jsPDF justify text

问题:

I'm trying to apply some changes on jsPDF library to be able to justify text.

I'm having trouble to find the right value for Tw (word spacing).

In jspdf.js (L:1413) I have added this code:

if (align) {
    ...                
    else if (align === 'justify') {
       left = x;
    }
    else {
        throw new Error('Unrecognized alignment option, use "center" or "right".');
    }
    prevX = x;
    text = '(' + da[0];

    let pdfPageWidth = this.internal.pageSize.width;
    let wordSpacing;
    if( align === 'justify' ) {
        let fontSize = this.internal.getFontSize();
        let nWords = da[0].trim().split(/\s+/).length;
        let textWidth = this.getStringUnitWidth(da[0].replace(/\s+/g, '')) / this.internal.scaleFactor;
        wordSpacing = (Math.max(0, (pdfPageWidth - textWidth) / Math.max(1, nWords - 1));
        wordSpacing += ' Tw\n';
        text = wordSpacing + text;
    }
    ...
}

The idea was to extract the space width by doing (pageWidth - textWidth) / numberOfWords -1. I can't get the correct word space.

Output example

BT
/F1 16 Tf
18.4 TL
0 g
28.35 756.85 Td
19.00357142857142 Tw
(And a little bit it adélkfjalké.) Tj
ET

Is there an encoding problem?

Thanks for your help.

回答1:

I answered you on github I wrote my own justification code into my refactored jsPDF according to your suggestion.

Check it out...

https://github.com/MrRio/jsPDF/issues/1016#issuecomment-329957940

Edited:

Oh wait, I can probably help with a direct answer. I think you just have to change it like this:

var wordSpacing = (Math.max(0, (pdfPageWidth - textWidth) / Math.max(1, nWords - 1)) * this.internal.scaleFactor);

if (align) {
    ...                
    else if (align === 'justify') {
        var wordSpacingPerLine = [];
        for (var i = 0, len = da.length; i < len; i++) {
            wordSpacingPerLine.push(((this.internal.pageSize.width - lineWidths[i]) / (da[i].split(" ").length - 1) * k).toFixed(2));
        }
    }
    else {
        throw new Error('Unrecognized alignment option, use "center" or "right".');
    }
    prevX = x;
    text = '(' + da[0];

    let pdfPageWidth = this.internal.pageSize.width;
    let wordSpacing;
    if( align === 'justify' ) {
        text =  wordSpacingPerLine[0]  + ' Tw\n' + text;
    }
    ...
}

You have to do add the specific WordSpacing for every line except the last line. Last line is then left aligned.

Here an example:

BT
/F1 16 Tf
18.4 TL
0 g
4.869500000212597 Tw
28.35 813.54 Td
(Lorem ipsum dolor sit amet, consetetur abore et dolore) Tj
3.5284444446334158 Tw
0.00 -18.40 Td
(magna aliquyam erat, sed diam voluptua. At vero eos et) Tj
2.0876000001700574 Tw
0.00 -18.40 Td
(accusam et justo duo dolores et ea rebum. Stet clita kasd) Tj
1.329500000212585 Tw
0.00 -18.40 Td
(gubergren, no sea takimata sanctus est Lorem ipsum dolor) Tj
1.329500000212585 Tw
0.00 -18.40 Td
(sit amet.) Tj
ET

回答2:

After many tries I have found the working code solution :D. It works also with array of text as param.

        } else if (align === 'justify') {
          left = x;
        }
        else {
          throw new Error(
            'Unrecognized alignment option, use "center" or "right".'
          );
        }
        prevX = x;
        text = '(' + da[0];

        var pdfPageWidth = this.internal.pageSize.width;
        var wordSpacing;
        var fontSize = this.internal.getFontSize();
        if( align === 'justify' ) {
          var nWords = da[0].trim().split(/\s+/).length;
          var textWidth = this.getStringUnitWidth(da[0]) * fontSize / k;

          wordSpacing = (Math.max(0, ((pdfPageWidth - x - marginRight) - textWidth) / Math.max(1, nWords - 1))) * k;
          // Do not justify if wordSpacing is too high
          wordSpacing = ( wordSpacing > 50 ? 0 : wordSpacing ) + ' Tw\n';

          text = wordSpacing + text;
        }

        for (var i = 1, len = da.length; i < len; i++) {
          var delta = maxLineLength - lineWidths[i];
          if (align === "center") delta /= 2;
          if (align === "justify") { // TODO: improve code duplication
            delta = 0;
            var nWords = da[i].trim().split(/\s+/).length;
            var textWidth = this.getStringUnitWidth(da[i]) * fontSize / k;

            wordSpacing = (Math.max(0, ((pdfPageWidth - x - marginRight) - textWidth) / Math.max(1, nWords - 1))) * k;
            // Do not justify if wordSpacing is too high
            wordSpacing = ( wordSpacing > 50 ? 0 : wordSpacing ) + ' Tw\n';
            text += ") Tj\n" + ((left - prevX) + delta) + " -" + leading + " Td\n" + wordSpacing + "(" + da[i];
          } else {
            // T* = x-offset leading Td ( text )
            text += ") Tj\n" + ((left - prevX) + delta) + " -" + leading + " Td (" + da[i];
          }
          prevX = left + delta;
        }
      } else {
        text = ' 0 Tw\n (' + da.join(") Tj\nT* (");
      }

Here is my PR

回答3:

When using a custom font (ttf etc) Justify text can be done with a javascript to place all words on the correct position. See stackoverflow justify text with custom font