C++ SkPaint::getAlpha方法代码示例

bool SkColorShader::setContext(const SkBitmap& device, const SkPaint& paint,
                               const SkMatrix& matrix) {
    if (!this->INHERITED::setContext(device, paint, matrix)) {
        return false;
    }

    SkColor c;
    unsigned a;
    
    if (fInheritColor) {
        c = paint.getColor();
        a = SkColorGetA(c);
    } else {
        c = fColor;
        a = SkAlphaMul(SkColorGetA(c), SkAlpha255To256(paint.getAlpha()));
    }

    unsigned r = SkColorGetR(c);
    unsigned g = SkColorGetG(c);
    unsigned b = SkColorGetB(c);

    // we want this before we apply any alpha
    fColor16 = SkPack888ToRGB16(r, g, b);

    if (a != 255) {
        a = SkAlpha255To256(a);
        r = SkAlphaMul(r, a);
        g = SkAlphaMul(g, a);
        b = SkAlphaMul(b, a);
    }
    fPMColor = SkPackARGB32(a, r, g, b);

    return true;
}

    static bool Supports(const SkPixmap& dst, const SkPixmap& src, const SkPaint& paint) {
        if (dst.colorType() != src.colorType()) {
            return false;
        }
        if (dst.info().gammaCloseToSRGB() != src.info().gammaCloseToSRGB()) {
            return false;
        }
        if (paint.getMaskFilter() || paint.getColorFilter() || paint.getImageFilter()) {
            return false;
        }
        if (0xFF != paint.getAlpha()) {
            return false;
        }
        SkBlendMode mode = paint.getBlendMode();
        if (SkBlendMode::kSrc == mode) {
            return true;
        }
        if (SkBlendMode::kSrcOver == mode && src.isOpaque()) {
            return true;
        }

        // At this point memcpy can't be used. The following check for using SrcOver.

        if (dst.colorType() != kN32_SkColorType || !dst.info().gammaCloseToSRGB()) {
            return false;
        }

        return SkBlendMode::kSrcOver == mode;
    }

void SkBaseDevice::drawImageLattice(const SkImage* image,
                                    const SkCanvas::Lattice& lattice, const SkRect& dst,
                                    const SkPaint& paint) {
    SkLatticeIter iter(lattice, dst);

    SkRect srcR, dstR;
    SkColor c;
    bool isFixedColor = false;
    const SkImageInfo info = SkImageInfo::Make(1, 1, kBGRA_8888_SkColorType, kUnpremul_SkAlphaType);

    while (iter.next(&srcR, &dstR, &isFixedColor, &c)) {
          if (isFixedColor || (srcR.width() <= 1.0f && srcR.height() <= 1.0f &&
                               image->readPixels(info, &c, 4, srcR.fLeft, srcR.fTop))) {
              // Fast draw with drawRect, if this is a patch containing a single color
              // or if this is a patch containing a single pixel.
              if (0 != c || !paint.isSrcOver()) {
                   SkPaint paintCopy(paint);
                   int alpha = SkAlphaMul(SkColorGetA(c), SkAlpha255To256(paint.getAlpha()));
                   paintCopy.setColor(SkColorSetA(c, alpha));
                   this->drawRect(dstR, paintCopy);
              }
        } else {
            this->drawImageRect(image, &srcR, dstR, paint, SkCanvas::kStrict_SrcRectConstraint);
        }
    }
}

bool DCShader::asFragmentProcessor(GrContext*, const SkPaint& paint, const SkMatrix& viewM,
                                   const SkMatrix* localMatrix, GrColor* color,
                                   GrFragmentProcessor** fp) const {
    *fp = SkNEW_ARGS(DCFP, (fDeviceMatrix));
    *color = GrColorPackA4(paint.getAlpha());
    return true;
}

    virtual void onDraw(int loops, SkCanvas* canvas) {
        const SkIPoint dim = this->getSize();
        SkRandom rand;

        SkPaint paint(fPaint);
        this->setupPaint(&paint);
        // explicitly need these
        paint.setAlpha(fPaint.getAlpha());
        paint.setAntiAlias(kBW != fFQ);
        paint.setLCDRenderText(kLCD == fFQ);

        const SkScalar x0 = SkIntToScalar(-10);
        const SkScalar y0 = SkIntToScalar(-10);

        paint.setTextSize(SkIntToScalar(12));
        for (int i = 0; i < loops; i++) {
            SkScalar x = x0 + rand.nextUScalar1() * dim.fX;
            SkScalar y = y0 + rand.nextUScalar1() * dim.fY;
            canvas->drawString(fText, x, y, paint);
        }

        paint.setTextSize(SkIntToScalar(48));
        for (int i = 0; i < loops / 4 ; i++) {
            SkScalar x = x0 + rand.nextUScalar1() * dim.fX;
            SkScalar y = y0 + rand.nextUScalar1() * dim.fY;
            canvas->drawString(fText, x, y, paint);
        }
    }

void SkGL::SetPaint(const SkPaint& paint, bool isPremul, bool justAlpha) {
    if (justAlpha) {
        SkGL::SetAlpha(paint.getAlpha());
    } else {
        SkGL::SetColor(paint.getColor());
    }

