Selenium Marionette getLocation nullpointer - selenium

Question

I'm encountering:
Exception in thread "main" java.lang.NullPointerException at org.openqa.selenium.remote.RemoteWebElement.getLocation(RemoteWebElement.java:338)
while trying to get a BufferedImage of the captcha at https://signup.live.com/:
public BufferedImage getCaptchaBufferedImage() throws IOException, InterruptedException {
System.out.println("Looking for captcha image");
this.wait.until(ExpectedConditions.visibilityOfElementLocated(By.id("hipTemplateContainer")));
System.out.println("Found image");
WebElement element = this.driver.findElement(By.id("hipTemplateContainer"));
System.out.println(element.getAttribute("outerHTML"));
List<WebElement> childs = element.findElements(By.xpath(".//*"));
WebElement firstChild = childs.get(0);
System.out.println(firstChild.getAttribute("outerHTML"));
List<WebElement> childs2 = firstChild.findElements(By.xpath(".//*"));
WebElement imageChild = childs2.get(0);
System.out.println(imageChild.getAttribute("outerHTML"));
((JavascriptExecutor) this.driver).executeScript("arguments[0].scrollIntoView(true);", imageChild);
String id = imageChild.getAttribute("id");
this.wait.until(ExpectedConditions.visibilityOfElementLocated(By.id(id)));
**Point point = firstChild.getLocation();**
byte[] img_bytes = ((TakesScreenshot) this.driver).getScreenshotAs(OutputType.BYTES);
BufferedImage imageScreen = ImageIO.read(new ByteArrayInputStream(img_bytes));
System.out.println("Downloaded image");
double d = Double.parseDouble(firstChild.getCssValue("height").split("px")[0]);
int height = (int) d;
double e = Double.parseDouble(firstChild.getCssValue("width").split("px")[0]);
int width = (int) e;
BufferedImage captcha = imageScreen.getSubimage(point.getX(), point.getY(), width, height);
JFrame frame = new JFrame();
frame.getContentPane().setLayout(new FlowLayout());
frame.getContentPane().add(new JLabel(new ImageIcon(captcha)));
frame.pack();
frame.setVisible(true);
return captcha;
}
I've looked all over the net, can't figure this one out.. Possible bug in Selenium 3.0? This code works if I skip getting the offset of the image and just hardcode the values in getSubImage()..

Answer 1

I tried for more than 2 hours and guess what? I found the issue.
Issue:
It is because getScreenshotAs is taking only the visible part of the page (after scrolling to the captcha) but not complete the page, hence resulting in all the issues. It resulted in the Y coordinate returned by the Point (1041), is relative to the complete web page, but the screenshot image has different Y-coordinate for the captcha (300) relative to the partial page. hence resulted in the following exception:
java.awt.image.RasterFormatException: (y + height) is outside of Raster
X-coordinate is the same value in both complete web page and partial
web page.
so, hardcoding the Y-coordinate to 300 solved the issue temporararliy. BUt the actual issue is that why screenshot is not taken for the complete page instead of jus visible page. may be the bug in the latest geckodriver (firefox driver). tried in Firefox 49 version with Selenium 3 version, geckodriver v0.1.11 and Java 1.8.
Following is the code. please try and let me know:
driver.get("https://signup.live.com/");
driver.manage().window().maximize();
System.out.println("Looking for captcha image");
WebDriverWait wait = new WebDriverWait(driver, 10);
wait.until(ExpectedConditions.visibilityOfElementLocated(By.id("hipTemplateContainer")));
System.out.println("Found image");
WebElement element = driver.findElement(By.id("hipTemplateContainer"));
System.out.println(element.getAttribute("outerHTML"));
List<WebElement> childs = element.findElements(By.xpath(".//*"));
WebElement firstChild = childs.get(0);
System.out.println(firstChild.getAttribute("outerHTML"));
List<WebElement> childs2 = firstChild.findElements(By.xpath(".//*"));
WebElement imageChild = childs2.get(0);
System.out.println(imageChild.getAttribute("outerHTML"));
((JavascriptExecutor) driver).executeScript("arguments[0].scrollIntoView(true);", imageChild);
String id = imageChild.getAttribute("id");
wait.until(ExpectedConditions.visibilityOfElementLocated(By.id(id)));
Point point = imageChild.getLocation();
int width = imageChild.getSize().getWidth();
int height = imageChild.getSize().getHeight();
System.out.println("height: " + height + "\t weight : " + width);
System.out.println("X co-ordinate: " + point.getX());
System.out.println("Y co-ordinate: " + point.getY());
File screenshot = ((TakesScreenshot) driver).getScreenshotAs(OutputType.FILE);
FileUtils.copyFile(screenshot, new File("G:\\naveen\\screenshot.png"));
BufferedImage imageScreen = ImageIO.read(screenshot);
System.out.println("Downloaded image");
BufferedImage captcha = imageScreen.getSubimage(245, 300, width, height);
ImageIO.write(captcha, "png", screenshot);
FileUtils.copyFile(screenshot, new File("G:\\naveen\\screenshot1.png"));
JFrame frame = new JFrame();
frame.getContentPane().setLayout(new FlowLayout());
frame.getContentPane().add(new JLabel(new ImageIcon(captcha)));
frame.pack();
frame.setVisible(true);
Following are screenshots saved:
Only visible web page is saved.
sub image - captcha image: