等待图像完全加载 Selenium WebDriver

Question

看到有一个问题：Selenium-Webdriver Ruby --> How to wait for images to be full load after click

但似乎没有人直接回答：我需要等待图像完全加载，而不仅仅是在 DOM 中呈现，使用 selenium WebDriver。我该怎么办？ 目前我正在使用

  public static void waitUntilVisible(WebDriver webDriver, By locator) {
    WebDriverWait driverWait = new WebDriverWait(webDriver, TIMEOUT);
    driverWait.until(visibilityOfElementLocated(locator));
  }

它使用

  /**
   * An expectation for checking that an element is present on the DOM of a page and visible.
   * Visibility means that the element is not only displayed but also has a height and width that is
   * greater than 0.
   *
   * @param locator used to find the element
   * @return the WebElement once it is located and visible
   */
  public static ExpectedCondition<WebElement> visibilityOfElementLocated(
    final By locator) {
    return new ExpectedCondition<WebElement>() {
      @Override
      public WebElement apply(WebDriver driver) {
        try {
          return elementIfVisible(findElement(locator, driver));
        } catch (StaleElementReferenceException e) {
          return null;
        }
      }

      @Override
      public String toString() {
        return "visibility of element located by " + locator;
      }
    };
  }

但如果图像已经有高度和宽度，即使图像尚未加载，它也可能被视为可见

Answer 1

您可以执行一些 javascript 来询问 DOM。具体来说，就是HTMLImageElement的complete属性。

public static void waitUntilVisible(WebDriver webDriver, By locator) {
    WebDriverWait driverWait = new WebDriverWait(webDriver, TIMEOUT);
    WebElement el = webDriver.findElement(locator);
    driverWait.until(
        new Predicate<WebDriver>() {
            public boolean apply(WebDriver driver) {
                return ((JavascriptExecutor)driver).executeScript("return arguments[0].complete", el);
            }
        }
    );
}

但请注意complete：

返回一个布尔值，如果浏览器已完成获取图像，无论成功与否。如果图像没有 src 值，它也会显示为真。