Text Boxes

A text box is a shape carrying a text body, and the text body is paragraphs holding runs. Adding a box and filling it is a few calls; editing text that is already in a deck means walking down to the run and assigning its text field, because the TextBox wrapper has no reader for the paragraphs it already contains.

The two ways of getting at text on a slide are not interchangeable:

GetTextBoxes tests the txBox attribute, which layouts do not set on their placeholders, so a title or body from a template will never appear in its result. If a deck seems to have no text boxes, it is almost certainly a templated deck and you want the placeholder API instead. See Use a Template.

Editing existing text

ppt, err := presentation.Open("source.pptx")
if err != nil {
    panic(err)
}
defer ppt.Close()

tb := ppt.Slides()[0].GetTextBoxes()[0]
for _, p := range tb.X().TxBody.P {
    for _, tr := range p.EG_TextRun {
        if r := tr.TextRunChoice.R; r != nil {
            r.T = "Edited TextBox text"
        }
    }
}

X() drops out of the wrapper into the schema types, which is the only route to the existing content. EG_TextRun is a choice: TextRunChoice.R is a regular run, Br is a line break and Fld is a field such as a slide number. Only R carries text, and the other two leave it nil, so a paragraph containing a line break will panic a loop that dereferences R unconditionally. The example does not guard this; the snippet above does.

There is no setter for the text of an existing box, and no Paragraphs() method on TextBox the way there is on PlaceHolder. Assigning r.T is the supported way to change it.

Adding a text box

newTb := slide.AddTextBox()
newTb.SetOffsetX(measurement.Inch * 5)
newTb.SetOffsetY(measurement.Inch * 4)

newPara := newTb.AddParagraph()
newRun := newPara.AddRun()
newRun.SetText("New TextBox text")

SetOffsetX and SetOffsetY take a float64 in measurement units and write the same shape offset that Properties().SetPosition(x, y) writes with a measurement.Distance. Use whichever reads better; setting both is redundant, and the last call wins. A new box is 3 by 1 inches at the top left corner until you move or resize it.

Limitations

SetTextAnchor allocates fresh body properties for the box, discarding the square wrapping and autofit that AddTextBox set. Call it before anything else that touches the text body.

A text box with a text body and no paragraphs fails Validate with “slide shape with a txbody must contain paragraphs”, so add at least one paragraph to every box you create.

Text is not measured or reflowed by the library. The box keeps the size you gave it whatever the text does, and whether a viewer clips or shrinks the overflow is up to the autofit setting and the viewer.

Run the example

The example opens source.pptx, prints the text of every run in every text box on the first slide, rewrites the first run, adds a second box five inches across and four down, and saves mod.pptx.

git clone https://github.com/unidoc/unioffice-examples.git
cd unioffice-examples/presentation/textbox
go run main.go

If this is your first time using UniOffice, follow the getting started guide to create an API key and set up your development environment.

Sample input

Sample output

I am a TextBox 1
I am a TextBox 2
I am a TextBox 3