怎么在自定义ImageView上Draw东西，然后获取为Bitmap?

Question

public class MainActivity extends AppCompatActivity {

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    View view= View.inflate(this,R.layout.activity_main,null);
    //布局参数
    ViewGroup.LayoutParams layoutParams=new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
            ViewGroup.LayoutParams.WRAP_CONTENT);

    ImageView imageView=new ImageView(this);
    //设置布局参数
    imageView.setLayoutParams(layoutParams);
    imageView.setBackgroundColor(Color.RED);

    //把textview加入RelativeLayout中
    ((RelativeLayout)view).addView(imageView);

    //显示整个布局
    setContentView(view);
    setContentView(new SmileyView(this));




}

}

class SmileyView extends View {
private Paint mCirclePaint;
private float mCenterX;
private float mCenterY;
private float mRadius;

 public SmileyView(Context context) {
    this(context, null);
}

public SmileyView(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
}

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

private void initPaints() {
    mCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    mCirclePaint.setStyle(Paint.Style.FILL);
    mCirclePaint.setColor(Color.YELLOW);
}

 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
     int w = MeasureSpec.getSize(widthMeasureSpec);
     int h = MeasureSpec.getSize(heightMeasureSpec);

     int size = Math.min(w, h);
     setMeasuredDimension(size, size);
 }

 protected void onSizeChanged(int w, int h, int oldw, int oldh) {
     mCenterX = w / 2f;
     mCenterY = h / 2f;
     mRadius = Math.min(w, h) / 2f;
 }

protected void onDraw(Canvas canvas) {
    canvas.drawCircle(mCenterX, mCenterY, mRadius, mCirclePaint);
    // draw eyes


}

}

上面这个代码如何修改为在ImageView上显示画的圆，然后把ImageView转化成Bitmap？麻烦具体点，我小白

Answer 1

之前写过一个类似的，不过没自定义控件，在画布上画的文字，再把控件内容覆盖到上面，跟你这反过来就行了，你可以参考一下：

//截取scrollview的屏幕
public static Bitmap getScrollViewBitmap(NestedScrollView scrollView) {
        int h = 0;
        Bitmap bitmap;
        for (int i = 0; i < scrollView.getChildCount(); i++) {
                h += scrollView.getChildAt(i).getHeight();
        }
        // 创建相应大小的bitmap
        bitmap = Bitmap.createBitmap(scrollView.getMeasuredWidth(), h,
                        Bitmap.Config.ARGB_4444);
        final Canvas canvas = new Canvas(bitmap);
        canvas.drawColor(Color.parseColor("#FFFFFF"));
        drawTextToBitmap(scrollView.getContext(), canvas, scrollView.getMeasuredWidth(), h);
        scrollView.draw(canvas);
        return bitmap;
}

// 给图片添加水印
public static void drawTextToBitmap(Context context, Canvas canvas, int width, int height) {
        String logo = "戚大爷";
        Paint paint = new Paint();
        paint.setColor(SkinManager.getInstance().getResourceManager().getColor("future_text_bg"));
        paint.setAlpha(80);
        paint.setAntiAlias(true);
        paint.setTextSize((float) DensityUtil.dip2px(context, 30));
        canvas.save();
        canvas.rotate(-30);
        float textWidth = paint.measureText(logo);
        int index = 0;
        for (int positionY = -DensityUtil.dip2px(context, 30); positionY <= height; positionY += DensityUtil.dip2px(context, 80)) {
                float fromX = -0.75f * height + (index++ % 2) * textWidth;
                for (float positionX = fromX; positionX < width; positionX += textWidth * 2) {
                        canvas.drawText(logo, positionX, positionY, paint);
                }
        }
        canvas.restore();
}

希望能够帮助到你！