Screen Capture Update

2012-04-29 Screen Capture Update

My wife, the user of the Screen Capture application as described in http://www.sorescu.eu/article/120220221500/Free-Screen-Capture-application explained me that she needs to run it also while in Full Screen mode.

The application can be found at: http://static.sorescu.eu/applications/ScreenCapture-1204292122/Screen Capture.exe.

For this I had to hook to the Windows Hot Key events, after I registered with the desired shortcut.

The chosen shortcut is <CTRL>+<ALT>+<PRINT_SCREEN>, and the code update is as in file below. Main call as following:

Thread t=new Thread(new ThreadStart(ProcessHotKey));
            t.IsBackground=true;
            t.Start();

Worthy mentioning are the following:

I used
```
GetMessage(ref msg,IntPtr.Zero,0,0)
```
for avoiding message queues to any form, but to the current thread;
It was required
```
int hashCode=("hash-"+modifiers+"-"+key).GetHashCode();
```
to ensure that the Hot Key is unique in Windows;
The Hot Key handler had to be ran in a separate thread, using
```
new Thread(new ThreadStart(ProcessHotKey))
```

My sources of inspiration were:

RegisterHotKey.cs

#region Hot Key 
        [DllImport("user32.dll")]
        public static extern bool RegisterHotKey(IntPtr hWnd,int id,uint fsModifiers,int vk);
        public const int WM_HOTKEY=0x0312;
        public const int MOD_ALT=0x0001;
        public const int MOD_CONTROL=0x0002;
        public const int MOD_NOREPEAT=0x4000;
        public const int MOD_SHIFT=0x0004;
        public const int MOD_WIN=0x0008;
        [DllImport("user32")]
        public static extern
            bool GetMessage(ref Message lpMsg,IntPtr handle,uint mMsgFilterInMain,uint mMsgFilterMax);
        public static void ProcessHotKey() {
            uint modifiers=MOD_CONTROL|MOD_ALT;
            int key=(int)Keys.PrintScreen;
            int hashCode=("hash-"+modifiers+"-"+key).GetHashCode();
            if(!RegisterHotKey(IntPtr.Zero,hashCode,modifiers,key))
                throw new Exception("Key not registered");

            System.Windows.Forms.Message msg=new System.Windows.Forms.Message();
            while(GetMessage(ref msg,IntPtr.Zero,0,0))
                if(msg.Msg==WM_HOTKEY)
                    CaptureImage();
        }
        #endregion