Transparent windows under W2K or WXP

• Download source files - 5.71 Kb
• Download demo project - 30.5 Kb

Note: this would run only under Windows 2000 and the successors.

Introduction

Well - some time ago I wrote a few lines of code which came out to be a hit to some companies. This happened nearly 10 years ago. Those people were used to rent a software - so I finally gave in :)

Nowadays nearly everything is going to get not cheaper - I thought this would be the right time to give my old settled customers the opportunity to pay back my patience. I changed nearly every bit of code I knew working well to some code I expect to do the same ;) I didn't touch a piece of code on which I forgot the usage, so it wasn't much to do!

Multithreading, Inter Process Communication, Kernel Mode Execution, Native API-Support - hmmm, this you can talk to a sales engineer for centuries, he would keep on looking the same cool inter-face which means - he doesn't know what's going on but he has the key to the safe.

Time to posh up my UI ( Unique Identity - also known as User Interface )

My program is used by officials in charge - means: busy, critical on every change that doesn't make them do their job better.

They do need some information temporary but also need to view what they have in front with no change. This sounds like a popup window is needed and indeed this is what I have done there. The general feedback was: Yes we need what you show in your popup, and thanks, really nice but: We also need to see the things underneath the popup so we always don't have to move your information popup window around on the screen. Not so nice.

Pellucid was born. A popup-window showing the additional information in a flexible way by letting view the covered section of the original window. Reducing the amount of window-moves while looking cool.

This code does not work on machines with OS-versions lower than W2K because of the usage of window style WS_EX_LAYERED.

The classes

There are 3 classes doing the whole work:

PellucidChild is derived from CWnd and functions as a shell for the original control. It replaces the control's window procedure with its own. The reason for this was the requirement for the control being dragged by mouse as you do this on main windows by dragging the caption bar.

PellucidSelf is derived from CFrameWnd because this gives the opportunity of being placed anywhere on the screen. PellucidSelf becomes the parent of PellucidChild

Pellucid is the shell setting up all required connections between the original control, PellucidSelf and PellucidChild. It also makes the transparency by calling the appropriate functions in Pellucid::CreateSelf().

Usage

1. Include the header Pellucid.h where you want the transparent windows to be shown e.g.: MainFrm.h or any CDialog-derived window or ...
2. Add member variables of type Pellucid
3. Add member variables of type of control you want to be shown e.g. CEdit, CTreeCtrl ...
4. Create the control by using the appropriate Create functions
5. Create Pellucid
6. If you want to process the notification messages send by the controls then you have to insert message handler for WM_COMMAND and WM_NOTIFY messages
7. If you are done with Pellucid - the destructor will do the job or just call Pellucid::Destroy()

Sample for 1,2,3

///////////////////////////////////////////////////////////
// >> demo extension
//
#include "Pellucid.h"
///////////////////////////////////////////////////////////
// << demo extension
//
#include "ChildView.h"
class CMainFrame : public CFrameWnd
{
public:
    CMainFrame();
protected:
    DECLARE_DYNAMIC(CMainFrame)
// Attributes
public:
///////////////////////////////////////////////////////////
// >> demo extension
//
    Pellucid m_pellucid1;
    Pellucid m_pellucid2;
    Pellucid m_pellucid3;
    Pellucid m_pellucid4;
    Pellucid m_pellucid5;
    Pellucid m_pellucid6;
    CListBox m_listbox;
    CEdit m_edit;
    CTreeCtrl m_tree;
    CButton m_button;
    CButton m_button2;
    CButton m_checkbox;
///////////////////////////////////////////////////////////
// << demo extension
//

