Is there a view that reveals the baseline, median and/or cap height for lines of type?

Sandee -- In your example, green is baseline, lavender is the cap height. The bits that stick out below the baseline and above the x-height are called undershoot and overshoot, respectively. And in some fonts, serifs and flex can stick out above the cap height.

Marie -- Here is a script that places guides at the descender, baseline, x-height, cap height and descender of some selected text. (Unlike baseline, descender, and ascender, cap height and x-height are not available to scripts and determining them requires a convoluted method.) As it is, the script places guides only at the baseline and the cap height. To enable the three other guides, remove the two slashes at the beginning of the lines. To change the colour of the guides, change the RGB values. The guides are placed on a new layer, which you can hide or remove.

Peter

(function () {
  
  var page = app.windows[0].activePage;
  var lines = app.selection[0].lines.everyItem().getElements();
  var ch;
  var xcap;
  
  function characterHeights (ch) {
    app.scriptPreferences.measurementUnit = MeasurementUnits.POINTS;
    var o = {};
    var frame = app.documents[0].pages[0].textFrames.add ({geometricBounds: [0, 0, 20, 20], contents: 'x'});
    frame.paragraphs[0].appliedParagraphStyle = ch.appliedParagraphStyle;
    frame.textFramePreferences.firstBaselineOffset = FirstBaseline.X_HEIGHT;
    o.xHeight = frame.characters[0].baseline;
    frame.textFramePreferences.firstBaselineOffset = FirstBaseline.CAP_HEIGHT;
    o.capHeight = frame.characters[0].baseline;
    frame.remove();
    return o;
  }
  function addGuide (pos, colour) {
    page.guides.add (app.documents[0].layers.item ('metrics'), {
      guideType: GuideTypeOptions.RULER,
      location: pos,
      orientation: HorizontalOrVertical.HORIZONTAL,
      guideColor: colour,
    });
  }
  if (app.selection.length === 0 || !app.selection[0].hasOwnProperty('baseline')) {
    alert ('Select some text.');
    exit();
  }
  if (app.documents[0].layers.item ('metrics') === null) {
    app.documents[0].layers.add ({name: 'metrics'});
  }
  for (var i = 0; i < lines.length; i++) {
    ch = lines.characters[0];
    xcap = characterHeights (ch);
    //addGuide (ch.baseline - ch.ascent, [0, 255, 0]);   // Ascender
    addGuide (ch.baseline - xcap.capHeight, [255, 0, 0]);  // Cap height
    //addGuide (ch.baseline - xcap.xHeight, [255, 0, 0]);   // x height
    addGuide (ch.baseline, [0, 0, 255]);   // Baseline
    //addGuide (ch.baseline + ch.descent, [0, 255, 0]);   // Descender
  }
}());

MarieMeyer wrote: CC on a Mac. I'm wondering it there is a view that reveals the locations of the baseline, median and/or cap height for lines of type. I'd like to place some graphics and have them snap into place.

Hi Marie,

if your text is working with a baseline grid a placed graphic would snap to that grid.

For  cap-height or x-height you probably could select a character, "H" for cap-height, "x" for x-height and create a duplicate outline of the selection and align your graphic to the outlined character.

To get a duplicate outlined character just select a character and when on a Mac press the alt key and use menu Type > Create Outlines

Regards,
Uwe

No, but you can pull ruler guides out of the horizontal ruler to mark any or all three.