurse. Instead
            // we manually build a shader and draw that into our new mask
            SkPaint tmpPaint;
            tmpPaint.setAntiAlias(paint.isAntiAlias());
            tmpPaint.setDither(paint.isDither());
            SkPaint paintWithShader = make_paint_with_image(tmpPaint, bitmap, sampling);
            SkRect rr;
            rr.setIWH(bitmap.width(), bitmap.height());
            c.drawRect(rr, paintWithShader);
        }
        this->drawDevMask(mask, paint);
    }
}
#endif