ImageCropFilter

Introduction

The vtkImageCropFilter will crop a vtkImageData. This will only crop against
IJK-aligned planes.

Note this is slow on large datasets due to CPU-bound
cropping.

Methods

extend

Method used to decorate a given object (publicAPI+model) with vtkImageCropFilter characteristics.

Argument	Type	Required	Description
publicAPI		Yes	object on which methods will be bounds (public)
model		Yes	object on which data structure will be bounds (protected)
initialValues	IImageCropFilterInitialValues	No	(default: {})

getCroppingPlanes

Get The cropping planes, in IJK space.

getCroppingPlanesByReference

Get The cropping planes, in IJK space.

isResetAvailable

newInstance

Method used to create a new instance of vtkImageCropFilter

Argument	Type	Required	Description
initialValues	IImageCropFilterInitialValues	No	for pre-setting some of its content

requestData

Argument	Type	Required	Description
inData		Yes
outData		Yes

reset

setCroppingPlanes

Argument	Type	Required	Description
croppingPlanes		Yes

setCroppingPlanesFrom

Argument	Type	Required	Description
croppingPlanes		Yes

Source

index.d.ts

import { vtkAlgorithm, vtkObject } from "../../../interfaces";

type CroppingPlanes = number[];

/**
 *
 */
export interface IImageCropFilterInitialValues {
	croppingPlanes?: CroppingPlanes;
}

type vtkImageCropFilterBase = vtkObject & vtkAlgorithm;

export interface vtkImageCropFilter extends vtkImageCropFilterBase {

	/**
	 * Get The cropping planes, in IJK space.
	 * @default [0, 0, 0, 0, 0, 0].
	 */
	getCroppingPlanes(): CroppingPlanes;

	/**
	 * Get The cropping planes, in IJK space.
	 * @default [0, 0, 0, 0, 0, 0].
	 */
	getCroppingPlanesByReference(): CroppingPlanes;

	/**
	 *
	 */
	isResetAvailable(): boolean;

	/**
	 *
	 */
	reset(): void;

	/**
	 *
	 * @param inData
	 * @param outData
	 */
	requestData(inData: any, outData: any): void;

	/**
	 *
	 * @param croppingPlanes
	 */
	setCroppingPlanes(croppingPlanes: CroppingPlanes): boolean;

	/**
	 *
	 * @param croppingPlanes
	 */
	setCroppingPlanesFrom(croppingPlanes: CroppingPlanes): boolean;
}

/**
 * Method used to decorate a given object (publicAPI+model) with vtkImageCropFilter characteristics.
 *
 * @param publicAPI object on which methods will be bounds (public)
 * @param model object on which data structure will be bounds (protected)
 * @param {IImageCropFilterInitialValues} [initialValues] (default: {})
 */
export function extend(publicAPI: object, model: object, initialValues?: IImageCropFilterInitialValues): void;

/**
 * Method used to create a new instance of vtkImageCropFilter
 * @param {IImageCropFilterInitialValues} [initialValues] for pre-setting some of its content
 */
export function newInstance(initialValues?: IImageCropFilterInitialValues): vtkImageCropFilter;


/**
 * The vtkImageCropFilter will crop a vtkImageData. This will only crop against
 * IJK-aligned planes. 
 * 
 * Note this is slow on large datasets due to CPU-bound
 * cropping.
 */
export declare const vtkImageCropFilter: {
	newInstance: typeof newInstance;
	extend: typeof extend;
}
export default vtkImageCropFilter;

index.js

import macro from 'vtk.js/Sources/macros';
import vtkImageData from 'vtk.js/Sources/Common/DataModel/ImageData';
import vtkDataArray from 'vtk.js/Sources/Common/Core/DataArray';

const { vtkErrorMacro } = macro;

// ----------------------------------------------------------------------------
// vtkImageCropFilter methods
// ----------------------------------------------------------------------------

function vtkImageCropFilter(publicAPI, model) {
  // Set our className
  model.classHierarchy.push('vtkImageCropFilter');

  // --------------------------------------------------------------------------

  publicAPI.reset = () => {
    const data = publicAPI.getInputData();
    if (data) {
      publicAPI.setCroppingPlanes(...data.getExtent());
    }
  };

