Android: Allow QImageCapture to recover from camera still photo failingHEADdev

Currently, if a camera still photo capture fails, the QImageCapture
object is left waiting for an image indefinitely. Additionally, it
currently does not support queuing new image requests. This means
that whenever a still photo fails, it becomes impossible to take new
images using the QImageCapture object.

This patch does the following:
- Introduces internal methods to QFFmpegImageCapture to allow removing
a pending image from the queue
- Introduces a new QAndroidCamera event to report a failed still photo
image capture
- Connects the two

This allows a QImageCapture to stay in working state even when still
photo capture fails.

Pick-to: 6.10 6.9 6.8
Change-Id: I19b9b2d9e24a376f1372ec061b3a6213d1c58adc
Reviewed-by: Artem Dyomin <[email protected]>

6 files changed, 82 insertions, 19 deletions

diff --git a/src/android/jar/src/org/qtproject/qt/android/multimedia/QtCamera2.java b/src/android/jar/src/org/qtproject/qt/android/multimedia/QtCamera2.java
index eb913032f..0454ffe30 100644
--- a/src/android/jar/src/org/qtproject/qt/android/multimedia/QtCamera2.java
+++ b/src/android/jar/src/org/qtproject/qt/android/multimedia/QtCamera2.java
@@ -30,6 +30,12 @@ import org.qtproject.qt.android.UsedFromNativeCode;
 
 @TargetApi(23)
 class QtCamera2 {
+    // Should be called if an on-going still photo capture has failed to finish.
+    // This lets us submit an appropriate error and notify QImageCapture that there will
+    // be no photo emitted.
+    // TODO: In the future we should send a more descriptive error message to QImageCapture, and
+    // and pass it as a parameter here.
+    native void onStillPhotoCaptureFailed(String cameraId);
 
     CameraDevice mCameraDevice = null;
     QtVideoDeviceManager mVideoDeviceManager = null;
@@ -446,7 +452,7 @@ class QtCamera2 {
         private void onCaptureFailureEvent() {
             mShouldProcessIncomingEvents = false;
 
-            // TODO: Signal to QImageCapture that the capture failed.
+            onStillPhotoCaptureFailed(mCameraId);
 
             synchronized (mSyncedMembers) {
                 mSyncedMembers.mIsTakingStillPhoto = false;
@@ -560,7 +566,7 @@ class QtCamera2 {
             CaptureRequest request,
             CaptureFailure failure)
         {
-            // TODO: Signal to QImageCapture that the capture failed
+            onStillPhotoCaptureFailed(mCameraId);
             synchronized (mSyncedMembers) {
                 mSyncedMembers.mIsTakingStillPhoto = false;
             }
@@ -672,8 +678,10 @@ class QtCamera2 {
             submitNewStillPhotoCapture(cameraSettings);
         } catch (CameraAccessException e) {
             Log.w("QtCamera2", "Cannot get access to the camera: " + e);
-            // TODO: If we fail to start the still photo capture, then we should report back to the
-            // QImageCapture to signal an error on the capture ID, and try to return to previewing.
+            e.printStackTrace();
+            onStillPhotoCaptureFailed(mCameraId);
+            // TODO: Try to go back to previewing if applicable. If that fails too, shut down
+            // camera session and report QCamera as inactive.
         }
     }
 
diff --git a/src/plugins/multimedia/ffmpeg/qandroidcamera.cpp b/src/plugins/multimedia/ffmpeg/qandroidcamera.cpp
index 8940f95fd..edc301f98 100644
--- a/src/plugins/multimedia/ffmpeg/qandroidcamera.cpp
+++ b/src/plugins/multimedia/ffmpeg/qandroidcamera.cpp
@@ -749,6 +749,16 @@ void QAndroidCamera::onCaptureSessionFailed(int reason, long frameNumber)
                         .arg(reason));
 }
 
