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Uses virtual screen coordinates #22

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magicxor wants to merge 2 commits into from
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Uses virtual screen coordinates #22

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de7de4b
Uses virtual screen coordinates
magicxor Nov 24, 2025
5505971
Corrects mouse input for virtual screens
magicxor Nov 24, 2025
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35 changes: 23 additions & 12 deletions WinSyncScroll/ViewModels/MainViewModel.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -95,8 +95,10 @@ public sealed partial class MainViewModel : IDisposable
private Task? _mouseEventProcessingLoopTask;
private Task? _updateMouseHookRectsLoopTask;

private int _smCxScreen;
private int _smCyScreen;
private int _smXVirtualScreen;
private int _smYVirtualScreen;
private int _smCxVirtualScreen;
private int _smCyVirtualScreen;

private static readonly int SizeOfInput = Marshal.SizeOf<INPUT>();

Expand Down Expand Up @@ -144,8 +146,8 @@ private static INPUT CreateScrollInput(nuint mouseMessageId, int absoluteX, int
};
var dwFlags = mouseMessageId switch
{
WinApiConstants.WM_MOUSEWHEEL => MOUSE_EVENT_FLAGS.MOUSEEVENTF_WHEEL | MOUSE_EVENT_FLAGS.MOUSEEVENTF_ABSOLUTE | MOUSE_EVENT_FLAGS.MOUSEEVENTF_MOVE_NOCOALESCE,
WinApiConstants.WM_MOUSEHWHEEL => MOUSE_EVENT_FLAGS.MOUSEEVENTF_HWHEEL | MOUSE_EVENT_FLAGS.MOUSEEVENTF_ABSOLUTE | MOUSE_EVENT_FLAGS.MOUSEEVENTF_MOVE_NOCOALESCE,
WinApiConstants.WM_MOUSEWHEEL => MOUSE_EVENT_FLAGS.MOUSEEVENTF_WHEEL | MOUSE_EVENT_FLAGS.MOUSEEVENTF_VIRTUALDESK | MOUSE_EVENT_FLAGS.MOUSEEVENTF_ABSOLUTE | MOUSE_EVENT_FLAGS.MOUSEEVENTF_MOVE_NOCOALESCE,
WinApiConstants.WM_MOUSEHWHEEL => MOUSE_EVENT_FLAGS.MOUSEEVENTF_HWHEEL | MOUSE_EVENT_FLAGS.MOUSEEVENTF_VIRTUALDESK | MOUSE_EVENT_FLAGS.MOUSEEVENTF_ABSOLUTE | MOUSE_EVENT_FLAGS.MOUSEEVENTF_MOVE_NOCOALESCE,
_ => MOUSE_EVENT_FLAGS.MOUSEEVENTF_MOVE,
};
inputScroll.Anonymous.mi.dwFlags = dwFlags;
Expand All @@ -164,7 +166,7 @@ private static INPUT CreateMoveInput(int absoluteX, int absoluteY)
{
type = INPUT_TYPE.INPUT_MOUSE,
};
inputMove.Anonymous.mi.dwFlags = MOUSE_EVENT_FLAGS.MOUSEEVENTF_MOVE | MOUSE_EVENT_FLAGS.MOUSEEVENTF_ABSOLUTE | MOUSE_EVENT_FLAGS.MOUSEEVENTF_MOVE_NOCOALESCE;
inputMove.Anonymous.mi.dwFlags = MOUSE_EVENT_FLAGS.MOUSEEVENTF_MOVE | MOUSE_EVENT_FLAGS.MOUSEEVENTF_VIRTUALDESK | MOUSE_EVENT_FLAGS.MOUSEEVENTF_ABSOLUTE | MOUSE_EVENT_FLAGS.MOUSEEVENTF_MOVE_NOCOALESCE;
inputMove.Anonymous.mi.time = 0;
inputMove.Anonymous.mi.mouseData = 0;
inputMove.Anonymous.mi.dx = absoluteX;
Expand All @@ -176,9 +178,11 @@ private static INPUT CreateMoveInput(int absoluteX, int absoluteY)

