added gfx_screengrab module that draws the screens top left corner on…

… the led matrix

src/modules/gfx_screengrab.c

@@ -0,0 +1,101 @@
+// Simple screen grabber that draws the upper left corner of the screen to the display
+//
+// Copyright (c) 2019, X41 <whyareyoureadingmycode@x41.me>
+// 
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+#include <types.h>
+#include <matrix.h>
+#include <timers.h>
+#include <random.h>
+#include <stddef.h>
+#include <X11/Xlib.h>
+#include <X11/X.h>
+
+#define FPS 30
+#define FRAMETIME (T_SECOND / FPS)
+#define FRAMES (TIME_SHORT * FPS)
+
+static int modno;
+static int frame;
+static ulong nexttick;
+
+int width;
+int height;
+
+Display *display;
+Window root;
+XImage *image;
+
+unsigned long red_mask;
+unsigned long green_mask;
+unsigned long blue_mask;
+unsigned long pixel;
+unsigned char blue;
+unsigned char green;
+unsigned char red;
+
+int init(int moduleno, char* argstr) {
+	if (matrix_getx() < 3)
+		return 1;
+	modno = moduleno;
+
+	// grab X11 screen
+	display = XOpenDisplay(NULL);
+	root = DefaultRootWindow(display);
+	XWindowAttributes gwa;
+	XGetWindowAttributes(display, root, &gwa);
+
+	// use dimensions of matrix
+	width = matrix_getx();
+	height = matrix_gety();
+
+	// get first frame and set up color masks
+	image = XGetImage(display, root, 0, 0, width, height, AllPlanes, ZPixmap);
+	red_mask   = image->red_mask;
+	green_mask = image->green_mask;
+	blue_mask  = image->blue_mask;
+    return 0;
+}
+
+void reset(void) {
+		nexttick = udate();
+}
+
+int draw(int argc, char* argv[]) {
+	nexttick = udate() + FRAMETIME;
+
+	image = XGetImage(display,root, 0,0 , width,height,AllPlanes, ZPixmap);
+
+	for (int x = 0; x < width; x++){
+		for (int y = 0; y < height ; y++){
+			pixel = XGetPixel(image,x,y);
+
+			blue = pixel & blue_mask;
+			green = (pixel & green_mask) >> 8;
+			red = (pixel & red_mask) >> 16;
+
+			matrix_set(x, y, RGB(red, green, blue));
+		}
+	}
+	matrix_render();
+
+	if (frame >= FRAMES) { frame = 0; return 1;} // end drawing
+	timer_add(nexttick, modno, 0, NULL);
+
+	return 0;
+}
+
+int deinit(void) {
+	return 0;
+}