From 0b8471f238865dae36baee7d316e88fb7f2f7f8b Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sesse@samfundet.no>
Date: Sun, 20 Feb 2005 13:42:10 +0000
Subject: [PATCH] Make RotateScreen fade between the individual screens.

---
 bigscreen/rotatescreen.cpp | 83 ++++++++++++++++++++++++++++++--------
 bigscreen/rotatescreen.h   |  4 +-
 2 files changed, 69 insertions(+), 18 deletions(-)

diff --git a/bigscreen/rotatescreen.cpp b/bigscreen/rotatescreen.cpp
index 0997e5c..8e216cf 100644
--- a/bigscreen/rotatescreen.cpp
+++ b/bigscreen/rotatescreen.cpp
@@ -2,19 +2,22 @@
 #include "rotatescreen.h"
 
 RotateScreen::RotateScreen()
-	: valid(false), current_screen(0)
+	: valid(false), current_screen(0), in_fade(false)
 {
+	fadefrom_buf = new unsigned char[800 * 600 * 4];
 }
 
 RotateScreen::~RotateScreen()
 {
+	delete fadefrom_buf;
 }
 
 bool RotateScreen::check_invalidated()
 {
 	if (!valid)
 		return true;
-
+	if (in_fade)
+		return true;
 	if (needs_update())
 		return true;
 	
@@ -30,24 +33,70 @@ void RotateScreen::draw(unsigned char *buf)
 {
 	bool force = false;
 	
-	// push any invalidated screen first (for now)
-	for (unsigned i = 0; i < subscreens.size(); ++i) {
-		if (subscreens[i].screen->check_invalidated()) {
-			current_screen = i;
-			force = true;
-		}
-	}
+	// if we're in a fade, complete it before doing anything else
+	if (in_fade) {
+		struct timeval now;
+		gettimeofday(&now, NULL);
 
-	// check if we want to go to the next screen
-	if (valid && !force && needs_update()) {
-		current_screen = (current_screen + 1) % subscreens.size();
-		gettimeofday(&last_update, NULL);
-	}
+		double elapsed_fade = double(now.tv_sec - fade_started.tv_sec) +
+			double(now.tv_usec - fade_started.tv_usec) * 1.0e-6;
+		printf("fade: %f\n", elapsed_fade);
+		
+		if (elapsed_fade > 0.5) {
+			in_fade = false;
+			memcpy(buf, subscreens[current_screen].buf, 800 * 600 * 4);
+			printf("fade done\n");
+		} else {
+			// find the fade factors
+			int fr = unsigned(elapsed_fade/0.5 * 256.0);
+			int fg = unsigned(elapsed_fade/0.5 * 256.0);
+			int fb = unsigned(elapsed_fade/0.5 * 256.0);
+			int fa = unsigned(elapsed_fade/0.5 * 256.0);
+
+			unsigned char *sptr1 = fadefrom_buf;
+			unsigned char *sptr2 = subscreens[current_screen].buf;
+			unsigned char *dptr = buf;
 
-	if (subscreens[current_screen].screen->check_invalidated())
-		subscreens[current_screen].screen->draw(subscreens[current_screen].buf);
+			for (unsigned i = 0; i < 800 * 600; ++i) {
+				dptr[0] = sptr1[0] + (((int(sptr2[0]) - int(sptr1[0])) * fr) >> 8);
+				dptr[1] = sptr1[1] + (((int(sptr2[1]) - int(sptr1[1])) * fg) >> 8);
+				dptr[2] = sptr1[2] + (((int(sptr2[2]) - int(sptr1[2])) * fb) >> 8);
+				dptr[3] = sptr1[3] + (((int(sptr2[3]) - int(sptr1[3])) * fa) >> 8); 
+
+				sptr1 += 4, sptr2 += 4, dptr += 4;
+			}
+		}
+	} else {
+		// determine if we want to switch screens
 	
-	memcpy(buf, subscreens[current_screen].buf, 800 * 600 * 4);
+		unsigned old_current_screen = current_screen;
+		
+		// push any invalidated screen first (for now)
+		for (unsigned i = 0; i < subscreens.size(); ++i) {
+			if (subscreens[i].screen->check_invalidated()) {
+				current_screen = i;
+				force = true;
+			}
+		}
+
+		// check if we want to go to the next screen
+		if (valid && !force && needs_update()) {
+			current_screen = (current_screen + 1) % subscreens.size();
+			gettimeofday(&last_update, NULL);
+		}
+
+		if (current_screen != old_current_screen || subscreens[current_screen].screen->check_invalidated()) {
+			// initialize a fade
+			in_fade = true;
+			gettimeofday(&fade_started, NULL);
+			printf("starting fade\n");
+			
+			if (subscreens[current_screen].screen->check_invalidated())
+				subscreens[current_screen].screen->draw(subscreens[current_screen].buf);
+		
+			memcpy(fadefrom_buf, subscreens[old_current_screen].buf, 800 * 600 * 4);
+		}
+	}
 
 	if (!valid) {
 		valid = true;
diff --git a/bigscreen/rotatescreen.h b/bigscreen/rotatescreen.h
index 0883ca2..35931b5 100644
--- a/bigscreen/rotatescreen.h
+++ b/bigscreen/rotatescreen.h
@@ -17,11 +17,13 @@ struct Subscreen {
 
 class RotateScreen : public GenericScreen {
 private:
+	unsigned char *fadefrom_buf;
 	bool valid;
 	std::vector<Subscreen> subscreens;
 	unsigned current_screen;
 
-	struct timeval last_update;
+	struct timeval last_update, fade_started;
+	bool in_fade;
 
 	bool needs_update();
 	
-- 
2.39.2