From: Alexander Alekhin <alexander.a.alekhin@gmail.com>
Date: Tue, 18 Sep 2018 16:25:01 +0000 (+0000)
Subject: videoio: CAP_PROP_BACKEND property interface
X-Git-Tag: accepted/tizen/6.0/unified/20201030.111113~1^2~529^2~7^2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d3eed2cf238b97049406c5bf1782d06a34804fba;p=platform%2Fupstream%2Fopencv.git

videoio: CAP_PROP_BACKEND property interface
---

diff --git a/modules/videoio/include/opencv2/videoio.hpp b/modules/videoio/include/opencv2/videoio.hpp
index 92af74a..cfa2774 100644
--- a/modules/videoio/include/opencv2/videoio.hpp
+++ b/modules/videoio/include/opencv2/videoio.hpp
@@ -169,6 +169,7 @@ enum VideoCaptureProperties {
        CAP_PROP_AUTOFOCUS     =39,
        CAP_PROP_SAR_NUM       =40, //!< Sample aspect ratio: num/den (num)
        CAP_PROP_SAR_DEN       =41, //!< Sample aspect ratio: num/den (den)
+       CAP_PROP_BACKEND       =42, //!< current backend (enum VideoCaptureAPIs). Read-only property
 #ifndef CV_DOXYGEN
        CV__CAP_PROP_LATEST
 #endif
diff --git a/modules/videoio/src/cap.cpp b/modules/videoio/src/cap.cpp
index 6c1ad19..ff0bc6f 100644
--- a/modules/videoio/src/cap.cpp
+++ b/modules/videoio/src/cap.cpp
@@ -272,6 +272,8 @@ VideoCapture& VideoCapture::operator >> (UMat& image)
 
 bool VideoCapture::set(int propId, double value)
 {
+    CV_CheckNE(propId, (int)CAP_PROP_BACKEND, "Can set read-only property");
+
     if (!icap.empty())
         return icap->setProperty(propId, value);
     return cvSetCaptureProperty(cap, propId, value) != 0;
@@ -279,6 +281,17 @@ bool VideoCapture::set(int propId, double value)
 
 double VideoCapture::get(int propId) const
 {
+    if (propId == CAP_PROP_BACKEND)
+    {
+        int api = 0;
+        if (icap)
+            api = icap->isOpened() ? icap->getCaptureDomain() : 0;
+        else if (cap)
+            api = cap->getCaptureDomain();
+        if (api <= 0)
+            return -1.0;
+        return (double)api;
+    }
     if (!icap.empty())
         return icap->getProperty(propId);
     return cap ? cap->getProperty(propId) : 0;
@@ -358,6 +371,8 @@ bool VideoWriter::isOpened() const
 
 bool VideoWriter::set(int propId, double value)
 {
+    CV_CheckNE(propId, (int)CAP_PROP_BACKEND, "Can set read-only property");
+
     if (!iwriter.empty())
         return iwriter->setProperty(propId, value);
     return false;
@@ -365,6 +380,17 @@ bool VideoWriter::set(int propId, double value)
 
 double VideoWriter::get(int propId) const
 {
+    if (propId == CAP_PROP_BACKEND)
+    {
+        int api = 0;
+        if (iwriter)
+            api = iwriter->getCaptureDomain();
+        else if (writer)
+            api = writer->getCaptureDomain();
+        if (api <= 0)
+            return -1.0;
+        return (double)api;
+    }
     if (!iwriter.empty())
         return iwriter->getProperty(propId);
     return 0.;