Implement X11 onscreen framerate counter.

This FPS counter is disabled by default.

Change-Id: Ida04352dece25a212cb678c9ceca4c31d654f373
Reviewed-on: https://swiftshader-review.googlesource.com/12128
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>

src/Main/FrameBufferX11.cpp

diff --git a/src/Main/FrameBufferX11.cpp b/src/Main/FrameBufferX11.cpp
index a065198..36ba38f 100644
--- a/src/Main/FrameBufferX11.cpp
+++ b/src/Main/FrameBufferX11.cpp
@@ -15,6 +15,7 @@
 #include "FrameBufferX11.hpp"
 
 #include "libX11.hpp"
+#include "Timer.hpp"
 
 #include <sys/ipc.h>
 #include <sys/shm.h>
@@ -140,6 +141,30 @@
 		}
 
 		libX11->XSync(x_display, False);
+
+		if(false)   // Draw the framerate on screen
+		{
+			static double fpsTime = sw::Timer::seconds();
+			static int framesSec = 0;
+
+			double time = sw::Timer::seconds();
+			double delta = time - fpsTime;
+			framesSec++;
+
+			static double FPS = 0.0;
+
+			if(delta > 1.0)
+			{
+				FPS = framesSec / delta;
+
+				fpsTime = time;
+				framesSec = 0;
+			}
+
+			char string[256];
+			sprintf(string, "FPS: %.1f", FPS);
+			libX11->XDrawString(x_display, x_window, x_gc, 50, 50, string, strlen(string));
+		}
 	}
 }
 

src/Main/libX11.cpp

diff --git a/src/Main/libX11.cpp b/src/Main/libX11.cpp
index 9c056bf..f3723ff 100644
--- a/src/Main/libX11.cpp
+++ b/src/Main/libX11.cpp
@@ -35,6 +35,7 @@
 	XCreateImage = (XImage *(*)(Display*, Visual*, unsigned int, int, int, char*, unsigned int, unsigned int, int, int))getProcAddress(libX11, "XCreateImage");
 	XCloseDisplay = (int (*)(Display*))getProcAddress(libX11, "XCloseDisplay");
 	XPutImage = (int (*)(Display*, Drawable, GC, XImage*, int, int, int, int, unsigned int, unsigned int))getProcAddress(libX11, "XPutImage");
+	XDrawString = (int (*)(Display*, Drawable, GC, int, int, char*, int))getProcAddress(libX11, "XDrawString");
 
 	XShmQueryExtension = (Bool (*)(Display*))getProcAddress(libXext, "XShmQueryExtension");
 	XShmCreateImage = (XImage *(*)(Display*, Visual*, unsigned int, int, char*, XShmSegmentInfo*, unsigned int, unsigned int))getProcAddress(libXext, "XShmCreateImage");

src/Main/libX11.hpp

diff --git a/src/Main/libX11.hpp b/src/Main/libX11.hpp
index f9f88be..c188386 100644
--- a/src/Main/libX11.hpp
+++ b/src/Main/libX11.hpp
@@ -39,6 +39,7 @@
 	XImage *(*XCreateImage)(Display *display, Visual *visual, unsigned int depth, int format, int offset, char *data, unsigned int width, unsigned int height, int bitmap_pad, int bytes_per_line);
 	int (*XCloseDisplay)(Display *display);
 	int (*XPutImage)(Display *display, Drawable d, GC gc, XImage *image, int src_x, int src_y, int dest_x, int dest_y, unsigned int width, unsigned int height);
+	int (*XDrawString)(Display *display, Drawable d, GC gc, int x, int y, char *string, int length);
 
 	Bool (*XShmQueryExtension)(Display *display);
 	XImage *(*XShmCreateImage)(Display *display, Visual *visual, unsigned int depth, int format, char *data, XShmSegmentInfo *shminfo, unsigned int width, unsigned int height);