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Developing with Windows Explorer

Windows Explorer is a powerful resource-browsing and management application. Windows Explorer can be accessed as an integrated whole through Explorer.exe or the IExplorerBrowser interface. Windows Explorer (Explorer.exe) can be spawned as a separate process using ShellExecuteEx or a similar function.

Note  Command-line options for Explorer.exe are documented on the Microsoft Windows Support site in the article Windows Explorer Command-Line Options.

Open explorer windows can be discovered and programmed by using IShellWindows (CLSID_ShellWindows), and new instances of Windows Explorer can be created by using IWebBrowser2 (CLSID_ShellBrowserWindow).

The following code sample demonstrates how the Windows Explorer automation model can be used to create and discover explorer windows that are running.



#define _WIN32_WINNT 0x0600
#define _WIN32_IE 0x0700
#define _UNICODE

#include <windows.h>
#include <shobjidl.h>
#include <shlobj.h>
#include <shlwapi.h>
#include <strsafe.h>
#include <propvarutil.h>
 
#pragma comment(lib, "shlwapi.lib")
#pragma comment(lib, "ole32.lib")
#pragma comment(lib, "shell32.lib")
#pragma comment(lib, "propsys.lib")
 
// Use the Shell Windows object to find all of the explorer and IExplorer 
// windows and close them.
 
void CloseExplorerWindows()
{
    IShellWindows* psw;
    
    if (SUCCEEDED(CoCreateInstance(CLSID_ShellWindows, 
                                   NULL,  
                                   CLSCTX_LOCAL_SERVER, 
                                   IID_PPV_ARGS(&psw))))
    {
        VARIANT v = { VT_I4 };
        if (SUCCEEDED(psw->get_Count(&v.lVal)))
        {
            // Walk backward to make sure that the windows that close
            // do not cause the array to be reordered.
            while (--v.lVal >= 0)
            {
                IDispatch *pdisp;
                
                if (S_OK == psw->Item(v, &pdisp))
                {
                    IWebBrowser2 *pwb;
                    if (SUCCEEDED(pdisp->QueryInterface(IID_PPV_ARGS(&pwb))))
                    {
                        pwb->Quit();
                        pwb->Release();
                    }
                    pdisp->Release();
                }
            }
        }
        psw->Release();
    }
}
 
// Convert an IShellItem or IDataObject into a VARIANT that holds an IDList
// suitable for use with IWebBrowser2::Navigate2.
 
HRESULT InitVariantFromObject(IUnknown *punk, VARIANT *pvar)
{
    VariantInit(pvar);
 
    PIDLIST_ABSOLUTE pidl;
    HRESULT hr = SHGetIDListFromObject(punk, &pidl);
    if (SUCCEEDED(hr))
    {
        hr = InitVariantFromBuffer(pidl, ILGetSize(pidl), pvar);
        CoTaskMemFree(pidl);
    }
    return hr;
}
 
HRESULT ParseItemAsVariant(PCWSTR pszItem, IBindCtx *pbc, VARIANT *pvar)
{
    VariantInit(pvar);
 
    IShellItem *psi;
    HRESULT hr = SHCreateItemFromParsingName(pszItem, NULL, IID_PPV_ARGS(&psi));
    if (SUCCEEDED(hr))
    {
        hr = InitVariantFromObject(psi, pvar);
        psi->Release();
    }
    return hr;
}

HRESULT GetKnownFolderAsVariant(REFKNOWNFOLDERID kfid, VARIANT *pvar)
{
    VariantInit(pvar);
 
    PIDLIST_ABSOLUTE pidl;
    HRESULT hr = SHGetKnownFolderIDList(kfid, 0, NULL, &pidl);
    if (SUCCEEDED(hr))
    {
        hr = InitVariantFromBuffer(pidl, ILGetSize(pidl), pvar);
        CoTaskMemFree(pidl);
    }
    return hr;
}

HRESULT GetShellItemFromCommandLine(REFIID riid, void **ppv)
{
    *ppv = NULL;
    HRESULT hr = E_FAIL;

    int cArgs;
    PWSTR *ppszCmd = CommandLineToArgvW(GetCommandLineW(), &cArgs);
    if (ppszCmd && cArgs > 1)
    {
        WCHAR szSpec[MAX_PATH];
        StringCchCopyW(szSpec, ARRAYSIZE(szSpec), ppszCmd[1]);
        PathUnquoteSpacesW(szSpec);

        hr = szSpec[0] ? S_OK : E_FAIL;   // Protect against empty data
        if (SUCCEEDED(hr))
        {
            hr = SHCreateItemFromParsingName(szSpec, NULL, riid, ppv);
            if (FAILED(hr))
            {
                WCHAR szFolder[MAX_PATH];
                GetCurrentDirectoryW(ARRAYSIZE(szFolder), szFolder);

                hr = PathAppendW(szFolder, szSpec) ? S_OK : E_FAIL;
                if (SUCCEEDED(hr))
                {
                    hr = SHCreateItemFromParsingName(szFolder, NULL, riid, ppv);
                }
            }
        }
    }
    return hr;
}

