我正在尝试编写检查布局问题的Selenium测试。为此，我在Java端使用Selenium Webdriver，在＃34;浏览器中使用phantomjs。我想使用phantomjs因为它能够制作实际渲染组件的截图。
默认情况下，phantomjs使用抗锯齿渲染文本，这使得难以扫描文本（查找文本基线和进行简单的OCR）。
如何告诉phantomJS不使用抗锯齿？
答案 0 :(得分：0)
我使用以下脏技巧在Linux上禁用phantomjs抗锯齿。 PhantomJS是使用fontconfig构建的，这个库查找文件＆＃34; fonts.conf＆＃34;在多个位置：请参阅https://www.freedesktop.org/software/fontconfig/fontconfig-user.html。
通过创建以下fonts.conf，我们可以为fontconfig禁用抗锯齿：
<match target="font">
<edit mode="assign" name="antialias">
<bool>false</bool>
</edit>
</match>
其中一个位置由环境变量定义，根据规格：$ XDG_CONFIG_HOME / fontconfig / fonts.conf。因此，通过使用上述内容创建/tmp/phantomjs-config/fontconfig/fonts.conf之类的临时文件，然后将XDG_CONFIG_HOME设置为/ tmp / phantomjs-config，我们告诉fontconfig读取该文件。
但有一个问题：默认情况下，PhantomJSDriver类不允许设置环境变量。这很难过，因为底层的工作人员代码PhantomWebDriverService确实允许这样做。
为了解决这个问题，我创建了一个小助手类，在其中我从PhantomJSDriverService复制了一些受保护的方法：
public class MyPhantomDriverService {
public static PhantomJSDriverService createDefaultService(Capabilities desiredCapabilities, Map<String, String> env) {
Proxy proxy = null;
if (desiredCapabilities != null) {
proxy = Proxy.extractFrom(desiredCapabilities);
}
File phantomjsfile = findPhantomJS(desiredCapabilities, "https://github.com/ariya/phantomjs/wiki", "http://phantomjs.org/download.html");
File ghostDriverfile = findGhostDriver(desiredCapabilities, "https://github.com/detro/ghostdriver/blob/master/README.md", "https://github.com/detro/ghostdriver/downloads");
Builder builder = new Builder();
builder.usingPhantomJSExecutable(phantomjsfile)
.usingGhostDriver(ghostDriverfile)
.usingAnyFreePort()
.withProxy(proxy)
.withLogFile(new File("phantomjsdriver.log"))
.usingCommandLineArguments(findCLIArgumentsFromCaps(desiredCapabilities, "phantomjs.cli.args"))
.usingGhostDriverCommandLineArguments(findCLIArgumentsFromCaps(desiredCapabilities, "phantomjs.ghostdriver.cli.args"));
if(null != env)
builder.withEnvironment(env);
return builder.build();
}
public static File findPhantomJS(Capabilities desiredCapabilities, String docsLink, String downloadLink) {
String phantomjspath;
if (desiredCapabilities != null && desiredCapabilities.getCapability("phantomjs.binary.path") != null) {
phantomjspath = (String)desiredCapabilities.getCapability("phantomjs.binary.path");
} else {
phantomjspath = (new ExecutableFinder()).find("phantomjs");
phantomjspath = System.getProperty("phantomjs.binary.path", phantomjspath);
}
Preconditions.checkState(phantomjspath != null, "The path to the driver executable must be set by the %s capability/system property/PATH variable; for more information, see %s. The latest version can be downloaded from %s", "phantomjs.binary.path", docsLink, downloadLink);
File phantomjs = new File(phantomjspath);
checkExecutable(phantomjs);
return phantomjs;
}
protected static File findGhostDriver(Capabilities desiredCapabilities, String docsLink, String downloadLink) {
String ghostdriverpath;
if (desiredCapabilities != null && desiredCapabilities.getCapability("phantomjs.ghostdriver.path") != null) {
ghostdriverpath = (String)desiredCapabilities.getCapability("phantomjs.ghostdriver.path");
} else {
ghostdriverpath = System.getProperty("phantomjs.ghostdriver.path");