Sample for 4,5

///////////////////////////////////////////////////////////
// << demo extension
//
void CMainFrame::OnShow()
{
///////////////////////////////////////////////////////////
// >> demo extension
//
    int id = 42;
    m_listbox.Create (WS_CHILD | WS_VSCROLL | LBS_NOTIFY, 
                                    CRect(0,0,0,0),this,id);
    int i;
    // add some fake data to the listbox
    for(i = 0; i < 100; i ++) {
        CString s;
        s.Format (TEXT("listboxitem %d"),i+1);
        m_listbox.AddString (s);
    }
    CRect rw; // parent rectangle
    GetWindowRect(rw);
    CRect rp; // pellucid rectangle
    rp.SetRect (rw.left + 20,rw.top + 70,rw.left + 220,rw.top + 250);
    // m_pellucid1 is a container for m_listbox
    // note: the rectangle for the container is in screen coordinates,
    // the child rectangle is in client coordinates regarding to the
    // container
    m_pellucid1.Create (
        this,         // parent
        rp,         // position and size in screen coordinates
        &m_listbox,     // childwindow to capture
                // position and size of child
        CRect(15,15,rp.Width() - 15,rp.Height () - 15)
    );
    ///////////////////////////////////////////////////////
    //
    // Next pellucid plz - an edit control capture by pellucid2
    //
    id ++;
    m_edit.Create (WS_CHILD | ES_WANTRETURN | ES_MULTILINE, 
                                   CRect(0,0,0,0),this,id);
    m_edit.SetWindowText (TEXT("this editcontrol\r\nis made for you"));
    // m_pellucid2 is a container for m_edit
    rp.OffsetRect (rp.Width () + 10,0);
    rp.bottom = rp.top + 400;
    m_pellucid2.Create (
        this,           // parent
        rp,             // position and size in screen coordinates
        &m_edit,        // childwindow to capture
        CRect(15,15,185,375),     // position and size of child
        CSize(0,0),     // rounded corners ?
        RGB(0,128,128), // backgroundcolor of parent of childwindow
        170,            // how many steps to get visible
        170,            // how many steps to hide
        170,            // ( 0 == invisible .... 255 = opaque )
        true,           // special effect when mouse is over
        220);           // nearly opaque while mouse is over

...

Sample for 6

//////////////////////////////////////////////////////
// >> demo extension
//
BOOL CMainFrame::OnCommand(WPARAM wParam, LPARAM lParam)
{
            // ancient controls will yell on this message
            int lw = LOWORD(wParam);
            int hw = HIWORD(wParam);
            int sel;
            TCHAR s[100];
            CString s2;
            //
            // note : this is hardcoded - replace it with your
            // own smart encoding-algorithm for identifiers
            //
            if(lw == 42) {
                // this is our listbox thing
                switch(hw) {
                case LBN_SELCHANGE:
                    sel = ::SendMessage ((HWND) lParam,LB_GETCURSEL,0,0);
                    ::SendMessage((HWND)lParam,
                        LB_GETTEXT,sel,(LONG)(LPSTR)s);
                    SetWindowText(s);                            
                    break;
                case LBN_DBLCLK:
                    sel = ::SendMessage ((HWND) lParam,LB_GETCURSEL,0,0);
                    ::SendMessage((HWND)lParam,
                        LB_GETTEXT,sel,(LONG)(LPSTR)s);
                    s2 = s;
                    s2 +=  " double clicked";
                    SetWindowText(s2); 
                    break;
                }
            }

...


BOOL CMainFrame::OnNotify(WPARAM wParam, LPARAM lParam, LRESULT* pResult)
{
            // some controls feel special so they yell on this ....
            NMHDR *pnmhdr;
            pnmhdr = (NMHDR*)lParam;
            CString s;
            bool treeee = false;
            if(wParam == 44) {
               switch(pnmhdr->code) {
               case NM_CLICK:
                  s = " treecntrl click";
                  treeee = true;
                  break;
               case NM_DBLCLK:
                  s = " treecntrl dblclk";
                  treeee = true;
                  break;
                        }
               if(treeee)
                  // this is our tree thing
                  SetWindowText(s);
            }
           
            return CFrameWnd::OnNotify(wParam, lParam, pResult);
}

Sample for 7

void CMainFrame::OnPellucidDestroy()
{
   m_pellucid1.Destroy();
   m_pellucid2.Destroy ();
}