C# - Sending messages to Google Chrome from C# application

Question

I\'ve been searching around, and I haven\'t found how I would do this from C#.

I was wanting to make it so I could tell Google Chrome to go Forward,

Answer 1

This is a great site for interop constants:

pinvoke

Another way of finding the values is to search koders.com, using C# as the language, for WM_KEYDOWN or the constant you're after:

Koders.com search

&H values look like that's from VB(6). pinvoke and koders both return results for VK_BROWSER_FORWARD,

private const UInt32 WM_KEYDOWN        = 0x0100;
private const UInt32 WM_KEYUP          = 0x0101;

public const ushort VK_BROWSER_BACK = 0xA6;
public const ushort VK_BROWSER_FORWARD = 0xA7;
public const ushort VK_BROWSER_REFRESH = 0xA8;
public const ushort VK_BROWSER_STOP = 0xA9;
public const ushort VK_BROWSER_SEARCH = 0xAA;
public const ushort VK_BROWSER_FAVORITES = 0xAB;
public const ushort VK_BROWSER_HOME = 0xAC;

(It's funny how many wrong defintions of VK constants are floating about, considering VK_* are 1 byte 0-255 values, and people have made them uints).

Looks slightly different from your consts. I think the function you're after is SendInput (but I haven't tried it) as it's a virtual key.

[DllImport("User32.dll")]
private static extern uint SendInput(uint numberOfInputs, [MarshalAs(UnmanagedType.LPArray, SizeConst = 1)] KEYBOARD_INPUT[] input, int structSize);

Explanation about the parameters:

Parameters

• nInputs- Number of structures in the pInputs array.
• pInputs - Pointer to an array of INPUT structures. Each structure represents an event to be inserted into the keyboard or mouse input stream.
• cbSize - Specifies the size, in bytes, of an INPUT structure. If cbSize is not the size of an INPUT structure, the function fails.

This needs a KEYBOARD_INPUT type:

[StructLayout(LayoutKind.Sequential)] 
public struct KEYBOARD_INPUT
{ 
    public uint type; 
    public ushort vk; 
    public ushort scanCode; 
    public uint flags; 
    public uint time; 
    public uint extrainfo; 
    public uint padding1; 
    public uint padding2; 
}

And finally a sample, which I haven't tested if it works:

/*
typedef struct tagKEYBDINPUT {
    WORD wVk;
    WORD wScan;
    DWORD dwFlags;
    DWORD time;
    ULONG_PTR dwExtraInfo;
} KEYBDINPUT, *PKEYBDINPUT;
*/
public static void sendKey(int scanCode, bool press)
{
        KEYBOARD_INPUT[] input = new KEYBOARD_INPUT[1];
        input[0] = new KEYBOARD_INPUT();
        input[0].type = INPUT_KEYBOARD;
        input[0].vk = VK_BROWSER_BACK;

    uint result = SendInput(1, input, Marshal.SizeOf(input[0]));
}

Also you'll need to focus the Chrome window using SetForegroundWindow