AVFoundation: fix camera capture previews.

Generate the preview from a viewfinder frame and not from the final
JPG image. In addition, the preview is now rotated to always be in the
same orientation as the device at the time of capture.

Task-number: QTBUG-46971
Change-Id: I48851225738e50fbd89c2f94904bac366303a9ad
Reviewed-by: Christian Stromme <christian.stromme@theqtcompany.com>

src/plugins/avfoundation/camera/avfcamerasession.h

@@ -70,6 +70,7 @@ public:
     static int defaultCameraIndex();
     static const QList<AVFCameraInfo> &availableCameraDevices();
     static AVFCameraInfo cameraDeviceInfo(const QByteArray &device);
+    AVFCameraInfo activeCameraInfo() const { return m_activeCameraInfo; }
 
     void setVideoOutput(AVFCameraRendererControl *output);
     AVCaptureSession *captureSession() const { return m_captureSession; }
@@ -93,10 +94,12 @@ public Q_SLOTS:
     void processSessionStopped();
 
     void onCameraFrameFetched(const QVideoFrame &frame);
+
 Q_SIGNALS:
     void readyToConfigureConnections();
     void stateChanged(QCamera::State newState);
     void activeChanged(bool);
+    void newViewfinderFrame(const QVideoFrame &frame);
     void error(int error, const QString &errorString);
 
 private:
@@ -107,6 +110,7 @@ private:
 
     static int m_defaultCameraIndex;
     static QList<AVFCameraInfo> m_cameraDevices;
+    AVFCameraInfo m_activeCameraInfo;
 
     AVFCameraService *m_service;
     AVFCameraRendererControl *m_videoOutput;

src/plugins/avfoundation/camera/avfcamerasession.mm

@@ -333,6 +333,7 @@ void AVFCameraSession::attachVideoInputDevice()
             [m_captureSession removeInput:m_videoInput];
             [m_videoInput release];
             m_videoInput = 0;
+            m_activeCameraInfo = AVFCameraInfo();
         }
 
         AVCaptureDevice *videoDevice = m_service->videoDeviceControl()->createCaptureDevice();
@@ -346,6 +347,7 @@ void AVFCameraSession::attachVideoInputDevice()
             qWarning() << "Failed to create video device input";
         } else {
             if ([m_captureSession canAddInput:m_videoInput]) {
+                m_activeCameraInfo = m_cameraDevices.at(m_service->videoDeviceControl()->selectedDevice());
                 [m_videoInput retain];
                 [m_captureSession addInput:m_videoInput];
             } else {
@@ -414,6 +416,8 @@ FourCharCode AVFCameraSession::defaultCodec()
 
 void AVFCameraSession::onCameraFrameFetched(const QVideoFrame &frame)
 {
+    Q_EMIT newViewfinderFrame(frame);
+
     m_videoProbesMutex.lock();
     QSet<AVFMediaVideoProbeControl *>::const_iterator i = m_videoProbes.constBegin();
     while (i != m_videoProbes.constEnd()) {

src/plugins/avfoundation/camera/avfimagecapturecontrol.h

@@ -36,19 +36,24 @@
 
 #import <AVFoundation/AVFoundation.h>
 
+#include <QtCore/qqueue.h>
+#include <QtCore/qsemaphore.h>
 #include <QtMultimedia/qcameraimagecapturecontrol.h>
+#include <private/qvideooutputorientationhandler_p.h>
+#include "avfcamerasession.h"
 #include "avfstoragelocation.h"
 
 QT_BEGIN_NAMESPACE
 
-class AVFCameraSession;
-class AVFCameraService;
-class AVFCameraControl;
-
 class AVFImageCaptureControl : public QCameraImageCaptureControl
 {
 Q_OBJECT
 public:
+    struct CaptureRequest {
+        int captureId;
+        QSemaphore *previewReady;
+    };
+
     AVFImageCaptureControl(AVFCameraService *service, QObject *parent = 0);
     ~AVFImageCaptureControl();
 
