Reduced amount of overlapping rectangles sent to SDL. (Patch #1141.)

src/video.cpp

@@ -19,13 +19,17 @@
 
 #include "global.hpp"
 
-
 #include "font.hpp"
+#include "foreach.hpp"
 #include "image.hpp"
 #include "log.hpp"
 #include "preferences_display.hpp"
 #include "video.hpp"
 
+#include <vector>
+#include <map>
+#include <algorithm>
+
 static lg::log_domain log_display("display");
 #define LOG_DP LOG_STREAM(info, log_display)
 #define ERR_DP LOG_STREAM(err, log_display)
@@ -66,12 +70,129 @@ static unsigned int get_flags(unsigned int flags)
 }
 
 namespace {
-std::vector<SDL_Rect> update_rects;
-bool update_all = false;
+struct event {
+	int x, y, w, h;
+	bool in;
+	event(const SDL_Rect& rect, bool i) : x(i ? rect.x : rect.x + rect.w), y(rect.y), w(rect.w), h(rect.h), in(i) { }
+};
+bool operator<(const event& a, const event& b) {
+	if (a.x != b.x) return a.x < b.x;
+	if (a.in != b.in) return a.in;
+	if (a.y != b.y) return a.y < b.y;
+	if (a.h != b.h) return a.h < b.h;
+	if (a.w != b.w) return a.w < b.w;
+	return false;
+}
+bool operator==(const event& a, const event& b) {
+	return a.x == b.x && a.y == b.y && a.w == b.w && a.h == b.h && a.in == b.in;
 }
 
-static bool rect_contains(const SDL_Rect& a, const SDL_Rect& b) {
-	return a.x <= b.x && a.y <= b.y && a.x+a.w >= b.x+b.w && a.y+a.h >= b.y+b.h;
+struct segment {
+	int x, count;
+	segment() : x(0), count(0) { }
+	segment(int x, int count) : x(x), count(count) { }
+};
+
+
+std::vector<SDL_Rect> update_rects;
+std::vector<event> events;
+std::map<int, segment> segments;
+
+static void calc_rects()
+{
+	events.clear();
+
+	foreach (SDL_Rect const &rect, update_rects) {
+		events.push_back(event(rect, true));
+		events.push_back(event(rect, false));
+	}
+
+	std::sort(events.begin(), events.end());
+	std::vector<event>::iterator events_end = std::unique(events.begin(), events.end());
+
+	segments.clear();
+	update_rects.clear();
+
+	for (std::vector<event>::iterator iter = events.begin(); iter != events_end; ++iter) {
+		std::map<int, segment>::iterator lower = segments.find(iter->y);
+		if (lower == segments.end()) {
+			lower = segments.insert(std::make_pair(iter->y, segment())).first;
+			if (lower != segments.begin()) {
+				std::map<int, segment>::iterator prev = lower;
+				--prev;
+				lower->second = prev->second;
+			}
+		}
+
+		if (lower->second.count == 0) {
+			lower->second.x = iter->x;
+		}
+
+		std::map<int, segment>::iterator upper = segments.find(iter->y + iter->h);
+		if (upper == segments.end()) {
+			upper = segments.insert(std::make_pair(iter->y + iter->h, segment())).first;
+			std::map<int, segment>::iterator prev = upper;
+			--prev;
+			upper->second = prev->second;
+		}
+
+		if (iter->in) {
+			while (lower != upper) {
+				++lower->second.count;
+				++lower;
+			}
+		} else {
+			while (lower != upper) {
+				lower->second.count--;
+				if (lower->second.count == 0) {
+					std::map<int, segment>::iterator next = lower;
+					++next;
+
+					int x = lower->second.x, y = lower->first;
+					unsigned w = iter->x - x;
+					unsigned h = next->first - y;
+					SDL_Rect a = {x, y, w, h};
+
+					if (update_rects.size() == 0) {
+						update_rects.push_back(a);
+					} else {
+						SDL_Rect& p = update_rects.back(), n;
+						int pa = p.w * p.h, aa = w * h, s = pa + aa;
+						int thresh = 51;
+
+						n.w = std::max<int>(x + w, p.x + p.w);
+						n.x = std::min<int>(p.x, x);
+						n.w -= n.x;
+						n.h = std::max<int>(y + h, p.y + p.h);
+						n.y = std::min<int>(p.y, y);
+						n.h -= n.y;
+
+						if (s * 100 < thresh * n.w * n.h) {
+							update_rects.push_back(a);
+						} else {
+							p = n;
+						}
+					}
+
+					if (lower == segments.begin()) {
+						segments.erase(lower);
+					} else {
+						std::map<int, segment>::iterator prev = lower;
+						--prev;
+						if (prev->second.count == 0) segments.erase(lower);
+					}
+
+					lower = next;
+				} else {
+					++lower;
+				}
+			}
+		}
+	}
+}
+
+
+bool update_all = false;
 }
 
 static void clear_updates()
@@ -162,24 +283,6 @@ void update_rect(const SDL_Rect& rect_value)
 		}
 	}
 
-	for(std::vector<SDL_Rect>::iterator i = update_rects.begin();
-	    i != update_rects.end(); ++i) {
-		if(rect_contains(*i,rect)) {
-			return;
-		}
-
-		if(rect_contains(rect,*i)) {
-			*i = rect;
-			for(++i; i != update_rects.end(); ++i) {
-				if(rect_contains(rect,*i)) {
-					i->w = 0;
-				}
-			}
-
-			return;
-		}
-	}
-
 	update_rects.push_back(rect);
 }
 
@@ -302,17 +405,8 @@ void CVideo::flip()
 	if(update_all) {
 		::SDL_Flip(frameBuffer);
 	} else if(update_rects.empty() == false) {
-		size_t sum = 0;
-		for(size_t n = 0; n != update_rects.size(); ++n) {
-			sum += update_rects[n].w*update_rects[n].h;
-		}
-
-		const size_t redraw_whole_screen_threshold = 80;
-		if(sum > ((getx()*gety())*redraw_whole_screen_threshold)/100) {
-			::SDL_Flip(frameBuffer);
-		} else {
-			SDL_UpdateRects(frameBuffer,update_rects.size(),&update_rects[0]);
-		}
+		calc_rects();
+		SDL_UpdateRects(frameBuffer, update_rects.size(), &update_rects[0]);
 	}
 
 	clear_updates();