private (int X, int Y) CalculateAbsoluteCoordinates(int x, int y)
{
// Convert screen coordinates to absolute coordinates for SendInput
// Formula: ((coordinate - virtualScreenOffset) * 65536) / virtualScreenSize
return (
X: PInvoke.MulDiv(x, 65536, _smCxScreen),
Y: PInvoke.MulDiv(y, 65536, _smCyScreen)
X: PInvoke.MulDiv(x - _smXVirtualScreen, 65536, _smCxVirtualScreen),
Y: PInvoke.MulDiv(y - _smYVirtualScreen, 65536, _smCyVirtualScreen)
);
}

Expand Down Expand Up @@ -320,7 +324,7 @@ private async Task RunMouseEventProcessingLoopAsync(
var (sourceAbsoluteX, sourceAbsoluteY) = CalculateAbsoluteCoordinates(sourceEventX, sourceEventY);
var (targetAbsoluteX, targetAbsoluteY) = CalculateAbsoluteCoordinates(targetX, targetY);

_logger.LogTrace("Converted coordinates: Source=({SourceEventX},{SourceEventY}) -> ({SourceAbsoluteX},{SourceAbsoluteY}), Target=({TargetX},{TargetY}) -> ({TargetAbsoluteX},{TargetAbsoluteY}). _smCxScreen={SmCxScreen}, _smCyScreen={SmCyScreen}",
_logger.LogTrace("Converted coordinates: Source=({SourceEventX},{SourceEventY}) -> ({SourceAbsoluteX},{SourceAbsoluteY}), Target=({TargetX},{TargetY}) -> ({TargetAbsoluteX},{TargetAbsoluteY}). VirtualScreen={SmCxVirtualScreen}x{SmCyVirtualScreen}",
sourceEventX,
sourceEventY,
sourceAbsoluteX,
Expand All @@ -329,8 +333,8 @@ private async Task RunMouseEventProcessingLoopAsync(
targetY,
targetAbsoluteX,
targetAbsoluteY,
_smCxScreen,
_smCyScreen);
_smCxVirtualScreen,
_smCyVirtualScreen);

var inputMoveToTarget = CreateMoveInput(targetAbsoluteX, targetAbsoluteY);
var inputScrollTarget = CreateScrollInput(buffer.MouseMessageId, targetAbsoluteX, targetAbsoluteY, delta);
Expand Down Expand Up @@ -518,8 +522,15 @@ private void Start()
{
_logger.LogInformation("Starting scroll sync between \"{SourceWindow}\" and \"{TargetWindow}\"", Source.DisplayName, Target.DisplayName);

_smCxScreen = PInvoke.GetSystemMetrics(SYSTEM_METRICS_INDEX.SM_CXSCREEN);
_smCyScreen = PInvoke.GetSystemMetrics(SYSTEM_METRICS_INDEX.SM_CYSCREEN);
_smXVirtualScreen = PInvoke.GetSystemMetrics(SYSTEM_METRICS_INDEX.SM_XVIRTUALSCREEN);
_smYVirtualScreen = PInvoke.GetSystemMetrics(SYSTEM_METRICS_INDEX.SM_YVIRTUALSCREEN);
_smCxVirtualScreen = PInvoke.GetSystemMetrics(SYSTEM_METRICS_INDEX.SM_CXVIRTUALSCREEN);
_smCyVirtualScreen = PInvoke.GetSystemMetrics(SYSTEM_METRICS_INDEX.SM_CYVIRTUALSCREEN);
_logger.LogDebug("Virtual screen: offset=({XOffset},{YOffset}), size={Width}x{Height}",
_smXVirtualScreen,
_smYVirtualScreen,
_smCxVirtualScreen,
_smCyVirtualScreen);

AppState = AppState.Running;
}
Expand Down