Experimentally introduces adaptive quality intermediate buffers.

Outputs/DisplayMetrics.cpp

@@ -8,13 +8,72 @@
 
 #include "DisplayMetrics.hpp"
 
+#include <iostream>
+
 using namespace Outputs::Display;
 
+// MARK: Frame size estimation.
+
 void Metrics::announce_event(ScanTarget::Event event) {
+	switch(event) {
+		case ScanTarget::Event::EndHorizontalRetrace:
+			++lines_this_frame_;
+		break;
+		case ScanTarget::Event::EndVerticalRetrace:
+			add_line_total(lines_this_frame_);
+			lines_this_frame_ = 0;
+		break;
+		default: break;
+	}
 }
 
+void Metrics::add_line_total(int total) {
+//	std::cout << total << '\n';
+}
+
+float Metrics::lines_per_frame_estimate() {
+	return 1.0f;	// TODO.
+}
+
+// MARK: GPU processing speed decisions.
+
 void Metrics::announce_did_resize() {
+	frames_missed_ = frames_hit_ = 0;
 }
 
 void Metrics::announce_draw_status(size_t lines, std::chrono::high_resolution_clock::duration duration, bool complete) {
+	if(!complete) {
+		++frames_missed_;
+	} else {
+		++frames_hit_;
+	}
+
+	// Don't allow the record of history to extend too far into the past.
+	if(frames_hit_ + frames_missed_ > 200) {
+		// Subtract from whichever wasn't just incremented, to ensure the
+		// most recent information is more important than the historic stuff.
+		if(!complete) {
+			--frames_hit_;
+		} else {
+			--frames_missed_;
+		}
+
+		// Rebalance if either thing has gone negative.
+		if(frames_hit_ < 0) {
+			frames_missed_ += frames_hit_;
+			frames_hit_ = 0;
+		}
+		if(frames_missed_ < 0) {
+			frames_hit_ += frames_missed_;
+			frames_missed_ = 0;
+		}
+	}
+}
+
+bool Metrics::should_lower_resolution() {
+	// If less than 100 frames are on record, return no opinion; otherwise
+	// suggest a lower resolution if more than 10 frames in the last 100-200
+	// took too long to produce.
+	if(frames_hit_ + frames_missed_ < 100) return false;
+	return frames_missed_ > 10;
 }