Add ElanAP: Precision Touchpad absolute positioning by quanq026 · Pull Request #3 · InfinityGhost/SynAP

quanq026 · 2026-03-09T13:16:44Z

Summary

Adds ElanAP — a new project alongside SynAP that supports any Windows Precision Touchpad (Elan, Synaptics PTP, ALPS, etc.) instead of requiring Synaptics-specific drivers.

How it works

Uses Win32 Raw Input API (RegisterRawInputDevices with RIDEV_INPUTSINK) to read HID Precision Touchpad data
HidSharp 2.1.0 for HID descriptor parsing only (no exclusive device access)
Maps absolute touchpad coordinates to screen position, just like SynAP

Changes

Added ElanAP/ project (WPF, .NET 4.6.1, C# 5 compatible)
Added ElanAP to SynAP.sln
Updated README.md to cover both projects

Compatibility

Windows 10/11
.NET Framework 4.6.1+
Any Windows Precision Touchpad

- Win32 Raw Input API for universal PTP support (Elan, Synaptics, ALPS) - Deadzone blocking with low-level mouse hook - Drag-to-select area on visual map - Touchpad and screen resolution presets - Global hotkey F6 toggle - Zero-allocation hot path for minimal latency - Updated README and solution file

Copilot

Pull request overview

Adds a new WPF/.NET Framework project (ElanAP) alongside SynAP to provide absolute-positioning cursor control for osu! using Windows Precision Touchpad HID input (Raw Input + HidSharp), plus updates the solution and README to cover both projects.

Changes:

Added ElanAP/ project implementing Raw Input HID parsing + absolute cursor mapping, UI, tray icon, and hotkey toggle.
Added ElanAP to SynAP.sln so both projects build from the same solution.
Updated README.md to document SynAP vs ElanAP, features, and build steps.

Reviewed changes

Copilot reviewed 27 out of 29 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
SynAP.sln	Adds the ElanAP project and build configurations to the solution.
README.md	Updates documentation to cover both SynAP and ElanAP, including requirements/features/build.
ElanAP/ElanAP.csproj	New WPF project definition, references, resources, and compilation items.
ElanAP/packages.config	Adds HidSharp and compiler package dependencies.
ElanAP/API.cs	Implements Raw Input registration and HID report parsing (HidSharp) for PTP coordinates.
ElanAP/Driver.cs	Maps touch coordinates to screen coordinates and installs a low-level mouse hook.
ElanAP/MainWindow.xaml(.cs)	UI for bounds selection, presets, hotkey handling, config load/save, tray behavior.
ElanAP/Controls/*	Map visualization + drag-to-select and an in-app console UI.
ElanAP/Devices/*	Screen/touchpad bounds abstraction.
ElanAP/Tools/*	Small helper utilities and app metadata (paths/version).
ElanAP/NotifyIcon.cs	System tray icon wrapper for minimizing/restoring.
ElanAP/Windows/AboutBox.xaml(.cs)	About dialog UI and links.
ElanAP/* resources	App config, assembly info, icons.

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Copilot · 2026-03-09T13:24:57Z

+        private IntPtr MouseHookCallback(int nCode, IntPtr wParam, IntPtr lParam)
+        {
+            if (nCode >= 0 && (int)wParam == WM_MOUSEMOVE)
+            {
+                // Allow injected/synthetic moves (our own SetCursorPos), block hardware moves
+                var info = (MSLLHOOKSTRUCT)Marshal.PtrToStructure(lParam, typeof(MSLLHOOKSTRUCT));
+                if ((info.flags & LLMHF_INJECTED) == 0)
+                    return (IntPtr)1;
+            }
+            return CallNextHookEx(_hookId, nCode, wParam, lParam);


MouseHookCallback blocks all non-injected WM_MOUSEMOVE events (it doesn’t distinguish touchpad vs. external mouse, nor does it check whether the cursor is outside the configured area). This will prevent physical mice (and any non-injected cursor movement) from working while the driver is active, which is a significant usability/operational impact. If the goal is to block only touchpad-relative movement or only outside a deadzone, add a more selective filter or make this behavior optional/togglable.

Copilot · 2026-03-09T13:24:58Z

+                catch { }
+            }
+            throw new Exception("No HID Precision Touchpad found. Ensure Elan driver is installed.");
+        }


The exception message hard-codes “Ensure Elan driver is installed”, but the project/README claim support for any Windows Precision Touchpad (not vendor-specific). Update this message to avoid incorrectly suggesting an Elan-only requirement (and consider including a short actionable hint like checking Windows touchpad settings).

Copilot · 2026-03-09T13:24:58Z

+            StartButton.IsEnabled = API.IsAvailable;
+            if (!API.IsAvailable)
+                Console.Log(API, "API is unavailable. Please ensure an Elan HID touchpad is connected.");
+        }


This log message tells users to “ensure an Elan HID touchpad is connected”, which conflicts with the stated goal of supporting any Windows Precision Touchpad. Please make the guidance vendor-neutral (e.g., “Precision Touchpad detected/enabled”) to avoid misleading troubleshooting.

