render to image surface

initcairo.c

@@ -54,9 +54,17 @@ GraphicsInfo *initCairo(int screen, int mask, int width, int height, const char
 
 	XMapWindow(info->display, info->win);
 
+	// create xlib surface
 	info->surface = cairo_xlib_surface_create(info->display, info->win, visual, width, height);
 	cairo_xlib_surface_set_size(info->surface, width, height);
-	info->context->cairo = cairo_create(info->surface);
+	info->front_context = cairo_create(info->surface);
+	cairo_set_antialias(info->front_context, CAIRO_ANTIALIAS_NONE);
+
+	// create backbuffer surface
+	int stride = cairo_format_stride_for_width(CAIRO_FORMAT_ARGB32, width);
+	info->buffer = malloc(stride*height);
+	info->buffer_surface = cairo_image_surface_create_for_data(info->buffer, CAIRO_FORMAT_ARGB32, width, height, stride);
+	info->context->cairo = cairo_create(info->buffer_surface);
 	cairo_matrix_init_identity(&info->context->matrix);
 	info->context->width = width;
 	info->context->height = height;
@@ -65,11 +73,18 @@ GraphicsInfo *initCairo(int screen, int mask, int width, int height, const char
 	info->wm_protocols = XInternAtom(info->display, "WM_PROTOCOLS", 0);
 	XSetWMProtocols(info->display, info->win, &info->wm_delete_window, 1);
 
+	XFlush(info->display);
+
 	return info;
 }
 
 void destroyCairo(GraphicsInfo *info)
 {
+	cairo_destroy(info->context->cairo);
+	cairo_destroy(info->front_context);
+	cairo_surface_destroy(info->surface);
+	cairo_surface_destroy(info->buffer_surface);
+	free(info->buffer);
 	XDestroyWindow(info->display, info->win);
 	XFreeColormap(info->display, info->cmap);
 	XCloseDisplay(info->display);
@@ -107,26 +122,35 @@ int processStandardEvent(GraphicsInfo *info, XEvent *ev, void (*draw)(DrawingCon
 {
 	int state;
 	static int last_x, last_y;
+	int stride;
+	int status = STATUS_NOTHING;
 
 	switch(ev->type) {
 
 	case Expose:
-		draw(info->context);
+		return STATUS_REDRAW;
-		break;
 
 	case ConfigureNotify:
 		printf("ConfigureNotify Event, new dimensions: %d %d %d %d\n", ev->xconfigure.x, ev->xconfigure.y, ev->xconfigure.width, ev->xconfigure.height);
 		info->context->width = ev->xconfigure.width;
 		info->context->height = ev->xconfigure.height;
-		cairo_xlib_surface_set_size(info->surface, ev->xconfigure.width, ev->xconfigure.height);
+		cairo_xlib_surface_set_size(info->surface, info->context->width, info->context->height);
-		draw(info->context);
+
-		break;
+		cairo_destroy(info->context->cairo);
+		cairo_surface_destroy(info->buffer_surface);
+		free(info->buffer);
+		stride = cairo_format_stride_for_width(CAIRO_FORMAT_ARGB32, info->context->width);
+		info->buffer = malloc(stride*info->context->height);
+		info->buffer_surface = cairo_image_surface_create_for_data(info->buffer, CAIRO_FORMAT_ARGB32, info->context->width, info->context->height, stride);
+		info->context->cairo = cairo_create(info->buffer_surface);
+
+		return STATUS_REDRAW;
 
 	case KeyPress:
 		state = ev->xkey.state & (ShiftMask | LockMask | ControlMask);
 		if(state == 0 && ev->xkey.keycode == 24)
-			return true;
+			return STATUS_QUIT;
-		break;
+		return STATUS_NOTHING;
 
 	case ButtonPress:
 		if(ev->xbutton.button == 4) {
@@ -136,7 +160,7 @@ int processStandardEvent(GraphicsInfo *info, XEvent *ev, void (*draw)(DrawingCon
 			cairo_matrix_scale(&transform, 5.0/4.0, 5.0/4.0);
 			cairo_matrix_translate(&transform, -ev->xbutton.x, -ev->xbutton.y);
 			cairo_matrix_multiply(&info->context->matrix, &info->context->matrix, &transform);
-			draw(info->context);
+			status = STATUS_REDRAW;
 		} else if(ev->xbutton.button == 5) {
 			cairo_matrix_t transform;
 			cairo_matrix_init_identity(&transform);
@@ -144,11 +168,12 @@ int processStandardEvent(GraphicsInfo *info, XEvent *ev, void (*draw)(DrawingCon
 			cairo_matrix_scale(&transform, 4.0/5.0, 4.0/5.0);
 			cairo_matrix_translate(&transform, -ev->xbutton.x, -ev->xbutton.y);
 			cairo_matrix_multiply(&info->context->matrix, &info->context->matrix, &transform);
-			draw(info->context);
+			status = STATUS_REDRAW;
 		}
+
 		last_x = ev->xbutton.x;
 		last_y = ev->xbutton.y;
-		break;
+		return status;
 
 	case MotionNotify:
 		if(ev->xmotion.state & Button1Mask && !(ev->xmotion.state & ShiftMask)) {
@@ -159,7 +184,7 @@ int processStandardEvent(GraphicsInfo *info, XEvent *ev, void (*draw)(DrawingCon
 			cairo_matrix_init_identity(&transform);
 			cairo_matrix_translate(&transform, dx, dy);
 			cairo_matrix_multiply(&info->context->matrix, &info->context->matrix, &transform);
-			draw(info->context);
+			status = STATUS_REDRAW;
 		} else if(ev->xmotion.state & Button1Mask && ev->xmotion.state & ShiftMask) {
 			double width = (double) cairo_xlib_surface_get_width(info->surface);
 			double height = (double) cairo_xlib_surface_get_height(info->surface);
@@ -174,50 +199,67 @@ int processStandardEvent(GraphicsInfo *info, XEvent *ev, void (*draw)(DrawingCon
 			cairo_matrix_rotate(&transform, angle);
 			cairo_matrix_translate(&transform, -width/2, -height/2);
 			cairo_matrix_multiply(&info->context->matrix, &info->context->matrix, &transform);
-			draw(info->context);
+			status = STATUS_REDRAW;
 		}
+
 		last_x = ev->xmotion.x;
 		last_y = ev->xmotion.y;
-		break;
+
+		return status;
 
 	case ClientMessage:
 		if((Atom)ev->xclient.message_type == info->wm_protocols && (Atom)ev->xclient.data.l[0] == info->wm_delete_window) {
 //			printf("Window closed\n");
-			return true;
+			return STATUS_QUIT;
 		}
-		break;
+		return STATUS_NOTHING;
 	}
 
-	return 0;
+	return STATUS_NOTHING;
-
 }
 
 int checkEvents(GraphicsInfo *info, int (*process)(GraphicsInfo*, XEvent*), void (*draw)(DrawingContext*)) // get any events from the queue and the server, process them if neccessary, quit if wanted
 {
 	XEvent ev;
+	int x11_fd;
+	fd_set fds;
+	int status = STATUS_NOTHING, result;
 
-//	while(XCheckIfEvent(info->display, &ev, alwaysTruePredicate, NULL)) {  // we essentially want XCheckWindowEvent, but we want to avoid that events for other windows fill up the queue
+	int x11_event = 0;
 
+	if(XPending(info->display)) { // select() would miss events which are picked up already, so we have to catch them first
+		x11_event = 1;
+	} else {
+		x11_fd = ConnectionNumber(info->display);
+		FD_ZERO(&fds);
+		FD_SET(x11_fd, &fds);
+
+		select(x11_fd + 1, &fds, NULL, NULL, NULL);
+
+		if(FD_ISSET(x11_fd, &fds))
+			x11_event = 1;
+	}
+
+	if(x11_event) {
+		while(XPending(info->display)) {
 			XNextEvent(info->display, &ev);
 
 			if(ev.xany.window != info->win)
-		return 0;
+				continue;
 
-/*	if(ev.type == KeyRelease) { // deal with autorepeat
+			result = processStandardEvent(info, &ev, draw);
-		XEvent nev;
+			if(result == STATUS_QUIT)
-		if(XCheckIfEvent(info->display, &nev, alwaysTruePredicate, NULL)) { // is there another event?
+				return STATUS_QUIT;
-			if (nev.type == KeyPress && nev.xkey.time == ev.xkey.time && nev.xkey.keycode == ev.xkey.keycode) // which is equal, but KeyPress? Then it's just auto-repeat
+			else if(result == STATUS_REDRAW)
-				return 0; // so we ignore both
+				status = STATUS_REDRAW;
 
