当下流行播放器，实现图片动态旋转

终于来到了CSDN，在之前快一年的工作时间，已经得到CSDN许多关于技术上的问答解决方案，许多有营养的blog，让我学习成长。从今天开始和大家分享一下我的学习成果和面临过得问题。进入正题，平时个人喜好听歌，每每听歌的时候看到大多市面音乐app都会带有一个简略图的

动画，个人感觉很酷。前几天深入学习android中的View控件，了解其源码。
其中很多地方用到了一个类android.graphics.Matrix 是绘图工具中的矩阵一个类。
关于这个类的详细描述我就不多说了。大家可以参照这篇博文：

http://www.cnblogs.com/qiengo/archive/2012/06/30/2570874.html#code

个人感觉写的挺好，很升入很详细。其中最深入的就是这个矩阵变换实现4种变换：1、translation（平移）2、rotate(旋转)3、scale(缩放)4、错切(skew)。相对于每种变化我们都可以根据Matrix中的变换方法来实现。这里我们只是用到了旋转：`matrix.setRotate(degree, roundBitmap.getWidth() / 2f, roundBitmap.getHeight() / 2f)//其中第一个参数就是旋转的角度，第二个、第三个分别是旋转中心的x、y坐标。一般我们实现的旋转都是通过坐标中心实现的; canvas.drawBitmap(roundBitmap, matrix, null);// 第二个就是我们变化的对象`

就能实现旋转的效果了。下面放一张效果图。

 当然这里我没法给大家看动态的效果图。一般我们旋转看起来最舒服的 当然是圆形的图片。所以我们接下来还要做的就是把我们的图片切成圆形的。 这个该如何实现呢？其实当下开源的圆形库有很多。可以自行下载。 我这里也有一个自定义圆形切图类

public class ToBitmapUtil{    public static Bitmap toRoundBitmap(Bitmap bitmap) {    int width = bitmap.getWidth();    int height = bitmap.getHeight();    float roundPx;    float left,top,right,bottom,dst_left,dst_top,dst_right,dst_bottom;    if (width <= height) {//取长宽最小的，设置宽高相等，即先变成正方形            roundPx = width / 2;            top = 0;            bottom = width;            left = 0;            right = width;            height = width;            dst_left = 0;            dst_top = 0;            dst_right = width;            dst_bottom = width;    } else {            roundPx = height / 2;            float clip = (width - height) / 2;            left = clip;            right = width - clip;            top = 0;            bottom = height;            width = height;            dst_left = 0;            dst_top = 0;            dst_right = height;            dst_bottom = height;    }    //先定义的宽高得到正方形的位图对象      Bitmap output = Bitmap.createBitmap(width,                    height, Config.ARGB_8888);    Canvas canvas = new Canvas(output);//给位图设置画布对象    final int color = 0xff424242;    final Paint paint = new Paint();//定义画笔    final Rect src = new Rect((int)left, (int)top, (int)right, (int)bottom);    final Rect dst = new Rect((int)dst_left, (int)dst_top, (int)dst_right, (int)dst_bottom);    final RectF rectF = new RectF(dst);    paint.setAntiAlias(true);    canvas.drawARGB(0, 0, 0, 0);    paint.setColor(color);    canvas.drawRoundRect(rectF, roundPx, roundPx, paint);    paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));    canvas.drawBitmap(bitmap, src, dst, paint);    return output;}}

