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Android自定义组件：CirclerView

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Android自定义组件之CirclerView

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import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Shader;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.support.annotation.Nullable;
import android.support.v7.widget.AppCompatImageView;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.Toast;

public class CircleImageView extends AppCompatImageView {
    private float width;
    private float height;
    private float x;
    private float y;
    private float radius;
    private Paint paint;
    private Matrix matrix;

​    private int pressId;
​    private  int srcId;

​    public CircleImageView(Context context) {
​        this(context, null);
​    }

​    public CircleImageView(Context context, @Nullable AttributeSet attrs) {
​        this(context, attrs, 0);
​    }

​    public CircleImageView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
​        super(context, attrs, defStyleAttr);
​        paint = new Paint();
​        paint.setAntiAlias(true);   //设置抗锯齿
​        matrix = new Matrix();      //初始化缩放矩阵
​        for (int i = 0;i < attrs.getAttributeCount();i++){
​            String attrName = attrs.getAttributeName(i);
​            switch (attrName){
​                case "press":
​                    pressId = attrs.getAttributeResourceValue(i,0);
​                    break;
​                case "src":
​                    srcId = attrs.getAttributeResourceValue(i,0);
​                    break;
​            }
​        }
​    }

​    /**

- 测量控件的宽高，并获取其内切圆的半径
  /
      @Override
      protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  super.onMeasure(widthMeasureSpec, heightMeasureSpec);
  width = getMeasuredWidth();
  height = getMeasuredHeight();
  x = getX();
  y = getY();
  radius = Math.min(width, height)/2;
      }

​    @Override
​    protected void onDraw(Canvas canvas) {
​        Drawable drawable = getDrawable();
​        if (drawable == null) {
​            super.onDraw(canvas);
​            return;
​        }
​        if (drawable instanceof BitmapDrawable) {
​            paint.setShader(initBitmapShader((BitmapDrawable) drawable));//将着色器设置给画笔
​            canvas.drawCircle(width/2, height/2, radius, paint);//使用画笔在画布上画圆
​            return;
​        }
​        super.onDraw(canvas);
​    }

​    /**

- 获取ImageView中资源图片的Bitmap，利用Bitmap初始化图片着色器,通过缩放矩阵将原资源图片缩放到铺满整个绘制区域，避免边界填充
  /
      private BitmapShader initBitmapShader(BitmapDrawable drawable) {
  Bitmap bitmap = drawable.getBitmap();
  BitmapShader bitmapShader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
  float scale = Math.max(width / bitmap.getWidth(), height / bitmap.getHeight());
  matrix.setScale(scale, scale);//将图片宽高等比例缩放，避免拉伸
  bitmapShader.setLocalMatrix(matrix);
  return bitmapShader;
      }

​    @Override
​    public boolean onTouchEvent(MotionEvent event) {
​        int action = event.getAction();
​        switch (action){
​            case MotionEvent.ACTION_DOWN:
​                if(pressId != 0){
​                    this.setImageResource(pressId);
​                }
​                break;
​            case MotionEvent.ACTION_MOVE:
​                break;
​            case MotionEvent.ACTION_UP:
​                if (srcId != 0){
​                    this.setImageResource(srcId);
​                }
​                break;
​        }
​        return super.onTouchEvent(event);
​    }
}