问题
Is it possible to change the location of the Arrow / Stem in a Balloon Tooltip? Reason to change is because of a Button, located in the top of the screen, should have a tooltip below it.
broken image link removed
Above is the situation right now, I only need the arrow to be on the top-left side of the balloon.
回答1:
You do not need to do anything special as the placement is automatic according to MSDN. Do have you an issue with ballon tooltip ?
回答2:
I used InteropServices to call several User32.dll methods (CreateWindowEx, DestroyWindow, SetWindowPos and SendMessage) to use native Win32 tooltips instead of the WinForms-provided wrapper.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Drawing;
using System.ComponentModel;
/// <remarks>This classes implements the balloon tooltip.
/// http://stackoverflow.com/questions/2028466
/// I hated Microsoft WinForms QA department after I had to develop my own version of the tooltip class,
/// just to workaround a bug, that would only add ~5 lines of code into the system.windows.forms.dll when fixed properly.</remarks>
class BalloonToolTip : IDisposable
{
#region Unmanaged shit
[DllImport( "user32.dll" )]
static extern IntPtr CreateWindowEx( int exstyle, string classname, string windowtitle,
int style, int x, int y, int width, int height, IntPtr parent,
int menu, int nullvalue, int nullptr );
[DllImport( "user32.dll" )]
static extern int DestroyWindow( IntPtr hwnd );
[DllImport( "user32.dll" )]
static extern bool SetWindowPos( IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, int uFlags );
[DllImport( "user32.dll" )]
static extern int SendMessage( IntPtr hWnd, int Msg, int wParam, IntPtr lParam );
const int WS_POPUP = unchecked( (int)0x80000000 );
const int TTS_BALLOON = 0x40;
const int TTS_NOPREFIX = 0x02;
const int TTS_ALWAYSTIP = 0x01;
const int CW_USEDEFAULT = unchecked( (int)0x80000000 );
const int WM_USER = 0x0400;
IntPtr HWND_TOPMOST = new IntPtr( -1 );
const int SWP_NOSIZE = 0x0001;
const int SWP_NOMOVE = 0x0002;
const int SWP_NOACTIVATE = 0x0010;
const int WS_EX_TOPMOST = 0x00000008;
[StructLayout( LayoutKind.Sequential )]
public struct TOOLINFO
{
public int cbSize;
public int uFlags;
public IntPtr hwnd;
public IntPtr id;
private RECT m_rect;
public IntPtr nullvalue;
[MarshalAs( UnmanagedType.LPTStr )]
public string text;
public uint param;
public Rectangle rect
{
get
{
return new Rectangle( m_rect.left, m_rect.top, m_rect.right - m_rect.left, m_rect.bottom - m_rect.top );
}
set
{
m_rect.left = value.Left;
m_rect.top = value.Top;
m_rect.right = value.Right;
m_rect.bottom = value.Bottom;
}
}
}
[StructLayout( LayoutKind.Sequential )]
struct RECT
{
public int left;
public int top;
public int right;
public int bottom;
}
const int TTF_TRANSPARENT = 0x0100;
const int TTF_TRACK = 0x0020;
const int TTF_ABSOLUTE = 0x0080;
#endregion
#region Managed wrapper over some tooltip messages.
// The most useful part of the wrappers in this section is their documentation.
/// <summary>Send TTM_SETTITLE message to the tooltip.
