Manage Presentation Text in Node.js via .NET

What this page is about

Add a text box to a slide, then change its text, font size, and bold style in JavaScript with Aspose.Slides for Node.js via .NET.

Overview

In Aspose.Slides, text on a slide belongs to a shape. An auto shape, such as a rectangle, has a text frame; the text frame contains paragraphs, and each paragraph contains portions, which are runs of text with the same formatting. You change the text through the text frame and the font through the format of a portion.

This article adds a text box to a slide and saves the presentation. It then opens the saved file and changes the text box’s text, font size, and bold style.

The examples need a project set up as described in Installation. Save each example as a .js file in the project folder and run it from that folder with node.

Note

Aspose.Slides for Node.js via .NET has no API reference of its own. It mirrors the Aspose.Slides for .NET API with camelCase names, so the API links in this article lead to the matching classes and members in the Aspose.Slides for .NET API reference.

Add a Text Box

To add a text box, add an auto shape to a slide with the addAutoShape method and give it text with the addTextFrame method. The following example adds a rectangle to the first slide of a new presentation and saves the presentation as text-box.pptx:

const { Presentation, ShapeType, SaveFormat } = require("aspose.slides.via.net");

const presentation = new Presentation();
try {
    const slide = presentation.slides.get(0);

    // The position (x, y) and the size (width, height) are in points.
    const textBox = slide.shapes.addAutoShape(ShapeType.Rectangle, 100, 100, 500, 80);
    textBox.addTextFrame("Quarterly report");

    presentation.save("text-box.pptx", SaveFormat.Pptx);
    console.log("Saved text-box.pptx");
} finally {
    presentation.dispose();
}

The slide in text-box.pptx contains a rectangle, 500 points wide and 80 points high, with the text “Quarterly report” in the default font and size. The next example changes this text box.

Change the Text and Its Formatting

The following example opens text-box.pptx, which the previous example created, and gets the first shape on the first slide. Shapes such as pictures and tables have no text frame, so the example checks that the shape is an AutoShape before it uses the shape’s textFrame. It then does the following:

It replaces the text through the text property of the text frame. After that, the text frame contains one paragraph with one portion.
It gets that portion from the paragraphs and portions collections and reads its portionFormat.
It sets fontHeight, the font size in points, and fontBold, which takes a NullableBool value.

const { Presentation, AutoShape, NullableBool, SaveFormat } = require("aspose.slides.via.net");

const presentation = new Presentation("text-box.pptx");
try {
    const shape = presentation.slides.get(0).shapes.get(0);
    if (shape instanceof AutoShape) {
        const textFrame = shape.textFrame;
        textFrame.text = "Quarterly report: third quarter";

        const portionFormat = textFrame.paragraphs.get(0).portions.get(0).portionFormat;
        portionFormat.fontHeight = 32;
        portionFormat.fontBold = NullableBool.True;

        presentation.save("text-box-updated.pptx", SaveFormat.Pptx);
        console.log("Saved text-box-updated.pptx");
    } else {
        console.log("The first shape on the first slide is not an AutoShape.");
    }
} finally {
    presentation.dispose();
}

In text-box-updated.pptx, the text box shows “Quarterly report: third quarter” in bold 32-point type. Because the new text is a single portion, the two formatting properties apply to all of it. Without a license, every save adds an evaluation watermark. Because text-box.pptx was itself saved in evaluation mode, text-box-updated.pptx contains two; see Evaluate Aspose.Slides.

FAQ

Why does fontBold take a NullableBool value instead of true or false?

A portion can leave a property undefined and inherit it from the paragraph, the shape, or the slide’s layout and master. NullableBool.NotDefined means “inherit”, while NullableBool.True and NullableBool.False override the inherited value. Assigning true or false throws an error. For the same reason, fontHeight returns NaN when the portion inherits its font size.

How do I change the text color?

Set the fill of the portion format: assign FillType.Solid to portionFormat.fillFormat.fillType, and then assign a color such as "#FF0000" to portionFormat.fillFormat.solidFillColor.color. Add FillType to the names that you import from the package.

How do I format only part of the text?

Formatting belongs to portions, so put that part of the text in a portion of its own. Create the portion with Portion.CreatePortionFromText, append it to a paragraph with the add method of the paragraph’s portions collection, and then set the new portion’s portionFormat. Add Portion to the names that you import from the package.

Why does reading text return “… text has been truncated due to evaluation version limitation”?

Without a license, Aspose.Slides returns only the first five characters of any longer text that you read, such as textFrame.text, followed by this notice. Text that you write is saved in full. Apply a license as described in Licensing to read the complete text.

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