}
if (ghostdriverpath != null) {
File ghostdriver = new File(ghostdriverpath);
Preconditions.checkState(ghostdriver.exists(), "The GhostDriver does not exist: %s", ghostdriver.getAbsolutePath());
Preconditions.checkState(ghostdriver.isFile(), "The GhostDriver is a directory: %s", ghostdriver.getAbsolutePath());
Preconditions.checkState(ghostdriver.canRead(), "The GhostDriver is not a readable file: %s", ghostdriver.getAbsolutePath());
return ghostdriver;
} else {
return null;
}
}
protected static void checkExecutable(File exe) {
Preconditions.checkState(exe.exists(), "The driver executable does not exist: %s", exe.getAbsolutePath());
Preconditions.checkState(!exe.isDirectory(), "The driver executable is a directory: %s", exe.getAbsolutePath());
Preconditions.checkState(exe.canExecute(), "The driver is not executable: %s", exe.getAbsolutePath());
}
private static String[] findCLIArgumentsFromCaps(Capabilities desiredCapabilities, String capabilityName) {
if (desiredCapabilities != null) {
Object cap = desiredCapabilities.getCapability(capabilityName);
if (cap != null) {
if (cap instanceof String[]) {
return (String[])((String[])cap);
}
if (cap instanceof Collection) {
try {
Collection<String> capCollection = (Collection<String>)cap;
return (String[])capCollection.toArray(new String[capCollection.size()]);
} catch (Exception var4) {
System.err.println(String.format("Unable to set Capability '%s' as it was neither a String[] or a Collection<String>", capabilityName));
}
}
}
}
return new String[0];
}
}
使用这个新代码，我现在可以创建一个PhantomJSDriver，如下所示：
//-- 1. Make a temp directory which will contain our fonts.conf
String tmp = System.getProperty("java.io.tmpdir");
if(tmp == null) {
tmp = "/tmp";
}
File dir = new File(tmp + File.separator + "/_phantomjs-config/fontconfig");
dir.mkdirs();
if(! dir.exists()) {
throw new IOException("Can't create fontconfig directory to override phantomjs font settings at " + dir);
}
File conf = new File(dir, "fonts.conf");
String text = "<match target=\"font\">\n"
+ "<edit mode=\"assign\" name=\"antialias\">\n"
+ "<bool>false</bool>\n"
+ "</edit>\n"
+ "</match>";
try(FileOutputStream fos = new FileOutputStream(conf)) {
fos.write(text.getBytes("UTF-8"));
}
//-- Set the XDG_CONFIG_HOME envvar; this is used by fontconfig as one of its locations
Map<String, String> env = new HashMap<>();
env.put("XDG_CONFIG_HOME", dir.getParentFile().getAbsolutePath());
PhantomJSDriverService service = MyPhantomDriverService.createDefaultService(capabilities, env);
wd = new PhantomJSDriver(service, capabilities);
此代码最重要的问题是，如果有定义了抗锯齿的fonts.conf文件（如$ HOME / .fonts.conf），它可能会失败。但是对于我的测试用例，这个工作正常。
要在无头镀铬上禁用抗锯齿，请使用上面相同的代码生成fonts.conf文件，然后按如下方式分配Chrome webdriver：
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.chrome.ChromeDriverService;
import org.openqa.selenium.chrome.ChromeDriverService.Builder;
...
Map<String, String> env = new HashMap<>();
env.put("XDG_CONFIG_HOME", dir.getParentFile().getAbsolutePath());
Builder builder = new Builder();
builder.usingAnyFreePort();
builder.withEnvironment(env);
ChromeDriverService service = builder.build();
return new ChromeDriver(service, dc);