evdev 1.99.3

Devices may report middle mouse buttons even if they don't have one (PS/2
devices just don't know any better), so we can't be sure until we see the
event.

configure.ac

@@ -22,7 +22,7 @@
 
 AC_PREREQ(2.57)
 AC_INIT([xf86-input-evdev],
-        1.99.2,
+        1.99.3,
         [https://bugs.freedesktop.org/enter_bug.cgi?product=xorg],
         xf86-input-evdev)
 

man/evdev.man

@@ -10,6 +10,8 @@ evdev \- Generic Linux input driver
 .B  "  Driver \*qevdev\*q"
 .BI "  Option \*qDevice\*q   \*q" devpath \*q
 .BI "  Option \*qPath\*q     \*q" path \*q
+.BI "  Option \*qEmulate3Buttons\*q     \*q" True \*q
+.BI "  Option \*qEmulate3Timeout\*q     \*q" 50 \*q
 \ \ ...
 .B EndSection
 .fi
@@ -54,6 +56,17 @@ generally be of the form \*q/dev/input/by-path/xyz\*q, where xyz includes the
 name of the device. The mapping from device node to hardware is
 system-dependent. This option has precedence over the \*qDevice\*q option but
 one of \*qPath\*q or \*qDevice\*q must be given.
+.TP 7
+.BI "Option \*qEmulate3Buttons\*q \*q" boolean \*q
+Enable/disable the emulation of the third (middle) mouse button for mice
+which only have two physical buttons.  The third button is emulated by
+pressing both buttons simultaneously.  Default: on, until a middle mouse
+button event is registered.
+.TP 7
+.BI "Option \*qEmulate3Timeout\*q \*q" integer \*q
+Sets the timeout (in milliseconds) that the driver waits before deciding
+if two buttons where pressed "simultaneously" when 3 button emulation is
+enabled.  Default: 50.
 .SH AUTHORS
 Kristian Høgsberg.
 .SH "SEE ALSO"

src/Makefile.am

@@ -28,4 +28,6 @@
 @DRIVER_NAME@_drv_la_LDFLAGS = -module -avoid-version
 @DRIVER_NAME@_drv_ladir = @inputdir@
 
-@DRIVER_NAME@_drv_la_SOURCES = @DRIVER_NAME@.c
+@DRIVER_NAME@_drv_la_SOURCES = @DRIVER_NAME@.c \
+                               @DRIVER_NAME@.h \
+                               emuMB.c

src/emuMB.c

@@ -0,0 +1,308 @@
+/*
+ * Copyright 1990,91 by Thomas Roell, Dinkelscherben, Germany.
+ * Copyright 1993 by David Dawes <dawes@xfree86.org>
+ * Copyright 2002 by SuSE Linux AG, Author: Egbert Eich
+ * Copyright 1994-2002 by The XFree86 Project, Inc.
+ * Copyright 2002 by Paul Elliott
+ * (Ported from xf86-input-mouse, above copyrights taken from there)
+ * Copyright © 2008 University of South Australia
+ *
+ * Permission to use, copy, modify, distribute, and sell this software
+ * and its documentation for any purpose is hereby granted without
+ * fee, provided that the above copyright notice appear in all copies
+ * and that both that copyright notice and this permission notice
+ * appear in supporting documentation, and that the name of Red Hat
+ * not be used in advertising or publicity pertaining to distribution
+ * of the software without specific, written prior permission.  Red
+ * Hat makes no representations about the suitability of this software
+ * for any purpose.  It is provided "as is" without express or implied
+ * warranty.
+ *
+ * THE AUTHORS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
+ * NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+ * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+ * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+/* Middle mouse button emulation code. */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "evdev.h"
+
+/*
+ * Lets create a simple finite-state machine for 3 button emulation:
+ *
+ * We track buttons 1 and 3 (left and right).  There are 11 states:
+ *   0 ground           - initial state
+ *   1 delayed left     - left pressed, waiting for right
+ *   2 delayed right    - right pressed, waiting for left
+ *   3 pressed middle   - right and left pressed, emulated middle sent
+ *   4 pressed left     - left pressed and sent
+ *   5 pressed right    - right pressed and sent
+ *   6 released left    - left released after emulated middle
+ *   7 released right   - right released after emulated middle
+ *   8 repressed left   - left pressed after released left
+ *   9 repressed right  - right pressed after released right
+ *  10 pressed both     - both pressed, not emulating middle
+ *
+ * At each state, we need handlers for the following events
+ *   0: no buttons down
+ *   1: left button down
+ *   2: right button down
+ *   3: both buttons down
+ *   4: emulate3Timeout passed without a button change
+ * Note that button events are not deltas, they are the set of buttons being
+ * pressed now.  It's possible (ie, mouse hardware does it) to go from (eg)
+ * left down to right down without anything in between, so all cases must be
+ * handled.
+ *
+ * a handler consists of three values:
+ *   0: action1
+ *   1: action2
+ *   2: new emulation state
+ *
+ * action > 0: ButtonPress
+ * action = 0: nothing
+ * action < 0: ButtonRelease
+ *
+ * The comment preceeding each section is the current emulation state.
+ * The comments to the right are of the form
+ *      <button state> (<events>) -> <new emulation state>
+ * which should be read as
+ *      If the buttons are in <button state>, generate <events> then go to
+ *      <new emulation state>.
+ */
+static signed char stateTab[11][5][3] = {
+/* 0 ground */
+  {
+    {  0,  0,  0 },   /* nothing -> ground (no change) */
+    {  0,  0,  1 },   /* left -> delayed left */
+    {  0,  0,  2 },   /* right -> delayed right */
+    {  2,  0,  3 },   /* left & right (middle press) -> pressed middle */
+    {  0,  0, -1 }    /* timeout N/A */
+  },
+/* 1 delayed left */
+  {
+    {  1, -1,  0 },   /* nothing (left event) -> ground */
+    {  0,  0,  1 },   /* left -> delayed left (no change) */
+    {  1, -1,  2 },   /* right (left event) -> delayed right */
+    {  2,  0,  3 },   /* left & right (middle press) -> pressed middle */
+    {  1,  0,  4 },   /* timeout (left press) -> pressed left */
+  },
+/* 2 delayed right */
+  {
+    {  3, -3,  0 },   /* nothing (right event) -> ground */
+    {  3, -3,  1 },   /* left (right event) -> delayed left (no change) */
+    {  0,  0,  2 },   /* right -> delayed right (no change) */
+    {  2,  0,  3 },   /* left & right (middle press) -> pressed middle */
+    {  3,  0,  5 },   /* timeout (right press) -> pressed right */
+  },
+/* 3 pressed middle */
+  {
+    { -2,  0,  0 },   /* nothing (middle release) -> ground */
+    {  0,  0,  7 },   /* left -> released right */
+    {  0,  0,  6 },   /* right -> released left */
+    {  0,  0,  3 },   /* left & right -> pressed middle (no change) */
+    {  0,  0, -1 },   /* timeout N/A */
+  },
+/* 4 pressed left */
+  {
+    { -1,  0,  0 },   /* nothing (left release) -> ground */
+    {  0,  0,  4 },   /* left -> pressed left (no change) */
+    { -1,  0,  2 },   /* right (left release) -> delayed right */
+    {  3,  0, 10 },   /* left & right (right press) -> pressed both */
+    {  0,  0, -1 },   /* timeout N/A */
+  },
+/* 5 pressed right */
+  {
+    { -3,  0,  0 },   /* nothing (right release) -> ground */
+    { -3,  0,  1 },   /* left (right release) -> delayed left */
+    {  0,  0,  5 },   /* right -> pressed right (no change) */
+    {  1,  0, 10 },   /* left & right (left press) -> pressed both */
+    {  0,  0, -1 },   /* timeout N/A */
+  },
+/* 6 released left */
+  {
+    { -2,  0,  0 },   /* nothing (middle release) -> ground */
+    { -2,  0,  1 },   /* left (middle release) -> delayed left */
+    {  0,  0,  6 },   /* right -> released left (no change) */
+    {  1,  0,  8 },   /* left & right (left press) -> repressed left */
+    {  0,  0, -1 },   /* timeout N/A */
+  },
+/* 7 released right */
+  {
+    { -2,  0,  0 },   /* nothing (middle release) -> ground */
+    {  0,  0,  7 },   /* left -> released right (no change) */
+    { -2,  0,  2 },   /* right (middle release) -> delayed right */
+    {  3,  0,  9 },   /* left & right (right press) -> repressed right */
+    {  0,  0, -1 },   /* timeout N/A */
+  },
+/* 8 repressed left */
+  {
+    { -2, -1,  0 },   /* nothing (middle release, left release) -> ground */
+    { -2,  0,  4 },   /* left (middle release) -> pressed left */
+    { -1,  0,  6 },   /* right (left release) -> released left */
+    {  0,  0,  8 },   /* left & right -> repressed left (no change) */
+    {  0,  0, -1 },   /* timeout N/A */
+  },
+/* 9 repressed right */
+  {
+    { -2, -3,  0 },   /* nothing (middle release, right release) -> ground */
+    { -3,  0,  7 },   /* left (right release) -> released right */
+    { -2,  0,  5 },   /* right (middle release) -> pressed right */
+    {  0,  0,  9 },   /* left & right -> repressed right (no change) */
+    {  0,  0, -1 },   /* timeout N/A */
+  },
+/* 10 pressed both */
+  {
+    { -1, -3,  0 },   /* nothing (left release, right release) -> ground */
+    { -3,  0,  4 },   /* left (right release) -> pressed left */
+    { -1,  0,  5 },   /* right (left release) -> pressed right */
+    {  0,  0, 10 },   /* left & right -> pressed both (no change) */
+    {  0,  0, -1 },   /* timeout N/A */
+  },
+};
+
+
+int
+EvdevMBEmuTimer(InputInfoPtr pInfo)
+{
+    EvdevPtr pEvdev = pInfo->private;
+    int	sigstate;
+    int id;
+
+    sigstate = xf86BlockSIGIO ();
+
+    pEvdev->emulateMB.pending = FALSE;
+    if ((id = stateTab[pEvdev->emulateMB.state][4][0]) != 0) {
+        xf86PostButtonEvent(pInfo->dev, 0, abs(id), (id >= 0), 0, 0);
+        pEvdev->emulateMB.state =
+            stateTab[pEvdev->emulateMB.state][4][2];
+    } else {
+        ErrorF("Got unexpected buttonTimer in state %d\n",
+                pEvdev->emulateMB.state);
+    }
+
+    xf86UnblockSIGIO (sigstate);
+    return 0;
+}
+
+
+/**
+ * Emulate a middle button on button press.
+ *
+ * @param code Evdev event code (BTN_LEFT or BTN_RIGHT)
+ * @param press TRUE if press, FALSE if release.
+ *
+ * @return TRUE if event was swallowed by middle mouse button emulation, FALSE
+ * otherwise.
+ */
+BOOL
+EvdevMBEmuFilterEvent(InputInfoPtr pInfo, int code, BOOL press)
+{
+    EvdevPtr pEvdev = pInfo->private;
+    int id;
+    int *btstate;
+    int ret = FALSE;
+
+    if (!pEvdev->emulateMB.enabled)
+        return ret;
+
+    /* don't care about other buttons */
+    if (code != BTN_LEFT && code != BTN_RIGHT)
+        return ret;
+
+    btstate = &pEvdev->emulateMB.buttonstate;
+    if (press)
+        *btstate |= (code == BTN_LEFT) ? 0x1 : 0x2;
+    else
+        *btstate &= (code == BTN_LEFT) ? ~0x1 : ~0x2;
+
+    if ((id = stateTab[pEvdev->emulateMB.state][*btstate][0]) != 0)
+    {
+        xf86PostButtonEvent(pInfo->dev, 0, abs(id), (id >= 0), 0, 0);
+        ret = TRUE;
+    }
+    if ((id = stateTab[pEvdev->emulateMB.state][*btstate][1]) != 0)
+    {
+        xf86PostButtonEvent(pInfo->dev, 0, abs(id), (id >= 0), 0, 0);
+        ret = TRUE;
+    }
+
+    pEvdev->emulateMB.state =
+        stateTab[pEvdev->emulateMB.state][*btstate][2];
+
+    if (stateTab[pEvdev->emulateMB.state][4][0] != 0) {
+        pEvdev->emulateMB.expires = GetTimeInMillis () + pEvdev->emulateMB.timeout;
+        pEvdev->emulateMB.pending = TRUE;
+        ret = TRUE;
+    } else {
+        pEvdev->emulateMB.pending = FALSE;
+    }
+
+    return ret;
+}
+
+
+void EvdevMBEmuWakeupHandler(pointer data,
+                             int i,
+                             pointer LastSelectMask)
+{
+    InputInfoPtr pInfo = (InputInfoPtr)data;
+    EvdevPtr     pEvdev = (EvdevPtr)pInfo->private;
+    int ms;
+
+    if (pEvdev->emulateMB.pending)
+    {
+        ms = pEvdev->emulateMB.expires - GetTimeInMillis();
+        if (ms <= 0)
+            EvdevMBEmuTimer(pInfo);
+    }
+}
+
+void EvdevMBEmuBlockHandler(pointer data,
+                            struct timeval **waitTime,
+                            pointer LastSelectMask)
+{
+    InputInfoPtr    pInfo = (InputInfoPtr) data;
+    EvdevPtr        pEvdev= (EvdevPtr) pInfo->private;
+    int             ms;
+
+    if (pEvdev->emulateMB.pending)
+    {
+        ms = pEvdev->emulateMB.expires - GetTimeInMillis ();
+        if (ms <= 0)
+            ms = 0;
+        AdjustWaitForDelay (waitTime, ms);
+    }
+}
+
+void
+EvdevMBEmuPreInit(InputInfoPtr pInfo)
+{
+    EvdevPtr pEvdev = (EvdevPtr)pInfo->private;
+
+    pEvdev->emulateMB.enabled = xf86SetBoolOption(pInfo->options,
+                                                  "Emulate3Buttons", TRUE);
+    pEvdev->emulateMB.timeout = xf86SetIntOption(pInfo->options,
+                                                 "Emulate3Timeout", 50);
+    RegisterBlockAndWakeupHandlers (EvdevMBEmuBlockHandler,
+                                    EvdevMBEmuWakeupHandler,
+                                    (pointer)pInfo);
+
+}
+
+/* Enable/disable middle mouse button emulation. */
+void
+EvdevMBEmuEnable(InputInfoPtr pInfo, BOOL enable)
+{
+    EvdevPtr pEvdev = (EvdevPtr)pInfo->private;
+    pEvdev->emulateMB.enabled = enable;
+}

