wmaker: add support for _NET_WM_MOVERESIZE

This patch adds support for _NET_WM_MOVERESIZE hint as defined in EWMH
which allows a window without decorations to manage itself (moving/resizing).
The purpose is to fix the issue mentioned at https://github.com/window-maker/wmaker/issues/20

Tested with VS Code, Google Chrome, Steam and Discord.

Specs are available at https://specifications.freedesktop.org/wm/1.5/ar01s04.html#id-1.5.4

src/moveres.c

@@ -19,6 +19,7 @@
  */
 
 #include "wconfig.h"
+#include "wmspec.h"
 
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
@@ -1916,7 +1917,7 @@ int wMouseMoveWindow(WWindow * wwin, XEvent * ev)
 			break;
 
 		case ButtonRelease:
-			if (event.xbutton.button != ev->xbutton.button)
+			if (!wwin->moveresize.active && (event.xbutton.button != ev->xbutton.button))
 				break;
 
 			if (started) {
@@ -1964,6 +1965,10 @@ int wMouseMoveWindow(WWindow * wwin, XEvent * ev)
 					WMUnmapWidget(scr->gview);
 				}
 			}
+			if (wwin->moveresize.active) {
+				XUngrabPointer(dpy, CurrentTime);
+				wwin->moveresize.active = 0;
+			}
 			done = True;
 			break;
 
@@ -2101,8 +2106,13 @@ void wMouseResizeWindow(WWindow * wwin, XEvent * ev)
 		wwarning("internal error: tryein");
 		return;
 	}
-	orig_x = ev->xbutton.x_root;
-	orig_y = ev->xbutton.y_root;
+	if (ev->type == MotionNotify) {
+		orig_x = ev->xmotion.x_root;
+		orig_y = ev->xmotion.y_root;
+	} else {
+		orig_x = ev->xbutton.x_root;
+		orig_y = ev->xbutton.y_root;
+	}
 
 	started = 0;
 	wUnselectWindows(scr);
@@ -2113,6 +2123,29 @@ void wMouseResizeWindow(WWindow * wwin, XEvent * ev)
 	shiftl = XKeysymToKeycode(dpy, XK_Shift_L);
 	shiftr = XKeysymToKeycode(dpy, XK_Shift_R);
 
+	if (wwin->moveresize.active) {
+		int direction = wwin->moveresize.resize_edge;
+
+		res = 0;
+		is_resizebar = 0;
+		if (direction == _NET_WM_MOVERESIZE_SIZE_TOP)
+			res |= UP;
+		else if (direction == _NET_WM_MOVERESIZE_SIZE_BOTTOM)
+			res |= DOWN;
+		else if (direction == _NET_WM_MOVERESIZE_SIZE_LEFT)
+			res |= LEFT;
+		else if (direction == _NET_WM_MOVERESIZE_SIZE_RIGHT)
+			res |= RIGHT;
+		else if (direction == _NET_WM_MOVERESIZE_SIZE_TOPLEFT)
+			res |= (UP | LEFT);
+		else if (direction == _NET_WM_MOVERESIZE_SIZE_TOPRIGHT)
+			res |= (UP | RIGHT);
+		else if (direction == _NET_WM_MOVERESIZE_SIZE_BOTTOMLEFT)
+			res |= (DOWN | LEFT);
+		else if (direction == _NET_WM_MOVERESIZE_SIZE_BOTTOMRIGHT)
+			res |= (DOWN | RIGHT);
+	}
+
 	while (1) {
 		WMMaskEvent(dpy, KeyPressMask | ButtonMotionMask
 			    | ButtonReleaseMask | PointerMotionHintMask | ButtonPressMask | ExposureMask, &event);
@@ -2269,7 +2302,7 @@ void wMouseResizeWindow(WWindow * wwin, XEvent * ev)
 			break;
 
 		case ButtonRelease:
-			if (event.xbutton.button != ev->xbutton.button)
+			if (!wwin->moveresize.active && (event.xbutton.button != ev->xbutton.button))
 				break;
 
 			if (started) {
@@ -2291,6 +2324,11 @@ void wMouseResizeWindow(WWindow * wwin, XEvent * ev)
 				wWindowConfigure(wwin, fx, fy, fw, fh - vert_border);
 				wWindowSynthConfigureNotify(wwin);
 			}
+			if (wwin->moveresize.active) {
+				XUngrabPointer(dpy, CurrentTime);
+				wwin->moveresize.active = 0;
+			}
+
 			return;
 
 		default:

src/window.h

@@ -237,6 +237,12 @@ typedef struct WWindow {
 	int cmap_window_no;
 	Window *cmap_windows;
 
