aShot

WebDriver Screenshot utility

Takes a screenshot of a WebElement on different platforms (i.e. desktop browsers, iOS Simulator Mobile Safari, Android Emulator Browser)
Decorates screenshots
Provides flexible screenshot comparison

WebElement view

aShot takes a screenshot in three simple steps:

Capture a screenshot of the entire page
Find the element's size and position
Crop the original screenshot

As a result, aShot provides an image of the WebElement

Maven dependency

<dependency>
    <groupId>ru.yandex.qatools.ashot</groupId>
    <artifactId>ashot</artifactId>
    <version>1.5.2</version>
</dependency>

Capturing the entire page

Different WebDrivers take screenshots differently. Some WebDrivers provide a screenshot of the entire page while others handle the viewport only. aShot might be configured to handle browsers with the viewport problem. This example configuration gives a screenshot of the entire page even for Chrome, Mobile Safari, etc.

new AShot()
  .shootingStrategy(ShootingStrategies.viewportPasting(100))
  .takeScreenshot(webDriver);

There are built-in strategies in ShootingStrategies for different use cases. In case there are no suitable strategies it is possible to build it using existing strategies as decorators or implement your own.

CutStrategy cutting = new VariableCutStrategy(HEADER_IOS_8_MIN, HEADER_IOS_8_MAX, VIEWPORT_MIN_IOS_8_SIM);
ShootingStrategy rotating = new RotatingDecorator(cutting, ShootingStrategies.simple());
ShootingStrategy pasting = new ViewportPastingDecorator(rotating)
    .withScrollTimeout(scrollTimeout);   
new AShot()
  .shootingStrategy(pasting)
  .takeScreenshot(webDriver);

Capturing the WebElement

One can take a screenshot of particular WebElement(s). Just specify the element(s).

WebElement myWebElement = webDriver.findElement(By.cssSelector("#my_element"));
new AShot()
  .takeScreenshot(webDriver, myWebElement);

As noted earlier, aShot will find an element's size and position and crop the original image. WebDriver API provides a method to find the WebElement's coordinates but different WebDriver implementations behave differently. The most general approach to find coordinates is to use jQuery, so aShot uses jQuery by default. But some drivers have problems with Javascript execution such as OperaDriver. In this case there is another way to find the WebElement's coordinates.

new AShot()
  .coordsProvider(new WebDriverCoordsProvider()) //find coordinates with WebDriver API
  .takeScreenshot(webDriver, myWebElement);

Feel free to implement your own CoordsProvider. Pull requests are welcome.

Prettifying the screenshot

So, let's take a simple screenshot of the weather snippet at Yandex.com.

new AShot()
  .takeScreenshot(webDriver, yandexWeatherElement);

Here is the result.

DefaultCropper is used by default. Can we do better? Yes, we can.

new AShot()
  .withCropper(new IndentCropper()           // set custom cropper with indentation
                 .addIndentFilter(blur()))   // add filter for indented areas
  .takeScreenshot(driver, yandexWeatherElement);

This screenshot provides more information about position relative other elements and blurs indent in order to focus on the WebElement.

Screenshot comparison

.takeScreenshot() returns a Screenshot object which contains an image and data for comparison. One can ignore some WebElements from comparison.

Screenshot myScreenshot = new AShot()
  .addIgnoredElement(By.cssSelector("#weather .blinking_element")) // ignored element(s)
  .takeScreenshot(driver, yandexWeatherElement);

Use ImageDiffer to find a difference between two images.

ImageDiff diff = new ImageDiffer().makeDiff(myScreenshot, anotherScreenshot);
BufferedImage diffImage = diff.getMarkedImage(); // comparison result with marked differences

Several elements comparison

(since 1.2)
Sometimes one needs to take a screenshot of several independent elements. In this case aShot computes complex comparison area.

List<WebElement> elements = webDriver.findElements(By.cssSelector("#my_element, #popup"));
new AShot()
  .withCropper(new IndentCropper() 
                 .addIndentFilter(blur()))
  .takeScreenshot(webDriver, elements);

Here is the result.

One can see only specified elements (the header and the popup) are focused and will be compared if needed.

Ignoring of pixels with predefined color

You can set the color of pixels which should be excluded from comparison of screenshots.

ImageDiffer imageDifferWithIgnored = new ImageDiffer().withIgnoredColor(Color.MAGENTA);
ImageDiff diff = imageDifferWithIgnored.makeDiff(templateWithSomeMagentaPixels, actualScreenshot);
assertFalse(diff.hasDiff());

Any pixels in template with color MAGENTA (255, 0, 255 in RGB) will be ignored during comparison.

vergeman / ashot