Text flowing over multiple pages in parallel columns skips a page

[rexxmagnus]

Bug Report

Description of the problem

When I add text in a column that flows over to the next page, then start a new column on the first page, the second column will not flow onto the second page but instead flows onto a new, third, page.

Code sample

`// create a document and pipe to a blob
var doc = new PDFDocument({ size: 'A4', layout: 'landscape', bufferPages: true, margin:28 });
var stream = doc.pipe(blobStream());

doc.text(lorem, 20, 200, {width:200});
doc.switchToPage(0);
doc.text(lorem, 300, 150, {width:200});

// end and display the document in the iframe to the right
doc.end();
stream.on('finish', function() {
iframe.src = stream.toBlobURL('application/pdf');
});`

Your environment

• pdfkit version: 0.11.0
• Node version: NA
• Browser version (if applicable): Firefox 84
• Operating System: Windows 10

[rexxmagnus]

I have a suggested fix that may work, but I haven't had time to study the codebase fully.
It seems that flowing onto the next page indiscriminately adds a new page, and I suggest to fix it by checking whether the current page is the last in the document and if so, adding a page. If it's not the last page in the document, jump to the next page.

in line_wrapper.js, the function
nextSection(options)

instead of this.document.addPage() immediately after the check to see whether text height is set, something like the following:

      // If using a pagebuffer, check whether the page is the last one
      if (!!this.document._pageBuffer){
        var pageIndex = this.document._pageBuffer.indexOf(this.document.page);
        // If the page is the last one in the buffer, add a new page.
        if (pageIndex == this.document._pageBuffer.length - 1){
            this.document.addPage();
        } else {
            // The page isn't the last in the buffer, so jump to the next page
            this.document.switchToPage(pageIndex + 1);
            // Now position the cursor at the top
            this.document.y = this.document.page.margins.top;
        }
      } else{
            // No pagebuffer?
          this.document.addPage();
      }

[ZobairQ]

Can you please check and accept the pull-request if that fixes the problem. I am having the same issue.