激战2直伤死灵:XButtonXP

Introduction

Looking around for a theme-aware toggle button that could display text and an icon, I could not find one, so XButtonXP is the result: a pushbutton that can also be a toggle button, and can display icon and/or text.

What's New in v1.3

In this version I have corrected (I believe) all the outstanding bugs that have been reported (see list), and added several new features:

• Grayscale icons - in previous version, icon on disabled button looked like this:

  

  In this version they look like:

  

• Transparent background for toolbar style - the parent's background is shown when mouse is not hovering:

  No hover
  Hover
  

• Multi-line text buttons - buttons with multiple lines of text are now supported using standard style BS_MULTILINE:

  

• Custom text and background colors - custom colors may now be used for button text and background colors:

  

XButtonXP in Action

Here is what XButtonXP looks like with themes: Icon on Left
Icon on Right
No Icon
No Text
Toggled
Disabled

And here is what XButtonXP looks like without themes: Icon on Left
Icon on Right
No Icon
No Text
Toggled
Disabled

XButtonXP can also be drawn using toolbar style: No Hover
Hover

CXButtonXP Implementation Notes

Theme Support

Normally, when you add manifest file to exe, all controls used by exe will be displayed as themed. However, this is not true of ownerdraw controls - the XP theming engine just ignores them. Since I needed an ownerdraw button, it meant that XButtonXP had to handle the XP theming support. I created the CXThemeHelper class to handle loading UXTHEME.DLL and getting theme function pointers via GetProcAddress(). To make CXThemeHelper lightweight and easy to reuse, I designed it as singleton class, so that there is only one copy of DLL's module handle and function pointers per process.

The first time that CXButtonXP::DrawItem() is called, the theme is opened for Button class:

Collapse | Copy Code

    if (ThemeHelper.IsThemeLibAvailable())    {        m_hTheme = ThemeHelper.OpenThemeData(m_hWnd, _T("Button"));    }

Aside from using theme functions for drawing the controls, one other thing CXButtonXP must do is handle WM_THEMECHANGED message, which is broadcast to every window following a theme change event:

Collapse | Copy Code

case WM_THEMECHANGED:{    if (IsThemed())    {        if (m_hTheme)        {            // when user changes themes, close current theme and re-open            ThemeHelper.CloseThemeData(m_hTheme);            m_hTheme = NULL;            m_bFirstTime = TRUE;        }    }}

CXThemeHelper API

The CXThemeHelper API includes:

• BOOL IsAppThemed()
• BOOL IsThemeActive()
• BOOL IsThemeLibAvailable()
• BOOL CloseThemeData(HTHEME hTheme)
• BOOL DrawThemeBackground()
• BOOL DrawThemeParentBackground()
• BOOL DrawThemeText()
• BOOL GetThemeBackgroundContentRect()
• HTHEME OpenThemeData()

Controlling XButtonXP Theming

CXButtonXP will use themes to draw button in the following circumstances:

1. The app is running on XP
2. Themes are enabled on system, and app has not been set to "Disable visual themes" via Properties dialog:

   

3. Themes have not been disabled via CXButtonXP::EnableTheming() function.

CXButtonXP Starting Point

I used Ewan Ward's article Native Win32 Theme aware Owner-draw Controls without MFC as starting point for XButtonXP. First, I adapted his code for MFC, and then used CXThemeHelper to enable theme support. The next step was to fix default button problem.

Default Button Problem

This problem plagues all ownerdraw buttons. Left uncorrected, it can give the visual appearance that there are multiple default buttons on dialog, and improperly handles ENTER key. Fortunately, Paolo Messina describes this problem in detail, and has written very nice class to transparently fix this problem for any ownerdraw button.

