1 files changed, 64 insertions, 0 deletions
diff --git a/shmximage.cpp b/shmximage.cpp
new file mode 100644
index 0000000..ea60ab0
--- /dev/null
+++ b/shmximage.cpp
@@ -0,0 +1,64 @@
+static int shm_error;
+static int (*X_handler)(Display *, XErrorEvent *) = NULL;
+
+static bool have_mitshm(Display *dpy)
+{
+    // Only use shared memory on local X servers
+    return X11_XShmQueryExtension(dpy) ? SDL_X11_HAVE_SHM : false;
+}
+
+static int shm_errhandler(Display *d, XErrorEvent *e)
+{
+    if (e->error_code == BadAccess) {
+        shm_error = True;
+        return 0;
+    }
+    return X_handler(d, e);
+}
+
+
+{
+    if (have_mitshm(display)) {
+        XShmSegmentInfo shminfo;
+
+        shminfo.shmid = shmget(IPC_PRIVATE, (size_t)h * (*pitch), IPC_CREAT | 0777);
+        if (shminfo.shmid >= 0) {
+            shminfo.shmaddr = (char *)shmat(shminfo.shmid, 0, 0);
+            shminfo.readOnly = False;
+            if (shminfo.shmaddr != (char *)-1) {
+                shm_error = False;
+                X_handler = X11_XSetErrorHandler(shm_errhandler);
+                X11_XShmAttach(display, shminfo);
+                XSync(display, False);
+                X11_XSetErrorHandler(X_handler);
+                if (shm_error) {
+                    shmdt(shminfo.shmaddr);
+                }
+            } else {
+                shm_error = True;
+            }
+            shmctl(shminfo.shmid, IPC_RMID, NULL);
+        } else {
+            shm_error = True;
+        }
+        if (!shm_error){
+            ximage = X11_XShmCreateImage(display, data->visual,
+                                               vinfo.depth, ZPixmap,
+                                               shminfo.shmaddr, shminfo,
+                                               w, h);
+            if (!ximage) {
+                X11_XShmDetach(display, shminfo);
+                X11_XSync(display, False);
+                shmdt(shminfo.shmaddr);
+            } else {
+                // Done!
+                ximage->byte_order = (SDL_BYTEORDER == SDL_BIG_ENDIAN) ? MSBFirst : LSBFirst;
+                *pixels = shminfo.shmaddr;
+                return true;
+            }
+        }
+    }
+}
+
+X11_XShmPutImage(display, data->xwindow, data->gc, data->ximage, x, y, x, y, w, h, False);
+