Google Sheets App Script - Custom Function to find RichText (Bold/Italic) locations - google-apps-script

Question

I'm currently working on a project that's using Google Sheets to keep track of/maintain some translations of text (effectively some meta-data and then 2 columns for the original text and the translation).
The final application has some word-wrapping constraints and a variable-width font, so I created a custom function in app script to apply line breaks in order to facilitate visualizing how it would look.
function preview(text)
{
if(text.startsWith('=')) // Copy of something else, so we don't care
return text;
text = text.trimEnd();
text = text.replace("<4A>", "\n\n"); // For the sake of the preview, just treat <4A> as a new box
text = text.replace(/\<&[a-zA-Z0-9]+\>/g,"────────"); // Assume the longest length (8 * 8)
text = text.replace(/<\*.>/g,""); // Get rid of exit codes
text = text.replace(/<S.+?>/g,""); // Get rid of special effects
var output = "";
var boxes = text.split("\n\n"); // Double newline is a forced new text box
for (var i = 0; i < boxes.length; i++)
{ // For each intentional text box
var box = boxes[i];
box = box.replace("<4E>","\n"); // Will technically forcibly always draw on the second line
var lines = box.split('\n');
var newboxFlag = false; // Flag to indicate if we draw a new line or new box
for (var j = 0; j < lines.length; j++)
{ // For each intentional line in this box
words = lines[j].split(' ');
var word = "";
var currentLineLen = 0;
for(var k = 0; k < words.length; k++)
{
word += words[k];
var wordWidth = 0;
for (var l = 0; l < word.length; l++)
{
var char = word.charAt(l);
wordWidth += getCharacterWidth(char);
}
if(wordWidth + currentLineLen > 0x89)
{ // This word won't fit on this line, so it goes to a new line
// Strip the first space, and just assume we don't have a string longer than 136 characters
word = word.substr(1);
wordWidth -= getCharacterWidth(' ');
// Add a new line and flip the newboxFlag
output += '\n';
if(newboxFlag) output += '\n';
newboxFlag ^= 1;
currentLineLen = 0;
}
currentLineLen += wordWidth
output += word;
word = " ";
}
if (j != lines.length - 1)
{
output += '\n'; // line length is reset at the top
if(newboxFlag) output += '\n';
newboxFlag ^= 1;
}
}
if(i != boxes.length - 1) output += '\n\n'; // If we're not on the last box, add the double new line
}
return output;
}
and I call it with =preview(<CELL>) (getCharacterWidth just pulls an integer from a character <-> width mapping).
This function works fine with raw text that does not contain any bold or italic characters.
The problem is, bold and italic characters often take more space than their normal counterparts, and in some cases will cause the previewed output text to incorrectly omit newlines where there should be some.
For example, the original text would be:
This is italic. This is bold. This is bold and italic.
=preview(text) should ideally be something like:
This is italic.
This is bold.
This is bold
and italic.
but instead, it might end up being like this:
This is italic.
This is bold. This
is bold and italic.
Since the additional width of the bold/italic characters is not being accounted for, the function believes it has enough space to fit another word on the line.
It's OK if I can't output it, but I at least need to be able to identify what text is bold or italic. In Google Sheets, how can I write a custom function that is aware of RichText?

Answer 1

Thanks to TheMaster's comments, I was able to create a solution by changing my function to the following:
function preview(startcol, startrow)
{
var str = String.fromCharCode(64 + startcol) + startrow;
var richtext = SpreadsheetApp.getActiveSpreadsheet().getRange(str).getRichTextValue();
var runs = richtext.getRuns();
...
and setting my call to
=preview(COLUMN(<CELL>), ROW(<CELL>))
By looping over the runs accounting for getTextStyle().IsBold() or .IsItalic(), I can account for the RichText attributes.
if(runs[i].getTextStyle().IsBold() && runs[i].getTextStyle().IsItalic())
{
wordWidth += getCharacterWidthBoldItalic(char);
}
else if(runs[i].getTextStyle().IsBold())
{
wordWidth += getCharacterWidthBold(char);
}
else if(runs[i].getTextStyle().IsItalic())
{
wordWidth += getCharacterWidthItalic(char);
}
else
{
wordWidth += getCharacterWidth(char);
}