MLKitBarcodeScanner - iOS crash based on processEveryNthFrame rate #1190

Author: EddyVerbruggen

src/mlkit/custommodel/index.ios.ts

@@ -18,13 +18,7 @@ export class MLKitCustomModel extends MLKitCustomModelBase {
     return this.modelInterpreter;
   }
 
-  runDetector(image: UIImage): void {
-    if (this.detectorBusy) {
-      return;
-    }
-
-    this.detectorBusy = true;
-
+  runDetector(image: UIImage, onComplete: () => void): void {
     const modelExpectsWidth = this.modelInputShape[1];
     const modelExpectsHeight = this.modelInputShape[2];
     const isQuantized = this.modelInputType !== "FLOAT32";
@@ -63,20 +57,20 @@ export class MLKitCustomModel extends MLKitCustomModelBase {
 
         if (this.labels.length !== probabilities.count) {
           console.log(`The number of labels (${this.labels.length}) is not equal to the interpretation result (${probabilities.count})!`);
-          return;
-        }
-
-        const result = <MLKitCustomModelResult>{
-          result: getSortedResult(this.labels, probabilities, this.maxResults)
-        };
+          onComplete();
+        } else {
+          const result = <MLKitCustomModelResult>{
+            result: getSortedResult(this.labels, probabilities, this.maxResults)
+          };
 
-        this.notify({
-          eventName: MLKitCustomModel.scanResultEvent,
-          object: this,
-          value: result
-        });
+          this.notify({
+            eventName: MLKitCustomModel.scanResultEvent,
+            object: this,
+            value: result
+          });
+        }
       }
-      this.detectorBusy = false;
+      onComplete();
     })
   }
 

src/mlkit/mlkit-cameraview.ios.ts

@@ -176,7 +176,7 @@ export abstract class MLKitCameraView extends MLKitCameraViewBase {
 
   abstract createSuccessListener(): any;
 
-  runDetector(image: UIImage) {
+  runDetector(image: UIImage, onComplete: () => void) {
     throw new Error("No custom detector implemented, so 'runDetector' can't do its thing");
   }
 }
@@ -190,6 +190,8 @@ class TNSMLKitCameraViewDelegateImpl extends NSObject implements TNSMLKitCameraV
   private detector: any;
   private onSuccessListener: any;
 
+  private detectorBusy = false;
+
   public static createWithOwnerResultCallbackAndOptions(owner: WeakRef<MLKitCameraView>, callback: (message: any) => void, options?: any): TNSMLKitCameraViewDelegateImpl {
     // defer initialisation because the framework may not be available / used
     if (TNSMLKitCameraViewDelegateImpl.ObjCProtocols.length === 0 && typeof (TNSMLKitCameraViewDelegate) !== "undefined") {
@@ -205,14 +207,30 @@ class TNSMLKitCameraViewDelegateImpl extends NSObject implements TNSMLKitCameraV
   }
 
   cameraDidOutputImage(image: UIImage): void {
-    if (image) {
-      if (this.detector.detectInImageCompletion) {
-        this.detector.detectInImageCompletion(this.uiImageToFIRVisionImage(image), this.onSuccessListener);
-      } else if (this.detector.processImageCompletion) {
-        this.detector.processImageCompletion(this.uiImageToFIRVisionImage(image), this.onSuccessListener);
-      } else {
-        this.owner.get().runDetector(image);
-      }
+    if (!image || this.detectorBusy) {
+      return;
+    }
+
+    this.detectorBusy = true;
+
+    const onComplete = () => {
+      this.detectorBusy = false;
+    };
+
+    if (this.detector.detectInImageCompletion) {
+      this.detector.detectInImageCompletion(this.uiImageToFIRVisionImage(image), (result, error) => {
+        this.onSuccessListener(result, error);
+        onComplete();
+      });
+
+    } else if (this.detector.processImageCompletion) {
+      this.detector.processImageCompletion(this.uiImageToFIRVisionImage(image), (result, error) => {
+        this.onSuccessListener(result, error);
+        onComplete();
+      });
+
+    } else {
+      this.owner.get().runDetector(image, onComplete);
     }
   }