@@ -64,8 +69,11 @@ public:
 private Q_SLOTS:
     void updateCaptureConnection();
     void updateReadyStatus();
+    void onNewViewfinderFrame(const QVideoFrame &frame);
 
 private:
+    void makeCapturePreview(CaptureRequest request, const QVideoFrame &frame, AVFCameraInfo cameraInfo, int screenOrientation);
+
     AVFCameraSession *m_session;
     AVFCameraControl *m_cameraControl;
     bool m_ready;
@@ -73,8 +81,14 @@ private:
     AVCaptureStillImageOutput *m_stillImageOutput;
     AVCaptureConnection *m_videoConnection;
     AVFStorageLocation m_storageLocation;
+    QVideoOutputOrientationHandler m_orientationHandler;
+
+    QMutex m_requestsMutex;
+    QQueue<CaptureRequest> m_captureRequests;
 };
 
+Q_DECLARE_TYPEINFO(AVFImageCaptureControl::CaptureRequest, Q_PRIMITIVE_TYPE);
+
 QT_END_NAMESPACE
 
 #endif

src/plugins/avfoundation/camera/avfimagecapturecontrol.mm

@@ -33,14 +33,15 @@
 
 #include "avfcameradebug.h"
 #include "avfimagecapturecontrol.h"
-#include "avfcamerasession.h"
 #include "avfcameraservice.h"
 #include "avfcameracontrol.h"
 
 #include <QtCore/qurl.h>
 #include <QtCore/qfile.h>
 #include <QtCore/qbuffer.h>
+#include <QtConcurrent/qtconcurrentrun.h>
 #include <QtGui/qimagereader.h>
+#include <private/qvideoframe_p.h>
 
 QT_USE_NAMESPACE
 
@@ -65,6 +66,10 @@ AVFImageCaptureControl::AVFImageCaptureControl(AVFCameraService *service, QObjec
     connect(m_cameraControl, SIGNAL(statusChanged(QCamera::Status)), SLOT(updateReadyStatus()));
 
     connect(m_session, SIGNAL(readyToConfigureConnections()), SLOT(updateCaptureConnection()));
+
+    connect(m_session, &AVFCameraSession::newViewfinderFrame,
+            this, &AVFImageCaptureControl::onNewViewfinderFrame,
+            Qt::DirectConnection);
 }
 
 AVFImageCaptureControl::~AVFImageCaptureControl()
@@ -106,9 +111,18 @@ int AVFImageCaptureControl::capture(const QString &fileName)
 
     qDebugCamera() << "Capture image to" << actualFileName;
 
-    int captureId = m_lastCaptureId;
+    CaptureRequest request = { m_lastCaptureId, new QSemaphore };
+    m_requestsMutex.lock();
+    m_captureRequests.enqueue(request);
+    m_requestsMutex.unlock();
+
     [m_stillImageOutput captureStillImageAsynchronouslyFromConnection:m_videoConnection
                         completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error) {
+
+        // Wait for the preview to be generated before saving the JPEG
+        request.previewReady->acquire();
+        delete request.previewReady;
+
         if (error) {
             QStringList messageParts;
             messageParts << QString::fromUtf8([[error localizedDescription] UTF8String]);
@@ -119,64 +133,72 @@ int AVFImageCaptureControl::capture(const QString &fileName)
             qDebugCamera() << "Image capture failed:" << errorMessage;
 
             QMetaObject::invokeMethod(this, "error", Qt::QueuedConnection,
-                                      Q_ARG(int, captureId),
+                                      Q_ARG(int, request.captureId),
                                       Q_ARG(int, QCameraImageCapture::ResourceError),
                                       Q_ARG(QString, errorMessage));
         } else {
-            qDebugCamera() << "Image captured:" << actualFileName;
+            qDebugCamera() << "Image capture completed:" << actualFileName;
-            //we can't find the exact time the image is exposed,
-            //but image capture is very fast on desktop, so emit it here
-            QMetaObject::invokeMethod(this, "imageExposed", Qt::QueuedConnection,
-                                      Q_ARG(int, captureId));
 
