Windows 7 taskbar state with minimal code

Question

What would be the shortest code to set the state of a Windows 7 taskbar button for a known window handle?

The goal is to write a console utility that changes the progress and state (colour) of the console window taskbar item from a batch script. While the script performs different tasks, the taskbar item of its console window should represent the current state.

I get the window handle with the GetConsoleWindow() function, but then it seems to require loads of COM and Shell API stuff that I don't understand. One example I've found uses a whole GUI application with MFC to demonstrate the API, but most of it is way too complicated for my little tool and I don't understand it well enough to remove the stuff I don't need.

The tool should compile on Windows 7 with VS2010 (C++) but also run on earlier Windows versions (doing nothing if a feature is not available).

Answer 1

I created a class to set the progress in the Win7 taskbar for a project at one time. It's a wrapper for the ITaskBarList3 interface available from the Windows Shell. It's specifically done with ITaskBarList3.SetProgressState and ITaskBarList3.SetProgressValue functions.

This is the code I dug up:

#include <shobjidl.h>
#include <windows.h>
#pragma comment(lib, "Shell32.lib")
#pragma comment(lib, "Ole32.lib")

class Win7TaskbarProgress  
{
public:
    Win7TaskbarProgress();
    virtual ~Win7TaskbarProgress();

    void SetProgressState(HWND hwnd, TBPFLAG flag);
    void SetProgressValue(HWND hwnd, ULONGLONG ullCompleted, ULONGLONG ullTotal);

private:
    bool Init();
    ITaskbarList3* m_pITaskBarList3;
    bool m_bFailed;
};

Win7TaskbarProgress::Win7TaskbarProgress()
{
    m_pITaskBarList3 = NULL;
    m_bFailed = false;
}

Win7TaskbarProgress::~Win7TaskbarProgress()
{
    if (m_pITaskBarList3)   
    {
        m_pITaskBarList3->Release();
        CoUninitialize();
    }
}

void Win7TaskbarProgress::SetProgressState( HWND hwnd, TBPFLAG flag )
{
    if (Init())
        m_pITaskBarList3->SetProgressState(hwnd, flag);
}

void Win7TaskbarProgress::SetProgressValue( HWND hwnd, ULONGLONG ullCompleted, ULONGLONG ullTotal )
{
    if (Init())
        m_pITaskBarList3->SetProgressValue(hwnd, ullCompleted, ullTotal);
}

bool Win7TaskbarProgress::Init()
{
    if (m_pITaskBarList3)
        return true;

    if (m_bFailed)
        return false;
    
    // Initialize COM for this thread...
    CoInitialize(NULL);
    
    CoCreateInstance(CLSID_TaskbarList, NULL, CLSCTX_INPROC_SERVER, IID_ITaskbarList3, (void **)&m_pITaskBarList3);

    if (m_pITaskBarList3)
        return true;

    m_bFailed = true;
    CoUninitialize();
    return false;
}