我正在使用Selenium Grid在不同的PC上执行GWT Web应用程序的跨浏览器测试。我面临的问题是，生成的屏幕截图（在测试期间拍摄）的大小对于不同的PC是不同的，我想让我的代码通用，即设置屏幕截图的一些默认大小。这是我的代码，我用它来截取屏幕截图，然后将生成的图像与我PC上本地存储的图像进行比较。
首先，我将调用CallScreenshotAndCompareImage方法 arguments（canvas，className）。
这里canvas是WebElement 表示GWT应用程序中的HTML5画布。
FileBase是我项目中本地存储的文件，fileActual是生成的截图图片。
public class Browser {
//ThreadLocal will provide thread-safe tests
protected ThreadLocal<RemoteWebDriver> threadLocal = null;
String serverMachine = "xxx.xxx.xxx.xxx:xxx/hub"; //IP Address of hub
@BeforeTest
@Parameters("browser")
public void setup(String browser) throws MalformedURLException{
if(browser.equalsIgnoreCase("chrome")) {
System.setProperty("webdriver.chrome.driver", ".src/Drivers/chromedriver.exe");
DesiredCapabilities capability = null;
capability = DesiredCapabilities.chrome();
capability.setPlatform(Platform.WINDOWS);
capability.setBrowserName("chrome");
createRemoteWebDriver(capability);
}
else if(browser.equalsIgnoreCase("firefox")) {
System.setProperty("webdriver.gecko.driver", ".src/Drivers/geckodriver.exe");
DesiredCapabilities capability = null;
capability = DesiredCapabilities.firefox();
capability.setPlatform(Platform.WINDOWS);
capability.setBrowserName("firefox");
createRemoteWebDriver(capability);
}
}
public void createRemoteWebDriver(DesiredCapabilities capability) throws MalformedURLException {
threadLocal = new ThreadLocal<RemoteWebDriver>();
threadLocal.set(new RemoteWebDriver(new URL(serverMachine), capability));
}
public WebDriver getDriver() {
return threadLocal.get();
}
public void CallScreenshotAndCompareImage(WebElement element, String className) throws IOException, InterruptedException {
File fileBase1 = new File("./src/Images/baseDrawing"+className+"Chrome.png");
File fileBase2 = new File("./src/Images/baseDrawing"+className+"Firefox.png");
Capabilities cap = ((RemoteWebDriver) getDriver()).getCapabilities();
String browserName = cap.getBrowserName().toLowerCase();
File fileActual = new File("./src/Images/actualDrawing"+className+browserName+".png");
File elementImage = this.takeElementScreenshot(element,"png");
FileUtils.copyFile(elementImage, fileActual);
if(browserName.equalsIgnoreCase("chrome"))
this.compareImage(fileBase1,fileActual);
else if(browserName.equalsIgnoreCase("firefox"))
this.compareImage(fileBase2,fileActual);
Thread.sleep(3000);
}
public File takeElementScreenshot(WebElement element, String imageFormat) throws IOException{
Point elementXY = element.getLocation();
int elementHeight = element.getSize().getHeight();
int elementWidth = element.getSize().getWidth();
Rectangle elementRectArea = new Rectangle(elementWidth,elementHeight);
WrapsDriver wrapsDriver = (WrapsDriver) element;
File pageImage = ((TakesScreenshot)wrapsDriver.getWrappedDriver()).getScreenshotAs(OutputType.FILE);
BufferedImage bufferedImage = ImageIO.read(pageImage);
BufferedImage elementImage = bufferedImage.getSubimage(elementXY.getX(), elementXY.getY(), elementRectArea.width, elementRectArea.height);
ImageIO.write(elementImage, imageFormat, pageImage);
return pageImage;
}
public void compareImage(File fileBase, File fileActual) {
/*
STEPS:
1) For first image file, recognize the contents of the file and decodes it into a BufferedImage which can be directly used by Java 2D.
2) Get the raster from the bufferedImage object which is a copy of image data.
