How to enable desktop toast notifications through an AppUserModelID

Artigo
04/30/2018

This topic shows you how to create a shortcut for your app, assign it an AppUserModelID, and install it in the Start screen. We strongly recommend that you do this in the Windows Installer rather than in your app's code. Without a valid shortcut installed in the Start screen or in All Programs, you cannot raise a toast notification from a desktop app.

Note The example methods used in this topic are taken from the Desktop toast sample.

What you need to know

Technologies

Prerequisites

Libraries
- C++: Runtime.object.lib
- C#: Windows.Winmd
C#: Windows API Code Pack for Microsoft .NET Framework
A version of Microsoft Visual Studio that supports at least Windows 8

Instructions

Step 1: Prepare the shortcut to be created

This example first determines the path of the user's app data folder through the GetEnvironmentVariable function. It then composes the full path to the shortcut, determines that a shortcut of that name does not already exist at that location, and passes that information to another method which creates and installs the shortcut.

Note that the shortcut can be deployed per-user or per-app.


HRESULT DesktopToastsApp::TryCreateShortcut()
{
    wchar_t shortcutPath[MAX_PATH];
    DWORD charWritten = GetEnvironmentVariable(L"APPDATA", shortcutPath, MAX_PATH);
    HRESULT hr = charWritten > 0 ? S_OK : E_INVALIDARG;

    if (SUCCEEDED(hr))
    {
        errno_t concatError = wcscat_s(shortcutPath, ARRAYSIZE(shortcutPath), L"\\Microsoft\\Windows\\Start Menu\\Programs\\Desktop Toasts App.lnk");
 
        hr = concatError == 0 ? S_OK : E_INVALIDARG;
        if (SUCCEEDED(hr))
        {
            DWORD attributes = GetFileAttributes(shortcutPath);
            bool fileExists = attributes < 0xFFFFFFF;

            if (!fileExists)
            {
                hr = InstallShortcut(shortcutPath);  // See step 2.
            }
            else
            {
                hr = S_FALSE;
            }
        }
    }
    return hr;
}

Step 2: Create the shortcut and install it in the Start screen

This example also retrieves the shortcut's property store and sets the required System.AppUserModel.ID property from a previously defined variable, AppID.


HRESULT DesktopToastsApp::InstallShortcut(_In_z_ wchar_t *shortcutPath)
{
    wchar_t exePath[MAX_PATH];
    
    DWORD charWritten = GetModuleFileNameEx(GetCurrentProcess(), nullptr, exePath, ARRAYSIZE(exePath));

    HRESULT hr = charWritten > 0 ? S_OK : E_FAIL;
    
    if (SUCCEEDED(hr))
    {
        ComPtr<IShellLink> shellLink;
        hr = CoCreateInstance(CLSID_ShellLink, nullptr, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&shellLink));

        if (SUCCEEDED(hr))
        {
            hr = shellLink->SetPath(exePath);
            if (SUCCEEDED(hr))
            {
                hr = shellLink->SetArguments(L"");
                if (SUCCEEDED(hr))
                {
                    ComPtr<IPropertyStore> propertyStore;

                    hr = shellLink.As(&propertyStore);
                    if (SUCCEEDED(hr))
                    {
                        PROPVARIANT appIdPropVar;
                        hr = InitPropVariantFromString(AppId, &appIdPropVar);
                        if (SUCCEEDED(hr))
                        {
                            hr = propertyStore->SetValue(PKEY_AppUserModel_ID, appIdPropVar);
                            if (SUCCEEDED(hr))
                            {
                                hr = propertyStore->Commit();
                                if (SUCCEEDED(hr))
                                {
                                    ComPtr<IPersistFile> persistFile;
                                    hr = shellLink.As(&persistFile);
                                    if (SUCCEEDED(hr))
                                    {
                                        hr = persistFile->Save(shortcutPath, TRUE);
                                    }
                                }
                            }
                            PropVariantClear(&appIdPropVar);
                        }
                    }
                }
            }
        }
    }
    return hr;
}

Remarks

As an alternative to the approach shown in this topic, you can use a framework such as the Windows Installer XML (WiX) to generate the shortcut and deploy it as part of the Windows Installer. In that case, this code should be included in the MSI rather than in the app's code. For more information, see the sample WiX configuration file included with the Sending toast notifications from desktop apps sample.

Quickstart: Sending a toast notification from the desktop

Sending toast notifications from desktop apps sample

Application User Model IDs (AppUserModelIDs)

How to: Install the Windows Installer XML (WiX) Tools

Sending toast notifications from desktop apps sample

Toast notifications sample

Toast XML schema

Toast notification overview

Quickstart: Sending a toast notification

Quickstart: Sending a toast push notification

Guidelines and checklist for toast notifications

How to add images to a toast template