+	/* move/resize state for _NET_WM_MOVERESIZE support */
+	struct {
+		int active;			/* 1 if move/resize is in progress */
+		int resize_edge;		/* which edge for resize (0-7) */
+	} moveresize;
+
 	/* protocols */
 	WProtocols protocols;			/* accepted WM_PROTOCOLS */
 

src/wmspec.c

@@ -71,7 +71,7 @@ static Atom net_showing_desktop;
 /* Other Root Window Messages */
 static Atom net_close_window;
 static Atom net_moveresize_window;	/* TODO */
-static Atom net_wm_moveresize;	/* TODO */
+static Atom net_wm_moveresize;
 
 /* Application Window Properties */
 static Atom net_wm_name;
@@ -125,7 +125,7 @@ static Atom net_wm_strut;
 static Atom net_wm_strut_partial;	/* TODO: doesn't really fit into the current strut scheme */
 static Atom net_wm_icon_geometry;	/* FIXME: should work together with net_wm_handled_icons, gnome-panel-2.2.0.1 doesn't use _NET_WM_HANDLED_ICONS, thus present situation. */
 static Atom net_wm_icon;
-static Atom net_wm_pid;		/* TODO */
+static Atom net_wm_pid;
 static Atom net_wm_handled_icons;	/* FIXME: see net_wm_icon_geometry */
 static Atom net_wm_window_opacity;
 
@@ -226,35 +226,6 @@ static atomitem_t atomNames[] = {
 #define _NET_WM_STATE_ADD 1
 #define _NET_WM_STATE_TOGGLE 2
 
-#if 0
-/*
- * These constant provide information on the kind of window move/resize when
- * it is initiated by the application instead of by WindowMaker. They are
- * parameter for the client message _NET_WM_MOVERESIZE, as defined by the
- * FreeDesktop wm-spec standard:
- *   http://standards.freedesktop.org/wm-spec/1.5/ar01s04.html
- *
- * Today, WindowMaker does not support this at all (the corresponding Atom
- * is not added to the list in setSupportedHints), probably because there is
- * nothing it needs to do about it, the application is assumed to know what
- * it is doing, and WindowMaker won't get in the way.
- *
- * The definition of the constants (taken from the standard) are disabled to
- * avoid a spurious warning (-Wunused-macros).
- */
-#define _NET_WM_MOVERESIZE_SIZE_TOPLEFT      0
-#define _NET_WM_MOVERESIZE_SIZE_TOP          1
-#define _NET_WM_MOVERESIZE_SIZE_TOPRIGHT     2
-#define _NET_WM_MOVERESIZE_SIZE_RIGHT        3
-#define _NET_WM_MOVERESIZE_SIZE_BOTTOMRIGHT  4
-#define _NET_WM_MOVERESIZE_SIZE_BOTTOM       5
-#define _NET_WM_MOVERESIZE_SIZE_BOTTOMLEFT   6
-#define _NET_WM_MOVERESIZE_SIZE_LEFT         7
-#define _NET_WM_MOVERESIZE_MOVE              8	/* movement only */
-#define _NET_WM_MOVERESIZE_SIZE_KEYBOARD     9	/* size via keyboard */
-#define _NET_WM_MOVERESIZE_MOVE_KEYBOARD    10	/* move via keyboard */
-#endif
-
 static void observer(void *self, WMNotification *notif);
 static void wsobserver(void *self, WMNotification *notif);
 
@@ -294,9 +265,7 @@ static void setSupportedHints(WScreen *scr)
 	atom[i++] = net_workarea;
 	atom[i++] = net_supporting_wm_check;
 	atom[i++] = net_showing_desktop;
-#if 0
 	atom[i++] = net_wm_moveresize;
-#endif
 	atom[i++] = net_wm_desktop;
 #ifdef USE_XINERAMA
 	atom[i++] = net_wm_fullscreen_monitors;
@@ -1814,6 +1783,84 @@ Bool wNETWMProcessClientMessage(XClientMessageEvent *event)
 		}
 		return True;
 
