{WebTwainObject} Buffer Manage

/**

* Return the imageId of an image specified by the index.
* @param index The index of the image.

*/
IndexToImageID(index: number): number;

/**
 * Return the index of an image specified by the imageId.
 * @param imageId The imageId of the image.
 */
ImageIDToIndex(imageId: number): number;

/**
 * Remove all tags from the specified image.
 * @param index Specify the image.
 */
ClearImageTags(index: number): boolean;

/**
 * Filter images by the specified tag.
 * @param tag The tag used as the filter. If nothing or an empty string is used, the filter is cleared.
 */
FilterImagesByTag(tag: string): boolean;

/**
 * Set a default tag for newlay acquired images.
 * @param tag Specifies the tag.
 */
SetDefaultTag(tag: string): boolean;

/**
 * Add a tag to specified images.
 * @param indices Specifies images to be tagged.
 * @param tag Specify the tag.
 */
TagImages(indices: number[], tag: string): boolean;

/**
 * Return the pixel bit depth of the specified image.
 * @param index Specify the image.
 */
GetImageBitDepth(index: number): number;

/**
 * Return the height (in pixels) of the specified image.
 * @param index Specify the image.
 */
GetImageHeight(index: number): number;

/**
 * Return the width (in pixels) of the specified image.
 * @param index Specify the image.
 */
GetImageWidth(index: number): number;

/**
 * Return the horizontal resolution of the specified image.
 * @param index Specify the image.
 */
GetImageXResolution(index: number): number;

/**
 * Return the vertical resolution of the specified image.
 * @param index Specify the image.
 */
GetImageYResolution(index: number): number;

/**
 * Return the skew angle of the specified image.
 * @param index Specify the image.
 * @param successCallback A callback function that is executed if the request succeeds.
 * @param failureCallback A callback function that is executed if the request fails.
 * @argument angle The skew angle.
 * @argument errorCode The error code.
 * @argument errorString The error string.
 */
GetSkewAngle(
    index: number,
    successCallback?: (
        angle: number) => void,
    failureCallback?: (
        errorCode: number, 
        errorString: string) => void
): number | void;

/**
 * Return the skew angle of the specified rectangle on the specified image.
 * @param index Specify the image.
 * @param left The x-coordinate of the upper-left corner of the rectangle.
 * @param top The y-coordinate of the upper-left corner of the rectangle.
 * @param right The x-coordinate of the lower-right corner of the rectangle.
 * @param bottom The y-coordinate of the lower-right corner of the rectangle.
 * @param successCallback A callback function that is executed if the request succeeds.
 * @param failureCallback A callback function that is executed if the request fails.
 * @argument angle The skew angle.
 * @argument errorCode The error code.
 * @argument errorString The error string.
 */
GetSkewAngleEx(
    index: number,
    left: number,
    top: number,
    right: number,
    bottom: number,
    successCallback?: (
        angle: number) => void,
    failureCallback?: (
        errorCode: number, 
        errorString: string) => void
): number | void;

/**
 * Calculate the size in bytes of the specified image assuming it's resized to the given dimensions.
 * @param index Specify the image.
 * @param width Specify the width.
 * @param height Specify the height.
 */ 
GetImageSize(index: number, width: number, height: number): number;

/**
 * Calculate the size in bytes of the specified image assuming an expected file type.
 * @param index Specify the image.
 * @param type Sepcify the expected file type.
 */ 
GetImageSizeWithSpecifiedType(index: number, type: Dynamsoft.EnumDWT_ImageType | number): number;

/**
 * Calculate the size in bytes of all selected images assuming an expected file type.
 * @param type Sepcify the expected file type.
 */
GetSelectedImagesSize(type: Dynamsoft.EnumDWT_ImageType | number): number;

/**
 * Return the internal URL of the specified image. 
 * @param index Specify the image.
 * @param width The width of the image (>150).
 * @param height The height of the image (>150).
 */
GetImagePartURL(index: number, width?: number, height?: number): string;

/**
 * Return the direct URL of the specified image. 
 * @param index Specify the image.
 * @param width The width of the image (>150).
 * @param height The height of the image (>150).
 */
GetImageURL(index: number, width?: number, height?: number): string;

/**
 * Return the index of the current image in the buffer or 
 * Set the image specified by index as the current image.
 */
CurrentImageIndexInBuffer: number;

/**
 * Return how many images are held in the buffer
 */
readonly HowManyImagesInBuffer: number;

/**
 * Return or set how many images can be held in the buffer.
 */ 
MaxImagesInBuffer: number;

/**
 * Return the indices of the selected images.
 */
readonly SelectedImagesIndices: number[];

/**
 * Select all images and return the indices.
 */
SelectAllImages(): number[];

/**
 * Select the specified images.
 * @param indices Specify one or multiple images.
 */
SelectImages(indices: number[]): boolean;

/**
 * Change the position of an image in the buffer.
 * @param from Specify the original position by index.
 * @param to Specify the target position by index.
 */
MoveImage(from: number, to: number): boolean;

/**
 * Exchange the positions of two images.
 * @param index1 Specify the 1st image.
 * @param index2 Specify the 2nd image.
 */
SwitchImage(index1: number, index2: number): boolean;

/**

* Remove the specified image.
* @param index Specify the image.

*/
RemoveImage(index: number): boolean;

/**
 * Remove all images.
 */
RemoveAllImages(): boolean;

/**
 * Remove all selected images.
 */
RemoveAllSelectedImages(): boolean;

/**
 * Specify a aspect ratio to be used when selecting a rectangle on an image.
 */
SelectionRectAspectRatio: number; 

/**
 * Return the deviation of the pixels in the current image.
 */
readonly BlankImageCurrentStdDev: number;

/**
 * Return or set the maximum deviation of the pixels in an image which is used to determine whether the image is blank.
 */
BlankImageMaxStdDev: number;

/**
 * Returns or sets the dividing line between black and white.
 */
BlankImageThreshold: number;

/**
 * Return or set how much physical memory is allowed for storing images currently 
 * loaded in Dynamic Web TWAIN. Once the limit is reached, images will be cached on the hard disk.
 */
BufferMemoryLimit: number;

/** 
 * Check whether the specified image is blank.
 * @param index Specify the image.
 */ 
IsBlankImage(index: number): boolean;

/** 
 * Check whether the specified image is blank.
 * @param index Specify the image.
 */
IsBlankImageExpress(index: number): boolean;

/**
 * Return or set whether the feature of disk caching is enabled.
 */
IfAllowLocalCache: boolean;

/**
 * A built-in callback triggered when a change occurs in the buffer.
 * @argument indexString Array of the changed index(indices).
 * @argument type Operation type. 
   1 means new image(s) were added at the tail, 
   2 means image(s) were inserted before the current index, 
   3 means image(s) are deleted, 
   4 means image(s) are modified, 
 * @argument index Index of the current image.
 */
RegisterEvent('OnBitmapChanged',
    function (
        indexString: number[],
        type: number,
        index: number
    ) {}
): boolean; 

/**
 * A built-in callback triggered when the top index currently displayed in the viewer changes.
 * @argument index Index of the current image.
 */
RegisterEvent('OnTopImageInTheViewChanged',
    function (index: number) {}
): boolean; 

/**
 * A built-in callback triggered when images in the buffer are dragged to new positions.
 * @argument indexPairs The list of index changes.
 */
RegisterEvent('OnIndexChangeDragDropDone',
    function (indexPairs: Pair[]) {}
): boolean; 

Pair: [from: number, to: number];