path: root/src/rmd_get_frames.c

/******************************************************************************
*                            recordMyDesktop                                  *
*******************************************************************************
*                                                                             *
*            Copyright (C) 2006,2007,2008 John Varouhakis                     *
*                                                                             *
*                                                                             *
*   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 2 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, write to the Free Software               *
*   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA  *
*                                                                             *
*                                                                             *
*                                                                             *
*   For further information contact me at johnvarouhakis@gmail.com            *
******************************************************************************/

#include "config.h"
#include "rmd_get_frames.h"

#include "rmd_cache.h"
#include "rmd_frame.h"
#include "rmd_getzpixmap.h"
#include "rmd_poll_events.h"
#include "rmd_rectinsert.h"
#include "rmd_threads.h"
#include "rmd_update_image.h"
#include "rmd_yuv_utils.h"
#include "rmd_types.h"

#include <X11/extensions/Xfixes.h>
#include <X11/extensions/XShm.h>

#include <limits.h>
#include <pthread.h>
#include <sys/shm.h>
#include <errno.h>
#include <stdlib.h>
#include <time.h>


/* clip_event_area dejavu */
static void clip_dummy_pointer_area(XRectangle *area, XRectangle *clip, XRectangle *res)
{
	res->x =	(((area->x + area->width >= clip->x) &&
			  (area->x <= clip->x + clip->width)) ?
			 ((area->x <= clip->x) ? clip->x : area->x) : -1);

	res->y =	(((area->y + area->height >= clip->y) &&
			  (area->y <= clip->y + clip->height)) ?
			 ((area->y <= clip->y) ? clip->y : area->y) : -1);

	res->width =	(area->x <= clip->x) ? area->width - (clip->x - area->x) :
			(area->x <= clip->x + clip->width) ?
			(clip->width - area->x + clip->x < area->width) ?
			clip->width - area->x + clip->x : area->width : 0;

	res->height =	(area->y <= clip->y) ? area->height - (clip->y - area->y) :
			(area->y <= clip->y + clip->height) ?
			(clip->height - area->y + clip->y < area->height) ?
			clip->height - area->y + clip->y : area->height : 0;

	if (res->x + res->width > clip->x + clip->width)
		res->width = clip->x + clip->width - res->x;

	if (res->y + res->height > clip->y + clip->height)
		res->height = clip->y + clip->height - res->y;
}

#define MARK_BUFFER_AREA_C(	data,							\
				x_tm,							\
				y_tm,							\
				width_tm,						\
				height_tm,						\
				buffer_width,						\
				__depth__) {						\
											\
	register u_int##__depth__##_t *datapi = 					\
			((u_int##__depth__##_t *)data) + y_tm * buffer_width + x_tm;	\
											\
	for (int k = 0; k < height_tm; k++) {						\
		for (int i = 0; i < width_tm; i++) {					\
			*datapi += 1;							\
			datapi++;							\
		}									\
		datapi += buffer_width - width_tm;					\
	}										\
}

static void mark_buffer_area(	unsigned char *data,
				int x_tm, int y_tm,
				int width_tm, int height_tm,
				int buffer_width, int depth)
{
	if ((depth == 24) || (depth == 32)) {
		MARK_BUFFER_AREA_C(	data,
					x_tm,
					y_tm,
					width_tm,
					height_tm,
					buffer_width,
					32);
	} else {
		MARK_BUFFER_AREA_C(	data,
					x_tm,
					y_tm,
					width_tm,
					height_tm,
					buffer_width,
					16);
	}
}

//besides taking the first screenshot, this functions primary purpose is to
//initialize the structures and memory.
static int rmdFirstFrame(ProgData *pdata, Image *image)
{
	const XRectangle	*rrect = &pdata->brwin.rrect;

	if (pdata->args.noshared) {
		image->ximage = XGetImage(	pdata->dpy,
						pdata->specs.root,
						rrect->x,
						rrect->y,
						rrect->width,
						rrect->height,
						AllPlanes,
						ZPixmap);
	} else {
		image->ximage = XShmCreateImage(pdata->dpy,
						pdata->specs.visual,
						pdata->specs.depth,
						ZPixmap,
						NULL,
						&image->shm_info,
						rrect->width,
						rrect->height);

		image->shm_info.shmid = shmget(	IPC_PRIVATE,
						image->ximage->bytes_per_line *
						image->ximage->height,
						IPC_CREAT|0777);

		if (image->shm_info.shmid == -1) {
			fprintf(stderr, "Failed to obtain shared memory segment!\n");
			return 12;
		}

		image->shm_info.shmaddr = image->ximage->data = shmat(image->shm_info.shmid, NULL, 0);
		image->shm_info.readOnly = False;
		shmctl(image->shm_info.shmid, IPC_RMID, NULL);

		if (!XShmAttach(pdata->dpy, &image->shm_info)) {
			fprintf(stderr, "Failed to attach shared memory to proccess.\n");
			return 12;
		}

		XShmGetImage(	pdata->dpy,
				pdata->specs.root,
				image->ximage,
				rrect->x,
				rrect->y,
				AllPlanes);
	}

	rmdUpdateYuvBuffer(	&pdata->enc_data->yuv,
				(unsigned char *)image->ximage->data,
				NULL,
				0,
				0,
				rrect->width,
				rrect->height,
				pdata->args.no_quick_subsample,
				pdata->specs.depth);

	return 0;
}

//make a deep copy
static void rmdBRWinCpy(BRWindow *target, BRWindow *source)
{
	target->winrect = source->winrect;
	target->rrect = source->rrect;
	target->windowid = source->windowid;
}

//recenters the capture area to the mouse
//without exiting the display bounding box
static void rmdMoveCaptureArea(	XRectangle *rect,
				int cursor_x,
				int cursor_y,
				int width,
				int height)
{
	int t_x = 0, t_y = 0;

	t_x = cursor_x - rect->width / 2;
	t_x = (t_x >> 1) << 1;
	rect->x = (t_x < 0) ? 0 : ((t_x + rect->width > width) ? width - rect->width : t_x);
	t_y = cursor_y - rect->height / 2;
	t_y = (t_y >> 1) << 1;
	rect->y = (t_y < 0 ) ? 0 : ((t_y + rect->height > height) ? height - rect->height : t_y);
}


static void rmdBlocksReset(unsigned int blocks_w, unsigned int blocks_h)
{
	memset(yblocks, 0, blocks_w * blocks_h * sizeof(*yblocks));
	memset(ublocks, 0, blocks_w * blocks_h * sizeof(*ublocks));
	memset(vblocks, 0, blocks_w * blocks_h * sizeof(*vblocks));
}


/**
*   Extract cache blocks from damage list
*
* \param root Root entry of the list with damaged areas
*
* \param x_offset left x of the recording area
*
* \param y_offset upper y of the recording area
*
* \param blocks_w Width of image in blocks
*
* \param blocks_h Height of image in blocks
*/
static void rmdBlocksFromList(	RectArea   **root,
				unsigned int x_offset,
				unsigned int y_offset,
				unsigned int blocks_w,
				unsigned int blocks_h)
{
	rmdBlocksReset(blocks_w, blocks_h);

	for (RectArea *temp = *root; temp; temp = temp->next) {
		int	row_start, row_end, column_start, column_end;

		column_start	= ((int)(temp->rect.x - x_offset)) / Y_UNIT_WIDTH;
		column_end	= ((int)(temp->rect.x + (temp->rect.width - 1) - x_offset)) / Y_UNIT_WIDTH;
		row_start	= ((int)(temp->rect.y - y_offset)) / Y_UNIT_WIDTH;
		row_end		= ((int)(temp->rect.y + (temp->rect.height - 1) - y_offset)) / Y_UNIT_WIDTH;

		for (int i = row_start; i < row_end + 1; i++) {
			for (int j = column_start; j < column_end + 1; j++) {

				int	blockno = i * blocks_w + j;

				yblocks[blockno] = 1;
				ublocks[blockno] = 1;
				vblocks[blockno] = 1;
			}
		}
	}
}


static struct timespec us_to_timespec(unsigned us)
{
	return (struct timespec){
		.tv_sec = us / 1000000,
		.tv_nsec = (us % 1000000) * 1000,
	};
}


