java - iText7.1.3 将 SVG 添加到 PdfDocument 中

Question

使用iText 7.1.3并尝试将 SVG 文件添加到 PdfDocument 会产生不呈现长度为 1 的文本的输出。我发现可能问题出在哪里。 请iText团队成员检查一下。

try {
      SvgConverter.drawOnCanvas(svgUrl.openStream(), pdfCanvas_, imageLlx, imageLly);
} catch (IOException e) {
      e.printStackTrace();
}

调试器调用:

processText:255, DefaultSvgProcessor (com.itextpdf.svg.processors.impl)
visit:212, DefaultSvgProcessor (com.itextpdf.svg.processors.impl)
visit:204, DefaultSvgProcessor (com.itextpdf.svg.processors.impl)
visit:204, DefaultSvgProcessor (com.itextpdf.svg.processors.impl)
executeDepthFirstTraversal:153, DefaultSvgProcessor (com.itextpdf.svg.processors.impl)
process:106, DefaultSvgProcessor (com.itextpdf.svg.processors.impl)
process:768, SvgConverter (com.itextpdf.svg.converter)
convertToXObject:555, SvgConverter (com.itextpdf.svg.converter)
convertToXObject:590, SvgConverter (com.itextpdf.svg.converter)
drawOnCanvas:380, SvgConverter (com.itextpdf.svg.converter)

在函数processText中，在修剪尾随空格行中

trimmedText = SvgTextUtil.trimTrailingWhitespace("A");

对于trimmedText = A(长度= 1)返回空字符串

/**
* Process the text contained in the text-node
*
* @param textNode node containing text to process
*/
private void processText(ITextNode textNode) {
    ISvgNodeRenderer parentRenderer = this.processorState.top();

    if (parentRenderer instanceof TextSvgNodeRenderer) {
        // when svg is parsed by jsoup it leaves all whitespace in text element as is. Meaning that
        // tab/space indented xml files will retain their tabs and spaces.
        // The following regex replaces all whitespace with a single space.
        //TODO(RND-906) evaluate regex and trim methods
        String trimmedText = textNode.wholeText().replaceAll("\\s+", " ");
        //Trim leading whitespace
        trimmedText = SvgTextUtil.trimLeadingWhitespace(trimmedText);
        //Trim trailing whitespace
        trimmedText = SvgTextUtil.trimTrailingWhitespace(trimmedText);
        parentRenderer.setAttribute(SvgConstants.Attributes.TEXT_CONTENT, trimmedText);
    }
}

Answer 1

您指出的trimTrailingWhitespace确实存在错误

public static String trimTrailingWhitespace(String toTrim) {
    if(toTrim == null){
        return "";
    }
    int end = toTrim.length();
    if (end > 0) {
        int current = end - 1;
        while (current > 0) {
            char currentChar = toTrim.charAt(current);
            if (Character.isWhitespace(currentChar) && !(currentChar == '\n' || currentChar == '\r')) {
                //if the character is whitespace and not a newline, increase current
                current--;
            } else {
                break;
            }
        }
        if(current == 0){
            return "";
        }else {
            return toTrim.substring(0, current + 1);
        }
    }else{
        return toTrim;
    }
}

正如注释 //if the character iswhitespace and not a newline,increase current 后跟 current--; 已经表明，此方法是 trimLeadingWhitespace(其中相同注释后的行确实增加当前)修改为在String的另一端工作范围。但不幸的是，修改是不正确的:如果字符串在位置 0 处有非空白字符且此后只有空白，则它会被错误地视为空。

修复方法是替换

while (current > 0)

由

while (current >= 0)

和

if(current == 0)

由

if(current < 0)

这样就解决了

if (end > 0) {
    [...]
}else{
    return toTrim;
}

此外，

围绕[...]的框架变得不必要。 while 循环可以更紧凑地表述为 for 循环，例如像这样:

public static String trimTrailingWhitespace(String toTrim) {
    if (toTrim == null) {
        return "";
    }
    int current = toTrim.length() - 1;
    for ( ; current >= 0; current--) {
        char currentChar = toTrim.charAt(current);
        if (!(Character.isWhitespace(currentChar) && !(currentChar == '\n' || currentChar == '\r'))) {
            break;
        }
    }
    return current < 0 ? "" : toTrim.substring(0, current + 1);
}