[Bug Fix] add enableCamera method to fix app crash (#696)

* [Android] Add CxxBuffer to native PaddleSegModel

* [Android] Add PaddleSeg android app example

* [Android] Add SCRFD android app example

* [Doc] fix typos

* [Android] revert camera setting changes

* [Bug Fix] fixed ppdet postprocess empty result error

* [Android] add enableCamera method to fix app crash

java/android/app/src/main/java/com/baidu/paddle/fastdeploy/app/examples/classification/ClassificationMainActivity.java

@@ -306,6 +306,8 @@ public class ClassificationMainActivity extends Activity implements View.OnClick
         // Open camera until the permissions have been granted
         if (!checkAllPermissions()) {
             svPreview.disableCamera();
+        } else {
+            svPreview.enableCamera();
         }
         svPreview.onResume();
     }

java/android/app/src/main/java/com/baidu/paddle/fastdeploy/app/examples/detection/DetectionMainActivity.java

@@ -305,6 +305,8 @@ public class DetectionMainActivity extends Activity implements View.OnClickListe
         // Open camera until the permissions have been granted
         if (!checkAllPermissions()) {
             svPreview.disableCamera();
+        } else {
+            svPreview.enableCamera();
         }
         svPreview.onResume();
     }

java/android/app/src/main/java/com/baidu/paddle/fastdeploy/app/examples/facedet/FaceDetMainActivity.java

@@ -300,6 +300,8 @@ public class FaceDetMainActivity extends Activity implements View.OnClickListene
         // Open camera until the permissions have been granted
         if (!checkAllPermissions()) {
             svPreview.disableCamera();
+        } else {
+            svPreview.enableCamera();
         }
         svPreview.onResume();
     }

java/android/app/src/main/java/com/baidu/paddle/fastdeploy/app/examples/ocr/OcrMainActivity.java

@@ -306,6 +306,8 @@ public class OcrMainActivity extends Activity implements View.OnClickListener, C
         // Open camera until the permissions have been granted
         if (!checkAllPermissions()) {
             svPreview.disableCamera();
+        } else {
+            svPreview.enableCamera();
         }
         svPreview.onResume();
     }

java/android/app/src/main/java/com/baidu/paddle/fastdeploy/app/examples/segmentation/SegmentationMainActivity.java

@@ -287,6 +287,8 @@ public class SegmentationMainActivity extends Activity implements View.OnClickLi
         // Open camera until the permissions have been granted
         if (!checkAllPermissions()) {
             svPreview.disableCamera();
+        } else {
+            svPreview.enableCamera();
         }
         svPreview.onResume();
     }

java/android/app/src/main/java/com/baidu/paddle/fastdeploy/app/ui/view/CameraSurfaceView.java

@@ -278,6 +278,10 @@ public class CameraSurfaceView extends GLSurfaceView implements Renderer,
         disableCamera = true;
     }
 
+    public void enableCamera() {
+        disableCamera = false;
+    }
+
     public void switchCamera() {
         releaseCamera();
         selectedCameraId = (selectedCameraId + 1) % numberOfCameras;