/* subtract t2 from t1, return difference in microseconds */
static unsigned timespec_delta_in_us(struct timespec *t1, struct timespec *t2)
{
	unsigned	us = (t1->tv_sec - t2->tv_sec) * 1000000;

	us += t1->tv_nsec / 1000;
	us -= t2->tv_nsec / 1000;

	return us;
}


/* Synchronize the next frame with either just time, or if there's
 * an audio stream, with the audio stream.
 *
 * Returns wether a new frame should be acquired, or if the current
 * yuv contents should be reused as-is (when too far behind).
 */
static boolean sync_next_frame(ProgData *pdata)
{
	int	avd, delay_us;

	assert(pdata);

	if (pdata->args.nosound) {
		struct timespec	now;

		/* when there's no audio timeline to synchronize with,
		 * drive avd entirely from CLOCK_MONOTONIC
		 */
		clock_gettime(CLOCK_MONOTONIC, &now);

		if (pdata->last_frame_ts.tv_sec) {
			pthread_mutex_lock(&pdata->avd_mutex);
			pdata->avd -= timespec_delta_in_us(&now, &pdata->last_frame_ts);
			pthread_mutex_unlock(&pdata->avd_mutex);
		}

		pdata->last_frame_ts = now;
	}

	pthread_mutex_lock(&pdata->avd_mutex);
	avd = pdata->avd;
	pthread_mutex_unlock(&pdata->avd_mutex);

	delay_us = (int)pdata->frametime_us + avd;
	if (delay_us > 1000 /* only bother sleeping when > 1ms */) {
		struct timespec	delay;

		delay = us_to_timespec(delay_us);
		nanosleep(&delay, NULL);

		/* update avd post-sleep */
		pthread_mutex_lock(&pdata->avd_mutex);
		avd = pdata->avd;
		pthread_mutex_unlock(&pdata->avd_mutex);
	}


	/* refresh the frame unless we're way too far behind */
	return (avd > 2 * -(int)MAX(pdata->frametime_us, pdata->periodtime_us));
}


/* Advances *frameno according to avd, returns wether frameno was advanced. */
static boolean advance_frameno(ProgData *pdata, unsigned *frameno)
{
	int	increment, avd;

	assert(pdata);

	pthread_mutex_lock(&pdata->avd_mutex);
	avd = pdata->avd;

	if (avd > (int)MAX(pdata->frametime_us, pdata->periodtime_us)) {
		/* if we're far ahead, don't produce a frame */
		increment = 0;
	} else if (avd > 0) {
		/* if we're just a little ahead, produce a frame */
		increment = 1;
	} else if (avd <= 2 * -(int)MAX(pdata->frametime_us, pdata->periodtime_us)) {
		/* if we're far behind, clone as many frames as fit to ~avd=0 */
		increment = -avd / (int)pdata->frametime_us;
	} else {
		/* if we're just a little behind produce a frame */
		increment = 1;
	}

	pdata->avd += increment * (int)pdata->frametime_us;
	pthread_mutex_unlock(&pdata->avd_mutex);

	(*frameno) += increment;
#if 0
	printf("avd=%i increment=%u periodtime_us=%u frametime_us=%u\n", avd, increment, pdata->periodtime_us, pdata->frametime_us);
#endif
	return (increment > 0);
}


static boolean paused(ProgData *pdata)
{
	pthread_mutex_lock(&pdata->pause_mutex);
	if (pdata->pause_state_changed) {
		pdata->pause_state_changed = FALSE;

		if (!pdata->paused) {
			pdata->paused = TRUE;
			fprintf(stderr, "STATE:PAUSED\n");
		} else {
			pdata->paused = FALSE;
			fprintf(stderr, "STATE:RECORDING\n");
			pthread_cond_broadcast(&pdata->pause_cond);
		}
	}
	pthread_mutex_unlock(&pdata->pause_mutex);

