Android自定義圓形圖片工具類(CTRL+C加CTRL+V直接使用)

先貼一下工具類的代碼！可直接複製粘貼

public class RoundImageView extends ImageView {


    private Paint mPaint; //畫筆

    private int mRadius; //圓形圖片的半徑

    private float mScale; //圖片的縮放比例

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

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

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

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        //因為是圓形圖片，所以應該讓寬高保持一致
        int size = Math.min(getMeasuredWidth(), getMeasuredHeight());
        mRadius = size / 2;

        setMeasuredDimension(size, size);
    }

    @Override
    protected void onDraw(Canvas canvas) {

        mPaint = new Paint();
        Bitmap bitmap = drawableToBitmap(getDrawable());

        //初始化BitmapShader，傳入bitmap對象
        BitmapShader bitmapShader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);

        //計算縮放比例
        mScale = (mRadius * 2.0f) / Math.min(bitmap.getHeight(), bitmap.getWidth());

        Matrix matrix = new Matrix();
        matrix.setScale(mScale, mScale);
        bitmapShader.setLocalMatrix(matrix);


        mPaint.setShader(bitmapShader);

        //畫圓形，指定好中心點坐標、半徑、畫筆
        canvas.drawCircle(mRadius, mRadius, mRadius, mPaint);
    }

    //寫一個drawble轉BitMap的方法
    private Bitmap drawableToBitmap(Drawable drawable) {
        if (drawable instanceof BitmapDrawable) {
            BitmapDrawable bd = (BitmapDrawable) drawable;
            return bd.getBitmap();
        }
        int w = drawable.getIntrinsicWidth();
        int h = drawable.getIntrinsicHeight();
        Bitmap bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, w, h);
        drawable.draw(canvas);
        return bitmap;
    }

}

　現在一個圓形圖片已經完成了90%，接下來就是佈局文件，在這裡我只寫了一個簡單的佈局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:gravity="center">

    <com.bc.rcmpapp.util.RoundImageView
        android:id="@+id/round_img"
        android:scaleType="fitCenter"
        android:layout_width="30dp"
        android:layout_height="30dp"
　　　　 android:src="@drawable/ic_launcher"/> 

</LinearLayout>

　　最後需要在Activity中載入！找到對應的佈局即可

RoundImageView imageView = (RoundImageView)findViewById(R.id.round_img);

　　紫色的標記是需要聲明圖片為自己定義的RoundImageView.java文件的位置

　　紅色標註的需要聲明對應的RoundImageView

　　接下來圓形圖片就成功了！繼續對圖片進行操作吧