我已经思考了几天,但我认为我缺乏一些关于Windows和WPF内部工作的基本理解来解决这个问题。
问题在于:
我创建了一个窗口,应该让我在Aero标题栏上绘制wpf控件(就像office一样)。只要我不向窗口添加Hwndhost元素,它就可以正常工作。但是,一旦我添加了Hwndhost元素,每当我调整大小时,框架和HwndHost就会开始闪烁得非常厉害(其他元素似乎可以正确呈现)。我还尝试使用来自WPF Shell Integration library的自定义框架窗口实现,结果是相同的,所以我认为这不完全是我的错。
以下代码是一个简单的可编译程序,可重现此问题。示例使用c#编写,但答案不必如此。
using System;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Interop;
using System.Windows.Media;
using System.Windows.Threading;
namespace DwmTest {
class Program {
[STAThread]
static void Main( ) {
var w = new CustomFrameWindow{ Content = new WindowHost() };
w.Show( );
((Border)VisualTreeHelper.GetChild( w, 0 )).Margin = new Thickness( 11, 33, 11, 11 );
Dispatcher.Run( );
}
}
public class CustomFrameWindow : Window {
const int resizeFrameWidth = 11;
const int captionHeight = 33;
public enum HT { CLIENT = 1, CAPTION = 2, LEFT = 10, RIGHT, TOP, TOPLEFT, TOPRIGHT, BOTTOM, BOTTOMLEFT, BOTTOMRIGHT }
[StructLayout( LayoutKind.Sequential )]
public struct Margins { public int left, right, top, bottom; }
[DllImport( "user32.dll" )]
public static extern bool SetWindowPos( IntPtr hWnd, IntPtr hWndInsertAfter, int x, int y, int cx, int cy, int flags );
[DllImport( "dwmapi.dll" )]
public static extern bool DwmDefWindowProc( IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, out IntPtr result );
[DllImport( "dwmapi.dll", PreserveSig = false )]
public static extern void DwmExtendFrameIntoClientArea( IntPtr hwnd, ref Margins pMarInset );
protected override void OnSourceInitialized( EventArgs e ) {
base.OnSourceInitialized( e );
var hWndSource = HwndSource.FromHwnd( new WindowInteropHelper( this ).Handle );
hWndSource.CompositionTarget.BackgroundColor = Colors.Transparent;
var nonClientArea = new Margins{
left = resizeFrameWidth, top = captionHeight, bottom = resizeFrameWidth, right = resizeFrameWidth
};
DwmExtendFrameIntoClientArea( hWndSource.Handle, ref nonClientArea );
hWndSource.AddHook( WndProc );
// FRAMECHANGED | NOMOVE | NOSIZE
SetWindowPos( hWndSource.Handle, new IntPtr( ), 0, 0, 0, 0, 0x0020 | 0x0002 | 0x0001 );
}
private IntPtr WndProc( IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled ) {
switch( msg ) {
case 0x0083: // NCCALCSIZE
if( wParam != IntPtr.Zero ) handled = true;
break;
case 0x0084: // NCHITTEST
handled = true;
IntPtr dwmHitTest;
if( DwmDefWindowProc( hwnd, msg, wParam, lParam, out dwmHitTest ) ) {
return dwmHitTest;
}
var mousePosition = PointFromScreen( new Point( lParam.ToInt32( ) & 0xFFFF, lParam.ToInt32( ) >> 16 ) );
var isTop = mousePosition.Y <= resizeFrameWidth;
var isBottom = mousePosition.Y >= ActualHeight - resizeFrameWidth;
var isLeft = mousePosition.X <= resizeFrameWidth;
var isRight = mousePosition.X >= ActualWidth - resizeFrameWidth;
var hitTest = HT.CLIENT;
if( isTop ) {
if( isLeft ) hitTest = HT.TOPLEFT;
else if( isRight ) hitTest = HT.TOPRIGHT;
else hitTest = HT.TOP;
}
else if( isBottom ) {
if( isLeft ) hitTest = HT.BOTTOMLEFT;
else if( isRight ) hitTest = HT.BOTTOMRIGHT;
else hitTest = HT.BOTTOM;
}
else if( isLeft ) hitTest = HT.LEFT;
else if( isRight ) hitTest = HT.RIGHT;
else if( mousePosition.Y <= captionHeight ) hitTest = HT.CAPTION;
return new IntPtr( (int)hitTest );
}
return IntPtr.Zero;
}
}
public class WindowHost : HwndHost {
[DllImport( "user32.dll", SetLastError = true )]
static extern IntPtr CreateWindowEx( IntPtr exStyle, string lpClassName,string lpWindowName,int dwStyle,int x,int y,int nWidth,int nHeight,IntPtr hWndParent,IntPtr hMenu,IntPtr hInstance,IntPtr lpParam );
protected override HandleRef BuildWindowCore( HandleRef hWndParent ) {
return new HandleRef( this, CreateWindowEx( IntPtr.Zero, "static", "", 0x40000000, 0, 0, 200, 200, hWndParent.Handle, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero ) );
}
protected override void DestroyWindowCore( HandleRef hwnd ) { }
}
}