src/vs/editor/browser/viewParts/lines/viewLine.ts/RenderedViewLine/getVisibleRangesForRange
class RenderedViewLine:	public getVisibleRangesForRange(lineNumber: number, startColumn: number, endColumn: number, context: DomReadingContext): FloatHorizontalRange[] | null {
		if (!this.domNode) {
			return null;
		}
		if (this._pixelOffsetCache !== null) {
			// the text is LTR
			const startOffset = this._readPixelOffset(this.domNode, lineNumber, startColumn, context);
			if (startOffset === -1) {
				return null;
			}

			const endOffset = this._readPixelOffset(this.domNode, lineNumber, endColumn, context);
			if (endOffset === -1) {
				return null;
			}

			return [new FloatHorizontalRange(startOffset, endOffset - startOffset)];
		}

		return this._readVisibleRangesForRange(this.domNode, lineNumber, startColumn, endColumn, context);
	}