use functions for context access instead of member access

modules/v4d/src/detail/clvacontext.cpp

@@ -16,27 +16,33 @@ CLVAContext::CLVAContext(FrameBufferContext& mainFbContext) : mainFbContext_(mai
 bool CLVAContext::capture(std::function<void(cv::UMat&)> fn, cv::UMat& output) {
     cv::Size fbSize = mainFbContext_.size();
 #ifndef __EMSCRIPTEN__
-    if (!context_.empty()) {
+    if (hasContext()) {
-        CLExecScope_t scope(context_);
+        CLExecScope_t scope(getCLExecContext());
 #endif
         fn(readFrame_);
+        if (readFrame_.empty())
+            return false;
+        resizePreserveAspectRatio(readFrame_, readRGBBuffer_, mainFbContext_.size());
+        cv::cvtColor(readRGBBuffer_, output, cv::COLOR_RGB2BGRA);
 #ifndef __EMSCRIPTEN__
     } else {
+        CLExecScope_t scope(mainFbContext_.getCLExecContext());
+        readFrame_ = cv::UMat();
         fn(readFrame_);
-    }
-#endif
         if (readFrame_.empty())
             return false;
         resizePreserveAspectRatio(readFrame_, readRGBBuffer_, mainFbContext_.size());
         cv::cvtColor(readRGBBuffer_, output, cv::COLOR_RGB2BGRA);
+    }
+#endif
 
     return true;
 }
 
 void CLVAContext::write(std::function<void(const cv::UMat&)> fn, cv::UMat& input) {
 #ifndef __EMSCRIPTEN__
-    if (!context_.empty()) {
+    if (hasContext()) {
-        CLExecScope_t scope(context_);
+        CLExecScope_t scope(getCLExecContext());
 #endif
         cv::cvtColor(input, writeRGBBuffer_, cv::COLOR_BGRA2RGB);
         fn(writeRGBBuffer_);