Add C xcb shm examples

+all: xcbshm xcbshm2
+
+xcbshm2: xcbshm2.c
+	gcc -o $@ -lxcb -lxcb-shm -lxcb-image $<
+
+xcbshm: xcbshm.c
+	gcc -o $@ -lxcb -lxcb-shm -lxcb-image $<
+
+.PHONY: clean
+
+clean:
+	@rm -f xcbshm xcbshm2

+/**
+ * \file
+ * [: description :]
+ *
+ * \author
+ * Georg Hopp <georg@steffers.org>
+ *
+ * \copyright
+ * Copyright © 2019 Georg Hopp
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+// http://stackoverflow.com/questions/27745131
+
+#include <sys/ipc.h>
+#include <sys/shm.h>
+
+#include <xcb/xcb.h>
+#include <xcb/xcb_image.h>
+#include <xcb/shm.h>
+
+#include <stdio.h>
+
+#define W 512
+#define H 512
+
+
+int main(){
+	//connect to the X server and get screen
+	xcb_connection_t* connection = xcb_connect(NULL, NULL);
+	xcb_screen_t* screen = xcb_setup_roots_iterator(xcb_get_setup(connection)).data;
+
+	//create a window
+	uint32_t value_mask = XCB_CW_BACK_PIXEL|XCB_CW_EVENT_MASK;
+	uint32_t value_list[2] = {screen->black_pixel, XCB_EVENT_MASK_EXPOSURE};
+	xcb_window_t window = xcb_generate_id(connection);
+	xcb_create_window(connection, screen->root_depth, window, screen->root, 0, 0, W, H, 0,
+			XCB_WINDOW_CLASS_INPUT_OUTPUT, screen->root_visual, value_mask, value_list);
+
+	//create a graphic context
+	value_mask = XCB_GC_FOREGROUND|XCB_GC_GRAPHICS_EXPOSURES;
+	value_list[0] = screen->black_pixel;
+	value_list[1] = 0;
+	xcb_gcontext_t gcontext = xcb_generate_id(connection);
+	xcb_create_gc(connection, gcontext, window, value_mask, value_list);
+
+	//map the window onto the screen
+	xcb_map_window(connection, window);
+	xcb_flush(connection);
+
+	//Shm test
+	xcb_shm_segment_info_t info;
+	xcb_shm_query_version_reply(connection, xcb_shm_query_version(connection), NULL);
+
+	info.shmid   = shmget(IPC_PRIVATE, W*H*4, IPC_CREAT|0777);
+	info.shmaddr = shmat(info.shmid, 0, 0);
+	info.shmseg = xcb_generate_id(connection);
+	xcb_shm_attach(connection, info.shmseg, info.shmid, 0);
+	shmctl(info.shmid, IPC_RMID, 0);
+	uint8_t* data = info.shmaddr;
+
+	xcb_pixmap_t pix = xcb_generate_id(connection);
+	xcb_shm_create_pixmap(connection, pix, window, W, H, screen->root_depth, info.shmseg, 0);
+
+
+	uint8_t lala[W*H*4] = {0};
+	const xcb_setup_t* setup = xcb_get_setup(connection);
+	xcb_format_t* fmt = xcb_setup_pixmap_formats(setup);
+	printf("scanline_pad %u  depth %u  bpp %u  byte_order %u\n",
+			fmt->scanline_pad, fmt->depth, fmt->bits_per_pixel, setup->image_byte_order);
+	xcb_image_t* img = xcb_image_create(W,H, XCB_IMAGE_FORMAT_Z_PIXMAP,
+			fmt->scanline_pad, 24, 32, 0, setup->image_byte_order, XCB_IMAGE_ORDER_LSB_FIRST, lala, W*H*4, lala);
+
+	// xcb_image_shm_get(connection, window, img, info, 0,0, XCB_IMAGE_FORMAT_Z_PIXMAP);
+	// xcb_image_shm_put(connection, window, img, info, 0,0, XCB_IMAGE_FORMAT_Z_PIXMAP);
+
+
+	// --------------------------------------------------------------
+	uint i = 0;
+	while(1){
+		data[i++] = 0xff;
+		xcb_copy_area(connection, pix, window, gcontext, 0, 0, 0, 0, W, H);
+		xcb_flush(connection);
+	}
+
+	xcb_shm_detach(connection, info.shmseg);
+	shmdt(info.shmaddr);
+
+	xcb_free_pixmap(connection, pix);
+	xcb_destroy_window(connection, window);
+	xcb_disconnect(connection);
+}
+
+// vim: set ts=4 sw=4:

+/**
+ * \file
+ * [: description :]
+ *
+ * \author
+ * Georg Hopp <georg@steffers.org>
+ *
+ * \copyright
+ * Copyright © 2019 Georg Hopp
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include <sys/ipc.h>
+#include <sys/shm.h>
+
+#include <xcb/xcb.h>
+#include <xcb/shm.h>
+#include <xcb/xcb_image.h>
+
+
+#define WID 512
+#define HEI 512
+
+
+int main(){
+	xcb_connection_t*       connection;
+	xcb_window_t            window;
+	xcb_screen_t*           screen;
+	xcb_gcontext_t          gcontext;
+	xcb_generic_event_t*    event;
+
+	uint32_t value_mask;
+	uint32_t value_list[2];
+
+	//connect to the X server and get screen
+
+	connection = xcb_connect(NULL, NULL);
+	screen = xcb_setup_roots_iterator(xcb_get_setup(connection)).data;
+
+	//create a window
+
+	value_mask = XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK;
+	value_list[0] = screen->black_pixel;
+	value_list[1] = XCB_EVENT_MASK_EXPOSURE;
+
+	window = xcb_generate_id(connection);
+
+	xcb_create_window(
+			connection,
+			screen->root_depth,
+			window,
+			screen->root,
+			0, 0,
+			WID, HEI,
+			0,
+			XCB_WINDOW_CLASS_INPUT_OUTPUT,
+			screen->root_visual,
+			value_mask, value_list
+			);
+
+	//create a graphic context
+
+	value_mask = XCB_GC_FOREGROUND | XCB_GC_GRAPHICS_EXPOSURES;
+	value_list[0] = screen->black_pixel;
+	value_list[1] = 0;
+
+	gcontext = xcb_generate_id(connection);
+	xcb_create_gc(connection, gcontext, window, value_mask, value_list);
+
+	//map the window onto the screen
+
+	xcb_map_window(connection, window);
+	xcb_flush(connection);
+
+
+	//Shm test
+	xcb_shm_query_version_reply_t*  reply;
+	xcb_shm_segment_info_t          info;
+
+	reply = xcb_shm_query_version_reply(
+			connection,
+			xcb_shm_query_version(connection),
+			NULL
+			);
+
+	if(!reply || !reply->shared_pixmaps){
+		printf("Shm error...\n");
+		exit(0);
+	}
+
+	info.shmid   = shmget(IPC_PRIVATE, WID*HEI*4, IPC_CREAT | 0777);
+	info.shmaddr = shmat(info.shmid, 0, 0);
+
+	info.shmseg = xcb_generate_id(connection);
+	xcb_shm_attach(connection, info.shmseg, info.shmid, 0);
+	shmctl(info.shmid, IPC_RMID, 0);
+
+	uint32_t* data = (uint32_t*)info.shmaddr;
+
+	xcb_pixmap_t pix = xcb_generate_id(connection);
+	xcb_shm_create_pixmap(
+			connection,
+			pix,
+			window,
+			WID, HEI,
+			screen->root_depth,
+			info.shmseg,
+			0
+			);
+
+	int i = 0;
+	while(1){
+		usleep(10000);
+
+		data[i] = 0xFFFFFF;
+		i++;
+
+		xcb_copy_area(
+				connection,
+				pix,
+				window,
+				gcontext,
+				0, 0, 0, 0,
+				WID, HEI
+				);
+
+		xcb_flush(connection);
+	}
+
+	xcb_shm_detach(connection, info.shmseg);
+	shmdt(info.shmaddr);
+
+	xcb_free_pixmap(connection, pix);
+
+	xcb_destroy_window(connection, window);
+	xcb_disconnect(connection);
+
+	return 0;
+}
+
+// vim: set ts=4 sw=4: