Implemented visual state detection functionality for revent workloads

- Added statedetect.py in utils which is a standalone module that
    contains all the methods needed for state detection

  - Modified the setup() and run() methods of the GameWorkload class
    in common/android/workload.py to have a parameter that enables
    state checks and run the check after setup and run if requested.

State detection uses the template matching method available in
OpenCV to determine the state of the workload by detecting
predefined unique elements on a screenshot from the device.

wlauto/common/android/workload.py

@@ -27,6 +27,8 @@ from wlauto.exceptions import WorkloadError, ResourceError, ConfigError
 from wlauto.utils.android import ApkInfo, ANDROID_NORMAL_PERMISSIONS
 from wlauto.utils.types import boolean
 from wlauto.utils.revent import ReventParser
+from wlauto import File
+import wlauto.utils.statedetect as state_detector
 import wlauto.common.android.resources
 
 
@@ -389,6 +391,24 @@ class ReventWorkload(Workload):
         self.device.push_file(self.revent_run_file, self.on_device_run_revent)
         self.device.push_file(self.revent_setup_file, self.on_device_setup_revent)
 
+    def _check_statedetection_files(self, context):
+        try:
+            self.statedefs_dir = context.resolver.get(File(self, 'state_definitions'))
+        except ResourceError:
+            self.logger.warning("State definitions directory not found. Disabling state detection.")
+            self.check_states = False
+
+    def check_state(self, context, phase):
+        try:
+            self.logger.info("\tChecking workload state...")
+            screenshotPath = os.path.join(context.output_directory, "screen.png")
+            self.device.capture_screen(screenshotPath)
+            stateCheck = state_detector.verify_state(screenshotPath, self.statedefs_dir, phase)
+            if not stateCheck:
+                raise WorkloadError("Unexpected state after setup")
+        except state_detector.StateDefinitionError as e:
+            msg = "State definitions or template files missing or invalid ({}). Skipping state detection."
+            self.logger.warning(msg.format(e.message))
 
 class AndroidUiAutoBenchmark(UiAutomatorWorkload, AndroidBenchmark):
 
@@ -450,6 +470,9 @@ class GameWorkload(ApkWorkload, ReventWorkload):
 
     parameters = [
         Parameter('install_timeout', default=500, override=True),
+        Parameter('check_states', kind=bool, default=False, global_alias='check_game_states',
+                  description="""Use visual state detection to verify the state of the workload
+                  after setup and run"""),
         Parameter('assets_push_timeout', kind=int, default=500,
                   description='Timeout used during deployment of the assets package (if there is one).'),
         Parameter('clear_data_on_reset', kind=bool, default=True,
@@ -469,6 +492,8 @@ class GameWorkload(ApkWorkload, ReventWorkload):
     def init_resources(self, context):
         ApkWorkload.init_resources(self, context)
         ReventWorkload.init_resources(self, context)
+        if self.check_states:        
+            self._check_statedetection_files(self, context)
 
     def setup(self, context):
         ApkWorkload.setup(self, context)
@@ -476,6 +501,10 @@ class GameWorkload(ApkWorkload, ReventWorkload):
         time.sleep(self.loading_time)
         ReventWorkload.setup(self, context)
 
+        # state detection check if it's enabled in the config
+        if self.check_states:
+            self.check_state(self, context, "setup_complete")
+
     def do_post_install(self, context):
         ApkWorkload.do_post_install(self, context)
         self._deploy_assets(context, self.assets_push_timeout)
@@ -495,6 +524,10 @@ class GameWorkload(ApkWorkload, ReventWorkload):
         ReventWorkload.run(self, context)
 
     def teardown(self, context):
+        # state detection check if it's enabled in the config
+        if self.check_states:
+            self.check_state(self, context, "run_complete")
+
         if not self.saved_state_file:
             ApkWorkload.teardown(self, context)
         else: