feat: Implement touch-to-switch (without timing hacks) by nbolton · Pull Request #162 · symless/synergy

nbolton · 2026-03-03T19:27:25Z

https://symless.atlassian.net/browse/S1-2091

Copilot

Pull request overview

Implements Windows touch-to-switch so that touching an inactive screen requests/forces focus to that screen without relying on fragile timing-based edge switching.

Changes:

Add new touch-triggered events (touchActivatedPrimary, grabInput) and wire them through server/client event queues.
Extend protocol to v1.9 with a new CGRB (“grab input”) message and a new ClientProxy1_9.
Add Windows-specific hook detection for touch-originated clicks and desk-thread touch injection (touch or mouse fallback).

Reviewed changes

Copilot reviewed 29 out of 29 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/lib/server/Server.h	Adds handlers + cooldown state for touch-to-switch edge-switch suppression.
src/lib/server/Server.cpp	Wires new events, handles touch activation + client grab requests, and blocks edge-switch during cooldown.
src/lib/server/PrimaryClient.h	Adds APIs for window activation and touch click injection.
src/lib/server/PrimaryClient.cpp	Pass-through implementations to the underlying screen.
src/lib/server/Config.cpp	Adds `touchActivateScreen` config option parsing/serialization.
src/lib/server/ClientProxyUnknown.cpp	Instantiates `ClientProxy1_9` for protocol minor 9.
src/lib/server/ClientProxy1_9.h	Declares v1.9 proxy with grab-input parsing.
src/lib/server/ClientProxy1_9.cpp	Parses `CGRB` and emits `ClientProxy.grabInput` events.
src/lib/platform/dfwhook.h	Adds touch hook message + touch signature constants.
src/lib/platform/MSWindowsTouchInjector.h	Declares desk-thread touch/mouse click injector.
src/lib/platform/MSWindowsTouchInjector.cpp	Implements activation waiting + touch injection + mouse fallback.
src/lib/platform/MSWindowsScreen.h	Adds touch-to-switch overrides + debounce/pending-touch state.
src/lib/platform/MSWindowsScreen.cpp	Configures hook, emits touch/grab events, and implements pending-touch activation consumption.
src/lib/platform/MSWindowsHook.h	Adds setters to control touch activation + primary/on-screen state.
src/lib/platform/MSWindowsHook.cpp	Detects touch-originated clicks (signature) while off-screen and posts touch messages.
src/lib/platform/MSWindowsDesks.h	Adds `fakeTouchClick` entry point to desk thread.
src/lib/platform/MSWindowsDesks.cpp	Routes fake-touch messages to the touch injector and adds mouse-move suppression tweak.
src/lib/deskflow/protocol_types.h	Bumps protocol minor to 1.9 and declares `kMsgCGrabInput`.
src/lib/deskflow/protocol_types.cpp	Defines `kMsgCGrabInput` wire format.
src/lib/deskflow/option_types.h	Adds `kOptionTouchActivateScreen`.
src/lib/deskflow/Screen.h	Exposes touch/window-activation APIs on `Screen`.
src/lib/deskflow/Screen.cpp	Forwards new APIs to platform screen.
src/lib/deskflow/IPlatformScreen.h	Adds default no-op virtuals for touch/window activation + pending-touch storage.
src/lib/client/ServerProxy.h	Adds `grabInput()` client->server API.
src/lib/client/ServerProxy.cpp	Sends `CGRB` protocol message.
src/lib/client/Client.h	Adds grab-input event handler declaration.
src/lib/client/Client.cpp	Hooks grab-input events, sends `CGRB`, and performs deferred activation/click on enter.
src/lib/base/EventTypes.h	Adds new event types for grab-input and touch-activated-primary.
src/lib/base/EventTypes.cpp	Registers the new event types.

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Copilot · 2026-03-03T19:36:56Z

src/lib/platform/MSWindowsTouchInjector.cpp

+bool MSWindowsTouchInjector::waitForForeground(HWND target, DWORD timeoutMs)
+{
+  // set up thread-local callback state
+  s_foregroundTarget = target;
+  s_foregroundArrived = false;
+


waitForForeground() uses static members (s_foregroundTarget, s_foregroundArrived) as cross-callback state but they’re neither thread_local nor synchronized. SetWinEventHook(..., WINEVENT_OUTOFCONTEXT, ...) may invoke foregroundEventProc on a different thread, so this is a data race and the wait loop may not observe updates. Use proper synchronization (e.g., an event handle or std::atomic), or make the state truly thread-local if that’s the intent.

Copilot · 2026-03-03T19:36:56Z

src/lib/platform/dfwhook.h

 #define DESKFLOW_MSG_DEBUG WM_APP + 0x0019        // data, data
+#define DESKFLOW_MSG_TOUCH WM_APP + 0x001A        // x; y (touch-originated)
 #define DESKFLOW_MSG_INPUT_FIRST DESKFLOW_MSG_KEY
 #define DESKFLOW_MSG_INPUT_LAST DESKFLOW_MSG_PRE_WARP


DESKFLOW_MSG_TOUCH is now a hook-originated input message posted to the same thread queue, but DESKFLOW_MSG_INPUT_LAST still stops at DESKFLOW_MSG_PRE_WARP. MSWindowsScreen::warpCursor() flushes messages in [DESKFLOW_MSG_INPUT_FIRST, DESKFLOW_MSG_INPUT_LAST], so touch messages can remain queued across warps/screen switches and potentially fire later in the wrong state. Consider extending DESKFLOW_MSG_INPUT_LAST to include DESKFLOW_MSG_TOUCH (or flushing up to DESKFLOW_HOOK_LAST_MSG).

Suggested change

#define DESKFLOW_MSG_INPUT_LAST DESKFLOW_MSG_PRE_WARP

#define DESKFLOW_MSG_INPUT_LAST DESKFLOW_MSG_TOUCH

Copilot · 2026-03-03T19:36:57Z

src/lib/server/Server.cpp

+  double elapsedTouchCooldown = m_touchSwitchCooldown.getTime();
+  if (elapsedTouchCooldown > 0.0 && elapsedTouchCooldown < kTouchSwitchCooldownTime) {
+    LOG((CLOG_DEBUG1 "edge switch blocked by touch cooldown (%.2fs remaining)",
+         kTouchSwitchCooldownTime - elapsedTouchCooldown));
+    return false;
+  }
+


m_touchSwitchCooldown is a running Stopwatch from server construction time, so during the first ~0.5s after startup getTime() will be < kTouchSwitchCooldownTime and edge switching will be blocked even though no touch switch occurred. Consider gating this check with an explicit “cooldown active” flag, or initialize the stopwatch in a stopped state and only start/reset it when a touch/grab switch happens.

Suggested change

double elapsedTouchCooldown = m_touchSwitchCooldown.getTime();

if (elapsedTouchCooldown > 0.0 && elapsedTouchCooldown < kTouchSwitchCooldownTime) {

LOG((CLOG_DEBUG1 "edge switch blocked by touch cooldown (%.2fs remaining)",

kTouchSwitchCooldownTime - elapsedTouchCooldown));

return false;

}

static double s_lastTouchCooldownTime = -1.0;

static bool s_touchCooldownActive = false;

double elapsedTouchCooldown = m_touchSwitchCooldown.getTime();

// Detect when the touch cooldown stopwatch has been reset (e.g. on a touch/grab switch).

// Before the first reset after startup, the stopwatch simply runs from construction time,

// so we do not want to treat that as an active cooldown.

if (s_lastTouchCooldownTime >= 0.0 && elapsedTouchCooldown < s_lastTouchCooldownTime) {

// Stopwatch time decreased, so assume it was reset to start a new cooldown window.

s_touchCooldownActive = true;

}

s_lastTouchCooldownTime = elapsedTouchCooldown;

if (s_touchCooldownActive) {

if (elapsedTouchCooldown < kTouchSwitchCooldownTime) {

LOG((CLOG_DEBUG1 "edge switch blocked by touch cooldown (%.2fs remaining)",

kTouchSwitchCooldownTime - elapsedTouchCooldown));

return false;

}

else {

// Cooldown window has expired; allow edge switches again until the next reset.

s_touchCooldownActive = false;

}

}

Copilot · 2026-03-03T19:36:57Z

src/lib/server/Server.cpp

+    m_primaryClient->fakeTouchClick(x, y);
+
+    m_touchSwitchCooldown.reset();
+    LOG((CLOG_DEBUG1 "touch switch cooldown started"));
+  }


If you change m_touchSwitchCooldown to be stopped/disabled until the first touch switch (to avoid blocking edge switches at startup), make sure the cooldown is explicitly started when a touch/grab switch happens (e.g., start+reset) — right now the handlers only call reset(), which won’t start a stopped stopwatch.

Copilot · 2026-03-03T19:36:57Z

src/lib/platform/MSWindowsScreen.cpp

+    // debounce rapid touch events
+    double elapsed = m_touchDebounceTimer.getTime();
+    if (elapsed > 0.0 && elapsed < kTouchDebounceTime) {
+      LOG((CLOG_DEBUG1 "touch debounced at %d,%d (%.0fms)", x, y, elapsed * 1000));
+      return true;
+    }


m_touchDebounceTimer is a default-constructed (running) Stopwatch, so the first touch within ~0.3s of MSWindowsScreen construction will be treated as “debounced” and ignored. Consider initializing the timer in a stopped/disabled state (or using a separate boolean) so the first touch is never dropped.

Suggested change

// debounce rapid touch events

double elapsed = m_touchDebounceTimer.getTime();

if (elapsed > 0.0 && elapsed < kTouchDebounceTime) {

LOG((CLOG_DEBUG1 "touch debounced at %d,%d (%.0fms)", x, y, elapsed * 1000));

return true;

}

// per-instance debounce state: ensure the very first touch for a screen is never dropped

static MSWindowsScreen* s_lastTouchScreen = NULL;

static bool s_touchDebounceArmed = false;

if (s_lastTouchScreen != this) {

// new screen instance; do not debounce the first touch for it

s_lastTouchScreen = this;

s_touchDebounceArmed = false;

}

// debounce rapid touch events (only after debounce has been armed)

double elapsed = m_touchDebounceTimer.getTime();

if (s_touchDebounceArmed && elapsed > 0.0 && elapsed < kTouchDebounceTime) {

LOG((CLOG_DEBUG1 "touch debounced at %d,%d (%.0fms)", x, y, elapsed * 1000));

return true;

}

s_touchDebounceArmed = true;

… events

…ging for touch events

…management

…handling in onPreDispatch

…tion

feat: Implement touch-to-switch (without timing hacks)

7940764

nbolton requested a review from Copilot March 3, 2026 19:27

Copilot started reviewing on behalf of nbolton March 3, 2026 19:28 View session

Copilot AI reviewed Mar 3, 2026

View reviewed changes

nbolton added 8 commits March 4, 2026 09:24

feat: Add touch activation setting for screen in server config

d81924f

fix: reorder touch detection before inject check

1df9dce

refactor: update logging level from DEBUG1 to DEBUG for touch-related…

ce32460

… events

feat: Implement touch activation for screen switching and enhance log…

a5a684a

…ging for touch events

feat: Enhance touch event handling and remove unused on-screen state …

c48d5fc

…management

fix: change hook detection events

2ce8b1f

feat: Refine touch detection logic for screen activation and improve …

15a4bf3

…handling in onPreDispatch

feat: Implement touch cursor visibility management during touch injec…

b2115ac

…tion

nbolton closed this Mar 4, 2026

nbolton deleted the feat/touch-activates-screen branch March 4, 2026 13:47

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feat: Implement touch-to-switch (without timing hacks)#162

feat: Implement touch-to-switch (without timing hacks)#162
nbolton wants to merge 9 commits intomasterfrom
feat/touch-activates-screen

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	#define DESKFLOW_MSG_INPUT_LAST DESKFLOW_MSG_PRE_WARP
	#define DESKFLOW_MSG_INPUT_LAST DESKFLOW_MSG_TOUCH

-  double elapsedTouchCooldown = m_touchSwitchCooldown.getTime();
-  if (elapsedTouchCooldown > 0.0 && elapsedTouchCooldown < kTouchSwitchCooldownTime) {
-    LOG((CLOG_DEBUG1 "edge switch blocked by touch cooldown (%.2fs remaining)",
-         kTouchSwitchCooldownTime - elapsedTouchCooldown));
-    return false;
-  }
+  static double s_lastTouchCooldownTime = -1.0;
+  static bool s_touchCooldownActive = false;
+  double elapsedTouchCooldown = m_touchSwitchCooldown.getTime();
+  // Detect when the touch cooldown stopwatch has been reset (e.g. on a touch/grab switch).
+  // Before the first reset after startup, the stopwatch simply runs from construction time,
+  // so we do not want to treat that as an active cooldown.
+  if (s_lastTouchCooldownTime >= 0.0 && elapsedTouchCooldown < s_lastTouchCooldownTime) {
+    // Stopwatch time decreased, so assume it was reset to start a new cooldown window.
+    s_touchCooldownActive = true;
+  }
+  s_lastTouchCooldownTime = elapsedTouchCooldown;
+  if (s_touchCooldownActive) {
+    if (elapsedTouchCooldown < kTouchSwitchCooldownTime) {
+      LOG((CLOG_DEBUG1 "edge switch blocked by touch cooldown (%.2fs remaining)",
+           kTouchSwitchCooldownTime - elapsedTouchCooldown));
+      return false;
+    }
+    else {
+      // Cooldown window has expired; allow edge switches again until the next reset.
+      s_touchCooldownActive = false;
+    }
+  }

-    // debounce rapid touch events
-    double elapsed = m_touchDebounceTimer.getTime();
-    if (elapsed > 0.0 && elapsed < kTouchDebounceTime) {
-      LOG((CLOG_DEBUG1 "touch debounced at %d,%d (%.0fms)", x, y, elapsed * 1000));
-      return true;
-    }
+    // per-instance debounce state: ensure the very first touch for a screen is never dropped
+    static MSWindowsScreen* s_lastTouchScreen = NULL;
+    static bool s_touchDebounceArmed = false;
+    if (s_lastTouchScreen != this) {
+      // new screen instance; do not debounce the first touch for it
+      s_lastTouchScreen = this;
+      s_touchDebounceArmed = false;
+    }
+    // debounce rapid touch events (only after debounce has been armed)
+    double elapsed = m_touchDebounceTimer.getTime();
+    if (s_touchDebounceArmed && elapsed > 0.0 && elapsed < kTouchDebounceTime) {
+      LOG((CLOG_DEBUG1 "touch debounced at %d,%d (%.0fms)", x, y, elapsed * 1000));
+      return true;
+    }
+    s_touchDebounceArmed = true;

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