how to get kerning and tracking value using extendscript?

[Arunkumar25715058ufpl]

Hi,

Please help to get kerning and tracking value for each character using extendscript.

I try this

var textFrame = doc.selection[i];
var textRange = textFrame.textRange;
var textCharactersAll = textRange.characters;
for (var i = 0; i < textCharactersAll.length; i++) {
	var character = textCharactersAll[i];
	var tracking = character.characterAttributes.tracking;
	// Log or do whatever you want with the tracking value
	alert("Character " + (i+1) + " tracking: " + tracking);
	
}

[RobOctopus · Accepted solution]

the text range and the characters are conflicting. text range doesnt havent characters in this instance. the characters are a part of the text frame and the text range is part of the text frame. both of the below examples gave me correct answers for the tracking

/*using Characters from a textFrame */
var TF = app.activeDocument.selection[0];
var textCharactersAll = TF.characters;
for (var i = 0; i < textCharactersAll.length; i++) {
	var character = textCharactersAll[i];
	var tracking = character.characterAttributes.tracking;
	// Log or do whatever you want with the tracking value
	alert("Character " + (i+1) + " tracking: " + tracking);
}

/*using a textRange and the indexes of it */
var TF = app.activeDocument.selection[0];
var TR = TF.textRanges;
for (var i = 0; i < TR.length; i++) {
	var character = TR[i];
	var tracking = character.characterAttributes.tracking;
	// Log or do whatever you want with the tracking value
	alert("Character " + (i+1) + " tracking: " + tracking);
}

side note: good idea to not create variables that are the same name as the value you are getting. it can get confusing later on. A lot of example code will just throw "my" in front of whatever to help signify that the variable is something you created. I replaced textFRame and textRange with TF and TR respectively

[Arunkumar25715058ufpl]

Hi RobOctopus,

Thanks for your reply. Now, I am getting the tracking values as per your suggestion. how to get kerning values?

[m1b]

Hi @Arunkumar25715058ufpl, you can use

var km = myCharacter.kerningMethod;
var k = myCharacter.kerning;

You must check kerningMethod first, because if the kerningMethod is an AutoKernType then it will not have a kerning value and may throw an error. if you want to set the kerning, then set the kerningMethod to AutoKernType.NOAUTOKERN.

- Mark

[Arunkumar25715058ufpl]

Hi Mark,

Kerning Method is AutoKernType.AUTO. But i need to get second character value (200) only.

[m1b · Accepted solution]

Hi @Arunkumar25715058ufpl, surprisingly I couldn't find how to do this.

As a workaround, I wrote this script that should achieve what you need. It converts a TextFrame to manual kerning. If you just want the values (without converting) you can just collect the `k` var and return an array of the kerning values.

Let me know if it helps.

- Mark

/**
 * Example code to convert auto-kerned text into manual kerning.
 * There must be an easier way... right? I just don't know it.
 * @author m1b
 * @discussion https://community.adobe.com/t5/illustrator-discussions/how-to-get-kerning-and-tracking-value-using-extendscript/m-p/14502970
 */
(function () {

    var doc = app.activeDocument,
        myTextFrame = doc.selection[0] || 0;

    if (
        !myTextFrame
        || 'TextFrame' !== myTextFrame.constructor.name
    )
        return alert('Please select a text frame and try again.');

    // read the kerning values
    var kerningValues = getKerning(myTextFrame);

    // apply them to the text frame
    applyKerning(myTextFrame, kerningValues);

    // alert(kerningValues);

})();

/**
 * Returns the textFrame's kerning values as an array.
 * @author m1b
 * @version 2024-03-22
 * @param {TextFrame} textFrame - an Illustrator TextFrame.
 * @returns {Array<Number>} - the kerning values.
 */
function getKerning(textFrame) {

    // we'll assume zero kerning before first character
    var kerning = [];

    // work with a duplicate textFrame, unrotated
    var dup = textFrame.duplicate(),
        len = dup.characters.length - 1,
        r = getRotationFromMatrix(dup.matrix);

    if (0 !== r)
        // unrotate it (otherwise `width` is meaningless)
        dup.rotate(-r);

    // the master width
    var width = dup.width;

    // get the manual values
    for (var i = 0; i <= len; i++) {
        try {
            kerning[i] = dup.characters[i].kerning;
        } catch (error) { }
    };

    // now determine auto kerning values using duplicates
    for (var i = 0, ch, tf; i < len; i++) {

        if (undefined != kerning[i + 1])
            continue;

        tf = dup.duplicate();
        ch = tf.characters[i];

        // remove auto kerning (kerning will be zero)
        ch.kerningMethod = AutoKernType.NOAUTOKERN;

        // calculate auto kerning amount by change in width
        kerning[i + 1] = Math.round((width - tf.width) * 1000 / ch.size)

        tf.remove();

    }

    dup.remove();

    return kerning;

};

/**
 * Apply an array of kerning values to a textFrame.
 * @author m1b
 * @version 2024-03-22
 * @param {TextFrame} textFrame - an Illustrator TextFrame.
 * @param {Array<Number>} kerning - array of kerning values.
 */
function applyKerning(textFrame, kerning) {

    // remove auto kerning
    textFrame.textRange.kerningMethod = AutoKernType.NOAUTOKERN;

    var len = Math.min(textFrame.characters.length, kerning.length);

    for (var i = len - 1; i >= 0; i--)
        if (undefined != kerning[i])
            textFrame.characters[i].kerning = kerning[i];

};

/**
 * Returns the rotation amount, in degrees,
 * of the given (not skewed) matrix.
 * @param {Matrix} matrix - an Illustrator Matrix.
 * @returns {Number}
 */
function getRotationFromMatrix(matrix) {

    if (matrix.constructor.name !== 'Matrix')
        throw Error("getRotationFromMatrix: bad `matrix` supplied.");

    // calculate the horizontal and vertical scaling factors
    var sX = Math.sqrt(matrix.mValueA * matrix.mValueA + matrix.mValueC * matrix.mValueC),
        radians = Math.acos(matrix.mValueA / sX),
        degrees = radians * (180 / Math.PI);

    return Math.round(degrees * 1000) / 1000;

};

Edit 2024-03-22: updated code due to bugs found by @Arunkumar25715058ufpl. Split into `getKerning` and `applyKerning` functions. Now handles mix of manual and auto kerning values.

[Arunkumar25715058ufpl]

Hi Mark,

I run your code it returns the k value as 0 or -10 only. I attached my ai file. Also, I set kerning manually in Illustrator for the second character. I try to get that value using extendscript.

[Arunkumar25715058ufpl]

Hi Mark,

Example ai file

https://www.dropbox.com/scl/fi/5mzt8a07ujbxzzjkyaip8/kerningexample.ai?rlkey=65bav9so6v23tlc984rjmfy... 

[m1b]

Thanks @Arunkumar25715058ufpl, sorry about the bug! I have updated code now.

- Mark

[Arunkumar25715058ufpl]

Hi Mark,

Thanks for your support. Now I get the kerning values.