code: function _drawImageBitmap(evt, imageBitmap, alwaysVisible) {
    const eventData = evt.detail;
    const context = getNewContext(eventData.canvasContext.canvas);
  
    const canvasTopLeft = external.cornerstone.pixelToCanvas(eventData.element, {
      x: 0,
      y: 0,
    });
  
    const canvasTopRight = external.cornerstone.pixelToCanvas(eventData.element, {
      x: eventData.image.width,
      y: 0,
    });
  
    const canvasBottomRight = external.cornerstone.pixelToCanvas(
      eventData.element,
      {
        x: eventData.image.width,
        y: eventData.image.height,
      }
    );
  
    const cornerstoneCanvasWidth = external.cornerstoneMath.point.distance(
      canvasTopLeft,
      canvasTopRight
    );
    const cornerstoneCanvasHeight = external.cornerstoneMath.point.distance(
      canvasTopRight,
      canvasBottomRight
    );
  
    const canvas = eventData.canvasContext.canvas;
    const viewport = eventData.viewport;
  
    context.imageSmoothingEnabled = false;
    context.globalAlpha = getLayerAlpha(alwaysVisible);
  
    transformCanvasContext(context, canvas, viewport);
  
    const canvasViewportTranslation = {
      x: viewport.translation.x * viewport.scale,
      y: viewport.translation.y * viewport.scale,
    };
  
    context.drawImage(
      imageBitmap,
      canvas.width / 2 - cornerstoneCanvasWidth / 2 + canvasViewportTranslation.x,
      canvas.height / 2 -
        cornerstoneCanvasHeight / 2 +
        canvasViewportTranslation.y,
      cornerstoneCanvasWidth,
      cornerstoneCanvasHeight
    );
  
    context.globalAlpha = 1.0;
  
    resetCanvasContextTransform(context);
  }
docs: Draws the ImageBitmap the canvas.
  
  @private
  @param  {Object} evt description
  @param {ImageBitmap} imageBitmap
  @param {Boolean} alwaysVisible
  @returns {void}