Source

File: wp-admin/includes/media.php

function wp_media_insert_url_form( $default_view = 'image' ) {
	/** This filter is documented in wp-admin/includes/media.php */
	if ( ! apply_filters( 'disable_captions', '' ) ) {
		$caption = '
		<tr class="image-only">
			<th scope="row" class="label">
				<label for="caption"><span class="alignleft">' . __( 'Image Caption' ) . '</span></label>
			</th>
			<td class="field"><textarea id="caption" name="caption"></textarea></td>
		</tr>';
	} else {
		$caption = '';
	}

	$default_align = get_option( 'image_default_align' );

	if ( empty( $default_align ) ) {
		$default_align = 'none';
	}

	if ( 'image' === $default_view ) {
		$view        = 'image-only';
		$table_class = '';
	} else {
		$view        = 'not-image';
		$table_class = $view;
	}

	return '
	<p class="media-types"><label><input type="radio" name="media_type" value="image" id="image-only"' . checked( 'image-only', $view, false ) . ' /> ' . __( 'Image' ) . '</label> &nbsp; &nbsp; <label><input type="radio" name="media_type" value="generic" id="not-image"' . checked( 'not-image', $view, false ) . ' /> ' . __( 'Audio, Video, or Other File' ) . '</label></p>
	<p class="media-types media-types-required-info">' .
		/* translators: %s: Asterisk symbol (*). */
		sprintf( __( 'Required fields are marked %s' ), '<span class="required">*</span>' ) .
	'</p>
	<table class="describe ' . $table_class . '"><tbody>
		<tr>
			<th scope="row" class="label" style="width:130px;">
				<label for="src"><span class="alignleft">' . __( 'URL' ) . '</span> <span class="required">*</span></label>
				<span class="alignright" id="status_img"></span>
			</th>
			<td class="field"><input id="src" name="src" value="" type="text" required onblur="addExtImage.getImageData()" /></td>
		</tr>

		<tr>
			<th scope="row" class="label">
				<label for="title"><span class="alignleft">' . __( 'Title' ) . '</span> <span class="required">*</span></label>
			</th>
			<td class="field"><input id="title" name="title" value="" type="text" required /></td>
		</tr>

		<tr class="not-image"><td></td><td><p class="help">' . __( 'Link text, e.g. &#8220;Ransom Demands (PDF)&#8221;' ) . '</p></td></tr>

		<tr class="image-only">
			<th scope="row" class="label">
				<label for="alt"><span class="alignleft">' . __( 'Alternative Text' ) . '</span></label>
			</th>
			<td class="field"><input id="alt" name="alt" value="" type="text" required />
			<p class="help">' . __( 'Alt text for the image, e.g. &#8220;The Mona Lisa&#8221;' ) . '</p></td>
		</tr>
		' . $caption . '
		<tr class="align image-only">
			<th scope="row" class="label"><p><label for="align">' . __( 'Alignment' ) . '</label></p></th>
			<td class="field">
				<input name="align" id="align-none" value="none" onclick="addExtImage.align=\'align\'+this.value" type="radio"' . ( 'none' === $default_align ? ' checked="checked"' : '' ) . ' />
				<label for="align-none" class="align image-align-none-label">' . __( 'None' ) . '</label>
				<input name="align" id="align-left" value="left" onclick="addExtImage.align=\'align\'+this.value" type="radio"' . ( 'left' === $default_align ? ' checked="checked"' : '' ) . ' />
				<label for="align-left" class="align image-align-left-label">' . __( 'Left' ) . '</label>
				<input name="align" id="align-center" value="center" onclick="addExtImage.align=\'align\'+this.value" type="radio"' . ( 'center' === $default_align ? ' checked="checked"' : '' ) . ' />
				<label for="align-center" class="align image-align-center-label">' . __( 'Center' ) . '</label>
				<input name="align" id="align-right" value="right" onclick="addExtImage.align=\'align\'+this.value" type="radio"' . ( 'right' === $default_align ? ' checked="checked"' : '' ) . ' />
				<label for="align-right" class="align image-align-right-label">' . __( 'Right' ) . '</label>
			</td>
		</tr>

		<tr class="image-only">
			<th scope="row" class="label">
				<label for="url"><span class="alignleft">' . __( 'Link Image To:' ) . '</span></label>
			</th>
			<td class="field"><input id="url" name="url" value="" type="text" /><br />

			<button type="button" class="button" value="" onclick="document.forms[0].url.value=null">' . __( 'None' ) . '</button>
			<button type="button" class="button" value="" onclick="document.forms[0].url.value=document.forms[0].src.value">' . __( 'Link to image' ) . '</button>
			<p class="help">' . __( 'Enter a link URL or click above for presets.' ) . '</p></td>
		</tr>
		<tr class="image-only">
			<td></td>
			<td>
				<input type="button" class="button" id="go_button" style="color:#bbb;" onclick="addExtImage.insert()" value="' . esc_attr__( 'Insert into Post' ) . '" />
			</td>
		</tr>
		<tr class="not-image">
			<td></td>
			<td>
				' . get_submit_button( __( 'Insert into Post' ), '', 'insertonlybutton', false ) . '
			</td>
		</tr>
	</tbody></table>';
}