code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC licenses this file
  // to you under the Apache License, Version 2.0 (the
  // "License"); you may not use this file except in compliance
  // with the License.  You may obtain a copy of the License at
  //
  //   http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing,
  // software distributed under the License is distributed on an
  // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  // KIND, either express or implied.  See the License for the
  // specific language governing permissions and limitations
  // under the License.
  
  package org.openqa.selenium.interactions;
  
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  import org.junit.jupiter.api.Test;
  import org.openqa.selenium.By;
  import org.openqa.selenium.JavascriptExecutor;
  import org.openqa.selenium.WebDriver;
  import org.openqa.selenium.WebElement;
  import org.openqa.selenium.testing.JupiterTestBase;
  
  /** Tests operations that involve scroll wheel. */
  class DefaultWheelTest extends JupiterTestBase {
  
    private Actions getBuilder(WebDriver driver) {
      return new Actions(driver);
    }
  
    @Test
    void shouldScrollToElement() {
      driver.get(
          appServer.whereIs("scrolling_tests/frame_with_nested_scrolling_frame_out_of_view.html"));
      WebElement iframe = driver.findElement(By.tagName("iframe"));
  
      assertFalse(inViewport(iframe));
  
      getBuilder(driver).scrollToElement(iframe).perform();
  
      assertTrue(inViewport(iframe));
    }
  
    @Test
    void shouldScrollFromElementByGivenAmount() {
      driver.get(
          appServer.whereIs("scrolling_tests/frame_with_nested_scrolling_frame_out_of_view.html"));
      WebElement iframe = driver.findElement(By.tagName("iframe"));
      WheelInput.ScrollOrigin scrollOrigin = WheelInput.ScrollOrigin.fromElement(iframe);
  
      getBuilder(driver).scrollFromOrigin(scrollOrigin, 0, 200).perform();
  
      driver.switchTo().frame(iframe);
      WebElement checkbox = driver.findElement(By.name("scroll_checkbox"));
      assertTrue(inViewport(checkbox));
    }
  
    @Test
    void shouldScrollFromElementByGivenAmountWithOffset() {
      driver.get(
          appServer.whereIs("scrolling_tests/frame_with_nested_scrolling_frame_out_of_view.html"));
      WebElement footer = driver.findElement(By.tagName("footer"));
      WheelInput.ScrollOrigin scrollOrigin = WheelInput.ScrollOrigin.fromElement(footer, 0, -50);
  
      getBuilder(driver).scrollFromOrigin(scrollOrigin, 0, 200).perform();
  
      WebElement iframe = driver.findElement(By.tagName("iframe"));
      driver.switchTo().frame(iframe);
      WebElement checkbox = driver.findElement(By.name("scroll_checkbox"));
      assertTrue(inViewport(checkbox));
    }
  
    @Test
    void throwErrorWhenElementOriginIsOutOfViewport() {
      assertThrows(
          MoveTargetOutOfBoundsException.class,
          () -> {
            driver.get(
                appServer.whereIs(
                    "scrolling_tests/frame_with_nested_scrolling_frame_out_of_view.html"));
            WebElement footer = driver.findElement(By.tagName("footer"));
            WheelInput.ScrollOrigin scrollOrigin = WheelInput.ScrollOrigin.fromElement(footer, 0, 50);
  
            getBuilder(driver).scrollFromOrigin(scrollOrigin, 0, 200).perform();
          });
    }
  
    @Test
    void shouldScrollFromViewportByGivenAmount() {
      driver.get(
          appServer.whereIs("scrolling_tests/frame_with_nested_scrolling_frame_out_of_view.html"));
      WebElement footer = driver.findElement(By.tagName("footer"));
      int deltaY = footer.getRect().y;
  
      getBuilder(driver).scrollByAmount(0, deltaY).perform();
  
      assertTrue(inViewport(footer));
    }
  
    @Test
    void shouldScrollFromViewportByGivenAmountFromOrigin() {
      driver.get(appServer.whereIs("scrolling_tests/frame_with_nested_scrolling_frame.html"));
      WheelInput.ScrollOrigin scrollOrigin = WheelInput.ScrollOrigin.fromViewport(10, 10);
  
      getBuilder(driver).scrollFromOrigin(scrollOrigin, 0, 200).perform();
  
      WebElement iframe = driver.findElement(By.tagName("iframe"));
      driver.switchTo().frame(iframe);
      WebElement checkbox = driver.findElement(By.name("scroll_checkbox"));
      assertTrue(inViewport(checkbox));
    }
  
    @Test
    void throwErrorWhenOriginOffsetIsOutOfViewport() {
      assertThrows(
          MoveTargetOutOfBoundsException.class,
          () -> {
            driver.get(appServer.whereIs("scrolling_tests/frame_with_nested_scrolling_frame.html"));
            WheelInput.ScrollOrigin scrollOrigin = WheelInput.ScrollOrigin.fromViewport(-10, -10);
  
            getBuilder(driver).scrollFromOrigin(scrollOrigin, 0, 200).perform();
          });
    }
  
    private boolean inViewport(WebElement element) {
  
      String script =
          "for(var e=arguments[0],f=e.offsetTop,t=e.offsetLeft,o=e.offsetWidth,n=e.offsetHeight;\n"
              + "e.offsetParent;)f+=(e=e.offsetParent).offsetTop,t+=e.offsetLeft;\n"
              + "return"
              + " f<window.pageYOffset+window.innerHeight&&t<window.pageXOffset+window.innerWidth&&f+n>\n"
              + "window.pageYOffset&&t+o>window.pageXOffset";
  
      return (boolean) ((JavascriptExecutor) driver).executeScript(script, element);
    }
  }
  