+// Called by Java background thread if the on-going still-photo capture fails.
+void QAndroidCamera::onStillPhotoCaptureFailed()
+{
+    // TODO: Emit a more descriptive error signal. At the time of writing, there is no
+    // suitable QImageCapture::Error enumerator for this scenario.
+    emit onImageCaptureFailed(
+        QImageCapture::Error::ResourceError,
+        QStringLiteral("Unknown error"));
+}
+
 } // namespace QFFmpeg
 
 // JNI logic
@@ -868,23 +878,34 @@ static void onCaptureSessionFailed(JNIEnv *env, jobject obj, jstring cameraId, j
 }
 Q_DECLARE_JNI_NATIVE_METHOD(onCaptureSessionFailed)
 
+static void onStillPhotoCaptureFailed(JNIEnv *env, jobject obj, jstring cameraId)
+{
+    Q_UNUSED(env);
+    Q_UNUSED(obj);
+    GET_CAMERA(cameraId);
+
+    camera->onStillPhotoCaptureFailed();
+}
+Q_DECLARE_JNI_NATIVE_METHOD(onStillPhotoCaptureFailed)
+
 bool QFFmpeg::QAndroidCamera::registerNativeMethods()
 {
     static const bool registered = []() {
         return QJniEnvironment().registerNativeMethods(
-                QtJniTypes::Traits<QtJniTypes::QtCamera2>::className(),
-                {
-                        Q_JNI_NATIVE_METHOD(onCameraOpened),
-                        Q_JNI_NATIVE_METHOD(onCameraDisconnect),
-                        Q_JNI_NATIVE_METHOD(onCameraError),
-                        Q_JNI_NATIVE_METHOD(onCaptureSessionConfigured),
-                        Q_JNI_NATIVE_METHOD(onCaptureSessionConfigureFailed),
-                        Q_JNI_NATIVE_METHOD(onCaptureSessionFailed),
-                        Q_JNI_NATIVE_METHOD(onPreviewFrameAvailable),
-                        Q_JNI_NATIVE_METHOD(onStillPhotoAvailable),
-                        Q_JNI_NATIVE_METHOD(onSessionActive),
-                        Q_JNI_NATIVE_METHOD(onSessionClosed),
-                });
+            QtJniTypes::Traits<QtJniTypes::QtCamera2>::className(),
+            {
+                Q_JNI_NATIVE_METHOD(onCameraOpened),
+                Q_JNI_NATIVE_METHOD(onCameraDisconnect),
+                Q_JNI_NATIVE_METHOD(onCameraError),
+                Q_JNI_NATIVE_METHOD(onCaptureSessionConfigured),
+                Q_JNI_NATIVE_METHOD(onCaptureSessionConfigureFailed),
+                Q_JNI_NATIVE_METHOD(onCaptureSessionFailed),
+                Q_JNI_NATIVE_METHOD(onPreviewFrameAvailable),
+                Q_JNI_NATIVE_METHOD(onStillPhotoAvailable),
+                Q_JNI_NATIVE_METHOD(onSessionActive),
+                Q_JNI_NATIVE_METHOD(onSessionClosed),
+                Q_JNI_NATIVE_METHOD(onStillPhotoCaptureFailed),
+            });
     }();
     return registered;
 }
diff --git a/src/plugins/multimedia/ffmpeg/qandroidcamera_p.h b/src/plugins/multimedia/ffmpeg/qandroidcamera_p.h
index 43c10f2f2..4bd16979a 100644
--- a/src/plugins/multimedia/ffmpeg/qandroidcamera_p.h
+++ b/src/plugins/multimedia/ffmpeg/qandroidcamera_p.h
@@ -20,6 +20,8 @@
 #include <QtCore/qjniobject.h>
 #include <QtCore/qobject.h>
 
+#include <QtMultimedia/qimagecapture.h>
+
 #include <QtFFmpegMediaPluginImpl/private/qffmpeghwaccel_p.h>
 
