自定義View

先使用BitmapFactory.decodeResource()來獲取一個位圖Bitmap，其中第一個引數為資源，第二個引數為要修改的圖片

然後使用Shader對其進行操作

對於BitmapShader有幾種模式{CLAMP拉伸，REPEAT重複，MIRROR映象}，這裡選CLAMP

然後將獲得的bitmap繪製成圓形

這樣便可以在佈局中使用這個view了

程式碼如下

import android.view.View;

import com.example.administrator.copyqq01.R;

/**
 * Created by Administrator on 2016/6/7.
 * 實現image的圓形顯示
 */
public class ImageViewRound extends View {

    private Bitmap bitmap;
    private Paint paint;
    private BitmapShader bitmapShader;

    public ImageViewRound(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }


    public ImageViewRound(Context context, AttributeSet attrs) {
        super(context, attrs);
    }


    public ImageViewRound(Context context) {
        super(context);
    }

    //如何動態的載入R.drawable.get2資源？
    @Override
    protected void onDraw(Canvas canvas) {
        bitmap= BitmapFactory.decodeResource(getResources(), R.drawable.get2);
        bitmapShader=new BitmapShader(bitmap, Shader.TileMode.CLAMP,Shader.TileMode.CLAMP);
        paint=new Paint();
        paint.setShader(bitmapShader);
        canvas.drawCircle(50,50,50,paint);
    }
}
 

繼承一個Drawable，在其中的建構函式中對傳入的Bitmap進行設定，在佈局中加入一個ImageView（或者其他什麼的），然後在程式碼中對imageView進行設定

import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.ColorFilter;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.drawable.Drawable;

/**
 * Created by Administrator on 2016/7/3.
 */
public class RoundImageDrawable extends Drawable {

    private Paint mPaint;
    private Bitmap mBitmap;
    private RectF rectF;

    public RoundImageDrawable(Bitmap bitmap){
        mBitmap=bitmap;
        BitmapShader bitmapShader=new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        mPaint=new Paint();
        mPaint.setAntiAlias(true);//抗鋸齒
        mPaint.setShader(bitmapShader);
    }

    @Override
    public void setBounds(int left,int top,int right,int bottom) {
        super.setBounds(left,top,right,bottom);
        rectF=new RectF(left,top,right,bottom);
    }

    @Override
    public void draw(Canvas canvas) {

        canvas.drawRoundRect(rectF,30,30,mPaint);
    }

    @Override
    public int getIntrinsicHeight() {
        return mBitmap.getHeight();
    }

    @Override
    public int getIntrinsicWidth() {
        return mBitmap.getWidth();
    }

    @Override
    public void setAlpha(int alpha) {

        mPaint.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(ColorFilter colorFilter) {

        mPaint.setColorFilter(colorFilter);
    }

    @Override
    public int getOpacity() {
        return PixelFormat.TRANSLUCENT;//設定透明
    }
}
 

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.widget.ImageView;


/**
 * Created by Administrator on 2016/3/7.
 */
public class MainActivity extends Activity {



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Bitmap bitmap= BitmapFactory.decodeResource(getResources(),R.drawable.mv);
        ImageView imageView=(ImageView)findViewById(R.id.id_one);
        imageView.setImageDrawable(new RoundImageDrawable(bitmap));
    }
}
 

參考