this.documentToScreenPosition = function()

in lib/ace/edit_session.js [2212:2305]
81 lines of code
22 McCabe index (conditional complexity)

    this.documentToScreenPosition = function(docRow, docColumn) {
        // Normalize the passed in arguments.
        if (typeof docColumn === "undefined")
            var pos = this.$clipPositionToDocument(docRow.row, docRow.column);
        else
            pos = this.$clipPositionToDocument(docRow, docColumn);

        docRow = pos.row;
        docColumn = pos.column;

        var screenRow = 0;
        var foldStartRow = null;
        var fold = null;

        // Clamp the docRow position in case it's inside of a folded block.
        fold = this.getFoldAt(docRow, docColumn, 1);
        if (fold) {
            docRow = fold.start.row;
            docColumn = fold.start.column;
        }

        var rowEnd, row = 0;


        var rowCache = this.$docRowCache;
        var i = this.$getRowCacheIndex(rowCache, docRow);
        var l = rowCache.length;
        if (l && i >= 0) {
            var row = rowCache[i];
            var screenRow = this.$screenRowCache[i];
            var doCache = docRow > rowCache[l - 1];
        } else {
            var doCache = !l;
        }

        var foldLine = this.getNextFoldLine(row);
        var foldStart = foldLine ?foldLine.start.row :Infinity;

        while (row < docRow) {
            if (row >= foldStart) {
                rowEnd = foldLine.end.row + 1;
                if (rowEnd > docRow)
                    break;
                foldLine = this.getNextFoldLine(rowEnd, foldLine);
                foldStart = foldLine ?foldLine.start.row :Infinity;
            }
            else {
                rowEnd = row + 1;
            }

            screenRow += this.getRowLength(row);
            row = rowEnd;

            if (doCache) {
                this.$docRowCache.push(row);
                this.$screenRowCache.push(screenRow);
            }
        }

        // Calculate the text line that is displayed in docRow on the screen.
        var textLine = "";
        // Check if the final row we want to reach is inside of a fold.
        if (foldLine && row >= foldStart) {
            textLine = this.getFoldDisplayLine(foldLine, docRow, docColumn);
            foldStartRow = foldLine.start.row;
        } else {
            textLine = this.getLine(docRow).substring(0, docColumn);
            foldStartRow = docRow;
        }
        var wrapIndent = 0;
        // Clamp textLine if in wrapMode.
        if (this.$useWrapMode) {
            var wrapRow = this.$wrapData[foldStartRow];
            if (wrapRow) {
                var screenRowOffset = 0;
                while (textLine.length >= wrapRow[screenRowOffset]) {
                    screenRow ++;
                    screenRowOffset++;
                }
                textLine = textLine.substring(
                    wrapRow[screenRowOffset - 1] || 0, textLine.length
                );
                wrapIndent = screenRowOffset > 0 ? wrapRow.indent : 0;
            }
        }
        
        if (this.lineWidgets && this.lineWidgets[row] && this.lineWidgets[row].rowsAbove)
            screenRow += this.lineWidgets[row].rowsAbove;

        return {
            row: screenRow,
            column: wrapIndent + this.$getStringScreenWidth(textLine)[0]
        };
    };