Copilot · 2026-03-09T13:24:59Z

+        public void ProcessRawInput(IntPtr lParam)
+        {
+            if (!_running) return;
+
+            uint dwSize = 0;
+            GetRawInputData(lParam, RID_INPUT, IntPtr.Zero, ref dwSize, _headerSize);
+            if (dwSize == 0) return;
+
+            // Reuse buffer — grow only if needed
+            if (_rawBuffer.Length < (int)dwSize)
+                _rawBuffer = new byte[(int)dwSize];
+
+            IntPtr buffer = Marshal.AllocHGlobal((int)dwSize);
+            try
+            {
+                if (GetRawInputData(lParam, RID_INPUT, buffer, ref dwSize, _headerSize) != dwSize)
+                    return;
+
+                // Read dwType directly from unmanaged memory (offset 0 of RAWINPUTHEADER)
+                uint dwType = (uint)Marshal.ReadInt32(buffer, 0);
+                if (dwType != RIM_TYPEHID) return;
+
+                // Copy only the HID payload portion, not the full buffer
+                int hidOffset = (int)_headerSize;
+                int payloadLen = (int)dwSize - hidOffset;
+                if (payloadLen < 8) return;
+
+                Marshal.Copy(buffer + hidOffset, _rawBuffer, 0, payloadLen);
+
+                int dwSizeHid = BitConverter.ToInt32(_rawBuffer, 0);
+                int dwCount = BitConverter.ToInt32(_rawBuffer, 4);
+                if (dwSizeHid <= 0 || dwCount <= 0) return;
+
+                // Reuse report buffer — grow only if needed
+                if (_reportBuffer.Length < dwSizeHid)
+                    _reportBuffer = new byte[dwSizeHid];
+
+                for (int r = 0; r < dwCount; r++)
+                {
+                    int offset = 8 + r * dwSizeHid;
+                    if (offset + dwSizeHid > payloadLen) break;
+                    Array.Copy(_rawBuffer, offset, _reportBuffer, 0, dwSizeHid);
+                    ParseReport(_reportBuffer);
+                }
+            }
+            finally
+            {
+                Marshal.FreeHGlobal(buffer);
+            }


ProcessRawInput allocates and frees unmanaged memory (Marshal.AllocHGlobal/FreeHGlobal) for every WM_INPUT message. This is on the hot path and contradicts the “zero-allocation hot path” goal; it can become a perf bottleneck under high report rates. Consider reusing a single unmanaged buffer (grow as needed) or switching to a pinned managed buffer/unsafe stackalloc pattern to avoid per-message heap allocations.

Copilot · 2026-03-09T13:24:59Z

+            string iconPath = @"ElanAP.Icon.ico";
+            Assembly assembly = Assembly.GetExecutingAssembly();
+
+            var stream = assembly.GetManifestResourceStream(iconPath);
+            if (stream != null)
+                Icon.Icon = new System.Drawing.Icon(stream);
+            Icon.MouseClick += NotifyIcon_Click;
+            Icon.Text = "ElanAP " + "v" + Info.AssemblyVersion;
+        }


GetManifestResourceStream() returns a Stream that should be disposed. Currently it’s left open after creating the Icon, which can leak a handle until process exit. Wrap the stream usage in a using/dispose block (or copy into a MemoryStream before constructing the Icon).

Copilot · 2026-03-09T13:24:59Z

+        public static readonly DependencyProperty ForegroundAreaProperty = DependencyProperty.Register(
+            "ForegroundArea", typeof(Area), typeof(MapArea));
+
+        public static readonly DependencyProperty BackgroundAreaProperty = DependencyProperty.Register(
+            "BackgroundArea", typeof(Area), typeof(MapArea));


ForegroundAreaProperty/BackgroundAreaProperty are registered without a PropertyChangedCallback. When these dependency properties are set via binding (e.g., when Config is replaced after loading a .cfg), WPF updates the DP storage without invoking the CLR wrapper setters, so UpdateCanvas() won’t run and the rectangles can get out of sync. Register the DPs with FrameworkPropertyMetadata including a change callback (and optionally AffectsRender) to call UpdateCanvas().

Copilot · 2026-03-09T13:24:59Z

+        public void Start(IntPtr hwnd)
+        {
+            if (API.IsAvailable)
+            {
+                FireOutput("Starting...");
+
+                ScaleX = ScreenArea.Width / TouchpadArea.Width;
+                ScaleY = ScreenArea.Height / TouchpadArea.Height;
+


Start() and RefreshCache() divide by TouchpadArea.Width/Height without guarding against 0. With a missing/invalid default.cfg, Configuration initializes these to 0, and pressing Start will throw (division by zero) and/or produce invalid scaling. Consider validating ScreenArea/TouchpadArea dimensions before enabling Start (and/or early-return with a user-visible status message).

Copilot AI review requested due to automatic review settings March 9, 2026 13:16

Copilot started reviewing on behalf of quanq026 March 9, 2026 13:17 View session

Copilot AI reviewed Mar 9, 2026

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quanq026 changed the title ~~Add ElanAP: Precision Touchpad absolute positioning for osu!~~ Add ElanAP: Precision Touchpad absolute positioning Mar 10, 2026

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quanq026 commented Mar 9, 2026 •

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quanq026 commented Mar 9, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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quanq026 commented Mar 9, 2026 •

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