	return pdata->paused;
}


/* This thread just samples the recorded window in response to rmdTimer's
 * triggers, updating the yuv buffer hopefully at the desired frame rate.
 * Following every update, the frameno is propogated to capture_frameno
 * and image_buffer_ready is signaled for the cache/encode side to consume the
 * yuv buffer.
 */
void *rmdGetFrames(ProgData *pdata)
{
	int	blocks_w = pdata->enc_data->yuv.y_width / Y_UNIT_WIDTH,
		blocks_h = pdata->enc_data->yuv.y_height / Y_UNIT_WIDTH;
	unsigned int msk_ret;
	XRectangle mouse_pos_abs, mouse_pos_rel, mouse_pos_temp;
	BRWindow temp_brwin;
	Window root_ret, child_ret; //Frame
	XFixesCursorImage *xcim = NULL;
	Image image = {}, image_back = {};	//the image that holds
						//the current full screenshot
	int init_img1 = 0, init_img2 = 0, img_sel, d_buff;
	unsigned frameno = 0;

	rmdThreadsSetName("rmdGetFrames");

	img_sel = d_buff = pdata->args.full_shots;

	if ((init_img1 = rmdFirstFrame(pdata, &image) != 0)) {
		if (pdata->args.encOnTheFly) {
			if (remove(pdata->args.filename)) {
				perror("Error while removing file:\n");
			} else {
				fprintf(stderr,	"SIGABRT received, file %s removed\n",
						pdata->args.filename);
			}
		} else {
			rmdPurgeCache(pdata->cache_data, !pdata->args.nosound);
		}

		exit(init_img1);
	}

	if (d_buff) {
		if ((init_img2 = rmdFirstFrame(pdata, &image_back) != 0)) {
			if (pdata->args.encOnTheFly) {
				if (remove(pdata->args.filename)) {
					perror("Error while removing file:\n");
				} else{
					fprintf(stderr,	"SIGABRT received, file %s removed\n",
							pdata->args.filename);
				}
			} else {
				rmdPurgeCache(pdata->cache_data, !pdata->args.nosound);
			}

			exit(init_img2);
		}
	}

	if (!pdata->args.noframe) {
		pdata->shaped_w = rmdFrameInit(	pdata->dpy,
						pdata->specs.screen,
						pdata->specs.root,
						pdata->brwin.rrect.x,
						pdata->brwin.rrect.y,
						pdata->brwin.rrect.width,
						pdata->brwin.rrect.height);

		XSelectInput(pdata->dpy, pdata->shaped_w, ExposureMask);
	}

	mouse_pos_abs.x = mouse_pos_temp.x = 0;
	mouse_pos_abs.y = mouse_pos_temp.y = 0;
	mouse_pos_abs.width = mouse_pos_temp.width = pdata->dummy_p_size;
	mouse_pos_abs.height = mouse_pos_temp.height = pdata->dummy_p_size;
	
	//This is the the place where we call XSelectInput
	//and arrange so that we listen for damage on all
	//windows
	rmdInitEventsPolling(pdata);

	while (pdata->running) {

		if (paused(pdata)) {
			/* just pump events while paused, so shortcuts can work for unpausing */
			nanosleep(&(struct timespec) { .tv_nsec = 100000000 }, NULL);
			rmdEventLoop(pdata);
			continue;
		}

		if (sync_next_frame(pdata)) {
			//read all events and construct list with damage
			//events (if not full_shots)
			rmdEventLoop(pdata);

			/* TODO: refactor this inherited spaghetti into functions */

			//switch back and front buffers (full_shots only)
			if (d_buff)
				img_sel = img_sel ? 0 : 1;

			rmdBRWinCpy(&temp_brwin, &pdata->brwin);


			if (	pdata->args.xfixes_cursor ||
				pdata->args.have_dummy_cursor ||
				pdata->args.follow_mouse) {


				// Pointer sequence:
				// * Mark previous position as dirty with rmdRectInsert()
				// * Update to new position
				// * Mark new position as dirty with rmdRectInsert()
				if (	!pdata->args.full_shots &&
					mouse_pos_temp.x >= 0 &&
					mouse_pos_temp.y >= 0 &&
					mouse_pos_temp.width > 0 &&
					mouse_pos_temp.height > 0) {
					rmdRectInsert(&pdata->rect_root, &mouse_pos_temp);
				}

