xcbshm.c
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/**
* \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: