Improve screen capture correctness and timing

components/rgbd-sources/src/sources/screencapture/screencapture.cpp

@@ -109,6 +109,11 @@ ScreenCapture::~ScreenCapture() {
 	#endif
 }
 
+void ScreenCapture::swap() {
+	cur_ts_ = cap_ts_;
+	sframe_.swapTo(frame_);
+}
+
 bool ScreenCapture::retrieve() {
 	if (!ready_) return false;
 	cv::Mat img;
@@ -118,19 +123,21 @@ bool ScreenCapture::retrieve() {
     img = cv::Mat(params_.height, params_.width, CV_8UC4, impl_state_->ximg->data);
 	#endif
 
-	frame_.reset();
-	frame_.setOrigin(&state_);
+	sframe_.reset();
+	sframe_.setOrigin(&state_);
 
 	if (!img.empty()) {
-		frame_.create<cv::cuda::GpuMat>(Channel::Colour).upload(img);
+		sframe_.create<cv::cuda::GpuMat>(Channel::Colour).upload(img);
 	}
 
+	cap_ts_ = timestamp_;
+
 	return true;
 }
 
 bool ScreenCapture::compute(int n, int b) {
 	if (!ready_) return false;
-	host_->notify(timestamp_, frame_);
+	host_->notify(cur_ts_, frame_);
     return true;
 }
 

components/rgbd-sources/src/sources/screencapture/screencapture.hpp

@@ -23,12 +23,16 @@ class ScreenCapture : public ftl::rgbd::detail::Source {
 	~ScreenCapture();
 
 	bool capture(int64_t ts) { timestamp_ = ts; return true; };
+	void swap() override;
 	bool retrieve();
 	bool compute(int n=-1, int b=-1);
 	bool isReady();
 
 	private:
 	bool ready_;
+	int64_t cap_ts_;
+	int64_t cur_ts_;
+	ftl::rgbd::Frame sframe_;
 
 	ImplState *impl_state_;
 };