/**
 * Checks if the provided string is a valid data URL.
 *
 * This function verifies that the input string is a non-null string, does not
 * contain the specific data URL for `.x-icon` images, and matches the
 * `isDataUrlRegex` regular expression for data URLs.
 *
 * The function returns `true` if the string is a valid data URL and `false`
 * otherwise.
 *
 * @param {string} s - The string to check for being a data URL.
 * @returns {boolean} - Returns `true` if the string is a valid data URL,
 *                      `false` otherwise.
 *
 * @example
 * // Valid data URLs
 * console.log(isDataUrl('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUA...')); // true
 * console.log(isDataUrl('data:text/plain;charset=utf-8,Hello%20World!')); // true
 *
 * // Invalid data URLs
 * console.log(isDataUrl('data:image/x-icon;base64,...')); // false (contains x-icon)
 * console.log(isDataUrl('not-a-data-url')); // false
 * console.log(isDataUrl(null)); // false
 */
export declare const isDataUrl: (s: string) => boolean;
/**
 * Checks if the provided source is a valid image source.
 *
 * This function verifies whether the input `src` is a valid image source by performing
 * several checks:
 *
 * 1. **Non-null String Check**: It first checks if `src` is a non-null string using the
 *    `isNonNullString` function.
 *
 * 2. **Trim Whitespace**: The function trims any leading or trailing whitespace from the
 *    source string to ensure accurate validation.
 *
 * 3. **Blob URL Handling**: If the source starts with `blob:http`, it removes the `blob:`
 *    prefix for further validation. Note that `ltrim` should be defined elsewhere in your code.
 *
 * 4. **Validation Checks**: The function then checks if the modified source is:
 *    - A valid data URL using the `isDataUrl` function.
 *    - A string that matches common image file extensions (e.g., `.bmp`, `.jpg`, `.jpeg`,
 *      `.png`, `.gif`, `.svg`) using a regular expression.
 *    - A string that starts with `data:image/`, indicating it is a data URL for an image.
 *
 * The function returns `true` if any of these conditions are met, indicating that the source
 * is a valid image source; otherwise, it returns `false`.
 *
 * @param {any} src - The source to validate as an image source.
 * @returns {boolean} - Returns `true` if the source is a valid image source,
 *                      `false` otherwise.
 *
 * @example
 * // Valid image sources
 * console.log(isValidImageSrc('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUA...')); // true
 * console.log(isValidImageSrc('https://example.com/image.jpg')); // true
 * console.log(isValidImageSrc('image.png')); // true (if file extension is valid)
 *
 * // Invalid image sources
 * console.log(isValidImageSrc(null)); // false
 * console.log(isValidImageSrc('')); // false
 * console.log(isValidImageSrc('not-a-valid-url')); // false
 * console.log(isValidImageSrc('blob:http://example.com/...')); // true (if valid blob URL)
 */
export declare const isValidImageSrc: (src: any) => any;