@kitware/vtk.js/Rendering/Misc/TextureLODsDownloader.js

Visualization Toolkit for the Web

import { m as macro } from '../../macros2.js';

const {
  vtkErrorMacro
} = macro;

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

const getRemoteFileSize = url =>
// This function only works if the server provides a 'Content-Length'.
// For some reason, the 'Content-Length' header does not appear to be
// given for CORS HEAD requests on firefox. So this will not work on
// firefox if the images do not have the same origin as the html file.
// TODO: figure out how to make this work for CORS requests on firefox.
new Promise((resolve, reject) => {
  const xhr = new XMLHttpRequest();
  xhr.open('HEAD', url, true);
  xhr.onreadystatechange = () => {
    if (xhr.readyState === 4) {
      if (xhr.status === 200) {
        const size = xhr.getResponseHeader('Content-Length');
        resolve(size);
      } else {
        console.log('Failed to get remote file size of', url);
        reject(xhr);
      }
    }
  };
  xhr.send();
});

// ----------------------------------------------------------------------------
// vtkTextureLODsDownloader methods
// ----------------------------------------------------------------------------

function vtkTextureLODsDownloader(publicAPI, model) {
  // Set our className
  model.classHierarchy.push('vtkTextureLODsDownloader');
  const internal = {
    downloadStack: []
  };

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

  publicAPI.startDownloads = () => {
    if (!model.texture) {
      vtkErrorMacro('Texture was not set.');
      return;
    }
    if (!model.files || model.files.length === 0) {
      vtkErrorMacro('No files set.');
      return;
    }
    let baseUrl = model.baseUrl;
    if (baseUrl && !baseUrl.endsWith('/')) {
      baseUrl += '/';
    }

    // Create the download stack
    internal.downloadStack = [];
    model.files.forEach(file => internal.downloadStack.push(`${baseUrl}${file}`));
    const downloadNextTexture = () => {
      if (internal.downloadStack.length === 0) {
        return;
      }

      // For later use
      const asyncDownloadNextTexture = () => {
        setTimeout(downloadNextTexture, model.waitTimeBetweenDownloads);
      };
      const img = new Image();
      if (model.crossOrigin) {
        img.crossOrigin = model.crossOrigin;
      }
      const url = internal.downloadStack.shift();
      getRemoteFileSize(url).then(size => {
        if (!size || size / 1024 > model.maxTextureLODSize) {
          if (!size) {
            console.log('Failed to get image size');
          } else {
            console.log('Skipping image', url, ', because it is larger', 'than the max texture size:', model.maxTextureLODSize, 'KiB');
          }
          asyncDownloadNextTexture();
          return;
        }
        img.src = url;
        // Decode the image asynchronously in an attempt to prevent a
        // freeze during rendering.
        // In theory, this should help, but my profiling indicates that
        // it does not help much... maybe it is running in the main
        // thread anyways?
        img.decode().then(() => {
          model.texture.setImage(img);
          if (model.stepFinishedCallback) {
            model.stepFinishedCallback();
          }
          asyncDownloadNextTexture();
        }).catch(encodingError => {
          console.log('Failed to decode image:', img.src);
          console.log('Error is:', encodingError);
          asyncDownloadNextTexture();
        });
      }).catch(xhr => {
        console.log('Failed to get size of:', url);
        console.log('status was:', xhr.status);
        console.log('statusText was:', xhr.statusText);
        asyncDownloadNextTexture();
      });
    };
    setTimeout(downloadNextTexture, model.waitTimeToStart);
  };
}

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

const DEFAULT_VALUES = {
  baseUrl: '',
  files: [],
  texture: null,
  crossOrigin: undefined,
  // The max texture LOD file size in KiB
  maxTextureLODSize: 50000,
  stepFinishedCallback: null,
  // These are in milliseconds
  waitTimeToStart: 4000,
  waitTimeBetweenDownloads: 0
};

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

function extend(publicAPI, model) {
  let initialValues = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : {};
  Object.assign(model, DEFAULT_VALUES, initialValues);
  macro.obj(publicAPI, model);

  // Create get-set macros
  macro.setGet(publicAPI, model, ['baseUrl', 'files', 'texture', 'crossOrigin', 'maxTextureLODSize', 'stepFinishedCallback', 'waitTimeToStart', 'waitTimeBetweenDownloads']);

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

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

const newInstance = macro.newInstance(extend, 'vtkTextureLODsDownloader');

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

var vtkTextureLODsDownloader$1 = {
  newInstance,
  extend
};

export { vtkTextureLODsDownloader$1 as default, extend, newInstance };