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。
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