import com.ms.dll.DllLib;
 import com.ms.dll.Root;
 import com.ms.dll.Callback;
 
 public class Win32ColorDlg extends Callback {
     public static final int NUM_CUST_COLORS = 16;
     public static final int COLOR_SIZE_IN_BYTES = 4;
     public int[] cust = new int[NUM_CUST_COLORS];
 
     public static final int CC_RGBINIT    = 0x00000001;
     public static final int CC_FULLOPEN   = 0x00000002;
     public static final int CC_ENABLEHOOK = 0x00000010;
 
     public static final int WM_LBUTTONUP  = 0x0202;
     public static final int WM_CHAR       = 0x0102;
 
     public CHOOSECOLOR cc = new CHOOSECOLOR();
 
     public static void main(String args[]) {
         Win32ColorDlg dlg = new Win32ColorDlg();
         int c = dlg.getColor();
         System.out.println("r,g,b = " + (c & 0xFF) + "," + ((c >> 8) & 0xFF) + 
                            "," + ((c >> 16) & 0xFF));
 
         for (int i = 0; i < NUM_CUST_COLORS; i++)
         System.out.println("custom[" + i + "] = " + (dlg.cust[i] & 0xFF) + "," +
            ((dlg.cust[i] >> 8) & 0xFF) + "," + ((dlg.cust[i] >> 16) & 0xFF));
     }
 
     public int getColor(){
         // Allocate the necessary memory block (in bytes)
         int custColorPtr = DllLib.allocCoTaskMem(NUM_CUST_COLORS *
                                                 COLOR_SIZE_IN_BYTES);
 
         // Set the default colors of the array to white
         for (int i = 0; i < NUM_CUST_COLORS; i++) 
             cust[i] = 0x00FFFFFF;
 
         // Params (source array, array offset, dest ptr, # of array elements)
         DllLib.copy(cust, 0, custColorPtr, NUM_CUST_COLORS);
 
         // Create a pointer to the dialog's callback procedure
         int hook = Root.alloc(this);
 
         cc.lStructSize = DllLib.sizeOf(CHOOSECOLOR.class);
         cc.hwndOwner = GetActiveWindow();  // Call API
         cc.hInstance = 0; 
         cc.rgbResult = 0;
         cc.lpCustColors = custColorPtr;
         cc.flags = CC_RGBINIT | CC_ENABLEHOOK | CC_FULLOPEN ;
         cc.lpfnHook = DllLib.addrOf(hook);
 
         // Call the API
         ChooseColor(cc);
 
         // Params (source ptr, destination array, array offset
        // number of array elements)
         DllLib.copy(custColorPtr, cust, 0, NUM_CUST_COLORS);
 
         // Free up allocated memory
         DllLib.freeCoTaskMem(custColorPtr);
         Root.free(hook);
 
         return cc.rgbResult;
     }
 
     // To extend Callback, you must implement a public method called "callback"
     public int callback(int hWnd, int msg, int wParam, int lParam) {
         if (((msg == WM_CHAR) && (wParam == 32)) || (msg == WM_LBUTTONUP)) 
             System.out.println("New color selected.");
         return 0;
     }
 
 /** @dll.import("COMDLG32") */
 static native boolean ChooseColor (CHOOSECOLOR pChoosecolor);
 
 /** @dll.import("USER32") */
 public static native int GetActiveWindow();
 }
 
 /** @dll.struct() */
 class CHOOSECOLOR {
     public int lStructSize;
     public int hwndOwner;
     public int hInstance;
     public int rgbResult;
     public int lpCustColors;
     public int flags;
     public int lCustData;
     public int lpfnHook;
     public String lpTemplateName;
 }