-			XPutBackEvent(info->display, &nev); // otherwise put the event back, we will consider it in the next round
+			result = process(info, &ev);
+			if(result == STATUS_QUIT)
+				return STATUS_QUIT;
+			else if(result == STATUS_REDRAW)
+				status = STATUS_REDRAW;
 		}
-		} */
+	}
-
+
-	if(processStandardEvent(info, &ev, draw))
+	return status;
-		return 1;
-
-	if(process(info, &ev))
-		return 1; // quit event queue and application
-
-	return 0;
 }

initcairo.h

@@ -12,6 +12,10 @@
 #include <cairo.h>
 #include <cairo-xlib.h>
 
+#define STATUS_NOTHING 0
+#define STATUS_REDRAW 1
+#define STATUS_QUIT 2
+
 typedef struct {
 	cairo_t *cairo;
 	cairo_matrix_t matrix;
@@ -33,6 +37,11 @@ typedef struct {
 	Atom wm_protocols;
 	Atom wm_delete_window;
 	cairo_surface_t *surface;
+	cairo_t *front_context;
+
+	cairo_surface_t *buffer_surface;
+	unsigned char *buffer;
+
 	struct timeval start_time;
 	unsigned long frames;
 	double elapsed, frametime;

limit_set.c

@@ -358,14 +358,8 @@ void drawAttractors(DrawingContext *ctx)
 
 void draw(DrawingContext *ctx)
 {
-	struct timeval current_time;
-	gettimeofday(&current_time, 0);
-	double start_time = current_time.tv_sec + current_time.tv_usec*1e-6;
-
 	cairo_t *C = ctx->cairo;
-	updateDimensions(ctx);
 
-	cairo_push_group(C);
 	cairo_set_source_rgb(C, 1, 1, 1);
 	cairo_paint(C);
 
@@ -378,7 +372,6 @@ void draw(DrawingContext *ctx)
 	cairo_set_line_cap(C, CAIRO_LINE_CAP_ROUND);
 
 	if(limit_curve_valid) {
-
 		if(show_limit) {
 			int last_inside = 0;
 			for(int i = 0; i < n_group_elements; i++) {
@@ -421,13 +414,7 @@ void draw(DrawingContext *ctx)
 	sprintf(buf, "t = %.8f", parameter);
 	cairo_show_text(C, buf);
 
-	cairo_pop_group_to_source(C);
-	cairo_paint(C);
 	cairo_surface_flush(cairo_get_target(C));
-
-	gettimeofday(&current_time, 0);
-	double end_time = current_time.tv_sec + current_time.tv_usec*1e-6;
-	printf("draw() finished in %g seconds\n", end_time - start_time);
 }
 
 void setup()
@@ -544,10 +531,10 @@ int processEvent(GraphicsInfo *info, XEvent *ev)
 			break;
 		}
 
-		draw(info->context);
+		return STATUS_REDRAW;
 	}
 
-	return 0;
+	return STATUS_NOTHING;
 }
 
 int main()
@@ -586,7 +573,24 @@ int main()
 
 	startTimer(info);
 
-	while(!checkEvents(info, processEvent, draw)) {
+	while(1) {
+		int result = checkEvents(info, processEvent, NULL);
+		if(result == STATUS_QUIT)
+			return 0;
+		else if(result == STATUS_REDRAW) {
+			struct timeval current_time;
+			gettimeofday(&current_time, 0);
+			double start_time = current_time.tv_sec + current_time.tv_usec*1e-6;
+
+			updateDimensions(info->context);
+			draw(info->context);
+			cairo_set_source_surface(info->front_context, info->buffer_surface, 0, 0);
+			cairo_paint(info->front_context);
+
+			gettimeofday(&current_time, 0);
+			double end_time = current_time.tv_sec + current_time.tv_usec*1e-6;
+			printf("drawing finished in %g seconds\n", end_time - start_time);
+		}
 		waitUpdateTimer(info);
 	}