  // --------------------------------------------------------------------------

  publicAPI.requestData = (inData, outData) => {
    // implement requestData
    const input = inData[0];

    if (!input) {
      vtkErrorMacro('Invalid or missing input');
      return;
    }

    const scalars = input.getPointData().getScalars();

    if (!scalars) {
      vtkErrorMacro('No scalars from input');
      return;
    }

    const extent = input.getExtent();
    const cropped =
      model.croppingPlanes && model.croppingPlanes.length === 6
        ? extent.map((e, i) => {
            if (i % 2 === 0) {
              // min plane
              return Math.max(e, Math.round(model.croppingPlanes[i]));
            }
            // max plane
            return Math.min(e, Math.round(model.croppingPlanes[i]));
          })
        : extent.slice();

    if (
      cropped[0] === extent[0] &&
      cropped[1] === extent[1] &&
      cropped[2] === extent[2] &&
      cropped[3] === extent[3] &&
      cropped[4] === extent[4] &&
      cropped[5] === extent[5]
    ) {
      const sameAsInput = vtkImageData.newInstance();
      sameAsInput.shallowCopy(input); // Force new mtime
      outData[0] = sameAsInput;
      return;
    }

    // reorder if needed
    for (let i = 0; i < 3; ++i) {
      if (cropped[i * 2] > cropped[i * 2 + 1]) {
        [cropped[i * 2], cropped[i * 2 + 1]] = [
          cropped[i * 2 + 1],
          cropped[i * 2],
        ];
      }
    }

    // restrict crop bounds based on extent bounds
    for (let i = 0; i < 6; i += 2) {
      // min case
      cropped[i] = Math.max(cropped[i], extent[i]);
      // max case
      cropped[i + 1] = Math.min(cropped[i + 1], extent[i + 1]);
    }

    const numberOfComponents = scalars.getNumberOfComponents();
    const componentSize =
      (cropped[1] - cropped[0] + 1) *
      (cropped[3] - cropped[2] + 1) *
      (cropped[5] - cropped[4] + 1) *
      numberOfComponents;
    const scalarsData = scalars.getData();

    const dims = input.getDimensions();
    const jStride = numberOfComponents * dims[0];
    const kStride = numberOfComponents * dims[0] * dims[1];
    const beginOffset = (cropped[0] - extent[0]) * numberOfComponents;
    const stripSize = (cropped[1] - cropped[0] + 1) * numberOfComponents; // +1 because subarray end is exclusive

    // crop image
    const croppedArray = new scalarsData.constructor(componentSize);
    let index = 0;
    for (let k = cropped[4]; k <= cropped[5]; ++k) {
      for (let j = cropped[2]; j <= cropped[3]; ++j) {
        const begin =
          beginOffset + (j - extent[2]) * jStride + (k - extent[4]) * kStride;
        const end = begin + stripSize;
        const slice = scalarsData.subarray(begin, end);
        croppedArray.set(slice, index);
        index += slice.length;
      }
    }
    const outImage = vtkImageData.newInstance({
      extent: cropped,
      origin: input.getOrigin(),
      direction: input.getDirection(),
      spacing: input.getSpacing(),
    });

    const croppedScalars = vtkDataArray.newInstance({
      name: scalars.getName(),
      numberOfComponents,
      values: croppedArray,
    });

    outImage.getPointData().setScalars(croppedScalars);

    outData[0] = outImage;
  };

  publicAPI.isResetAvailable = () => {
    if (model.croppingPlanes == null || model.croppingPlanes.length === 0) {
      return false;
    }
    const data = publicAPI.getInputData();
    if (data) {
      const originalExtent = data.getExtent();
      const findDifference = originalExtent.find(
        (v, i) => Math.abs(model.croppingPlanes[i] - v) > Number.EPSILON
      );
      return findDifference !== undefined;
    }
    return false;
  };
}

// ----------------------------------------------------------------------------
// Object factory
// ----------------------------------------------------------------------------

const DEFAULT_VALUES = {
  // croppingPlanes: null,
};

// ----------------------------------------------------------------------------

export function extend(publicAPI, model, initialValues = {}) {
  Object.assign(model, DEFAULT_VALUES, initialValues);

  // Make this a VTK object
  macro.obj(publicAPI, model);

  // Also make it an algorithm with one input and one output
  macro.algo(publicAPI, model, 1, 1);

  // no orientation support yet
  macro.setGetArray(publicAPI, model, ['croppingPlanes'], 6);

  // Object specific methods
  vtkImageCropFilter(publicAPI, model);
}

// ----------------------------------------------------------------------------

export const newInstance = macro.newInstance(extend, 'vtkImageCropFilter');

// ----------------------------------------------------------------------------

export default { newInstance, extend };