Android 自定义圆形头像列表展示导致RecyclerView滑动卡顿和闪烁

Android 自定义圆形头像列表展示导致RecyclerView滑动卡顿和闪烁

我们一提到圆形头像，就会想到自定义ImageView。而普通的自定义圆形头像一般都是如下定义的。

自定义的圆形ImageView

/**
 * 圆形ImageView，可设置最多两个宽度不同且颜色不同的圆形边框。 .这个控件在列表中会很卡!!!
 * 此自定义不允许在列表中使用，会造成列表卡顿严重
 * 
 * @author
 */
public class RoundImageView extends androidx.appcompat.widget.AppCompatImageView {
	private int mBorderThickness = 0;
	private Context mContext;
	private int defaultColor = 0xFFFFFFFF;
	// 如果只有其中一个有值，则只画一个圆形边框
	private int mBorderOutsideColor = 0;
	private int mBorderInsideColor = 0;
	// 控件默认长、宽
	private int defaultWidth = 0;
	private int defaultHeight = 0;

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

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

	public RoundImageView(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		mContext = context;
		setCustomAttributes(attrs);
	}

	private void setCustomAttributes(AttributeSet attrs) {
		TypedArray a = mContext.obtainStyledAttributes(attrs, R.styleable.roundedimageview);

		mBorderThickness = a.getDimensionPixelSize(R.styleable.roundedimageview_border_thickness, 0);
		mBorderOutsideColor = a.getColor(R.styleable.roundedimageview_border_outside_color, defaultColor);
		mBorderInsideColor = a.getColor(R.styleable.roundedimageview_border_inside_color, defaultColor);
		
		a.recycle();
	}

	public static Bitmap drawableToBitmap(Drawable drawable) {
		try {
			Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(),
					drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565);
			Canvas canvas = new Canvas(bitmap);
			// canvas.setBitmap(bitmap);
			drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());
			drawable.draw(canvas);
			return bitmap;
		} catch (Exception e) {
			return null;
		}
	}

	private Bitmap getBitmapFromDrawable(Drawable drawable) {
		if (drawable == null) {
			return null;
		}

		if (drawable instanceof BitmapDrawable) {
			return ((BitmapDrawable) drawable).getBitmap();
		}

		return drawableToBitmap(drawable);

	}

	@Override
	protected void onDraw(Canvas canvas) {
		Drawable drawable = getDrawable();

		if (drawable == null) {
			return;
		}

		if (getWidth() <= 0 || getHeight() <= 0) {
			return;
		}
		this.measure(0, 0);
		// if (drawable.getClass() == NinePatchDrawable.class)
		// return;
		// Bitmap b = ((BitmapDrawable) drawable).getBitmap();
		Bitmap b = getBitmapFromDrawable(drawable);
		if (b!=null) {
			Bitmap bitmap = b.copy(Bitmap.Config.ARGB_8888, true);
			if (defaultWidth == 0) {
				defaultWidth = getWidth();
			}
			if (defaultHeight == 0) {
				defaultHeight = getHeight();
			}

			int radius = 0;
			if (mBorderInsideColor != defaultColor && mBorderOutsideColor != defaultColor) {// 定义画两个边框，分别为外圆边框和内圆边框
				radius = (defaultWidth < defaultHeight ? defaultWidth : defaultHeight) / 2 - 2 * mBorderThickness;
				// 画内圆
				drawCircleBorder(canvas, radius + mBorderThickness / 2, mBorderInsideColor);
				// 画外圆
				drawCircleBorder(canvas, radius + mBorderThickness + mBorderThickness / 2, mBorderOutsideColor);
			} else if (mBorderInsideColor != defaultColor && mBorderOutsideColor == defaultColor) {// 定义画一个边框
				radius = (defaultWidth < defaultHeight ? defaultWidth : defaultHeight) / 2 - mBorderThickness;
				drawCircleBorder(canvas, radius + mBorderThickness / 2, mBorderInsideColor);
			} else if (mBorderInsideColor == defaultColor && mBorderOutsideColor != defaultColor) {// 定义画一个边框
				radius = (defaultWidth < defaultHeight ? defaultWidth : defaultHeight) / 2 - mBorderThickness;
				drawCircleBorder(canvas, radius + mBorderThickness / 2, mBorderOutsideColor);
			} else {// 没有边框
				radius = (defaultWidth < defaultHeight ? defaultWidth : defaultHeight) / 2;
			}
			Bitmap roundBitmap = getCroppedRoundBitmap(bitmap, radius);
			canvas.drawBitmap(roundBitmap, defaultWidth / 2 - radius, defaultHeight / 2 - radius, null);
		}
	}

	/**
	 * 获取裁剪后的圆形图片
	 * 
	 * @param radius
	 *            半径
	 */
	public Bitmap getCroppedRoundBitmap(Bitmap bmp, int radius) {
		Bitmap scaledSrcBmp;
		int diameter = radius * 2;

