Add qt_real_to_fraction() helper function.

Private API meant to be used by plugins whose backends expect frame
rate values represented by a ratio.
The function implementation was moved from the AVFoundation plugin
to the QtMultimedia library.

Change-Id: I555b9d5da5ca3bae88992ed03501869fb731e45f
Reviewed-by: Christian Stromme <christian.stromme@theqtcompany.com>

3 files changed, 12 insertions, 44 deletions

diff --git a/src/plugins/avfoundation/camera/avfcamerautility.h b/src/plugins/avfoundation/camera/avfcamerautility.h
index 42005a502..64093645f 100644
--- a/src/plugins/avfoundation/camera/avfcamerautility.h
+++ b/src/plugins/avfoundation/camera/avfcamerautility.h
@@ -160,8 +160,6 @@ inline QSysInfo::MacVersion qt_OS_limit(QSysInfo::MacVersion osxVersion,
 
 typedef QPair<qreal, qreal> AVFPSRange;
 AVFPSRange qt_connection_framerates(AVCaptureConnection *videoConnection);
-typedef QPair<int, int> AVFRational;
-AVFRational qt_float_to_rational(qreal par, int limit);
 
 #if QT_MAC_PLATFORM_SDK_EQUAL_OR_ABOVE(__MAC_10_7, __IPHONE_7_0)
 
diff --git a/src/plugins/avfoundation/camera/avfcamerautility.mm b/src/plugins/avfoundation/camera/avfcamerautility.mm
index f45169d07..3668bb124 100644
--- a/src/plugins/avfoundation/camera/avfcamerautility.mm
+++ b/src/plugins/avfoundation/camera/avfcamerautility.mm
@@ -36,6 +36,7 @@
 
 #include <QtCore/qvector.h>
 #include <QtCore/qpair.h>
+#include <private/qmultimediautils_p.h>
 
 #include <functional>
 #include <algorithm>
@@ -77,42 +78,6 @@ AVFPSRange qt_connection_framerates(AVCaptureConnection *videoConnection)
     return newRange;
 }
 
-AVFRational qt_float_to_rational(qreal par, int limit)
-{
-    Q_ASSERT(limit > 0);
-
-    // In Qt we represent pixel aspect ratio
-    // as a rational number (we use QSize).
-    // AVFoundation describes dimensions in pixels
-    // and in pixels with width multiplied by PAR.
-    // Represent this PAR as a ratio.
-    int a = 0, b = 1, c = 1, d = 1;
-    qreal mid = 0.;
-    while (b <= limit && d <= limit) {
-        mid = qreal(a + c) / (b + d);
-
-        if (qAbs(par - mid) < 0.000001) {
-            if (b + d <= limit)
-                return AVFRational(a + c, b + d);
-            else if (d > b)
-                return AVFRational(c, d);
-            else
-                return AVFRational(a, b);
-        } else if (par > mid) {
-            a = a + c;
-            b = b + d;
-        } else {
-            c = a + c;
-            d = b + d;
-        }
-    }
-
-    if (b > limit)
-        return AVFRational(c, d);
-
-    return AVFRational(a, b);
-}
-
 #if QT_MAC_PLATFORM_SDK_EQUAL_OR_ABOVE(__MAC_10_7, __IPHONE_7_0)
 
 namespace {
@@ -264,10 +229,13 @@ QSize qt_device_format_pixel_aspect_ratio(AVCaptureDeviceFormat *format)
     if (!res.width || !resPAR.width)
         return QSize();
 
-    const AVFRational asRatio(qt_float_to_rational(resPAR.width > res.width
-                                                   ? res.width / qreal(resPAR.width)
-                                                   : resPAR.width / qreal(res.width), 200));
-    return QSize(asRatio.first, asRatio.second);
+    int n, d;
+    qt_real_to_fraction(resPAR.width > res.width
+                        ? res.width / qreal(resPAR.width)
+                        : resPAR.width / qreal(res.width),
+                        &n, &d);
+
+    return QSize(n, d);
 }
 
 AVCaptureDeviceFormat *qt_find_best_resolution_match(AVCaptureDevice *captureDevice,
diff --git a/src/plugins/avfoundation/camera/avfcameraviewfindersettingscontrol.mm b/src/plugins/avfoundation/camera/avfcameraviewfindersettingscontrol.mm
index 05f28898d..c5da1c343 100644
--- a/src/plugins/avfoundation/camera/avfcameraviewfindersettingscontrol.mm
+++ b/src/plugins/avfoundation/camera/avfcameraviewfindersettingscontrol.mm
@@ -45,6 +45,7 @@
 #include <QtCore/qvector.h>
 #include <QtCore/qdebug.h>
 #include <QtCore/qlist.h>
+#include <private/qmultimediautils_p.h>
 
 #include <algorithm>
 
@@ -129,8 +130,9 @@ CMTime qt_adjusted_frame_duration(AVFrameRateRange *range, qreal fps)
     if (fps >= range.maxFrameRate)
         return range.minFrameDuration;
 
-    const AVFRational timeAsRational(qt_float_to_rational(1. / fps, 1000));
-    return CMTimeMake(timeAsRational.first, timeAsRational.second);
+    int n, d;
+    qt_real_to_fraction(1. / fps, &n, &d);
+    return CMTimeMake(n, d);
 }
 
 void qt_set_framerate_limits(AVCaptureDevice *captureDevice,