/// TODO [very low]: implement the custom icon, if needed. </summary>
/// <param name="_wndTooltip">HWND of the tooltip</param>
/// <param name="_icon">Standard icon</param>
/// <param name="_title">The title string</param>
internal static int SetTitle( IntPtr _wndTooltip, ToolTipIcon _icon, string _title )
{
const int TTM_SETTITLE = WM_USER + 33;
var tempptr = IntPtr.Zero;
try
{
tempptr = Marshal.StringToHGlobalUni( _title );
return SendMessage( _wndTooltip, TTM_SETTITLE, (int)_icon, tempptr );
}
finally
{
if( IntPtr.Zero != tempptr )
{
Marshal.FreeHGlobal( tempptr );
tempptr = IntPtr.Zero;
}
}
}
/// <summary>Send a message that wants LPTOOLINFO as the lParam</summary>
/// <param name="_wndTooltip">HWND of the tooltip.</param>
/// <param name="_msg">window message to send</param>
/// <param name="_wParam">wParam value</param>
/// <param name="_ti">TOOLINFO structure that goes to the lParam field. The cbSize field must be set.</param>
internal static int SendToolInfoMessage( IntPtr _wndTooltip, int _msg, int _wParam, TOOLINFO _ti )
{
var tempptr = IntPtr.Zero;
try
{
tempptr = Marshal.AllocHGlobal( _ti.cbSize );
Marshal.StructureToPtr( _ti, tempptr, false );
return SendMessage( _wndTooltip, _msg, _wParam, tempptr );
}
finally
{
if( IntPtr.Zero != tempptr )
{
Marshal.FreeHGlobal( tempptr );
tempptr = IntPtr.Zero;
}
}
}
/// <summary>Registers a tool with a ToolTip control</summary>
/// <param name="_wndTooltip">HWND of the tooltip</param>
/// <param name="_ti">TOOLINFO structure containing information that the ToolTip control needs to display text for the tool.</param>
/// <returns>Returns true if successful.</returns>
internal static bool AddTool( IntPtr _wndTooltip, TOOLINFO _ti )
{
const int TTM_ADDTOOL = WM_USER + 50;
int res = SendToolInfoMessage( _wndTooltip, TTM_ADDTOOL, 0, _ti );
return Convert.ToBoolean( res );
}
/// <summary>Registers a tool with a ToolTip control</summary>
/// <param name="_wndTooltip">HWND of the tooltip</param>
/// <param name="_ti">TOOLINFO structure containing information that the ToolTip control needs to display text for the tool.</param>
internal static void DelTool( IntPtr _wndTooltip, TOOLINFO _ti )
{
const int TTM_DELTOOL = WM_USER + 51;
SendToolInfoMessage( _wndTooltip, TTM_DELTOOL, 0, _ti );
}
internal static void UpdateTipText( IntPtr _wndTooltip, TOOLINFO _ti )
{
const int TTM_UPDATETIPTEXT = WM_USER + 57;
SendToolInfoMessage( _wndTooltip, TTM_UPDATETIPTEXT, 0, _ti );
}
/// <summary>Activates or deactivates a tracking ToolTip</summary>
/// <param name="_wndTooltip">HWND of the tooltip</param>
/// <param name="bActivate">Value specifying whether tracking is being activated or deactivated</param>
/// <param name="_ti">Pointer to a TOOLINFO structure that identifies the tool to which this message applies</param>
internal static void TrackActivate( IntPtr _wndTooltip, bool bActivate, TOOLINFO _ti )
{
const int TTM_TRACKACTIVATE = WM_USER + 17;
SendToolInfoMessage( _wndTooltip, TTM_TRACKACTIVATE, Convert.ToInt32( bActivate ), _ti );
}
/// <summary>returns (LPARAM) MAKELONG( pt.X, pt.Y )</summary>
internal static IntPtr makeLParam( Point pt )
{
int res = ( pt.X & 0xFFFF );
res |= ( ( pt.Y & 0xFFFF ) << 16 );
return new IntPtr( res );
}
/// <summary>Sets the position of a tracking ToolTip</summary>
/// <param name="_wndTooltip">HWND of the tooltip.</param>
/// <param name="pt">The point at which the tracking ToolTip will be displayed, in screen coordinates.</param>
internal static void TrackPosition( IntPtr _wndTooltip, Point pt )
{
const int TTM_TRACKPOSITION = WM_USER + 18;
SendMessage( _wndTooltip, TTM_TRACKPOSITION, 0, makeLParam( pt ) );
}
/// <summary>Sets the maximum width for a ToolTip window</summary>
/// <param name="_wndTooltip">HWND of the tooltip.</param>
/// <param name="pxWidth">Maximum ToolTip window width, or -1 to allow any width</param>
/// <returns>the previous maximum ToolTip width</returns>
internal static int SetMaxTipWidth( IntPtr _wndTooltip, int pxWidth )
{
const int TTM_SETMAXTIPWIDTH = WM_USER + 24;
return SendMessage( _wndTooltip, TTM_SETMAXTIPWIDTH, 0, new IntPtr( pxWidth ) );
}
#endregion
/// <summary>Sets the information that a ToolTip control maintains for a tool (not currently used).</summary>
/// <param name="act"></param>
internal void AlterToolInfo( Action<TOOLINFO> act )
{
const int TTM_GETTOOLINFO = WM_USER + 53;
const int TTM_SETTOOLINFO = WM_USER + 54;
var tempptr = IntPtr.Zero;
try
{
tempptr = Marshal.AllocHGlobal( m_toolinfo.cbSize );
Marshal.StructureToPtr( m_toolinfo, tempptr, false );
SendMessage( m_wndToolTip, TTM_GETTOOLINFO, 0, tempptr );
m_toolinfo = (TOOLINFO)Marshal.PtrToStructure( tempptr, typeof( TOOLINFO ) );
act( m_toolinfo );
Marshal.StructureToPtr( m_toolinfo, tempptr, false );
SendMessage( m_wndToolTip, TTM_SETTOOLINFO, 0, tempptr );
}
finally
{
Marshal.FreeHGlobal( tempptr );
}
}
readonly Control m_ownerControl;
// The ToolTip's HWND
IntPtr m_wndToolTip = IntPtr.Zero;
/// <summary>The maximum width for a ToolTip window.
