Question

请高手指导如何在MFC里面用滑块控件调节播放器音量？？

Answer 1

用mixerGetControlDetails / mixerSetControlDetails 来获取或修改设置
http://www.codeproject.com/audio/mixerSetControlDetails.asp

// #include <mmsystem.h>
// link with winmm.lib

MMRESULT rc; // Return code.
HMIXER hMixer; // Mixer handle used in mixer API calls.
MIXERCONTROL mxc; // Holds the mixer control data.
MIXERLINE mxl; // Holds the mixer line data.
MIXERLINECONTROLS mxlc; // Obtains the mixer control.

// 打开mixer. 单声卡的deviceID为0.
rc = mixerOpen(&hMixer, 0,0,0,0);
if (MMSYSERR_NOERROR != rc) {
// Couldn't open the mixer.
}

// 初始化MIXERLINE结构体.
ZeroMemory(&mxl,sizeof(mxl));
mxl.cbStruct = sizeof(mxl);

// 指出需要获取的通道，扬声器用MIXERLINE_COMPONENTTYPE_DST_SPEAKERS
mxl.dwComponentType = MIXERLINE_COMPONENTTYPE_DST_SPEAKERS;

rc = mixerGetLineInfo((HMIXEROBJ)hMixer, &mxl,
MIXER_GETLINEINFOF_COMPONENTTYPE);
if (MMSYSERR_NOERROR == rc) {
// Couldn't get the mixer line.
}

// 取得控制器.
ZeroMemory(&mxlc, sizeof(mxlc));
mxlc.cbStruct = sizeof(mxlc);
mxlc.dwLineID = mxl.dwLineID;
mxlc.dwControlType = MIXERCONTROL_CONTROLTYPE_VOLUME;
mxlc.cControls = 1;
mxlc.cbmxctrl = sizeof(mxc);
mxlc.pamxctrl = &mxc;
ZeroMemory(&mxc, sizeof(mxc));
mxc.cbStruct = sizeof(mxc);
rc = mixerGetLineControls((HMIXEROBJ)hMixer,&mxlc,
MIXER_GETLINECONTROLSF_ONEBYTYPE);
if (MMSYSERR_NOERROR != rc) {
// Couldn't get the control.
}

// 获取控制器中的值的音量范围：mxc.Bounds.lMinimum到mxc.Bounds.lMaximum.

MIXERCONTROLDETAILS mxcd; // Gets the control values.
MIXERCONTROLDETAILS_SIGNED volStruct; // Gets the control values.
long volume; // Holds the final volume value.

// 初始化MIXERCONTROLDETAILS结构体
ZeroMemory(&mxcd, sizeof(mxcd));
mxcd.cbStruct = sizeof(mxcd);
mxcd.cbDetails = sizeof(volStruct);
mxcd.dwControlID = mxc.dwControlID;
mxcd.paDetails = &volStruct;
mxcd.cChannels = 1;

// 获得音量值
rc = mixerGetControlDetails((HMIXEROBJ)hMixer, &mxcd,
MIXER_GETCONTROLDETAILSF_VALUE);
if (MMSYSERR_NOERROR == rc) {
// Couldn't get the current volume.
}
volume = volStruct.lValue;

volStruct.lValue = 25000; //想要设置的值
rc = mixerSetControlDetails((HMIXEROBJ)hMixer, &mxcd,
MIXER_SETCONTROLDETAILSF_VALUE);