				if (pdata->args.xfixes_cursor) {
					xcim = XFixesGetCursorImage(pdata->dpy);
					mouse_pos_abs.x = xcim->x - xcim->xhot;
					mouse_pos_abs.y = xcim->y - xcim->yhot;
					mouse_pos_abs.width = xcim->width;
					mouse_pos_abs.height = xcim->height;
				} else {
					XQueryPointer(	pdata->dpy,
							pdata->specs.root,
							&root_ret, &child_ret,
							(int *)&mouse_pos_abs.x,
							(int *)&mouse_pos_abs.y,
							(int *)&mouse_pos_rel.x,
							(int *)&mouse_pos_rel.y,
							&msk_ret);
				}

				clip_dummy_pointer_area(&mouse_pos_abs, &temp_brwin.rrect, &mouse_pos_temp);
				if (	mouse_pos_temp.x >= 0 &&
					mouse_pos_temp.y >= 0 &&
					mouse_pos_temp.width > 0 &&
					mouse_pos_temp.height > 0) {

					//there are 3 capture scenarios:
					// * Xdamage
					// * full-shots with double buffering
					// * full-shots on a single buffer
					//The last one cannot be reached through
					//this code (see above how the d_buf variable is set), but
					//even if it could, it would not be of interest regarding the
					//marking of the cursor area. Single buffer means full repaint
					//on every frame so there is no need for marking at all.

					if (!pdata->args.full_shots) {
						rmdRectInsert(&pdata->rect_root, &mouse_pos_temp);
					} else if (d_buff) {
						unsigned char *back_buff= img_sel ?
									((unsigned char*)image.ximage->data) :
									((unsigned char*)image_back.ximage->data);

						mark_buffer_area(
							back_buff,
							mouse_pos_temp.x - temp_brwin.rrect.x,
							mouse_pos_temp.y - temp_brwin.rrect.y,
							mouse_pos_temp.width, mouse_pos_temp.height, temp_brwin.rrect.width,
							pdata->specs.depth
						);
					}
				}
			}

			if (pdata->args.follow_mouse) {
				rmdMoveCaptureArea(	&pdata->brwin.rrect,
							mouse_pos_abs.x + pdata->args.xfixes_cursor ? xcim->xhot : 0,
							mouse_pos_abs.y + pdata->args.xfixes_cursor ? xcim->yhot : 0,
							pdata->specs.width,
							pdata->specs.height);

				if (!pdata->args.noframe)
					rmdMoveFrame(	pdata->dpy,
							pdata->shaped_w,
							temp_brwin.rrect.x,
							temp_brwin.rrect.y);
			}

			if (!pdata->args.full_shots) {
				pthread_mutex_lock(&pdata->yuv_mutex);
				rmdUpdateImage(	pdata->dpy,
						&pdata->enc_data->yuv,
						&pdata->specs,
						&pdata->rect_root,
						&temp_brwin,
						pdata->enc_data,
						&image,
						pdata->args.noshared,
						pdata->shm_opcode,
						pdata->args.no_quick_subsample);

				rmdBlocksFromList(	&pdata->rect_root,
							temp_brwin.rrect.x,
							temp_brwin.rrect.y,
							blocks_w,
							blocks_h);

				pthread_mutex_unlock(&pdata->yuv_mutex);
			} else {
				unsigned char *front_buff = !img_sel ?	((unsigned char*)image.ximage->data):
									((unsigned char*)image_back.ximage->data);
				unsigned char *back_buff = !d_buff ? NULL : (img_sel ?
									((unsigned char*)image.ximage->data):
									((unsigned char*)image_back.ximage->data));

				if (pdata->args.noshared) {
					rmdGetZPixmap(	pdata->dpy,
							pdata->specs.root,
							image.ximage->data,
							temp_brwin.rrect.x,
							temp_brwin.rrect.y,
							temp_brwin.rrect.width,
							temp_brwin.rrect.height);
				} else {
					XShmGetImage(	pdata->dpy,
							pdata->specs.root,
							((!img_sel) ? image.ximage : image_back.ximage),
							temp_brwin.rrect.x,
							temp_brwin.rrect.y,
							AllPlanes);
				}

				pthread_mutex_lock(&pdata->yuv_mutex);
				rmdBlocksReset(blocks_w, blocks_h);
				rmdUpdateYuvBuffer(	&pdata->enc_data->yuv,
							front_buff,
							back_buff,
							0,
							0,
							temp_brwin.rrect.width,
							temp_brwin.rrect.height,
							pdata->args.no_quick_subsample,
							pdata->specs.depth);

				pthread_mutex_unlock(&pdata->yuv_mutex);
			}

			if (pdata->args.xfixes_cursor || pdata->args.have_dummy_cursor) {
				int mouse_xoffset, mouse_yoffset;