		// 为了防止宽高不相等，造成圆形图片变形，因此截取长方形中处于中间位置最大的正方形图片
		int bmpWidth = bmp.getWidth();
		int bmpHeight = bmp.getHeight();
		int squareWidth = 0, squareHeight = 0;
		int x = 0, y = 0;
		Bitmap squareBitmap;
		if (bmpHeight > bmpWidth) {// 高大于宽
			squareWidth = squareHeight = bmpWidth;
			x = 0;
			y = (bmpHeight - bmpWidth) / 2;
			// 截取正方形图片
			squareBitmap = Bitmap.createBitmap(bmp, x, y, squareWidth, squareHeight);
		} else if (bmpHeight < bmpWidth) {// 宽大于高
			squareWidth = squareHeight = bmpHeight;
			x = (bmpWidth - bmpHeight) / 2;
			y = 0;
			squareBitmap = Bitmap.createBitmap(bmp, x, y, squareWidth, squareHeight);
		} else {
			squareBitmap = bmp;
		}

		if (squareBitmap.getWidth() != diameter || squareBitmap.getHeight() != diameter) {
			scaledSrcBmp = Bitmap.createScaledBitmap(squareBitmap, diameter, diameter, true);

		} else {
			scaledSrcBmp = squareBitmap;
		}
		Bitmap output = Bitmap.createBitmap(scaledSrcBmp.getWidth(), scaledSrcBmp.getHeight(), Config.ARGB_8888);
		Canvas canvas = new Canvas(output);

		Paint paint = new Paint();
		Rect rect = new Rect(0, 0, scaledSrcBmp.getWidth(), scaledSrcBmp.getHeight());

		paint.setAntiAlias(true);
		paint.setFilterBitmap(true);
		paint.setDither(true);
		canvas.drawARGB(0, 0, 0, 0);
		canvas.drawCircle(scaledSrcBmp.getWidth() / 2, scaledSrcBmp.getHeight() / 2, scaledSrcBmp.getWidth() / 2,
				paint);
		paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
		canvas.drawBitmap(scaledSrcBmp, rect, rect, paint);
		// bitmap回收(recycle导致在布局文件XML看不到效果)
		// bmp.recycle();
		// squareBitmap.recycle();
		// scaledSrcBmp.recycle();
		bmp = null;
		squareBitmap = null;
		scaledSrcBmp = null;
		return output;
	}

	/**
	 * 边缘画圆
	 */
	private void drawCircleBorder(Canvas canvas, int radius, int color) {
		Paint paint = new Paint();
		/* 去锯齿 */
		paint.setAntiAlias(true);
		paint.setFilterBitmap(true);
		paint.setDither(true);
		paint.setColor(color);
		/* 设置paint的 style 为STROKE：空心 */
		paint.setStyle(Paint.Style.STROKE);
		/* 设置paint的外框宽度 */
		paint.setStrokeWidth(mBorderThickness);
		canvas.drawCircle(defaultWidth / 2, defaultHeight / 2, radius, paint);
	}

}

上面就是自定义的圆形头像，单独用一点儿问题都没有。可以定义白框，切图等，满足大部分圆形头像的需求。使用时，只需要在xml中引用即可。

 <com.android.redwine.ui.RoundImageView
                        android:layout_width="match_parent"
                        android:layout_height="match_parent"
                        android:scaleType="centerCrop"
                        android:src="@drawable/head_default" />

但上面的自定义有一个很大的缺陷，并且是不可避免的。就是在RecyclerView和ListView中循环显示的时候会出现列表卡顿的十分的严重，并且显示的图片还是出现闪烁问题。闪烁问题我试过网上的各种解决办法：1.设置tag，2、设置默认图等等都不行。因为闪烁问题是ImageView的setImageDrawable导致的，而自定义RoundImageView设置图片也就是通过setImageDrawable来设置的。这就对立了，所以我想能不能换一种方式去显示列表的图片，我找到了。

在RecyclerView和ListView中显示圆形头像

在这里不得不说Glide框架的强大了，Glide中就有直接展示圆形图片的方法：

RoundedBitmapDrawable bitmapDrawable = RoundedBitmapDrawableFactory.create(context.getResources(), resource);
                            bitmapDrawable.setCircular(true);
                            imageView.setImageDrawable(bitmapDrawable);

我们来看看具体的使用：

/**
     *头像,带默认图片的
     * BitmapImageViewTarget解决自定义圆形头像在RecyclerView中滑动卡顿以及出现闪烁问题
     * @param context
     * @param imageView
     * @param url
     * @param radius
     */
    public static void initGlideRoundImageHead(Context context, ImageView imageView, String url,final float radius) {
        if (context!=null) {
            Glide.with(imageView.getContext())
                    .load(url)
                    .asBitmap()
                    .placeholder(R.drawable.head_default)
                    .transform(new GlideRoundImage(context, radius))
                    .diskCacheStrategy(DiskCacheStrategy.SOURCE)
                    .into(new BitmapImageViewTarget(imageView){
                        @Override
                        protected void setResource(Bitmap resource) {
                            RoundedBitmapDrawable bitmapDrawable = RoundedBitmapDrawableFactory.create(context.getResources(), resource);
                            bitmapDrawable.setCircular(true);
                            imageView.setImageDrawable(bitmapDrawable);
                        }
                    });
        }else {
            Log.i("Utils.class ", "Picture loading failed,context is null");
        }
    }

稍微懂一点儿代码的就能看懂，BitmapImageViewTarget就是用来设置圆形图片的，很简便的方法。这个时候在xml中就不要用自定义的圆形ImageView了，就用普通的ImageView就行。

综上所述，列表中自定义的圆形图片展示导致列表滑动卡顿验证并且闪烁。所以我们在页面上显示普通的圆形图像时，就用我们自定义的ImageView，这样就能自定义圆形的样式，而在列表中还是用普通的ImageView就行，通过Glide的BitmapImageViewTarget去设置圆形图片。这是我项目中的bug，亲测有效。

本文地址：https://blog.csdn.net/u014714188/article/details/107484654