    GLenum sm = GL_ONE;
    GLenum dm = GL_ONE_MINUS_SRC_ALPHA;

    SkXfermode* mode = paint.getXfermode();
    SkXfermode::Coeff sc, dc;
    if (mode && mode->asCoeff(&sc, &dc)) {
        sm = gXfermodeCoeff2Blend[sc];
        dm = gXfermodeCoeff2Blend[dc];
    }

    // hack for text, which is not-premul (afaik)
    if (!isPremul) {
        if (GL_ONE == sm) {
            sm = GL_SRC_ALPHA;
        }
    }

    glEnable(GL_BLEND);
    glBlendFunc(sm, dm);

    if (paint.isDither()) {
        glEnable(GL_DITHER);
    } else {
        glDisable(GL_DITHER);
    }
}

/**
 * Draw a single path element of the clip stack into the accumulation bitmap
 */
void GrSWMaskHelper::draw(const SkPath& path, const SkStrokeRec& stroke, SkRegion::Op op,
                          bool antiAlias, uint8_t alpha) {

    SkPaint paint;
    if (stroke.isHairlineStyle()) {
        paint.setStyle(SkPaint::kStroke_Style);
        paint.setStrokeWidth(SK_Scalar1);
    } else {
        if (stroke.isFillStyle()) {
            paint.setStyle(SkPaint::kFill_Style);
        } else {
            paint.setStyle(SkPaint::kStroke_Style);
            paint.setStrokeJoin(stroke.getJoin());
            paint.setStrokeCap(stroke.getCap());
            paint.setStrokeWidth(stroke.getWidth());
        }
    }
    paint.setAntiAlias(antiAlias);

    if (SkRegion::kReplace_Op == op && 0xFF == alpha) {
        SkASSERT(0xFF == paint.getAlpha());
        fDraw.drawPathCoverage(path, paint);
    } else {
        paint.setXfermodeMode(op_to_mode(op));
        paint.setColor(SkColorSetARGB(alpha, alpha, alpha, alpha));
        fDraw.drawPath(path, paint);
    }
}

	bool draw(SkCanvas* canvas, const SkString& newText, SkScalar x, SkScalar y, SkPaint& paint)
	{
		SkScalar scale;

		if (fInterp.timeToValues(SkTime::GetMSecs(), &scale) == SkInterpolator::kFreezeEnd_Result)
		{
			canvas->drawText(newText.c_str(), newText.size(), x, y, paint);
			return false;
		}
		else
		{
			U8 alpha = paint.getAlpha();
			SkScalar above, below;
			(void)paint.measureText(nil, 0, &above, &below);
			SkScalar height = below - above;
			SkScalar dy = SkScalarMul(height, scale);
			if (scale < 0)
				height = -height;

			// draw the old
			paint.setAlpha((U8)SkScalarMul(alpha, SK_Scalar1 - SkScalarAbs(scale)));
			canvas->drawText(fOldText.c_str(), fOldText.size(), x, y - dy, paint);
			// draw the new
			paint.setAlpha((U8)SkScalarMul(alpha, SkScalarAbs(scale)));
			canvas->drawText(newText.c_str(), newText.size(), x, y + height - dy, paint);
			// restore the paint
			paint.setAlpha(alpha);
			return true;
		}
	}

 static bool Supports(const SkPixmap& dst, const SkPixmap& src, const SkPaint& paint) {
     if (dst.colorType() != src.colorType()) {
         return false;
     }
     if (dst.info().profileType() != src.info().profileType()) {
         return false;
     }
     if (paint.getMaskFilter() || paint.getColorFilter() || paint.getImageFilter()) {
         return false;
     }
     if (0xFF != paint.getAlpha()) {
         return false;
     }
     SkXfermode::Mode mode;
     if (!SkXfermode::AsMode(paint.getXfermode(), &mode)) {
         return false;
     }
     if (SkXfermode::kSrc_Mode == mode) {
         return true;
     }
     if (SkXfermode::kSrcOver_Mode == mode && src.isOpaque()) {
         return true;
     }
     return false;
 }