				//avoid segfaults
				clip_dummy_pointer_area(&mouse_pos_abs, &temp_brwin.rrect, &mouse_pos_temp);
				mouse_xoffset = mouse_pos_temp.x - mouse_pos_abs.x;
				mouse_yoffset = mouse_pos_temp.y - mouse_pos_abs.y;

				if ((mouse_xoffset < 0) || (mouse_xoffset > mouse_pos_abs.width))
					mouse_xoffset = 0;

				if ((mouse_yoffset < 0) || (mouse_yoffset > mouse_pos_abs.height))
					mouse_yoffset = 0;

				//draw the cursor
				if (	(mouse_pos_temp.x >= 0) &&
					(mouse_pos_temp.y >= 0) &&
					(mouse_pos_temp.width > 0) &&
					(mouse_pos_temp.height > 0)) {

						if (pdata->args.xfixes_cursor) {
							rmdXFixesPointerToYuv(
								&pdata->enc_data->yuv,
								((unsigned char*)xcim->pixels),
								mouse_pos_temp.x - temp_brwin.rrect.x,
								mouse_pos_temp.y - temp_brwin.rrect.y,
								mouse_pos_temp.width,
								mouse_pos_temp.height,
								mouse_xoffset,
								mouse_yoffset,
								xcim->width-mouse_pos_temp.width
							);
						} else {
							rmdDummyPointerToYuv(
								&pdata->enc_data->yuv,
								pdata->dummy_pointer,
								mouse_pos_temp.x - temp_brwin.rrect.x,
								mouse_pos_temp.y - temp_brwin.rrect.y,
								mouse_pos_temp.width,
								mouse_pos_temp.height,
								mouse_xoffset,
								mouse_yoffset,
								pdata->npxl
							);
						}

					if (d_buff) {
						//make previous cursor position dirty
						//on the currently front buffer (which
						//will be the back buffer next time it's
						//used)
						unsigned char *front_buff = !img_sel ?
									((unsigned char*)image.ximage->data) :
									((unsigned char*)image_back.ximage->data);

						mark_buffer_area(
							front_buff,
							mouse_pos_temp.x - temp_brwin.rrect.x,
							mouse_pos_temp.y - temp_brwin.rrect.y,
							mouse_pos_temp.width,
							mouse_pos_temp.height,
							temp_brwin.rrect.width,
							pdata->specs.depth
						);
					}

				}

				if (pdata->args.xfixes_cursor) {
					XFree(xcim);
					xcim = NULL;
				}
			}

			if (!pdata->args.full_shots)
				rmdClearList(&pdata->rect_root);
		}

		if (advance_frameno(pdata, &frameno)) {
			/* notify the encoder of additional frames */
			pthread_mutex_lock(&pdata->img_buff_ready_mutex);
			pdata->capture_frameno = frameno;
			pthread_cond_signal(&pdata->image_buffer_ready);
			pthread_mutex_unlock(&pdata->img_buff_ready_mutex);
		}
	}

	/* Make sure the encoder/cacher doen't get lost in pthread_cond_wait indefinitely,
	 * now that !pdata->running they will exit their wait loops.
	 */
	pthread_cond_signal(&pdata->image_buffer_ready);

	/* Same for waiters on pause_cond in case we quit from being paused */
	pthread_mutex_lock(&pdata->pause_mutex);
	pdata->paused = FALSE;
	pthread_cond_broadcast(&pdata->pause_cond);
	pthread_mutex_unlock(&pdata->pause_mutex);

	if (!pdata->args.noframe)
		XDestroyWindow(pdata->dpy, pdata->shaped_w);

	if (!pdata->args.noshared) {
		XShmDetach(pdata->dpy, &image.shm_info);
		shmdt(image.shm_info.shmaddr);
		if (d_buff) {
			XShmDetach(pdata->dpy, &image_back.shm_info);
			shmdt(image_back.shm_info.shmaddr);
		}
	}

	pthread_exit(&errno);
}