Add support for "-image" locator type

src/main/java/io/appium/java_client/AppiumDriver.java

@@ -64,7 +64,7 @@
 */
 @SuppressWarnings("unchecked")
 public class AppiumDriver<T extends WebElement>
-    extends DefaultGenericMobileDriver<T> implements ComparesImages {
+    extends DefaultGenericMobileDriver<T> implements ComparesImages, FindsByImage<T> {
 
     private static final ErrorHandler errorHandler = new ErrorHandler(new ErrorCodesMobile(), true);
     // frequently used command parameters

src/main/java/io/appium/java_client/FindsByImage.java

@@ -0,0 +1,63 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * See the NOTICE file distributed with this work for additional
+ * information regarding copyright ownership.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.appium.java_client;
+
+import org.openqa.selenium.NoSuchElementException;
+import org.openqa.selenium.WebElement;
+
+import java.util.List;
+
+public interface FindsByImage<T extends WebElement> extends FindsByFluentSelector<T> {
+    /**
+     * Performs the lookup for a single element by matching its image template
+     * to the current full screen shot. This type of locator requires OpenCV libraries
+     * and bindings for NodeJS to be installed on the server machine. Lookup options
+     * fine-tuning might be done via {@link HasSettings#setSetting(Setting, Object)}.
+     *
+     * @param b64Template base64-encoded template image string. Supported image formats are the same
+     *                    as for OpenCV library.
+     * @return The first element that matches the given selector
+     * @throws NoSuchElementException when no element is found
+     * @see <a href="https://github.com/appium/appium/blob/master/docs/en/writing-running-appium/image-comparison.md">
+     * The documentation on Image Comparison Features</a>
+     * @see <a href="https://github.com/appium/appium-base-driver/blob/master/lib/basedriver/device-settings.js">
+     * The settings available for lookup fine-tuning</a>
+     * @since Appium 1.8.2
+     */
+    default T findElementByImage(String b64Template) {
+        return findElement(MobileSelector.IMAGE.toString(), b64Template);
+    }
+
+    /**
+     * Performs the lookup for a list of elements by matching them to image template
+     * in the current full screen shot. This type of locator requires OpenCV libraries
+     * and bindings for NodeJS to be installed on the server machine. Lookup options
+     * fine-tuning might be done via {@link HasSettings#setSetting(Setting, Object)}.
+     *
+     * @param b64Template base64-encoded template image string. Supported image formats are the same
+     *                    as for OpenCV library.
+     * @return a list of elements that match the given selector or an empty list
+     * @see <a href="https://github.com/appium/appium/blob/master/docs/en/writing-running-appium/image-comparison.md">
+     * The documentation on Image Comparison Features</a>
+     * @see <a href="https://github.com/appium/appium-base-driver/blob/master/lib/basedriver/device-settings.js">
+     * The settings available for lookup fine-tuning</a>
+     * @since Appium 1.8.2
+     */
+    default List<T> findElementsByImage(String b64Template) {
+        return findElements(MobileSelector.IMAGE.toString(), b64Template);
+    }
+}

src/main/java/io/appium/java_client/MobileBy.java

@@ -120,6 +120,23 @@ public static By iOSNsPredicateString(final String iOSNsPredicateString) {
     public static By windowsAutomation(final String windowsAutomation) {
         return new ByWindowsAutomation(windowsAutomation);
     }
+
+    /**
+     * This locator strategy is available only if OpenCV libraries and
+     * NodeJS bindings are installed on the server machine.
+     *
+     * @see <a href="https://github.com/appium/appium/blob/master/docs/en/writing-running-appium/image-comparison.md">
+     * The documentation on Image Comparison Features</a>
+     * @see <a href="https://github.com/appium/appium-base-driver/blob/master/lib/basedriver/device-settings.js">
+     * The settings available for lookup fine-tuning</a>
+     * @since Appium 1.8.2
+     * @param b64Template base64-encoded template image string. Supported image formats are the same
+     *                    as for OpenCV library.
+     * @return an instance of {@link ByImage}
+     */
+    public static By image(final String b64Template) {
+        return new ByImage(b64Template);
+    }
 
     public static class ByIosUIAutomation extends MobileBy implements Serializable {
 
@@ -146,7 +163,7 @@ public List<WebElement> findElements(SearchContext context) throws WebDriverExce
                     .findElementsByIosUIAutomation(getLocatorString());
             }
 
