[time picker] Only update time when updating input in TimePicker

packages/x-date-pickers/src/DesktopTimePicker/DesktopTimePicker.test.tsx

@@ -219,6 +219,37 @@ describe('<DesktopTimePicker />', () => {
     );
   });
 
+  it('should only update the time change editing through the input', () => {
+    const handleChange = spy();
+    render(
+      <DesktopTimePicker
+        ampm
+        onChange={handleChange}
+        open
+        renderInput={(params) => <TextField {...params} />}
+        value={adapterToUse.date('2019-01-01T04:20:00.000')}
+      />,
+    );
+
+    // call `onChange` with an invalid time
+    fireEvent.change(screen.getByRole('textbox'), {
+      target: { value: ':00 pm' },
+    });
+
+    expect(handleChange.callCount).to.equal(1);
+    expect(adapterToUse.isValid(handleChange.lastCall.args[0])).to.equal(false);
+
+    // call `onChange` with a valid time
+    fireEvent.change(screen.getByRole('textbox'), {
+      target: { value: '07:00 pm' },
+    });
+
+    expect(handleChange.callCount).to.equal(2);
+    expect(handleChange.lastCall.args[0]).toEqualDateTime(
+      adapterToUse.date('2019-01-01T19:00:00.000'),
+    );
+  });
+
   context('input validation', () => {
     const shouldDisableTime: TimePickerProps['shouldDisableTime'] = (value) => value === 10;
 

packages/x-date-pickers/src/DesktopTimePicker/DesktopTimePicker.tsx

@@ -18,6 +18,13 @@ const valueManager: PickerStateValueManager<unknown, unknown> = {
   parseInput: parsePickerInputValue,
   areValuesEqual: (utils: MuiPickersAdapter<unknown>, a: unknown, b: unknown) =>
     utils.isEqual(a, b),
+  mergeOldAndNewValues: (utils, prevValue, newValue) => {
+    if (prevValue == null) {
+      return newValue;
+    }
+
+    return utils.mergeDateAndTime(prevValue, newValue);
+  },
 };
 
 export interface DesktopTimePickerProps<TDate = unknown>

packages/x-date-pickers/src/MobileTimePicker/MobileTimePicker.tsx

@@ -15,6 +15,13 @@ const valueManager: PickerStateValueManager<unknown, unknown> = {
   parseInput: parsePickerInputValue,
   areValuesEqual: (utils: MuiPickersAdapter<unknown>, a: unknown, b: unknown) =>
     utils.isEqual(a, b),
+  mergeOldAndNewValues: (utils, prevValue, newValue) => {
+    if (prevValue == null) {
+      return newValue;
+    }
+
+    return utils.mergeDateAndTime(prevValue, newValue);
+  },
 };
 
 export interface MobileTimePickerProps<TDate = unknown>

packages/x-date-pickers/src/internals/hooks/useMaskedInput.tsx

@@ -79,6 +79,7 @@ export const useMaskedInput = ({
     setInnerInputValue(finalString);
 
     const date = finalString === null ? null : utils.parse(finalString, inputFormat);
+
     if (ignoreInvalidInputs && !utils.isValid(date)) {
       return;
     }

packages/x-date-pickers/src/internals/hooks/usePickerState.ts

@@ -12,6 +12,11 @@ export interface PickerStateValueManager<TInputValue, TDateValue> {
   ) => boolean;
   emptyValue: TDateValue;
   parseInput: (utils: MuiPickersAdapter<TDateValue>, value: TInputValue) => TDateValue;
+  mergeOldAndNewValues?: (
+    utils: MuiPickersAdapter<TDateValue>,
+    prevValue: TDateValue | null,
+    value: TDateValue,
+  ) => TDateValue;
 }
 
 export type PickerSelectionState = 'partial' | 'shallow' | 'finish';
@@ -49,7 +54,21 @@ export const usePickerState = <TInput, TDateValue>(
     return { committed: date, draft: date };
   }
 
-  const parsedDateValue = valueManager.parseInput(utils, value);
+  const parsedDateValue = React.useMemo(
+    () => valueManager.parseInput(utils, value),
+    [valueManager, utils, value],
+  );
+
+  const [lastValidDateValue, setLastValidDateValue] = React.useState<TDateValue | null>(
+    parsedDateValue,
+  );
+
+  React.useEffect(() => {
+    if (parsedDateValue != null) {
+      setLastValidDateValue(parsedDateValue);
+    }
+  }, [parsedDateValue]);
+
   const [draftState, dispatch] = React.useReducer(
     (state: Draftable<TDateValue>, action: DraftAction<TDateValue>): Draftable<TDateValue> => {
       switch (action.type) {
@@ -141,14 +160,24 @@ export const usePickerState = <TInput, TDateValue>(
     [acceptDate, disableCloseOnSelect, isMobileKeyboardViewOpen, draftState.draft],
   );
 
+  const handleInputChange = React.useCallback(
+    (date: TDateValue, keyboardInputValue?: string) => {
+      const cleanDate = valueManager.mergeOldAndNewValues
+        ? valueManager.mergeOldAndNewValues(utils, lastValidDateValue, date)
+        : date;
+      onChange(cleanDate, keyboardInputValue);
+    },
+    [onChange, valueManager, lastValidDateValue, utils],
+  );
+
   const inputProps = React.useMemo(
     () => ({
-      onChange,
+      onChange: handleInputChange,
       open: isOpen,
       rawValue: value,
       openPicker: () => setIsOpen(true),
     }),
-    [onChange, isOpen, value, setIsOpen],
+    [handleInputChange, isOpen, value, setIsOpen],
   );
 
   const pickerState = { pickerProps, inputProps, wrapperProps };