我们常用的语音输入法会根据我们说话的大小产生一些波动动画，那么这个动画是怎么实现的呢？其实很简单。原理：一张空的麦克风图像，一张满的麦克风图像，先绘制一张空的，然后再绘制一些满的，但是满的绘制之前，有一个圆形的clip区域，这个区域就是用来显示满的显示多少。另外有点注意，有些手机要打开软件加速，不然clip区域显示的是方形的而不是圆形的，看起来的效果就悲剧了。

图片资源我用的是讯飞的图片，

这张是背景图，.9格式的。

看源码:

package com.voice.bdv;

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Paint;

import android.graphics.PaintFlagsDrawFilter;

import android.graphics.Path;

import android.graphics.Rect;

import android.graphics.drawable.Drawable;

import android.util.AttributeSet;

import android.view.View;

public class ClipCircleView extends View {

private Drawable empty;

private Drawable full;

Path path;

PaintFlagsDrawFilter filter;

public ClipCircleView(Context paramContext, AttributeSet attrs) {

super(paramContext, attrs);

setLayerType(View.LAYER_TYPE_SOFTWARE, null);// 软件加速

}

public void init() {

try {

empty = MainActivity.getDrawable(getContext(), "voice_empty.png");

full = MainActivity.getDrawable(getContext(), "voice_full.png");

this.empty.setBounds(new Rect(-this.empty.getIntrinsicWidth() / 2,

-this.empty.getIntrinsicHeight() / 2, this.empty

.getIntrinsicWidth() / 2, this.empty

.getIntrinsicHeight() / 2));

this.full.setBounds(new Rect(-this.full.getIntrinsicWidth() / 2,

-this.full.getIntrinsicHeight() / 2, this.full

.getIntrinsicWidth() / 2, this.full

.getIntrinsicHeight() / 2));

filter = new PaintFlagsDrawFilter(Paint.ANTI_ALIAS_FLAG,

Paint.FILTER_BITMAP_FLAG);

path = new Path();

initPath(0);

} catch (Exception localException) {

localException.printStackTrace();

}

}

public void initPath(int paramInt) {

this.path.reset();

this.path.addCircle(0.0F, 0.0F, this.empty.getIntrinsicWidth()

* paramInt / 12, Path.Direction.CCW);

}

public void onDraw(Canvas paramCanvas) {

paramCanvas.save();

paramCanvas.setDrawFilter(filter);

paramCanvas.translate(getWidth() / 2, getHeight() / 2);

if (empty != null)

empty.draw(paramCanvas);

if (path != null)

paramCanvas.clipPath(path);

if (full != null)

full.draw(paramCanvas);

paramCanvas.restore();

}

public void finalize() throws Throwable {

this.empty = null;

this.full = null;

super.finalize();

}

protected void onMeasure(int paramInt1, int paramInt2) {

super.onMeasure(paramInt1, paramInt2);

int i = View.MeasureSpec.getSize(paramInt1);

int j = View.MeasureSpec.getSize(paramInt2);

Drawable localDrawable = getBackground();

if (localDrawable != null) {

i = localDrawable.getMinimumWidth();

j = localDrawable.getMinimumHeight();

}

setMeasuredDimension(resolveSize(i, paramInt1),

resolveSize(j, paramInt2));

}

}

以上是控件的源码，图片加载方法：

public static Bitmap getDrawable(Resources res, TypedValue value,

InputStream stream, Rect rect, BitmapFactory.Options options) {

if (options == null)

options = new BitmapFactory.Options();

if ((options.inDensity == 0) && (value != null)) {

int i = value.density;

if (i == 0)

options.inDensity = 160;

else if (i != 65535)

options.inDensity = i;

}

if ((options.inTargetDensity == 0) && (res != null))

options.inTargetDensity = res.getDisplayMetrics().densityDpi;

return BitmapFactory.decodeStream(stream, rect, options);

}

private static Drawable getDrawable(Resources res, Bitmap bitmap,

byte[] paramArrayOfByte, Rect rect, String path) {

if (paramArrayOfByte != null)

return new NinePatchDrawable(res, bitmap, paramArrayOfByte, rect,

path);

return new BitmapDrawable(res, bitmap);

}

public static Drawable getDrawable(Resources res, TypedValue value,

InputStream stream, String path, BitmapFactory.Options options) {

if (stream == null)

return null;

Rect rect = new Rect();

if (options == null)

options = new BitmapFactory.Options();

Bitmap bitmap = getDrawable(res, value, stream, rect, options);

if (bitmap != null) {

byte[] arrayOfByte = bitmap.getNinePatchChunk();

if ((arrayOfByte == null)

|| (!NinePatch.isNinePatchChunk(arrayOfByte))) {

arrayOfByte = null;

rect = null;

}

return getDrawable(res, bitmap, arrayOfByte, rect, path);

}

return null;

}

public static Drawable getDrawable(Context context, String path) {

try {

Resources res = context.getResources();

InputStream stream = context.getAssets().open(path);

TypedValue value = new TypedValue();

value.density = 240;

if (Build.VERSION.SDK_INT > 3) {

return getDrawable(res, value, stream, path, null);

}

return Drawable.createFromResourceStream(res, value, stream, path);

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return null;

}

以上加载图片方法可以自动加载.9格式的。

工程下载:bdvoice