In the Windows XP login screen, the password text box will warn you with a balloon tooltip if you accidentally turn Caps Lock on:
The balloon tooltip appears to be a Windows tooltip common control with the TTS_BALLOON style.
To replicate this functionality, I decided to write a function called ShowMsgBalloon() which, given a control and the various balloon tooltip parameters, creates and shows the balloon tooltip below the control.
The key insight to making ShowMsgBallon() work as intended was to use the TTF_TRACK option to create a tracking tooltip. This will immediately show the tooltip without requiring the user to position the mouse over the control. The main downside to using TTF_TRACK is that the tooltip will not move with the control if the window is moved; you need to manually move the tooltip using TTM_TRACKPOSITION as required. One could probably make this automatic by subclassing the tooltip’s parent control and handling WM_WINDOWPOSCHANGED messages.
Here is the source code to ShowMsgBalloon(). When you are done with the balloon, call DestroyWindow() on the returned HWND. Note: you may want your application to use comctl32.dll version 6 as it will lead to a nicer visual style, including a close button.
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#include <windows.h>
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#include <commctrl.h>
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// Options to ShowMsgBallon() (see dwOpts parameter). These are the
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// standard icon types for balloon tooltips.
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#define SMB_ICON_INFO (1 << 0)
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#define SMB_ICON_WARNING (1 << 1)
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#define SMB_ICON_ERROR (1 << 2)
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// Given the options passed to ShowMsgBalloon(), determine what
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// parameter to send to TTM_SETTITLE for the balloon tooltip’s icon.
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static DWORD
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GetTitleIcon(DWORD dwOpts)
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{
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if (dwOpts & SMB_ICON_INFO)
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return TTI_INFO;
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else if (dwOpts & SMB_ICON_WARNING)
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return TTI_WARNING;
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else if (dwOpts & SMB_ICON_ERROR)
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return TTI_ERROR;
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else
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return 0;
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}
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// Create and show a balloon tooltip immediately below the control
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// hwndCtrl with the given title, message, and options.
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HWND
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ShowMsgBalloon(HWND hwndCtrl, LPCTSTR szTitle, LPCTSTR szMsg,
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DWORD dwOpts)
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{
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HWND hwndRet = NULL;
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HWND hwndTT = NULL;
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TOOLINFO ti = { 0 };
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RECT rc;
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// Even though TTS_CLOSE is always specified, a close button will
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// only be shown if your application has a manifest that requires
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// comctl32.dll version 6.
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hwndTT = CreateWindow
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(
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TOOLTIPS_CLASS,
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TEXT(""),
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WS_POPUP | TTS_NOPREFIX | TTS_BALLOON | TTS_CLOSE,
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CW_USEDEFAULT, CW_USEDEFAULT,
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CW_USEDEFAULT, CW_USEDEFAULT,
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hwndCtrl,
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NULL,
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NULL,
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NULL
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);
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if (hwndTT == NULL)
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goto Cleanup;
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// By using TTTOOLINFO_V1_SIZE rather than sizeof(TOOLINFO),
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// we don’t require users to be using comctl32 version 6.
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ti.cbSize = TTTOOLINFO_V1_SIZE;
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ti.uFlags = TTF_TRACK;
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ti.hwnd = hwndCtrl;
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ti.lpszText = const_cast<LPTSTR>(szMsg);
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if (!SendMessage(hwndTT, TTM_ADDTOOL, 0, (LPARAM) &ti))
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goto Cleanup;
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if (!SendMessage(hwndTT, TTM_SETTITLE, GetTitleIcon(dwOpts),
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(LPARAM) szTitle))
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goto Cleanup;
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// Position the tooltip below the control
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if (!GetWindowRect(hwndCtrl, &rc))
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goto Cleanup;
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SendMessage(hwndTT, TTM_TRACKPOSITION, 0,
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MAKELONG(rc.left + 10, rc.bottom));
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// Show the tooltip
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if (!SendMessage(hwndTT, TTM_TRACKACTIVATE, TRUE, (LPARAM) &ti))
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goto Cleanup;
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hwndRet = hwndTT;
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hwndTT = NULL;
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Cleanup:
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if (hwndTT != NULL)
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::DestroyWindow(hwndTT);
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return hwndRet;
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}
July 21st, 2008 at 2:22 pm
The code worked fine for me, but I am curious to see how I could add a delegate for when the close button is pressed. I can destroy the window arbitrarily, but would like to set my HWND to null if the close button is pushed. Any idea?
July 21st, 2008 at 9:12 pm
Jared,
Perhaps you can subclass the HWND and capture the WM_CLOSE message.