android开发分享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。