PDFBox中的java渐变笔划

Question

我正在尝试使用JAVA PDFbox绘制渐变笔划颜色而非填充颜色的曲线，有人可以帮助我如何做到这一点吗

对于填充我正在使用的形状：

contentStream.clip();
contentStream.shadingFill(PdfUtils.createGradientColor(gradientFactors));

public static PDShadingType2 createGradientColor(GradientFactors gradientFactors) throws IOException {
    Color startColor = gradientFactors.getStartColor().getColor();
    Color endColor = gradientFactors.getEndColor().getColor();

    COSDictionary fdict = new COSDictionary();

    fdict.setInt(COSName.FUNCTION_TYPE, 2);

    COSArray domain = new COSArray();
    domain.add(COSInteger.get(0));
    domain.add(COSInteger.get(1));

    COSArray c0 = new COSArray();
    c0.add(new COSFloat(startColor.getRed() / 255f));
    c0.add(new COSFloat(startColor.getGreen() / 255f));
    c0.add(new COSFloat(startColor.getBlue() / 255f));

    COSArray c1 = new COSArray();
    c1.add(new COSFloat(endColor.getRed() / 255f));
    c1.add(new COSFloat(endColor.getGreen() / 255f));
    c1.add(new COSFloat(endColor.getBlue() / 255f));

    fdict.setItem(COSName.DOMAIN, domain);
    fdict.setItem(COSName.C0, c0);
    fdict.setItem(COSName.C1, c1);
    fdict.setInt(COSName.N, 1);

    PDFunctionType2 func = new PDFunctionType2(fdict);

    PDShadingType2 axialShading = new PDShadingType2(new COSDictionary());

    axialShading.setColorSpace(PDDeviceRGB.INSTANCE);
    axialShading.setShadingType(PDShading.SHADING_TYPE2);

    COSArray coords1 = new COSArray();
    coords1.add(new COSFloat(gradientFactors.getX1()));
    coords1.add(new COSFloat(gradientFactors.getY1()));
    coords1.add(new COSFloat(gradientFactors.getX2()));
    coords1.add(new COSFloat(gradientFactors.getY2()));

    axialShading.setCoords(coords1);
    axialShading.setFunction(func);

    return axialShading;
}

谁能帮我一下吗

Answer 1

正如Tilman已经指出的，您可以从着色创建一个PDColor：

PDShadingType2 shading = createGradientColor(...);
PDShadingPattern pattern = new PDShadingPattern();
pattern.setShading(shading);
COSName name = page.getResources().add(pattern);
PDColor color = new PDColor(name, new PDPattern(null));

然后用该颜色绘制，例如：

try (   PDPageContentStream canvas = new PDPageContentStream(document, page)) {
    canvas.setStrokingColor(color);
    canvas.setLineWidth(5);
    canvas.moveTo(0, 0);
    canvas.lineTo(500, 500);
    canvas.curveTo2(500, 250, 250, 250);
    canvas.curveTo1(0, 250, 0, 0);
    canvas.stroke();
}

假设渐变从0,0到500500从红色变为绿色，结果如下所示：

（DrawGradient测试testDrawWithGradientColor）