 QT_BEGIN_NAMESPACE
@@ -81,9 +83,11 @@ public slots:
     void onCaptureSessionFailed(int reason, long frameNumber);
     void onSessionActive();
     void onSessionClosed();
+    void onStillPhotoCaptureFailed();
 
-Q_SIGNALS:
+signals:
     void onStillPhotoCaptured(const QVideoFrame&);
+    void onImageCaptureFailed(QImageCapture::Error error, const QString &errMsg);
 
 private:
     bool isActivating() const { return m_state != State::Closed; }
diff --git a/src/plugins/multimedia/ffmpeg/qandroidimagecapture.cpp b/src/plugins/multimedia/ffmpeg/qandroidimagecapture.cpp
index 179412808..f9ad2e869 100644
--- a/src/plugins/multimedia/ffmpeg/qandroidimagecapture.cpp
+++ b/src/plugins/multimedia/ffmpeg/qandroidimagecapture.cpp
@@ -39,7 +39,19 @@ void QAndroidImageCapture::setupVideoSourceConnections()
             &QAndroidCamera::onStillPhotoCaptured,
             this,
             &QAndroidImageCapture::newVideoFrame);
-    } else
+
+        // The backend might call onImageCaptureFailed before the call to
+        // QAndroidImageCapture::doCapture() is finished and returns the request id to the user.
+        // Therefore we want to use queued connection for this to make sure any errors are raised
+        // after that function ends.
+        connect(
+            androidCamera,
+            &QAndroidCamera::onImageCaptureFailed,
+            this,
+            &QFFmpegImageCapture::cancelPendingImage,
+            Qt::QueuedConnection);
+    }
+    else
         QFFmpegImageCapture::setupVideoSourceConnections();
 }
 
diff --git a/src/plugins/multimedia/ffmpeg/qffmpegimagecapture.cpp b/src/plugins/multimedia/ffmpeg/qffmpegimagecapture.cpp
index 5ddb0f022..8e869ddba 100644
--- a/src/plugins/multimedia/ffmpeg/qffmpegimagecapture.cpp
+++ b/src/plugins/multimedia/ffmpeg/qffmpegimagecapture.cpp
@@ -135,6 +135,22 @@ void QFFmpegImageCapture::setCaptureSession(QPlatformMediaCaptureSession *sessio
     onVideoSourceChanged();
 }
 
+void QFFmpegImageCapture::cancelPendingImage(QImageCapture::Error error, const QString &errorMsg)
+{
+    if (m_pendingImages.empty()) {
+        qCDebug(qLcImageCapture) <<
+            "QImageCapture backend received an event to cancel a pending capture, "
+            "but no captures are pending. Most likely an internal Qt bug.";
+        return;
+    }
+
+    PendingImage cancelledImage = m_pendingImages.dequeue();
+
+    emit QPlatformImageCapture::error(cancelledImage.id, error, errorMsg);
+
+    updateReadyForCapture();
+}
+
 void QFFmpegImageCapture::updateReadyForCapture()
 {
     const bool ready = m_session && m_pendingImages.size() < MaxPendingImagesCount && m_videoSource
diff --git a/src/plugins/multimedia/ffmpeg/qffmpegimagecapture_p.h b/src/plugins/multimedia/ffmpeg/qffmpegimagecapture_p.h
index c5197156a..5c6d4fc5f 100644
--- a/src/plugins/multimedia/ffmpeg/qffmpegimagecapture_p.h
+++ b/src/plugins/multimedia/ffmpeg/qffmpegimagecapture_p.h
@@ -40,6 +40,8 @@ public:
 
     void setCaptureSession(QPlatformMediaCaptureSession *session);
 
+    void cancelPendingImage(QImageCapture::Error error, const QString &errorMsg);
+
 protected:
     virtual int doCapture(const QString &fileName);
     virtual void setupVideoSourceConnections();