我想更改程序的音量(而不是主音量).我现在有以下代码：
DllImport("winmm.dll")]
public static extern int waveOutGetVolume(IntPtr hwo,out uint dwVolume);
[DllImport("winmm.dll")]
public static extern int waveOutSetVolume(IntPtr hwo,uint dwVolume);
private void volumeBar_Scroll(object sender,EventArgs e)
{
// Calculate the volume that's being set
int NewVolume = ((ushort.MaxValue / 10) * volumeBar.Value);
// Set the same volume for both the left and the right channels
uint NewVolumeAllChannels = (((uint)NewVolume & 0x0000ffff) | ((uint)NewVolume << 16));
// Set the volume
waveOutSetVolume(IntPtr.Zero,NewVolumeAllChannels);
}
这仅适用于Win XP,而不适用于Windows 7(也可能不适用于Vista).我没有找到任何会在Win 7上实现相同的脚本,只是为了更改主卷(我不会追求).
解决方法
你的代码对我来说没问题(通过几个调整).这是在Windows 7 x64上运行的非常简单的WPF测试应用程序的代码：
XAML
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid>
<Slider Minimum="0" Maximum="10" ValueChanged="ValueChanged"/>
</Grid>
</Window>
C#
public partial class MainWindow
{
public MainWindow()
{
InitializeComponent();
}
private void ValueChanged(object sender,RoutedPropertyChangedEventArgs<double> e)
{
// Calculate the volume that's being set
double newVolume = ushort.MaxValue * e.NewValue / 10.0;
uint v = ((uint) newVolume) & 0xffff;
uint vAll = v | (v << 16);
// Set the volume
int retVal = NativeMethods.WaveOutSetVolume(IntPtr.Zero,vAll);
Debug.WriteLine(retVal);
bool playRetVal = NativeMethods.PlaySound("tada.wav",IntPtr.Zero,0x2001);
Debug.WriteLine(playRetVal);
}
}
static class NativeMethods
{
[DllImport("winmm.dll",EntryPoint = "waveOutSetVolume")]
public static extern int WaveOutSetVolume(IntPtr hwo,uint dwVolume);
[DllImport("winmm.dll",SetLastError = true)]
public static extern bool PlaySound(string pszSound,IntPtr hmod,uint fdwSound);
}
当我启动应用程序并移动滑块时,“音量混合器”中会出现一个额外的音量控制,它与滑块同步地从最小值移动到最大值.
您应该检查waveOutSetVolume的返回值.如果您的代码仍无效,它可能会为您提供线索.
