Text scaling problem with itext7, hidden margins?

问题

I'm trying to get this c# function from within a asp.netcore razor project using itext7 (7.1.7) to output a div containing text that scales up to within the constraints given with height and width. However, for some reason it seems there's some kind of hidden margin that will not scale the text to the boundaries of the given width and height, even though the margins are set to 0. At the moment the maximum text i get is only half of what it should be. Also, the paragraph, nor the div is actually set to the min width and min height.

Any help how to fix this is appreciated

public Div MakeScaledTxtDiv(string _displayTxt ,PdfFont _Pdffont, float _maxHeight, 
                                            float _maxWidth, Canvas _canvas, bool _showBorder)
    {
        Div nameDiv = new Div();

        iText.Kernel.Geom.Rectangle posRect = new iText.Kernel.Geom.Rectangle(_maxWidth,_maxHeight);

        Paragraph txtPara = new Paragraph()
            .SetVerticalAlignment(VerticalAlignment.MIDDLE)
            .SetTextAlignment(iText.Layout.Properties.TextAlignment.CENTER);

        if (_showBorder)
            txtPara.SetBorder(new DashedBorder(1));

        if (_maxHeight > 0)
            txtPara.SetMaxHeight(_maxHeight);

        if (_maxWidth > 0)
            txtPara.SetMaxWidth(_maxWidth);

        txtPara
            .SetMargin(0f)
            .SetPadding(0f)
            .SetFont(_Pdffont)
            .Add(_displayTxt);

        float fontSizeToSet = 1;
        float fontSizeMax = 42;
        float curFontSize = fontSizeMax;

        bool m_bGoodfit = false;
        while (!m_bGoodfit)
        {
            txtPara.SetFontSize(curFontSize);

            ParagraphRenderer renderer = (ParagraphRenderer)txtPara.CreateRendererSubTree().SetParent(_canvas.GetRenderer());

            LayoutContext context = new LayoutContext(new LayoutArea(1, posRect));
            var fits = renderer.Layout(context).GetStatus();
            if (fits == LayoutResult.FULL)
            {
                fontSizeToSet = curFontSize;
                m_bGoodfit = true;
            }
            else
            {
                curFontSize -= 1;
                if (curFontSize == 1)
                {
                    fontSizeToSet = curFontSize;
                    m_bGoodfit = true;
                }
            }
        }

        txtPara.SetFontSize(fontSizeToSet);

        if (_maxHeight > 0)
        {
            nameDiv.SetMinHeight(_maxHeight)
                    .SetMaxHeight(_maxHeight)
                    .SetHeight(_maxHeight);
        }

        if (_maxWidth > 0)
        {
            nameDiv.SetMinWidth(_maxWidth)
                    .SetMaxWidth(_maxWidth)
                    .SetWidth(_maxWidth);
        }

        nameDiv
            .SetMargin(0f)
            .SetPadding(0f)
            .SetVerticalAlignment(VerticalAlignment.MIDDLE)
            .SetTextAlignment(iText.Layout.Properties.TextAlignment.CENTER);

        if (_showBorder)
            nameDiv.SetBorder(new DottedBorder(1));

        nameDiv.Add(txtPara).SetVerticalAlignment(VerticalAlignment.MIDDLE);

        return nameDiv;
    }

回答1:

What worked for me was to change the multiplier number 0.7f slightly bigger in the code below (code referenced from https://stackoverflow.com/a/57929067/5490413).

It seems as that multiplier gets bigger/smaller, the space between the text and field bottom border grows/shrinks accordingly. Maybe start with 1.2f and find one that fits.

Paragraph linePara = new Paragraph().Add(lineTxt)
    .SetTextAlignment(iText.Layout.Properties.TextAlignment.CENTER).SetBorder(new DottedBorder(1))
    .SetMultipliedLeading(0.7f);
lineDiv.Add(linePara);

FYI I came across the exact issue you were facing: How to scale text within a fixed rectangle with itext7?

I tried with the answer posted there https://stackoverflow.com/a/57929067/5490413 and faced the same hidden bottom margin issue here.

来源：https://stackoverflow.com/questions/57971693/text-scaling-problem-with-itext7-hidden-margins

标签

pdf

asp.net-core

itext7