HRESULT GetShellItemFromCommandLineAsVariant(VARIANT *pvar)
{
    VariantInit(pvar);

    IShellItem *psi;
    HRESULT hr = GetShellItemFromCommandLine(IID_PPV_ARGS(&psi));
    if (SUCCEEDED(hr))
    {
        hr = InitVariantFromObject(psi, pvar);
        psi->Release();
    }
    return hr;
}

void OpenWindow()
{
    IWebBrowser2 *pwb;
    HRESULT hr = CoCreateInstance(CLSID_ShellBrowserWindow, 
                                  NULL,
                                  CLSCTX_LOCAL_SERVER, 
                                  IID_PPV_ARGS(&pwb));
    if (SUCCEEDED(hr))
    {
        CoAllowSetForegroundWindow(pwb, 0);

        pwb->put_Left(100);
        pwb->put_Top(100);
        pwb->put_Height(600);
        pwb->put_Width(800);
 
        VARIANT varTarget = {0};
        hr = GetShellItemFromCommandLineAsVariant(&varTarget);
        if (FAILED(hr))
        {
            hr = GetKnownFolderAsVariant(FOLDERID_UsersFiles, &varTarget);
        }

        if (SUCCEEDED(hr))
        {
            VARIANT vEmpty = {0};
            hr = pwb->Navigate2(&varTarget, &vEmpty, &vEmpty, &vEmpty, &vEmpty);
            if (SUCCEEDED(hr))
            {
                pwb->put_Visible(VARIANT_TRUE);
            }
            VariantClear(&varTarget);
        }
        pwb->Release();
    }
}

int WINAPI WinMain(HINSTANCE, HINSTANCE, LPSTR, int)
{
    HRESULT hr = CoInitializeEx(NULL, COINIT_APARTMENTTHREADED |  COINIT_DISABLE_OLE1DDE);
    if (SUCCEEDED(hr))
    {
        CloseExplorerWindows();

        OpenWindow();

        CoUninitialize();
    }
    return 0;
}

The Windows Explorer client area can be hosted by using the IExplorerBrowser interface. The Windows Explorer client and the namespace tree controls are standard components of Windows Vista and later. Developers can reuse the interfaces as building components. One common use of these controls is to create customized explorers appropriate to the problem domain.

The controls in Windows Explorer are classified into the following functional categories:

Navigation Controls

Navigation controls assist users in determining context and navigating the associated logical domain space, called the pagespace. For example, the pagespace for Windows Explorer is the Shell namespace. Pagespaces are composed of zero or more pages.

The following table lists and describes the navigation controls available in Windows Explorer in the Windows Vista and later operating systems.

Navigation controlDescription
Address Bar (Breadcrumb control)Displays the address of the current page in the pagespace. Breadcrumb buttons can be clicked to navigate to any ancestor in the pagespace. Users can also type URLs and paths to navigate.
Folder TreeProvides a new version of a tree control, optimized for large pagespaces.
TravelEnables relative navigation through web-style buttons such as Back and Forward.
TitleDisplays the current explorer name and context.
PagespaceDisplays the current branch of the pagespace. Pages can be ordered by different criteria. Users can click a page to navigate to it.

 

Command Controls

Command controls advertise the features and functionality of the Windows Explorer to users. These controls perform either general actions or actions specific to one selected item or items.

Command controlDescription
ToolbarDisplays buttons for commonly used commands (a new version of a command toolbar). Customization options include drop-down buttons, split buttons, optional descriptive text, and an overflow area.
HeroAppears as a single, optional, custom control in the center of the toolbar. It represents the primary command for the current context.
Menu BarPresents commands through menus.
Context MenuLists a contextually relevant subset of available commands that are displayed as a result of right-clicking an item.

 

Property and Preview Controls

Property and preview controls are used to preview items, and to view and edit item properties.

ControlDescription
PreviewDisplays a preview of the selected item, such as a thumbnail or a Live Icon.
PropertiesDisplays properties of the selected item. For multiple selections, it displays a summary of properties for the selected group of items. For a null selection, it displays a summary of properties for the current page (contents of the listview).

 

Filtering and View Controls

Filtering and view controls are used to manipulate the set of items in the listview and to change the presentation of items in the listview.

ControlDescription
FilterFilters or arranges items in a listview based on properties listed as columns. Clicking on a column sorts by that property.
WordwheelDynamically and incrementally filters the displayed items in a listview based on an input text string.
ViewEnables the user to change the view mode of a listview control. A slider can be used to determine icon size.

 

Listview Control

The listview control is used to view a set of items in one of four view modes: details, tiles, icons, or panorama. The listview control also enables the user to select and activate one or more items.

Caution  Although some of these controls have names and/or functionality that is similar to standard Windows Presentation Foundation (WPF) controls found in the System.Windows.Controls namespace, they are distinct classes.

These separate controls work together largely through events generated either by user interaction or by the controls themselves. The following table shows the three primary event categories.

Event categoryExample
NavigationGoing from one page to another.
SelectionChanging the current selection in the listview.
View ChangeChanging the presentation order or view mode in the listview.

 

 

 

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