Scroll to an exact position when clicking the scrollbar track doesn't…

… work in case of variable row heights and isVerticalScrollExact = true (#712)

Co-authored-by: Daniela Buzatu <daniela.buzatu@crispico.com>

src/reducers/index.js

@@ -213,12 +213,16 @@ const slice = createSlice({
       state.scrollX = scrollX;
     },
     updateRowHeights(state, action) {
-      const firstUpdatedRowIndex = action.payload || 0;
-      if (firstUpdatedRowIndex >= state.getInternal().rowUntilOffsetsAreExact) {
+      let firstUpdatedRowIndex = action.payload || 0;
+      if (firstUpdatedRowIndex >= state.rowSettings.rowsCount) {
         return;
       }
-      // Invalidate all the previous computed row heights till the updated row
-      state.getInternal().rowUntilOffsetsAreExact = firstUpdatedRowIndex;
+
+      // Recompute all the updated rows heights
+      while (firstUpdatedRowIndex < state.rowSettings.rowsCount) {
+        updateRowHeight(state, firstUpdatedRowIndex++);
+      }
+
       // Refresh the current scroll position according to the new row heights
       const currentScrollY =
         state
@@ -237,18 +241,28 @@ const slice = createSlice({
  * @param {!Object} state
  * @private
  */
-function initializeRowHeightsAndOffsets(state) {
-  const { rowHeight, rowsCount, subRowHeight } = state.rowSettings;
-  const defaultFullRowHeight = rowHeight + subRowHeight;
-  const rowOffsetIntervalTree = PrefixIntervalTree.uniform(
+export function initializeRowHeightsAndOffsets(state) {
+  const {
+    rowHeight,
     rowsCount,
-    defaultFullRowHeight
-  );
-  const scrollContentHeight = rowsCount * defaultFullRowHeight;
+    subRowHeight,
+    rowHeightGetter,
+    subRowHeightGetter,
+  } = state.rowSettings;
+  const defaultFullRowHeight = rowHeight + subRowHeight;
+  let scrollContentHeight = 0;
   const storedHeights = new Array(rowsCount);
   for (let idx = 0; idx < rowsCount; idx++) {
-    storedHeights[idx] = defaultFullRowHeight;
+    if (state.isVerticalScrollExact) {
+      storedHeights[idx] = rowHeightGetter(idx) + subRowHeightGetter(idx);
+    } else {
+      storedHeights[idx] = defaultFullRowHeight;
+    }
+    scrollContentHeight += storedHeights[idx];
   }
+
+  const rowOffsetIntervalTree = new PrefixIntervalTree(storedHeights);
+
   state.scrollContentHeight = scrollContentHeight;
   Object.assign(state.getInternal(), {
     rowOffsetIntervalTree,

test/reducers/initializeRowHeightsAndOffsets-test.js

@@ -0,0 +1,72 @@
+import { initializeRowHeightsAndOffsets } from '../../src/reducers';
+import { assert } from 'chai';
+import clone from 'lodash/clone';
+
+describe('initializeRowHeightsAndOffsets', function () {
+  let oldState;
+  let newState;
+  beforeEach(function () {
+    const createInternalStateGetter = () => {
+      const internalState = {};
+      return () => internalState;
+    };
+    oldState = {
+      getInternal: createInternalStateGetter(),
+      rowSettings: {
+        rowsCount: 80,
+        rowHeight: 125,
+        subRowHeight: 0,
+        rowHeightGetter: (rowIndex) => (rowIndex % 2 == 0 ? 100 : 200),
+        subRowHeightGetter: () => 0,
+      },
+    };
+    newState = clone(oldState);
+    newState.getInternal = createInternalStateGetter();
+  });
+  it('if isVerticalScrollExact = false then rowheight is used instead of rowHeightGetter() for all the rows', function () {
+    initializeRowHeightsAndOffsets(newState);
+    for (let rowIdx = 0; rowIdx < 80; rowIdx++) {
+      assert.strictEqual(
+        newState.getInternal().storedHeights[rowIdx],
+        125,
+        'expected stored height of 125 for each row'
+      );
+      assert.strictEqual(
+        newState.getInternal().rowOffsetIntervalTree.get(rowIdx),
+        125,
+        'expected row offsets for each row to be set to 125'
+      );
+    }
+    assert.strictEqual(
+      newState.scrollContentHeight,
+      10000,
+      'expected scrollContentHeight to be 10000'
+    );
+  });
+
+  it('if isVerticalScrollExact = true then rowHeightGetter() is used for all the rows', function () {
+    newState.isVerticalScrollExact = true;
+    initializeRowHeightsAndOffsets(newState);
+    for (let rowIdx = 0; rowIdx < 80; rowIdx++) {
+      const expectedRowHeight = rowIdx % 2 == 0 ? 100 : 200;
+      assert.strictEqual(
+        newState.getInternal().storedHeights[rowIdx],
+        expectedRowHeight,
+        'expected stored height of ' + expectedRowHeight + ' for row ' + rowIdx
+      );
+      assert.strictEqual(
+        newState.getInternal().rowOffsetIntervalTree.get(rowIdx),
+        expectedRowHeight,
+        'expected row offsets for row ' +
+          rowIdx +
+          ' to be set to ' +
+          expectedRowHeight
+      );
+    }
+    assert.strictEqual(
+      newState.scrollContentHeight,
+      12000,
+      'expected scrollContentHeight to be 12000'
+    );
+  });
+});