image.png
<!-- 使用音场效果必要的权限 -->
<uses-permission android:name="android.permission.RECORD_AUDIO" />
public class MainActivity extends AppCompatActivity {
// 定义播放声音的MediaPlayer
private MediaPlayer mPlayer;
// 定义系统的示波器
private Visualizer mVisualizer;
// 定义系统的均衡器
private Equalizer mEqualizer;
// 定义系统的重低音控制器
private BassBoost mBass;
// 定义系统的预设音场控制器
private PresetReverb mPresetReverb;
private LinearLayout layout;
private List<Short> reverbNames = new ArrayList<>();
private List<String> reverbVals = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// 设置控制音乐声音
setVolumeControlStream(AudioManager.STREAM_MUSIC);
layout = new LinearLayout(this);
layout.setOrientation(LinearLayout.VERTICAL);
setContentView(layout);
requestPermissions(new String[]{Manifest.permission.RECORD_AUDIO}, 0x123);
}
@Override
public void onRequestPermissionsResult(int requestCode,
@NonNull String[] permissions, @NonNull int[] grantResults) {
if (requestCode == 0x123 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// 创建MediaPlayer对象
mPlayer = MediaPlayer.create(this, R.raw.beautiful);
// 初始化示波器
setupVisualizer();
// 初始化均衡控制器
setupEqualizer();
// 初始化重低音控制器
setupBassBoost();
// 初始化预设音场控制器
setupPresetReverb();
// 开始播放音乐
mPlayer.start();
}
}
private void setupVisualizer() {
// 创建MyVisualizerView组件，用于显示波形图
final MyVisualizerView mVisualizerView = new MyVisualizerView(this);
mVisualizerView.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.
LayoutParams.MATCH_PARENT,
(int) (120f * getResources().getDisplayMetrics().density)));
// 将MyVisualizerView组件添加到layout容器中
layout.addView(mVisualizerView);
// 以MediaPlayer的AudioSessionId创建Visualizer
// 相当于设置Visualizer负责显示该MediaPlayer的音频数据
mVisualizer = new Visualizer(mPlayer.getAudioSessionId());
mVisualizer.setCaptureSize(Visualizer.getCaptureSizeRange()[1]);
// 为mVisualizer设置监听器
mVisualizer.setDataCaptureListener(new Visualizer.OnDataCaptureListener() {
@Override
public void onWaveFormDataCapture(Visualizer visualizer, byte[] waveform, int samplingRate) {
// 用waveform波形数据更新mVisualizerView组件
mVisualizerView.updateVisualizer(waveform);
}
@Override
public void onFftDataCapture(Visualizer visualizer, byte[] fft, int samplingRate) {
}
}, Visualizer.getMaxCaptureRate() / 2, true, false);
mVisualizer.setEnabled(true);
}
// 初始化均衡控制器的方法
private void setupEqualizer() {
// 以MediaPlayer的AudioSessionId创建Equalizer
// 相当于设置Equalizer负责控制该MediaPlayer
mEqualizer = new Equalizer(0, mPlayer.getAudioSessionId());
// 启用均衡控制效果
mEqualizer.setEnabled(true);
TextView eqTitle = new TextView(this);
eqTitle.setText("均衡器：");
layout.addView(eqTitle);
// 获取均衡控制器支持的最小值和最大值
final short minEQLevel = mEqualizer.getBandLevelRange()[0];
short maxEQLevel = mEqualizer.getBandLevelRange()[1];
// 获取均衡控制器支持的所有频率
short brands = mEqualizer.getNumberOfBands();
for (short i = 0; i < brands; i++) {
TextView eqTextView = new TextView(this);
// 创建一个TextView，用于显示频率
eqTextView.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.
LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT));
eqTextView.setGravity(Gravity.CENTER_HORIZONTAL);
// 设置该均衡控制器的频率
eqTextView.setText(mEqualizer.getCenterFreq(i) / 1000 + " Hz");
layout.addView(eqTextView);
// 创建一个水平排列组件的LinearLayout
LinearLayout tmpLayout = new LinearLayout(this);
tmpLayout.setOrientation(LinearLayout.HORIZONTAL);
// 创建显示均衡控制器最小值的TextView
TextView minDbTextView = new TextView(this);
minDbTextView.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.
LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));
// 显示均衡控制器的最小值
minDbTextView.setText(minEQLevel / 100 + " dB");
// 创建显示均衡控制器最大值的TextView
TextView maxDbTextView = new TextView(this);
maxDbTextView.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.
LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));
// 显示均衡控制器的最大值
maxDbTextView.setText(maxEQLevel / 100 + " dB");
LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
layoutParams.weight = 1f;
// 定义SeekBar作为调整工具
SeekBar bar = new SeekBar(this);
bar.setLayoutParams(layoutParams);
bar.setMax(maxEQLevel - minEQLevel);
bar.setProgress(mEqualizer.getBandLevel(i));
final short brand = i;
// 为SeekBar的拖动事件设置事件监听器
bar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
// 设置该频率的均衡值
mEqualizer.setBandLevel(brand, (short) (progress + minEQLevel));
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
});
// 使用水平排列组件的LinearLayout盛装三个组件
tmpLayout.addView(minDbTextView);
tmpLayout.addView(bar);
tmpLayout.addView(maxDbTextView);
// 将水平排列组件的LinearLayout添加到myLayout容器中
layout.addView(tmpLayout);
}
}
// 初始化重低音控制器
private void setupBassBoost() {
// 以MediaPlayer的AudioSessionId创建BassBoost
// 相当于设置BassBoost负责控制该MediaPlayer
mBass = new BassBoost(0, mPlayer.getAudioSessionId());
// 设置启用重低音效果
mBass.setEnabled(true);
TextView bbTitle = new TextView(this);
bbTitle.setText("重低音：");
layout.addView(bbTitle);
// 使用SeekBar作为重低音的调整工具
SeekBar bar = new SeekBar(this);
// 重低音的范围为0~1000
bar.setMax(1000);
bar.setProgress(0);
// 为SeekBar的拖动事件设置事件监听器
bar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
// 设置重低音的强度
mBass.setStrength((short) progress);
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
});
layout.addView(bar);
}
// 初始化预设音场控制器
private void setupPresetReverb() {
// 以MediaPlayer的AudioSessionId创建PresetReverb
// 相当于设置PresetReverb负责控制该MediaPlayer
mPresetReverb = new PresetReverb(0, mPlayer.getAudioSessionId());
// 设置启用预设音场控制
mPresetReverb.setEnabled(true);
TextView prTitle = new TextView(this);
prTitle.setText("音场");
layout.addView(prTitle);
// 获取系统支持的所有预设音场
for (short i = 0; i < mEqualizer.getNumberOfPresets(); i++) {
reverbNames.add(i);
reverbVals.add(mEqualizer.getPresetName(i));
}
// 使用Spinner作为音场选择工具
Spinner sp = new Spinner(this);
sp.setAdapter(new ArrayAdapter<>(MainActivity.this,
android.R.layout.simple_spinner_item, reverbVals));
// 为Spinner的列表项选中事件设置监听器
sp.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
// 设定音场
mEqualizer.usePreset(reverbNames.get(position));
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
layout.addView(sp);
}
@Override
public void onPause() {
super.onPause();
if (isFinishing() && mPlayer != null) {
// 释放所有对象
mVisualizer.release();
mEqualizer.release();
mPresetReverb.release();
mBass.release();
mPlayer.release();
mPlayer = null;
}
}
private static class MyVisualizerView extends View {
// bytes数组保存了波形抽样点的值
private byte[] bytes;
private float[] points;
private Paint paint = new Paint();
private Rect rect = new Rect();
private byte type = 0;
public MyVisualizerView(Context context) {
super(context);
// 设置画笔的属性
paint.setStrokeWidth(1f);
paint.setAntiAlias(true);
paint.setColor(Color.GREEN);
paint.setStyle(Paint.Style.FILL);
}
public void updateVisualizer(byte[] ftt) {
bytes = ftt;
// 通知该组件重绘自己
invalidate();
}
@Override
public boolean onTouchEvent(MotionEvent me) {
// 当用户触碰该组件时，切换波形类型
if (me.getAction() != MotionEvent.ACTION_DOWN) {
return false;
}
type++;
if (type >= 3) {
type = 0;
}
return true;
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (bytes == null) {
return;
}
// 绘制白色背景（主要为了印刷时好看）
canvas.drawColor(Color.WHITE);
// 使用rect对象记录该组件的宽度和高度
rect.set(0, 0, getWidth(), getHeight());
switch (type) {
// -------绘制块状的波形图-------
case 0:
for (int i = 0; i < bytes.length - 1; i++) {
float left = (getWidth() * i / (bytes.length - 1));
// 根据波形值计算该矩形的高度
float top = rect.height() - (byte) (bytes[i + 1] + 128) * rect.height() / 128;
float right = left + 1;
float bottom = rect.height();
canvas.drawRect(left, top, right, bottom, paint);
}
break;
// -------绘制柱状的波形图（每隔18个抽样点绘制一个矩形）-------
case 1:
for (int i = 0; i < bytes.length - 1; i += 18) {
float left = rect.width() * i / (bytes.length - 1);
// 根据波形值计算该矩形的高度
float top = rect.height() - (byte) (bytes[i + 1] + 128)
* rect.height() / 128;
float right = left + 6;
float bottom = rect.height();
canvas.drawRect(left, top, right, bottom, paint);
i += 18;
}
break;
// -------绘制曲线波形图-------
case 2:
// 如果points数组还未初始化
if (points == null || points.length < bytes.length * 4) {
points = new float[bytes.length * 4];
}
for (int i = 0; i < bytes.length - 1; i++) {
// 计算第i个点的x坐标
points[i * 4] = rect.width() * i / (bytes.length - 1);
// 根据bytes[i]的值（波形点的值）计算第i个点的y坐标
points[i * 4 + 1] = (rect.height() / 2)
+ ((byte) (bytes[i] + 128)) * 128
/ (rect.height() / 2);
// 计算第i+1个点的x坐标
points[i * 4 + 2] = rect.width() * (i + 1)
/ (bytes.length - 1);
// 根据bytes[i+1]的值（波形点的值）计算第i+1个点的y坐标
points[i * 4 + 3] = (rect.height() / 2)
+ ((byte) (bytes[i + 1] + 128)) * 128
/ (rect.height() / 2);
}
// 绘制波形曲线
canvas.drawLines(points, paint);
break;
}
}
}
}
image.png
摘抄至《疯狂Android讲义（第4版）》
网友评论