下面是自定义的圆形带动画的控件

public class CircleImage extends ImageView {      private int mBorderThickness = 0;      private Context mContext;      private int defaultColor = 0xFFFFFFFF;      // 如果只有其中一个有值，则只画一个圆形边框      private int mBorderOutsideColor = 0;      private int mBorderInsideColor = 0;      // 控件默认长、宽      private int defaultWidth = 0;      private int defaultHeight = 0;      private Bitmap bitmap;      private Matrix matrix;      float degree=0;    public CircleImage(Context context) {          super(context);          mContext = context;      }      public CircleImage(Context context, AttributeSet attrs) {          super(context, attrs);          mContext = context;          bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.love);          matrix = new Matrix();          setCustomAttributes(attrs);      }      public CircleImage(Context context, AttributeSet attrs, int defStyle) {          super(context, attrs, defStyle);          mContext = context;          setCustomAttributes(attrs);      }      private Handler handler=new Handler(){        @Override        public void handleMessage(Message msg) {            super.handleMessage(msg);            if(msg.what==0){                CircleImage.this.invalidate();            }        }    };    private void setCustomAttributes(AttributeSet attrs) {          TypedArray a = mContext.obtainStyledAttributes(attrs,                  R.styleable.circleView);          mBorderThickness = a.getDimensionPixelSize(                  R.styleable.circleView_roundedimageview_border_thickness, 0);          mBorderOutsideColor = a                  .getColor(R.styleable.circleView_roundedimageview_border_outside_color,                          defaultColor);          mBorderInsideColor = a.getColor(                  R.styleable.circleView_roundedimageview_border_inside_color, defaultColor);      }      @Override      protected void onDraw(Canvas canvas) {          Drawable drawable = getDrawable();          if (drawable == null) {              return;          }          if (getWidth() == 0 || getHeight() == 0) {              return;          }          this.measure(0, 0);          if (drawable.getClass() == NinePatchDrawable.class)              return;          Bitmap b = ((BitmapDrawable) drawable).getBitmap();          Bitmap bitmap = b.copy(Bitmap.Config.ARGB_8888, true);          if (defaultWidth == 0) {              defaultWidth = getWidth();          }          if (defaultHeight == 0) {              defaultHeight = getHeight();          }          // 保证重新读取图片后不会因为图片大小而改变控件宽、高的大小（针对宽、高为wrap_content布局的imageview，但会导致margin无效）          // if (defaultWidth != 0 && defaultHeight != 0) {          // LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(          // defaultWidth, defaultHeight);          // setLayoutParams(params);          // }          int radius = 0;          if (mBorderInsideColor != defaultColor                  && mBorderOutsideColor != defaultColor) {// 定义画两个边框，分别为外圆边框和内圆边框              radius = (defaultWidth < defaultHeight ? defaultWidth                      : defaultHeight) / 2 - 2 * mBorderThickness;              // 画内圆              drawCircleBorder(canvas, radius + mBorderThickness / 2,                      mBorderInsideColor);              // 画外圆              drawCircleBorder(canvas, radius + mBorderThickness                      + mBorderThickness / 2, mBorderOutsideColor);          } else if (mBorderInsideColor != defaultColor                  && mBorderOutsideColor == defaultColor) {// 定义画一个边框              radius = (defaultWidth < defaultHeight ? defaultWidth                      : defaultHeight) / 2 - mBorderThickness;              drawCircleBorder(canvas, radius + mBorderThickness / 2,                      mBorderInsideColor);          } else if (mBorderInsideColor == defaultColor                  && mBorderOutsideColor != defaultColor) {// 定义画一个边框              radius = (defaultWidth < defaultHeight ? defaultWidth                      : defaultHeight) / 2 - mBorderThickness;              drawCircleBorder(canvas, radius + mBorderThickness / 2,                      mBorderOutsideColor);          } else {// 没有边框              radius = (defaultWidth < defaultHeight ? defaultWidth                      : defaultHeight) / 2;          }          Bitmap roundBitmap = getCroppedRoundBitmap(bitmap, radius);  //        canvas.drawBitmap(roundBitmap, defaultWidth / 2 - radius, defaultHeight  //                / 2 - radius, null);          if(degree>=360){            degree=0;        }        degree+=0.5;        matrix.setRotate(degree, roundBitmap.getWidth() / 2f, roundBitmap.getHeight() / 2f);        canvas.drawBitmap(roundBitmap, matrix, null);          handler.sendEmptyMessageDelayed(0, 0);    }      /**      * 获取裁剪后的圆形图片      *       * @param radius      *            半径      */      public Bitmap getCroppedRoundBitmap(Bitmap bmp, int radius) {          Bitmap scaledSrcBmp;          int diameter = radius * 2;          // 为了防止宽高不相等，造成圆形图片变形，因此截取长方形中处于中间位置最大的正方形图片          int bmpWidth = bmp.getWidth();          int bmpHeight = bmp.getHeight();          int squareWidth = 0, squareHeight = 0;          int x = 0, y = 0;          Bitmap squareBitmap;          if (bmpHeight > bmpWidth) {// 高大于宽              squareWidth = squareHeight = bmpWidth;              x = 0;              y = (bmpHeight - bmpWidth) / 2;              // 截取正方形图片              squareBitmap = Bitmap.createBitmap(bmp, x, y, squareWidth,                      squareHeight);          } else if (bmpHeight < bmpWidth) {// 宽大于高              squareWidth = squareHeight = bmpHeight;              x = (bmpWidth - bmpHeight) / 2;              y = 0;              squareBitmap = Bitmap.createBitmap(bmp, x, y, squareWidth,                      squareHeight);          } else {              squareBitmap = bmp;          }          if (squareBitmap.getWidth() != diameter                  || squareBitmap.getHeight() != diameter) {              scaledSrcBmp = Bitmap.createScaledBitmap(squareBitmap, diameter,                      diameter, true);          } else {              scaledSrcBmp = squareBitmap;          }          Bitmap output = Bitmap.createBitmap(scaledSrcBmp.getWidth(),                  scaledSrcBmp.getHeight(), Config.ARGB_8888);          Canvas canvas = new Canvas(output);          Paint paint = new Paint();          Rect rect = new Rect(0, 0, scaledSrcBmp.getWidth(),                  scaledSrcBmp.getHeight());          paint.setAntiAlias(true);          paint.setFilterBitmap(true);          paint.setDither(true);          canvas.drawARGB(0, 0, 0, 0);          canvas.drawCircle(scaledSrcBmp.getWidth() / 2,                  scaledSrcBmp.getHeight() / 2, scaledSrcBmp.getWidth() / 2,                  paint);          paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));          canvas.drawBitmap(scaledSrcBmp, rect, rect, paint);          // bitmap回收(recycle导致在布局文件XML看不到效果)          // bmp.recycle();          // squareBitmap.recycle();          // scaledSrcBmp.recycle();          bmp = null;          squareBitmap = null;          scaledSrcBmp = null;          return output;      }      /**      * 边缘画圆      */      private void drawCircleBorder(Canvas canvas, int radius, int color) {          Paint paint = new Paint();          /* 去锯齿 */          paint.setAntiAlias(true);          paint.setFilterBitmap(true);          paint.setDither(true);          paint.setColor(color);          /* 设置paint的　style　为STROKE：空心 */          paint.setStyle(Paint.Style.STROKE);          /* 设置paint的外框宽度 */          paint.setStrokeWidth(mBorderThickness);          canvas.drawCircle(defaultWidth / 2, defaultHeight / 2, radius, paint);      }      public Bitmap getImageBitmap()      {          return bitmap;      }  }  

 `

其中做了图片外画圆的效果，这样更加真实，更加好看不生硬。
http://download.csdn.net/detail/qq_35522272/9586056 这个是项目源码。有需要的可以自行下载。