diff -urN ../xzoom-0.3.orig/xzoom.c ./xzoom.c

--- ../xzoom-0.3.orig/xzoom.c	Mon Dec  3 20:47:49 2001

+++ ./xzoom.c	Mon Dec  3 20:48:15 2001

@@ -26,6 +26,8 @@

                           optimized scaling routines

                           use memcpy() instead of memmove() ;-)

                           some other minor changes/fixes

+Egmont Koblinger          Added XSHM auto detection,

+                          -shm, -noshm and -autoshm option

 */

 #include <stdio.h>

@@ -82,6 +84,9 @@

 #define MAGX	MAG				/* horizontal magnification */

 #define MAGY	MAG				/* vertical magnification */

+int use_xshm = 1;

+int force_xshm = 0;

+

 int xgrab, ygrab;				/* where do we take the picture from */

 int magx = MAGX;

@@ -131,7 +136,7 @@

 	for(i = 0; i < 2; i++) {

-#ifdef XSHM

+if (use_xshm) { /*#ifdef XSHM*/

 		ximage[i] = XShmCreateImage(dpy,

 			DefaultVisualOfScreen(scr),

 			DefaultDepthOfScreen(scr),

@@ -167,11 +172,15 @@

 		ximage[i]->data = shminfo[i].shmaddr;

 		shminfo[i].readOnly = False;

-		XShmAttach(dpy, &shminfo[i]);

-		XSync(dpy, False);

+		if (XShmAttach(dpy, &shminfo[i]) || force_xshm) {

+			XSync(dpy, False);

-		shmctl(shminfo[i].shmid, IPC_RMID, 0);

-#else

+			shmctl(shminfo[i].shmid, IPC_RMID, 0);

+		} else {

+			use_xshm = 0;

+		}

+}

+if (!use_xshm) { /*#else*/

 		char *data;

 		data = malloc(BitmapUnit(dpy) / 8 * width[i] * height[i]);

@@ -186,7 +195,7 @@

 			exit(-1);

 		}

-#endif /* XSHM */

+} /*#endif*/ /* XSHM */

 	}

 	created_images = True;

 }

@@ -199,12 +208,12 @@

 		return;

 	for(i = 0; i < 2; i++) {

-#ifdef XSHM

+if (use_xshm) { /*#ifdef XSHM*/

 		XShmDetach(dpy, &shminfo[i]);	/* ask X11 to detach shared segment */

 		shmdt(shminfo[i].shmaddr);		/* detach it ourselves */

-#else

+} else { /*#else*/

 		free(ximage[i]->data);

-#endif

+} /*#endif*/

 		ximage[i]->data = NULL;			/* remove refrence to that address */

 		XDestroyImage(ximage[i]);		/* and destroy image */

 	}

@@ -217,6 +226,9 @@

 	fprintf(stderr, "Usage: %s [ args ]\n"

 		"Command line args:\n"

 		"-display displayname\n"

+		"-shm\n"

+		"-noshm\n"

+		"-autoshm\n"

 		"-mag magnification [ magnification ]\n"

 		"-geometry geometry\n"

 		"-source geometry\n"

@@ -346,6 +358,22 @@

 			continue;

 		}

+		if(!strcmp(argv[0], "-shm")) {

+			force_xshm = 1;

+			use_xshm = 1;

+			continue;

+		}

+		if(!strcmp(argv[0], "-noshm")) {

+			force_xshm = 0;

+			use_xshm = 0;

+			continue;

+		}

+		if(!strcmp(argv[0], "-autoshm")) {

+			force_xshm = 0;

+			use_xshm = 1;

+			continue;

+		}

+

 		if(!strcmp(argv[0], "-mag")) {

 			++argv; --argc;

@@ -793,14 +821,14 @@

 		}

-#ifdef XSHM

+if (use_xshm) { /*#ifdef XSHM*/

 		XShmGetImage(dpy, RootWindowOfScreen(scr), ximage[SRC],

 			xgrab, ygrab, AllPlanes);

-#else

+} else { /*#else*/

 		XGetSubImage(dpy, RootWindowOfScreen(scr),

 			xgrab, ygrab, width[SRC], height[SRC], AllPlanes,

 			ZPixmap, ximage[SRC], 0, 0);

-#endif

+} /*#endif*/

 #ifdef FRAME

 		if(buttonpressed) {	/* show the frame */

 			DRAW_FRAME();

@@ -815,11 +843,11 @@

 		else if (depth <= 8*sizeof(int))

 			scale32();

-#ifdef XSHM

+if (use_xshm) { /*#ifdef XSHM*/

 		XShmPutImage(dpy, win, gc, ximage[DST], 0, 0, 0, 0, width[DST], height[DST], False);

-#else

+} else { /*#else*/

 		XPutImage(dpy, win, gc, ximage[DST], 0, 0, 0, 0, width[DST], height[DST]);

-#endif

+} /*#endif*/

 		if(set_title) {

 			if(magx == magy && !flipx && !flipy && !flipxy)

 				sprintf(title, "%s x%d", progname, magx);

diff -urN ../xzoom-0.3.orig/xzoom.man ./xzoom.man

--- ../xzoom-0.3.orig/xzoom.man	Mon Dec  3 20:47:49 2001

+++ ./xzoom.man	Mon Dec  3 20:48:15 2001

@@ -9,6 +9,7 @@

 [ \-display \fIdisplayname\fP ] [ \-mag \fImag\fP [ \fImag\fP ] ]

 [ \-x ] [ \-y ] [ \-xy ]

 [ \-geometry \fIgeometry\fP ] [ \-source \fIgeometry\fP ]

+[ \-shm ] [ \-noshm ] [ \-autoshm ]

 .SH OPTIONS

 .LP

 .TP 5

@@ -38,6 +39,16 @@

 The dimensions of this area are multiplied by the magnification to

 get the size of \fBxzoom\fR's window. If these dimensions are given

 separately (by use of \-geometry ) then an error is reported.

+.TP 5

+.B \-shm

+Force XSHM extension.

+.TP 5

+.B \-noshm

+Disable XSHM extension.

+.TP 5

+.B \-autoshm

+Try to autodetect if XSHM is available. This is the default. Unfortunately

+this is not perfect, sometimes you need to manually give \-noshm.

 .br

 .SH DESCRIPTION

 .IR Xzoom

@@ -145,14 +156,7 @@

 delays would feel like poor response to user commands.

 .LP 5

 \(dg

-For best performance the shared memory extension for X11 is

-used. Xzoom will fail if it is compiled to use XSHM and its

-display is not on the local host.

-.LP 5

-\(dg

-The Ximage data is accessed directly, in a way which may

-not be portable. Xzoom will not run with display depth other

-than 8 bits per pixel.

+Auto detection of XSHM is far from perfect.

 .LP 5

 \(dg

 Xzoom is given with no warranty. It was tested only under