src/evdev.c

@@ -33,7 +33,6 @@
 #include <X11/XF86keysym.h>
 #include <X11/extensions/XIproto.h>
 
-#include <linux/input.h>
 #include <unistd.h>
 
 #include <misc.h>
@@ -44,10 +43,7 @@
 #include <exevents.h>
 #include <mipointer.h>
 
-#if defined(XKB)
+#include "evdev.h"
-/* XXX VERY WRONG.  this is a client side header. */
-#include <X11/extensions/XKBstr.h>
-#endif
 
 #include <xf86Module.h>
 
@@ -91,25 +87,6 @@
 #define MODEFLAG	8
 #define COMPOSEFLAG	16
 
-typedef struct {
-    int kernel24;
-    int screen;
-    int min_x, min_y, max_x, max_y;
-    int abs_x, abs_y, old_x, old_y;
-    int flags;
-    int tool;
-
-    /* XKB stuff has to be per-device rather than per-driver */
-    int noXkb;
-#ifdef XKB
-    char                    *xkb_rules;
-    char                    *xkb_model;
-    char                    *xkb_layout;
-    char                    *xkb_variant;
-    char                    *xkb_options;
-    XkbComponentNamesRec    xkbnames;
-#endif
-} EvdevRec, *EvdevPtr;
 
 static const char *evdevDefaults[] = {
     "XkbRules",     "base",
@@ -241,12 +218,15 @@ EvdevReadInput(InputInfoPtr pInfo)
             switch (ev.code) {
 	    /* swap here, pretend we're an X-conformant device. */
             case BTN_LEFT:
-                xf86PostButtonEvent(pInfo->dev, 0, 1, value, 0, 0);
+                if (!EvdevMBEmuFilterEvent(pInfo, ev.code, value))
+                    xf86PostButtonEvent(pInfo->dev, 0, 1, value, 0, 0);
                 break;
             case BTN_RIGHT:
-                xf86PostButtonEvent(pInfo->dev, 0, 3, value, 0, 0);
+                if (!EvdevMBEmuFilterEvent(pInfo, ev.code, value))
+                    xf86PostButtonEvent(pInfo->dev, 0, 3, value, 0, 0);
                 break;
             case BTN_MIDDLE:
+                EvdevMBEmuEnable(pInfo, FALSE);
                 xf86PostButtonEvent(pInfo->dev, 0, 2, value, 0, 0);
                 break;
 
@@ -726,7 +706,10 @@ EvdevAddAbsClass(DeviceIntPtr device)
     pEvdev->min_y = absinfo_y.minimum;
     pEvdev->max_y = absinfo_y.maximum;
 
-    if (!InitValuatorClassDeviceStruct(device, 2, GetMotionHistory,
+    if (!InitValuatorClassDeviceStruct(device, 2,
+#if GET_ABI_MAJOR(ABI_XINPUT_VERSION) < 3
+                                       GetMotionHistory,
+#endif
                                        GetMotionHistorySize(), Absolute))
         return !Success;
 
@@ -756,16 +739,19 @@ EvdevAddRelClass(DeviceIntPtr device)
 
     pInfo = device->public.devicePrivate;
 
-    if (!InitValuatorClassDeviceStruct(device, 2, GetMotionHistory,
+    if (!InitValuatorClassDeviceStruct(device, 2,
+#if GET_ABI_MAJOR(ABI_XINPUT_VERSION) < 3
+                                       GetMotionHistory,
+#endif
                                        GetMotionHistorySize(), Relative))
         return !Success;
 
     /* X valuator */
-    xf86InitValuatorAxisStruct(device, 0, 0, -1, 1, 0, 1);
+    xf86InitValuatorAxisStruct(device, 0, -1, -1, 1, 0, 1);
     xf86InitValuatorDefaults(device, 0);
 
     /* Y valuator */
-    xf86InitValuatorAxisStruct(device, 1, 0, -1, 1, 0, 1);
+    xf86InitValuatorAxisStruct(device, 1, -1, -1, 1, 0, 1);
     xf86InitValuatorDefaults(device, 1);
     xf86MotionHistoryAllocate(pInfo);
 
@@ -901,9 +887,14 @@ EvdevProbe(InputInfoPtr pInfo)
     int i, has_axes, has_buttons, has_keys;
     EvdevPtr pEvdev = pInfo->private;
 
-    if (ioctl(pInfo->fd, EVIOCGRAB, (void *)1) && errno == EINVAL) {
+    if (ioctl(pInfo->fd, EVIOCGRAB, (void *)1)) {
-        /* keyboards are unsafe in 2.4 */
+        if (errno == EINVAL) {
-        pEvdev->kernel24 = 1;
+            /* keyboards are unsafe in 2.4 */
+            pEvdev->kernel24 = 1;
+        } else {
+            xf86Msg(X_ERROR, "Grab failed. Device already configured?\n");
+            return 1;
+        }
     } else {
         ioctl(pInfo->fd, EVIOCGRAB, (void *)0);
     }
@@ -1018,10 +1009,6 @@ EvdevPreInit(InputDriverPtr drv, IDevPtr dev, int flags)
     pInfo->always_core_feedback = 0;
     pInfo->conf_idev = dev;
 