             NSData *nsJpgData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
             QByteArray jpgData = QByteArray::fromRawData((const char *)[nsJpgData bytes], [nsJpgData length]);
 
-            //Generate snap preview as downscalled image
-            {
-                QBuffer buffer(&jpgData);
-                QImageReader imageReader(&buffer);
-                QSize imgSize = imageReader.size();
-                int downScaleSteps = 0;
-                while (imgSize.width() > 800 && downScaleSteps < 8) {
-                    imgSize.rwidth() /= 2;
-                    imgSize.rheight() /= 2;
-                    downScaleSteps++;
-                }
-
-                imageReader.setScaledSize(imgSize);
-                QImage snapPreview = imageReader.read();
-
-                QMetaObject::invokeMethod(this, "imageCaptured", Qt::QueuedConnection,
-                                          Q_ARG(int, captureId),
-                                          Q_ARG(QImage, snapPreview));
-            }
-
-            qDebugCamera() << "Image captured" << actualFileName;
-
             QFile f(actualFileName);
             if (f.open(QFile::WriteOnly)) {
                 if (f.write(jpgData) != -1) {
                     QMetaObject::invokeMethod(this, "imageSaved", Qt::QueuedConnection,
-                                              Q_ARG(int, captureId),
+                                              Q_ARG(int, request.captureId),
                                               Q_ARG(QString, actualFileName));
                 } else {
                     QMetaObject::invokeMethod(this, "error", Qt::QueuedConnection,
-                                              Q_ARG(int, captureId),
+                                              Q_ARG(int, request.captureId),
                                               Q_ARG(int, QCameraImageCapture::OutOfSpaceError),
                                               Q_ARG(QString, f.errorString()));
                 }
             } else {
                 QString errorMessage = tr("Could not open destination file:\n%1").arg(actualFileName);
                 QMetaObject::invokeMethod(this, "error", Qt::QueuedConnection,
-                                          Q_ARG(int, captureId),
+                                          Q_ARG(int, request.captureId),
                                           Q_ARG(int, QCameraImageCapture::ResourceError),
                                           Q_ARG(QString, errorMessage));
             }
         }
     }];
 
-    return captureId;
+    return request.captureId;
+}
+
+void AVFImageCaptureControl::onNewViewfinderFrame(const QVideoFrame &frame)
+{
+    QMutexLocker locker(&m_requestsMutex);
+
+    if (m_captureRequests.isEmpty())
+        return;
+
+    CaptureRequest request = m_captureRequests.dequeue();
+    Q_EMIT imageExposed(request.captureId);
+
+    QtConcurrent::run(this, &AVFImageCaptureControl::makeCapturePreview,
+                      request,
+                      frame,
+                      m_session->activeCameraInfo(),
+                      m_orientationHandler.currentOrientation());
+}
+
+void AVFImageCaptureControl::makeCapturePreview(CaptureRequest request,
+                                                const QVideoFrame &frame,
+                                                AVFCameraInfo cameraInfo,
+                                                int screenOrientation)
+{
+    QTransform transform;
+    screenOrientation = 360 - screenOrientation;
+    if (cameraInfo.position == QCamera::FrontFace)
+        transform.rotate((screenOrientation + cameraInfo.orientation) % 360);
+    else
+        transform.rotate((screenOrientation + (360 - cameraInfo.orientation)) % 360);
+
+    Q_EMIT imageCaptured(request.captureId, qt_imageFromVideoFrame(frame).transformed(transform));
+
+    request.previewReady->release();
 }
 
 void AVFImageCaptureControl::cancelCapture()