+	} else if (event->message_type == net_wm_moveresize) {
+		XEvent fake_event;
+		int direction = event->data.l[2];
+		int x_root = event->data.l[0];
+		int y_root = event->data.l[1];
+		int button = event->data.l[3];
+		int junk;
+		Window junkw;
+		unsigned int mask;
+
+		if (direction == _NET_WM_MOVERESIZE_CANCEL) {
+			if (wwin->moveresize.active) {
+				memset(&fake_event, 0, sizeof(XEvent));
+				fake_event.type = ButtonRelease;
+				fake_event.xbutton.window = wwin->frame->core->window;
+				fake_event.xbutton.x_root = x_root;
+				fake_event.xbutton.y_root = y_root;
+				fake_event.xbutton.button = event->data.l[3];
+				XSendEvent(dpy, wwin->frame->core->window, False, ButtonReleaseMask, &fake_event);
+			}
+			return True;
+		}
+
+		/* Check if already in progress */
+		if (wwin->moveresize.active)
+			return True;
+
+		/* Check if the initiating button is actually pressed */
+		if (!XQueryPointer(dpy, wwin->screen_ptr->root_win, &junkw, &junkw,
+					&junk, &junk, &junk, &junk, &mask))
+			return True;
+
+		if (button > 0) {
+			unsigned int expected =
+				button == 1 ? Button1Mask :
+				button == 2 ? Button2Mask :
+				button == 3 ? Button3Mask :
+				0;
+
+			if (expected && !(mask & expected))
+				/* Race: button already released */
+				return True;
+		}
+
+		/* Check if operation is allowed */
+		if (direction == _NET_WM_MOVERESIZE_MOVE) {
+			if (WFLAGP(wwin, no_movable))
+				return True;
+		} else if (direction <= _NET_WM_MOVERESIZE_SIZE_LEFT) {
+			if (WFLAGP(wwin, no_resizable))
+				return True;
+		} else {
+			return True;
+		}
+
+		/* Grab the pointer for the operation */
+		if (XGrabPointer(dpy, wwin->frame->core->window, False,
+								ButtonReleaseMask | PointerMotionMask | ButtonPressMask,
+								GrabModeAsync, GrabModeAsync,
+								None, None, CurrentTime) != GrabSuccess)
+			return True;
+
+		/* Set up the move/resize state */
+		wwin->moveresize.active = 1;
+		wwin->moveresize.resize_edge = direction;
+
+		memset(&fake_event, 0, sizeof(XEvent));
+		fake_event.type = MotionNotify;
+		fake_event.xmotion.x_root = x_root;
+		fake_event.xmotion.y_root = y_root;
+		fake_event.xmotion.window = wwin->frame->core->window;
+		if (direction == _NET_WM_MOVERESIZE_MOVE)
+			wMouseMoveWindow(wwin, &fake_event);
+		else
+			wMouseResizeWindow(wwin, &fake_event);
+
+		return True;
+
 #ifdef USE_XINERAMA
 	} else if (event->message_type == net_wm_fullscreen_monitors) {
 		unsigned long top, bottom, left, right, src_indication;

src/wmspec.h

@@ -28,6 +28,26 @@
 #include "window.h"
 #include <X11/Xlib.h>
 
+/*
+ * These constant provide information on the kind of window move/resize when
+ * it is initiated by the application instead of by WindowMaker. They are
+ * parameter for the client message _NET_WM_MOVERESIZE, as defined by the
+ * FreeDesktop wm-spec standard:
+ *   http://standards.freedesktop.org/wm-spec/1.5/ar01s04.html
+ */
+#define _NET_WM_MOVERESIZE_SIZE_TOPLEFT      0
+#define _NET_WM_MOVERESIZE_SIZE_TOP          1
+#define _NET_WM_MOVERESIZE_SIZE_TOPRIGHT     2
+#define _NET_WM_MOVERESIZE_SIZE_RIGHT        3
+#define _NET_WM_MOVERESIZE_SIZE_BOTTOMRIGHT  4
+#define _NET_WM_MOVERESIZE_SIZE_BOTTOM       5
+#define _NET_WM_MOVERESIZE_SIZE_BOTTOMLEFT   6
+#define _NET_WM_MOVERESIZE_SIZE_LEFT         7
+#define _NET_WM_MOVERESIZE_MOVE              8	/* movement only */
+#define _NET_WM_MOVERESIZE_SIZE_KEYBOARD     9	/* size via keyboard */
+#define _NET_WM_MOVERESIZE_MOVE_KEYBOARD    10	/* move via keyboard */
+#define _NET_WM_MOVERESIZE_CANCEL           11	/* cancel operation */
+
 void wNETWMInitStuff(WScreen *scr);
 void wNETWMCleanup(WScreen *scr);
 void wNETWMUpdateWorkarea(WScreen *scr);