-            if (FindsByFluentSelector.class.isAssignableFrom(context.getClass())) {
+            if (FindsByFluentSelector.class.isAssignableFrom(contextClass)) {
                 return super.findElements(context);
             }
 
@@ -171,7 +188,7 @@ public List<WebElement> findElements(SearchContext context) throws WebDriverExce
                     .findElementByIosUIAutomation(getLocatorString());
             }
 
-            if (FindsByFluentSelector.class.isAssignableFrom(context.getClass())) {
+            if (FindsByFluentSelector.class.isAssignableFrom(contextClass)) {
                 return super.findElement(context);
             }
 
@@ -211,7 +228,7 @@ public List<WebElement> findElements(SearchContext context) throws WebDriverExce
                     .findElementsByAndroidUIAutomator(getLocatorString());
             }
 
-            if (FindsByFluentSelector.class.isAssignableFrom(context.getClass())) {
+            if (FindsByFluentSelector.class.isAssignableFrom(contextClass)) {
                 return super.findElements(context);
             }
 
@@ -236,7 +253,7 @@ public List<WebElement> findElements(SearchContext context) throws WebDriverExce
                     .findElementByAndroidUIAutomator(getLocatorString());
             }
 
-            if (FindsByFluentSelector.class.isAssignableFrom(context.getClass())) {
+            if (FindsByFluentSelector.class.isAssignableFrom(contextClass)) {
                 return super.findElement(context);
             }
 
@@ -275,7 +292,7 @@ public List<WebElement> findElements(SearchContext context) throws WebDriverExce
                     .findElementsByAccessibilityId(getLocatorString());
             }
 
-            if (FindsByFluentSelector.class.isAssignableFrom(context.getClass())) {
+            if (FindsByFluentSelector.class.isAssignableFrom(contextClass)) {
                 return super.findElements(context);
             }
 
@@ -300,7 +317,7 @@ public List<WebElement> findElements(SearchContext context) throws WebDriverExce
                     .findElementByAccessibilityId(getLocatorString());
             }
 
-            if (FindsByFluentSelector.class.isAssignableFrom(context.getClass())) {
+            if (FindsByFluentSelector.class.isAssignableFrom(contextClass)) {
                 return super.findElement(context);
             }
 
@@ -336,7 +353,7 @@ protected ByIosClassChain(String locatorString) {
                         .findElementsByIosClassChain(getLocatorString());
             }
 
-            if (FindsByFluentSelector.class.isAssignableFrom(context.getClass())) {
+            if (FindsByFluentSelector.class.isAssignableFrom(contextClass)) {
                 return super.findElements(context);
             }
 
@@ -360,7 +377,7 @@ protected ByIosClassChain(String locatorString) {
                         .findElementByIosClassChain(getLocatorString());
             }
 
-            if (FindsByFluentSelector.class.isAssignableFrom(context.getClass())) {
+            if (FindsByFluentSelector.class.isAssignableFrom(contextClass)) {
                 return super.findElement(context);
             }
 
@@ -396,7 +413,7 @@ protected ByIosNsPredicate(String locatorString) {
                         .findElementsByIosNsPredicate(getLocatorString());
             }
 
-            if (FindsByFluentSelector.class.isAssignableFrom(context.getClass())) {
+            if (FindsByFluentSelector.class.isAssignableFrom(contextClass)) {
                 return super.findElements(context);
             }
 