3) Get the DataBuffer associated with the raster.
4) Get the size of the all the banks(data arrays) for the DataBuffer object.
5) Repeat steps 1-4 for the second image file.
6) If sizes of both of the images are different, then images won't be same.
7) If sizes are same, then compare all the data array elements for both of the DataBuffer objects. If they are same. then both images will be same.
*/
try {
BufferedImage bufferedImage = ImageIO.read(fileBase);
DataBuffer dataBufferFirst = bufferedImage.getData().getDataBuffer();
int sizeFirst = dataBufferFirst.getSize();
BufferedImage bufferedImage2 = ImageIO.read(fileActual);
DataBuffer dataBufferSecond = bufferedImage2.getData().getDataBuffer();
int sizeSecond = dataBufferSecond.getSize();
int count=0;
Assert.assertEquals(sizeFirst, sizeSecond,"Size of Base Drawing and actual Drawing is not same");
if(sizeFirst == sizeSecond)
{
for(int i=0; i<sizeFirst; i++)
{
if(dataBufferFirst.getElem(i) != dataBufferSecond.getElem(i)) //getElem() returns the data array element at the specified index.
{
count++;
}
}
Assert.assertEquals(count, 0,"Both images are not same");
}
} catch (Exception e) {
Assert.fail("Failed to compare image files...!!!");
}
}
}
运行此代码后，当我比较基本（本地）图像和实际（生成）图像的属性时，这两个图像之间存在一点差异。
基本绘图：尺寸 - ＆gt; 253 KB，位深度 - ＆gt; 32，尺寸 - ＆gt; 1570 x 873像素
实际绘图：尺寸 - ＆gt; 232 KB，比特深度 - ＆gt; 24，尺寸 - ＆gt; 1570 x 873像素
其他所有图像的属性都是相同的。
我应该在代码中添加什么内容，以便从不同PC生成的屏幕截图始终具有相同的大小？
答案 0 :(得分：1)
问题不在于图像的大小，而在于基本图形中存在且在屏幕截图中缺失的Alpha通道（透明度）。
驱动程序应该返回PNG Base64编码的字符串。但没有说明它应该是24位RGB还是32位RGBA PNG。 因此，为了能够比较缓冲区，您首先必须将它们中的每一个转换为所需的颜色空间。
以下是一个例子：
public static void main(String[] args) throws Exception {
BufferedImage imageA = ImageIO.read(new File("C:\\temp\\img_24bits.png"));
BufferedImage imageB = ImageIO.read(new File("C:\\temp\\img_32bits.png"));
boolean same = isSameImage(imageA, imageB);
}
public static boolean isSameImage(BufferedImage imageA, BufferedImage imageB) throws IOException {
DataBufferInt bufferA = getImageBuffer(imageA);
DataBufferInt bufferB = getImageBuffer(imageB);
if (bufferA.getSize() != bufferB.getSize() || bufferA.getNumBanks() != bufferB.getNumBanks())
return false;
for (int i = 0; i < bufferA.getNumBanks(); ++i) {
if (!Arrays.equals(bufferA.getData(i), bufferB.getData(i)))
return false;
}
return true;
}
private static DataBufferInt getImageBuffer(BufferedImage img) throws IOException {
BufferedImage bi = new BufferedImage(img.getWidth(), img.getHeight(), BufferedImage.TYPE_INT_ARGB);
ColorConvertOp cco = new ColorConvertOp(bi.getColorModel().getColorSpace(), img.getColorModel().getColorSpace(), null);
cco.filter(img, bi);
return (DataBufferInt)bi.getRaster().getDataBuffer();
}
答案 1 :(得分：0)
虽然@Florent B。的答案给了我一个解决方案的方向，但这就是我为解决这个问题所做的工作。
答案 2 :(得分：-1)
我认为您必须使用命令来设置已执行驱动程序的分辨率。 为此，请添加Java
driver.manage().window().setSize(new Dimension (1280, 1024));
。 现在截图将始终具有相同的分辨率。