Android开发使用自定义View将圆角矩形绘制在Canvas上的方法

 /**   * Call this to create a new shader that will draw with a bitmap.   *   * @param bitmap      The bitmap to use inside the shader   * @param tileX       The tiling mode for x to draw the bitmap in.   * @param tileY       The tiling mode for y to draw the bitmap in.   */  public BitmapShader(Bitmap bitmap, TileMode tileX, TileMode tileY) {......}

package com.example.test;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.RectF;import android.graphics.Shader;import android.util.AttributeSet;import android.view.View;public class RounderCornerImageView extends View {  private Bitmap mImage;// source bitmap  private Paint mBitmapPaint;//paint  private RectF mBrounds;//rect  private float mRadius=20.0f;//round  public RounderCornerImageView(Context context) {    this(context, null);  }  public RounderCornerImageView(Context context, AttributeSet attrs) {    this(context, attrs, 0);  }  public RounderCornerImageView(Context context, AttributeSet attrs,      int defStyleAttr) {    super(context, attrs, defStyleAttr);    init();  }  private void init() {    mBitmapPaint=new Paint(Paint.ANTI_ALIAS_FLAG);    mBrounds=new RectF();  }  @Override  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {    // TODO Auto-generated method stub    int height,width;    height=width=0;    //obtain bitmap size    int imageHeight,imageWidth;    if (null!=mImage) {      imageHeight=imageWidth=0;    }else    {      imageHeight=mImage.getHeight();      imageWidth=mImage.getWidth();    }    //obtain best measure data and set on View    width=getMeasurement(widthMeasureSpec,imageWidth);    height=getMeasurement(heightMeasureSpec, imageHeight);    //set View last size    setMeasuredDimension(width, height);  }  /**   * measure width and height by specMode   **/  private int getMeasurement(int measureSpec, int contentSize) {    int specSize=MeasureSpec.getSize(measureSpec);    switch (MeasureSpec.getMode(measureSpec)) {    case MeasureSpec.AT_MOST:      return Math.min(specSize, contentSize);    case MeasureSpec.UNSPECIFIED:      return contentSize;    case MeasureSpec.EXACTLY:      return specSize;    default:      return 0;    }//switch  }  @Override  protected void onSizeChanged(int w, int h, int oldw, int oldh) {    if (w!=oldw || h!=oldh) {      int imageWidth,imageHeight;      if (null==mImage) {        imageWidth=imageHeight=0;      }else      {        imageWidth=mImage.getWidth();        imageHeight=mImage.getHeight();      }      //center point      int left=(w-imageWidth)/2;      int top=(h-imageHeight)/2;      mBrounds.set(left, top, left+imageWidth, top+imageHeight);      if (null!=mBitmapPaint.getShader()) {        Matrix m=new Matrix();        m.setTranslate(left, top);        mBitmapPaint.getShader().setLocalMatrix(m);      }    }  }  public void setImage(Bitmap bitmap) {    if (mImage!=bitmap) {      mImage=bitmap;      if (null!=mImage) {        BitmapShader shader=new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);        mBitmapPaint.setShader(shader);      }else {        mBitmapPaint.setShader(null);      }      requestLayout();//invalidated the layout of this view by onDraw()    }  }  @Override  protected void onDraw(Canvas canvas) {    super.onDraw(canvas);    if (null!=mBitmapPaint) {      //draw Round Rect      canvas.drawRoundRect(mBrounds, mRadius, mRadius, mBitmapPaint);    }  }}

package com.example.test;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Bundle;public class RoundActivity extends Activity{  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    RounderCornerImageView view=new RounderCornerImageView(this);    Bitmap souBitmap=BitmapFactory.decodeResource(getResources(), R.drawable.sun);    view.setImage(souBitmap);    setContentView(view);  }}