Keyboard Input

The final task was to ensure that SPACE and ENTER keys worked properly. On standard pushbutton, these keys produce button-click event. In order for XButtonXP to handle them in same way, I had to intercept WM_GETDLGCODE message, and ask for all keys. At the same time, I did not want to interfere with TAB key processing. The WM_GETDLGCODE message provides mechanism to do this, by returning appropriate code. Then, I added handlers for WM_KEYDOWN and WM_KEYUP, to catch ENTER and SPACE key presses. I converted these to WM_LBUTTONDOWN and WM_LBUTTONUP messages, to emulate mouse click.

CXButtonXP Functions

Here are functions in CXButtonXP:

FunctionDescriptionCXButtonXP& EnableTheming(BOOL bEnable)Enable visual themes for button.COLORREF GetBackgroundColor()Retrieve button custom background color (XBUTTONXP_NO_COLOR if none).BOOL GetDrawToolbar()Get toolbar style (TRUE = use toolbar style).COLORREF GetTextColor()Retrieve button custom text color (XBUTTONXP_NO_COLOR if none).BOOL GetToggle()Get toggle style (TRUE = button acts like toggle).BOOL GetToggleState()Get toggle state (TRUE = button is pressed).BOOL IsThemed()Get theming state (TRUE = visual theme is being used).CXButtonXP& SetBackgroundColor(COLORREF rgb = XBUTTONXP_NO_COLOR)Set button custom background color. Default is XBUTTONXP_NO_COLOR.CXButtonXP& SetDrawToolbar(BOOL bDrawToolbar)Set toolbar style. Default is FALSE.CXButtonXP& SetIcon(UINT nIDResource, ICON_ALIGNMENT ia = LEFT)Set icon from resource id.CXButtonXP& SetIcon(HICON hIcon, ICON_ALIGNMENT ia = LEFT)Set icon from HICON.CXButtonXP& SetIconAlignment(ICON_ALIGNMENT ia)Set icon alignment on button. Default is LEFT.CXButtonXP& SetTextColor(COLORREF rgb = XBUTTONXP_NO_COLOR)Set button custom text color. Default is XBUTTONXP_NO_COLOR.CXButtonXP& SetToggle(BOOL bIsToggle)Set toggle style. Default is FALSE.CXButtonXP& SetToggleState(BOOL bToggled)Set toggle state. Default is FALSE.

How to use

To integrate CXButtonXP into your app, you first need to add following files to your project:

• XButtonXP.cpp
• XButtonXP.h
• XThemeHelper.cpp
• XThemeHelper.h
• OddButton.cpp
• OddButton.h
• CreateGrayscaleIcon.h

Next, include header file XButtonXP.h in appropriate project files (typically the dialog header file). Now you are ready to start using CXButtonXP.

The demo app shows how to call XButtonXP:

Collapse | Copy Code

    m_XButtonXP.SetIcon(IDI_MFC, CXButtonXP::LEFT);

You can combine XButtonXP function calls like this:

Collapse | Copy Code

    m_XButtonXP.SetIcon(IDI_MFC, CXButtonXP::LEFT)               .SetToggle(FALSE)               .EnableTheming(TRUE)               .SetDrawToolbar(FALSE);

Tips & Tricks

1. The button must not have BS_OWNERDRAW property in dialog template.
2. When you include XButtonXP in your app, you might get error message about the symbol DFCS_HOT, even though you have installed Platform SDK. To fix this, you need to put this line in stdafx.h, before any includes: Collapse | Copy Code

   #define WINVER 0x0500

3. The compiler error message fatal error C1083: Cannot open include file: 'uxtheme.h': No such file or directory means that compiler cannot find uxtheme.h, which is in Microsoft Platform SDK. This is free download from Microsoft site. I would give url here, but Microsoft keeps changing download page for Platform SDK, so best thing is to google for it.
4. When custom colors are used for text or background, theming is automatically switched off.

Acknowledgments

• XButtonXP code is based partially on Ewan Ward's article Native Win32 Theme aware Owner-draw Controls without MFC.
• Thanks to Paolo Messina for his COddButton class.