SkPDFGraphicState::SkPDFGraphicState(const SkPaint& p)
    : fStrokeWidth(p.getStrokeWidth())
    , fStrokeMiter(p.getStrokeMiter())
    , fAlpha(p.getAlpha())
    , fStrokeCap(SkToU8(p.getStrokeCap()))
    , fStrokeJoin(SkToU8(p.getStrokeJoin()))
    , fMode(SkToU8(mode_for_pdf(p.getXfermode()))) {}

bool SkTransparentShader::setContext(const SkBitmap& device,
                                     const SkPaint& paint,
                                     const SkMatrix& matrix) {
    fDevice = &device;
    fAlpha = paint.getAlpha();

    return this->INHERITED::setContext(device, paint, matrix);
}

    void onDraw(SkCanvas* canvas) override {
        const struct {
            SkISize  size;
            SkScalar scaleX, scaleY;
            SkScalar opacity;
        } configs[] = {
            { SkISize::Make(200, 100), 1, 1, 1 },
            { SkISize::Make(200, 200), 1, 1, 1 },
            { SkISize::Make(200, 200), 1, 2, 1 },
            { SkISize::Make(400, 200), 2, 2, 1 },

            { SkISize::Make(200, 100), 1, 1, 0.9f  },
            { SkISize::Make(200, 200), 1, 1, 0.75f },
            { SkISize::Make(200, 200), 1, 2, 0.5f  },
            { SkISize::Make(400, 200), 2, 2, 0.25f },

            { SkISize::Make(200, 200), 0.5f, 1,    1 },
            { SkISize::Make(200, 200), 1,    0.5f, 1 },
            { SkISize::Make(200, 200), 0.5f, 0.5f, 1 },
            { SkISize::Make(200, 200), 2,    2,    1 },

            { SkISize::Make(200, 100), -1,  1, 1    },
            { SkISize::Make(200, 100),  1, -1, 1    },
            { SkISize::Make(200, 100), -1, -1, 1    },
            { SkISize::Make(200, 100), -1, -1, 0.5f },
        };

        const unsigned kDrawsPerRow = 4;
        const SkScalar kDrawSize = 250;

        for (size_t i = 0; i < SK_ARRAY_COUNT(configs); ++i) {
            SkPaint p;
            p.setAlpha(SkScalarRoundToInt(255 * configs[i].opacity));

            SkMatrix m = SkMatrix::MakeScale(configs[i].scaleX, configs[i].scaleY);
            if (configs[i].scaleX < 0) {
                m.postTranslate(SkIntToScalar(configs[i].size.width()), 0);
            }
            if (configs[i].scaleY < 0) {
                m.postTranslate(0, SkIntToScalar(configs[i].size.height()));
            }
            SkAutoTDelete<SkImageGenerator> gen(
                SkImageGenerator::NewFromPicture(configs[i].size, fPicture.get(), &m,
                                                 p.getAlpha() != 255 ? &p : nullptr));
            SkBitmap bm;
            gen->generateBitmap(&bm);

            const SkScalar x = kDrawSize * (i % kDrawsPerRow);
            const SkScalar y = kDrawSize * (i / kDrawsPerRow);

            p.setColor(0xfff0f0f0);
            p.setAlpha(255);
            canvas->drawRect(SkRect::MakeXYWH(x, y,
                                              SkIntToScalar(bm.width()),
                                              SkIntToScalar(bm.height())), p);
            canvas->drawBitmap(bm, x, y);
        }
    }

bool SkColorShader::asNewEffect(GrContext* context, const SkPaint& paint,
                                const SkMatrix* localMatrix, GrColor* grColor,
                                GrEffectRef** grEffect) const {
    *grEffect = NULL;
    SkColor skColor = fColor;
    U8CPU newA = SkMulDiv255Round(SkColorGetA(fColor), paint.getAlpha());
    *grColor = SkColor2GrColor(SkColorSetA(skColor, newA));
    return true;
}

    Sprite_D32_XferFilter(const SkBitmap& source, const SkPaint& paint)
        : SkSpriteBlitter(source) {
        fColorFilter = paint.getColorFilter();
        SkSafeRef(fColorFilter);

        fXfermode = paint.getXfermode();
        SkSafeRef(fXfermode);

        fBufferSize = 0;
        fBuffer = NULL;

        unsigned flags32 = 0;
        if (255 != paint.getAlpha()) {
            flags32 |= SkBlitRow::kGlobalAlpha_Flag32;
        }
        if (!source.isOpaque()) {
            flags32 |= SkBlitRow::kSrcPixelAlpha_Flag32;
        }

        fProc32 = SkBlitRow::Factory32(flags32);
        fAlpha = paint.getAlpha();
    }

 virtual const char* onGetName() {
     fName.printf("text_%g", SkScalarToFloat(fPaint.getTextSize()));
     if (fDoPos) {
         fName.append("_pos");
     }
     fName.appendf("_%s", fontQualityName(fPaint));
     if (SK_ColorBLACK != fPaint.getColor()) {
         fName.appendf("_%02X", fPaint.getAlpha());
     } else {
         fName.append("_BK");
     }
     return fName.c_str();
 }