@@ -420,7 +437,7 @@ protected ByIosNsPredicate(String locatorString) {
                         .findElementByIosNsPredicate(getLocatorString());
             }
 
-            if (FindsByFluentSelector.class.isAssignableFrom(context.getClass())) {
+            if (FindsByFluentSelector.class.isAssignableFrom(contextClass)) {
                 return super.findElement(context);
             }
 
@@ -456,7 +473,7 @@ protected ByWindowsAutomation(String locatorString) {
                     .findElementsByWindowsUIAutomation(getLocatorString());
             }
 
-            if (FindsByFluentSelector.class.isAssignableFrom(context.getClass())) {
+            if (FindsByFluentSelector.class.isAssignableFrom(contextClass)) {
                 return super.findElements(context);
             }
 
@@ -480,14 +497,70 @@ protected ByWindowsAutomation(String locatorString) {
                     .findElementByWindowsUIAutomation(getLocatorString());
             }
 
-            if (FindsByFluentSelector.class.isAssignableFrom(context.getClass())) {
+            if (FindsByFluentSelector.class.isAssignableFrom(contextClass)) {
                 return super.findElement(context);
             }
 
             throw formIllegalArgumentException(contextClass, FindsByIosNSPredicate.class,
                 FindsByWindowsAutomation.class);
         }
     }
+
+    public static class ByImage extends MobileBy implements Serializable {
+
+        protected ByImage(String b64Template) {
+            super(MobileSelector.IMAGE, b64Template);
+        }
+
+        /**
+         * {@inheritDoc}
+         *
+         * @throws WebDriverException when current session doesn't support the given selector or when
+         *      value of the selector is not consistent.
+         * @throws IllegalArgumentException when it is impossible to find something on the given
+         * {@link SearchContext} instance
+         */
+        @SuppressWarnings("unchecked")
+        @Override public List<WebElement> findElements(SearchContext context) {
+            Class<?> contextClass = context.getClass();
+
+            if (FindsByImage.class.isAssignableFrom(contextClass)) {
+                return FindsByImage.class.cast(context).findElementsByImage(getLocatorString());
+            }
+
+            if (FindsByFluentSelector.class.isAssignableFrom(contextClass)) {
+                return super.findElements(context);
+            }
+
+            throw formIllegalArgumentException(contextClass, FindsByImage.class, FindsByFluentSelector.class);
+        }
+
+        /**
+         * {@inheritDoc}
+         *
+         * @throws WebDriverException when current session doesn't support the given selector or when
+         *      value of the selector is not consistent.
+         * @throws IllegalArgumentException when it is impossible to find something on the given
+         * {@link SearchContext} instance
+         */
+        @Override public WebElement findElement(SearchContext context) {
+            Class<?> contextClass = context.getClass();
+
+            if (FindsByImage.class.isAssignableFrom(contextClass)) {
+                return FindsByImage.class.cast(context).findElementByImage(getLocatorString());
+            }
+
+            if (FindsByFluentSelector.class.isAssignableFrom(contextClass)) {
+                return super.findElement(context);
+            }
+
+            throw formIllegalArgumentException(contextClass, FindsByImage.class, FindsByFluentSelector.class);
+        }
+
+        @Override public String toString() {
+            return "By.Image: " + getLocatorString();
+        }
+    }
 }
 
 

src/main/java/io/appium/java_client/MobileSelector.java

@@ -22,7 +22,8 @@ public enum MobileSelector {
     IOS_UI_AUTOMATION("-ios uiautomation"),
     IOS_PREDICATE_STRING("-ios predicate string"),
     IOS_CLASS_CHAIN("-ios class chain"),
-    WINDOWS_UI_AUTOMATION("-windows uiautomation");
+    WINDOWS_UI_AUTOMATION("-windows uiautomation"),
+    IMAGE("-image");
 
     private final String selector;