/// If a ToolTip string exceeds the maximum width, the control breaks the text into multiple lines.</summary>
int m_pxMaxWidth = 200;
TOOLINFO m_toolinfo = new TOOLINFO();
public BalloonToolTip( Control owner )
{
m_ownerControl = owner;
// See http://msdn.microsoft.com/en-us/library/bb760252(VS.85).aspx#tooltip_sample_rect
m_toolinfo.cbSize = Marshal.SizeOf( typeof( TOOLINFO ) );
m_toolinfo.uFlags = TTF_TRANSPARENT | TTF_TRACK;
m_toolinfo.hwnd = m_ownerControl.Handle;
m_toolinfo.rect = m_ownerControl.Bounds;
}
/// <summary>Throws an exception if there's no alive WIN32 window.</summary>
void VerifyControlIsAlive()
{
if( IntPtr.Zero == m_wndToolTip )
throw new ApplicationException( "The control is not created, or is already destroyed." );
}
/// <summary>Create the balloon window.</summary>
public void Create()
{
if( IntPtr.Zero != m_wndToolTip )
Destroy();
// Create the tooltip control.
m_wndToolTip = CreateWindowEx( WS_EX_TOPMOST, "tooltips_class32",
string.Empty,
WS_POPUP | TTS_BALLOON | TTS_NOPREFIX | TTS_ALWAYSTIP,
CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
m_ownerControl.Handle, 0, 0, 0 );
if( IntPtr.Zero == m_wndToolTip )
throw new Win32Exception();
if( !SetWindowPos( m_wndToolTip, HWND_TOPMOST,
0, 0, 0, 0,
SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE ) )
throw new Win32Exception();
SetMaxTipWidth( m_wndToolTip, m_pxMaxWidth );
}
bool m_bVisible = false;
/// <summary>return true if the balloon is currently visible.</summary>
public bool bVisible
{
get
{
if( IntPtr.Zero == m_wndToolTip )
return false;
return m_bVisible;
}
}
/// <summary>Balloon title.
/// The balloon will only use the new value on the next Show() operation.</summary>
public string strTitle;
/// <summary>Balloon title icon.
/// The balloon will only use the new value on the next Show() operation.</summary>
public ToolTipIcon icon;
/// <summary>Balloon title icon.
/// The new value is updated immediately.</summary>
public string strText
{
get { return m_toolinfo.text; }
set
{
m_toolinfo.text = value;
if( bVisible )
UpdateTipText( m_wndToolTip, m_toolinfo );
}
}
/// <summary>Show the balloon.</summary>
/// <param name="pt">The balloon stem position, in the owner's client coordinates.</param>
public void Show( Point pt )
{
VerifyControlIsAlive();
if( m_bVisible ) Hide();
// http://www.deez.info/sengelha/2008/06/12/balloon-tooltips/
if( !AddTool( m_wndToolTip, m_toolinfo ) )
throw new ApplicationException( "Unable to register the tooltip" );
SetTitle( m_wndToolTip, icon, strTitle );
TrackPosition( m_wndToolTip, m_ownerControl.PointToScreen( pt ) );
TrackActivate( m_wndToolTip, true, m_toolinfo );
m_bVisible = true;
}
/// <summary>Hide the balloon if it's visible.
/// If the balloon was previously hidden, this method does nothing.</summary>
public void Hide()
{
VerifyControlIsAlive();
if( !m_bVisible ) return;
TrackActivate( m_wndToolTip, false, m_toolinfo );
DelTool( m_wndToolTip, m_toolinfo );
m_bVisible = false;
}
/// <summary>Destroy the balloon.</summary>
public void Destroy()
{
if( IntPtr.Zero == m_wndToolTip )
return;
if( m_bVisible ) Hide();
DestroyWindow( m_wndToolTip );
m_wndToolTip = IntPtr.Zero;
}
void IDisposable.Dispose()
{
Destroy();
}
}
Here's my article with the complete source code.
来源：https://stackoverflow.com/questions/2028466/c-set-position-of-the-arrow-in-a-tooltip-balloon