SendInput doesn't perform click mouse button unless I move cursor.
I would appreciate a help on this one, as I seems cannot wrap my head around it.
I have a program that perform mouse click on foreground window, in which I am using SendInput to emulate left mouse click. The issue is, that if I move cursor to clicking position than SendInput will make the click, however if I don't move cursor than no click happens even trough I do pass x and y points to the MouseInputData. I would like to perform left mouse click without the need of actually moving the cursor at all.
Bellow is the class I have (it fairly simple and stright forward)
namespace StackSolution.Classes
{
public static class SendInputClass
{
[DllImport("user32.dll", SetLastError = true)]
static extern uint SendInput(uint nInputs, ref INPUT pInputs, int cbSize);
[DllImport("user32.dll")]
static extern bool SetCursorPos(int X, int Y);
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool GetCursorPos(out Point lpPoint);
[StructLayout(LayoutKind.Sequential)]
struct INPUT
{
public SendInputEventType type;
public MouseKeybdhardwareInputUnion mkhi;
}
[StructLayout(LayoutKind.Explicit)]
struct MouseKeybdhardwareInputUnion
{
[FieldOffset(0)]
public MouseInputData mi;
[FieldOffset(0)]
public KEYBDINPUT ki;
[FieldOffset(0)]
public HARDWAREINPUT hi;
}
[StructLayout(LayoutKind.Sequential)]
struct KEYBDINPUT
{
public ushort wVk;
public ushort wScan;
public uint dwFlags;
public uint time;
public IntPtr dwExtraInfo;
}
[StructLayout(LayoutKind.Sequential)]
struct HARDWAREINPUT
{
public int uMsg;
public short wParamL;
public short wParamH;
}
struct MouseInputData
{
public int dx;
public int dy;
public uint mouseData;
public MouseEventFlags dwFlags;
public uint time;
public IntPtr dwExtraInfo;
}
[Flags]
enum MouseEventFlags : uint
{
MOUSEEVENTF_MOVE = 0x0001,
MOUSEEVENTF_LEFTDOWN = 0x0002,
MOUSEEVENTF_LEFTUP = 0x0004,
MOUSEEVENTF_RIGHTDOWN = 0x0008,
MOUSEEVENTF_RIGHTUP = 0x0010,
MOUSEEVENTF_MIDDLEDOWN = 0x0020,
MOUSEEVENTF_MIDDLEUP = 0x0040,
MOUSEEVENTF_XDOWN = 0x0080,
MOUSEEVENTF_XUP = 0x0100,
MOUSEEVENTF_WHEEL = 0x0800,
MOUSEEVENTF_VIRTUALDESK = 0x4000,
MOUSEEVENTF_ABSOLUTE = 0x8000
}
enum SendInputEventType : int
{
InputMouse,
InputKeyboard,
InputHardware
}
public static void ClickLeftMouseButton(int x, int y)
{
INPUT mouseInput = new INPUT();
mouseInput.type = SendInputEventType.InputMouse;
mouseInput.mkhi.mi.dx = x;
mouseInput.mkhi.mi.dy = y;
mouseInput.mkhi.mi.mouseData = 0;
//getting current cursor location
Point p;
if (GetCursorPos(out p))
SetCursorPos(x, y);
mouseInput.mkhi.mi.dwFlags = MouseEventFlags.MOUSEEVENTF_LEFTDOWN;
SendInput(1, ref mouseInput, Marshal.SizeOf(new INPUT()));
mouseInput.mkhi.mi.dwFlags = MouseEventFlags.MOUSEEVENTF_LEFTUP;
SendInput(1, ref mouseInput, Marshal.SizeOf(new INPUT()));
//returning cursor to previous position
SetCursorPos(p.X, p.Y);
}
}
}
Same ClickLeftMouseButton function will not click if I remove getting cursor position like that.
public static void ClickLeftMouseButton(int x, int y)
{
INPUT mouseInput = new INPUT();
mouseInput.type = SendInputEventType.InputMouse;
mouseInput.mkhi.mi.dx = x;
mouseInput.mkhi.mi.dy = y;
mouseInput.mkhi.mi.mouseData = 0;
mouseInput.mkhi.mi.dwFlags = MouseEventFlags.MOUSEEVENTF_LEFTDOWN;
SendInput(1, ref mouseInput, Marshal.SizeOf(new INPUT()));
mouseInput.mkhi.mi.dwFlags = MouseEventFlags.MOUSEEVENTF_LEFTUP;
SendInput(1, ref mouseInput, Marshal.SizeOf(new INPUT()));
}
Thank you in advance.
There are a few things you should consider when using the SendInput
function.
If you do not specify the MOUSEEVENTF_ABSOLUTE
flag then dx
and dy
(MouseInputData structure) are relative coordinates to the current mouse position. If you do specify MOUSEEVENTF_ABSOLUTE
then dx
and dy
are absolute coordinates between 0 and 65535. So if your x and y coordinates are screen coordinates you should use the following function to calculate dx
and dy
:
enum SystemMetric
{
SM_CXSCREEN = 0,
SM_CYSCREEN = 1,
}
[DllImport("user32.dll")]
static extern int GetSystemMetrics(SystemMetric smIndex);
int CalculateAbsoluteCoordinateX(int x)
{
return (x * 65536) / GetSystemMetrics(SystemMetric.SM_CXSCREEN);
}
int CalculateAbsoluteCoordinateY(int y)
{
return (y * 65536) / GetSystemMetrics(SystemMetric.SM_CYSCREEN);
}
Furthermore before you send the MOUSEDOWN and MOUSEUP events to via SendInput you have to move the mouse to the control you want to click on:
public static void ClickLeftMouseButton(int x, int y)
{
INPUT mouseInput = new INPUT();
mouseInput.type = SendInputEventType.InputMouse;
mouseInput.mkhi.mi.dx = CalculateAbsoluteCoordinateX(x);
mouseInput.mkhi.mi.dy = CalculateAbsoluteCoordinateY(y);
mouseInput.mkhi.mi.mouseData = 0;
mouseInput.mkhi.mi.dwFlags = MouseEventFlags.MOUSEEVENTF_MOVE |MouseEventFlags.MOUSEEVENTF_ABSOLUTE;
SendInput(1, ref mouseInput, Marshal.SizeOf(new INPUT()));
mouseInput.mkhi.mi.dwFlags = MouseEventFlags.MOUSEEVENTF_LEFTDOWN;
SendInput(1, ref mouseInput, Marshal.SizeOf(new INPUT()));
mouseInput.mkhi.mi.dwFlags = MouseEventFlags.MOUSEEVENTF_LEFTUP;
SendInput(1, ref mouseInput, Marshal.SizeOf(new INPUT()));
}
The above code assumes that x
and y
are screen pixel coordinates. You can calculate those coordinates for a button (the target) on a winform by using the following code:
Point screenCoordsCentre=
button1.PointToScreen(new Point(button1.Width/2, button1.Height/2));
Hope, this helps.