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>

1 files changed, 56 insertions, 34 deletions

diff --git a/src/plugins/avfoundation/camera/avfimagecapturecontrol.mm b/src/plugins/avfoundation/camera/avfimagecapturecontrol.mm
index c28ccef8e..4703f8727 100644
--- a/src/plugins/avfoundation/camera/avfimagecapturecontrol.mm
+++ b/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;
-            //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));
+            qDebugCamera() << "Image capture completed:" << actualFileName;
 
             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()