Strange spacing behavior when adding text followed by a change of font.

[mazzegi]

Given the following code

package main

import "github.com/signintech/gopdf"

var fontDir = "/usr/share/fonts/truetype/"

func main() {
    pdf := &gopdf.GoPdf{}
    pdf.Start(gopdf.Config{
        PageSize: *gopdf.PageSizeA4,
    })

    pdf.AddTTFFont("sans", fontDir+"dejavu/DejaVuSans.ttf")
    pdf.AddTTFFontWithOption("sans", fontDir+"dejavu/DejaVuSans-Bold.ttf", gopdf.TtfOption{Style: gopdf.Bold})
    pdf.SetMargins(30, 30, 40, 40)
    pdf.AddPage()

    x0 := pdf.GetX()
    pdf.SetFont("sans", "", 14)
    pdf.Text("lorem ")
    pdf.SetFont("sans", "B", 14)
    pdf.Text("amet")

    pdf.SetX(x0)
    pdf.SetY(pdf.GetY() + 20)
    pdf.SetFont("sans", "", 14)
    pdf.Text("lorem ")
    pdf.Text("ipsum ")
    pdf.SetFont("sans", "B", 14)
    pdf.Text("amet")

    pdf.SetX(x0)
    pdf.SetY(pdf.GetY() + 20)
    pdf.SetFont("sans", "", 14)
    pdf.Text("lorem ")
    pdf.Text("ipsum ")
    pdf.Text("dolor ")
    pdf.SetFont("sans", "B", 14)
    pdf.Text("amet")

    pdf.WritePdf("foo.pdf")
}

... produces that strange result:

It seems, that with every single call to pdf.Text() the spacing before the final bold amet get's bigger.

You may ask, why not combining several calls of pdf.Text() into one, but in reality this happens in a kind of automatism, where it's hard to avoid.

Any clues? Thanks

[nmaupu]

Same here just changing color bunch of times. Anybody has an idea on how to solve this ?

[nmaupu]

Here is an illustration of the problem.

I iterate over each char of the word Geisha and change the color of one given char. I do that 6 times. The later I change the color, wider is the space 🤷

[nmaupu]

After debug, the problem seems to be here: https://github.com/signintech/gopdf/blob/master/list_cache_content.go#L53

When adding char, it creates one "boxes" of chars per font configuration. When the font config is different (bold vs normal, new color, etc.), it creates a new "box". The coordinate x,y of the next "box" is calculated on the line above.

If I understand correctly the code, it adds the width of the "box" to x to float the box to the left. But in our case, the next box should be just behind the previous box and not x+previous_box_width if that make sense.

[nmaupu]

I fixed it https://github.com/signintech/gopdf/pull/232

[vantaboard]

@oneplus1000 can you close this issue if it has been resolved?