-    if (!(pEvdev = xcalloc(sizeof(*pEvdev), 1)))
-        return pInfo;
-    pInfo->private = pEvdev;
-
     if (!(pEvdev = xcalloc(sizeof(EvdevRec), 1)))
         return pInfo;
 
@@ -1037,6 +1024,8 @@ EvdevPreInit(InputDriverPtr drv, IDevPtr dev, int flags)
      */
     pEvdev->tool = 1;
 
+    EvdevMBEmuPreInit(pInfo);
+
     device = xf86CheckStrOption(dev->commonOptions, "Path", NULL);
     if (!device)
 	device = xf86CheckStrOption(dev->commonOptions, "Device", NULL);
@@ -1045,7 +1034,7 @@ EvdevPreInit(InputDriverPtr drv, IDevPtr dev, int flags)
 	xf86DeleteInput(pInfo, 0);
         return NULL;
     }
-	
+
     xf86Msg(deviceFrom, "%s: Device: \"%s\"\n", pInfo->name, device);
     do {
         pInfo->fd = open(device, O_RDWR, 0);

src/evdev.h

@@ -0,0 +1,80 @@
+/*
+ * Copyright © 2004-2008 Red Hat, Inc.
+ * Copyright © 2008 University of South Australia
+ *
+ * Permission to use, copy, modify, distribute, and sell this software
+ * and its documentation for any purpose is hereby granted without
+ * fee, provided that the above copyright notice appear in all copies
+ * and that both that copyright notice and this permission notice
+ * appear in supporting documentation, and that the name of Red Hat
+ * not be used in advertising or publicity pertaining to distribution
+ * of the software without specific, written prior permission.  Red
+ * Hat makes no representations about the suitability of this software
+ * for any purpose.  It is provided "as is" without express or implied
+ * warranty.
+ *
+ * THE AUTHORS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
+ * NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+ * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+ * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * Authors:
+ *	Kristian Høgsberg (krh@redhat.com)
+ *	Adam Jackson (ajax@redhat.com)
+ *	Peter Hutterer (peter@cs.unisa.edu.au)
+ */
+
+#ifndef EVDEV_H
+#define EVDEV_H
+
+#include <linux/input.h>
+
+#include <xf86Xinput.h>
+#include <xf86_OSproc.h>
+
+#if defined(XKB)
+/* XXX VERY WRONG.  this is a client side header. */
+#include <X11/extensions/XKBstr.h>
+#endif
+
+typedef struct {
+    int kernel24;
+    int screen;
+    int min_x, min_y, max_x, max_y;
+    int abs_x, abs_y, old_x, old_y;
+    int flags;
+    int tool;
+
+    /* XKB stuff has to be per-device rather than per-driver */
+    int noXkb;
+#ifdef XKB
+    char                    *xkb_rules;
+    char                    *xkb_model;
+    char                    *xkb_layout;
+    char                    *xkb_variant;
+    char                    *xkb_options;
+    XkbComponentNamesRec    xkbnames;
+#endif
+    /* Middle mouse button emulation */
+    struct {
+        BOOL                enabled;
+        BOOL                pending;     /* timer waiting? */
+        int                 buttonstate; /* phys. button state */
+        int                 state;       /* state machine (see bt3emu.c) */
+        Time                expires;     /* time of expiry */
+        Time                timeout;
+    } emulateMB;
+} EvdevRec, *EvdevPtr;
+
+/* Middle Button emulation */
+int  EvdevMBEmuTimer(InputInfoPtr);
+BOOL EvdevMBEmuFilterEvent(InputInfoPtr, int, BOOL);
+void EvdevMBEmuWakeupHandler(pointer, int, pointer);
+void EvdevMBEmuBlockHandler(pointer, struct timeval**, pointer);
+void EvdevMBEmuPreInit(InputInfoPtr);
+void EvdevMBEmuEnable(InputInfoPtr, BOOL);
+
+#endif