refactor: add getRanges function DataArray public api

Author: jmannau

Sources/Common/Core/DataArray/index.d.ts

@@ -83,6 +83,11 @@ export interface vtkDataArray extends vtkObject {
    */
   setRange(rangeValue: vtkRange, componentIndex: number): Range;
 
+  /**
+   *
+   */
+  getRanges(): vtkRange[];
+
   /**
    * Set the given tuple at the given index.
    * @param {Number} idx

Sources/Common/Core/DataArray/index.js

@@ -281,6 +281,22 @@ function vtkDataArray(publicAPI, model) {
     return model.rangeTuple;
   };
 
+  publicAPI.getRanges = () => {
+    /** @type {import('../../../interfaces').vtkRange[]} */
+    const ranges = [];
+    for (let i = 0; i < model.numberOfComponents; i++) {
+      const [min, max] = publicAPI.getRange(i);
+      /** @type {import('../../../interfaces').vtkRange} */
+      const range = {
+        min,
+        max,
+        component: i,
+      };
+      ranges.push(range);
+    }
+    return ranges;
+  };
+
   publicAPI.setTuple = (idx, tuple) => {
     const offset = idx * model.numberOfComponents;
     for (let i = 0; i < model.numberOfComponents; i++) {

Sources/Common/Core/DataArray/test/testDataArray.js

@@ -131,6 +131,36 @@ test('Test vtkDataArray getRange function with NaN values.', (t) => {
   t.end();
 });
 
+test('Test vtkDataArray getRanges function with single-channel data.', (t) => {
+  // create a data array with a single channel.
+  const newArray = new Uint16Array(256 * 3);
+
+  // fill the new array with the pattern 0,1,2,3,4,5, ..., 767.
+  for (let i = 0; i < 256 * 3; ++i) {
+    newArray[i] = i;
+  }
+
+  const da = vtkDataArray.newInstance({
+    numberOfComponents: 1,
+    values: newArray,
+  });
+
+  t.ok(
+    da.getRanges().length === 1,
+    'getRanges should return an array of 1 vtkRange objects'
+  );
+  t.ok(
+    da.getRanges()[0].min === 0,
+    'the first component returned by getRanges minimum value should be 0'
+  );
+  t.ok(
+    da.getRanges()[0].max === 767,
+    'the first component returned by getRanges maximum value should be 767'
+  );
+
+  t.end();
+});
+
 test('Test vtkDataArray getTuple', (t) => {
   const da = vtkDataArray.newInstance({
     numberOfComponents: 3,
@@ -202,6 +232,39 @@ test('Test vtkDataArray getRange function with multi-channel data.', (t) => {
   t.end();
 });
 
+test('Test vtkDataArray getRanges function with multi-channel data.', (t) => {
+  // create a data array with 3 channel data.
+  const newArray = new Uint16Array(256 * 3);
+
+  // fill the new array with the pattern 1,2,3, 1,2,3
+  // such that each channel has 1,1,1  2,2,2  3,3,3 respectively.
+  for (let i = 0; i < 256; ++i) {
+    newArray[i * 3] = i;
+    newArray[i * 3 + 1] = i * 2;
+    newArray[i * 3 + 2] = i * 3;
+  }
+
+  const da = vtkDataArray.newInstance({
+    numberOfComponents: 3,
+    values: newArray,
+  });
+
+  const ranges = da.getRanges();
+
+  t.ok(
+    ranges.length === 3,
+    'getRanges should return an array of 3 vtkRange objects'
+  );
+  t.ok(ranges[0].min === 0, 'component:0 minimum value should be 0');
+  t.ok(ranges[0].max === 255, 'component:0 maximum value should be 255');
+  t.ok(ranges[1].min === 0, 'component:1 minimum value should be 0');
+  t.ok(ranges[1].max === 510, 'component:1 maximum value should be 510');
+  t.ok(ranges[2].min === 0, 'component:2 minimum value should be 0');
+  t.ok(ranges[2].max === 765, 'component:2 maximum value should be 765');
+
+  t.end();
+});
+
 test('Test vtkDataArray insertNextTuple', (t) => {
   const dataArray = vtkDataArray.newInstance({
     dataType: VtkDataTypes.UNSIGNED_CHAR,

Sources/Rendering/OpenGL/ImageMapper/index.js

@@ -1323,17 +1323,7 @@ function vtkOpenGLImageMapper(publicAPI, model) {
           // range from the original scalars array and set the range to the
           // scalars array.  This means there is no need to re-calculate the
           // ranges for the scalars array.
-          ranges = [];
-          for (let i = 0; i < numComp; i++) {
-            const [min, max] = imgScalars.getRange(i);
-            /** @type{ import("../../../interfaces").vtkRange } */
-            const range = {
-              min,
-              max,
-              component: i,
-            };
-            ranges.push(range);
-          }
+          ranges = imgScalars.getRanges();
         }
       } else {
         vtkErrorMacro('Reformat slicing not yet supported.');