自定义图像视图在回收视图中退出屏幕后立即失去透明度

Question

我有一个自定义的 ImageView，它覆盖了 onDraw 方法，使用 Path 裁剪角，以给出给定半径的圆角。我有一个回收器视图，其中我在所有 4 个项目中都有这些自定义图像视图。现在的问题是这个自定义 ImageView 在第一次出现在列表中时呈现良好。一次只能容纳 2 个屏幕。当我向下滚动时，所有视图中一切都很好。我可以看到所有这些圆角。但是当我向上滚动到上一项时。现在，这些角在角落中失去透明度，并在列表中除第三项之外的所有项中变为黑色。onDraw 中的 Canvas 也有 isOpaque = true 。我已经尝试了很多方法，但似乎没有任何效果。这是代码

public class RoundedImageView extends ImageView
{
    private Paint mPaint;
    private int mCornerRadius = 0;
    private boolean mRoundedTopLeft = true, mRoundedBottomLeft = true, mRoundedTopRight = true, mRoundedBottomRight = true;
    public void setCornerRadius(int mCornerRadius)
    {
        this.mCornerRadius = mCornerRadius;
    }
    public void RoundCorners(boolean isRoundedTopLeft, boolean isRoundedTopRight, boolean isRoundedBottomLeft, boolean isRoundedBottomRight)
    {
        mRoundedTopLeft = isRoundedTopLeft;
        mRoundedBottomLeft = isRoundedBottomLeft;
        mRoundedBottomRight = isRoundedBottomRight;
        mRoundedTopRight = isRoundedTopRight;
    }
    public RoundedImageView(Context context)
    {
        super(context);
        if (Build.VERSION.SDK_INT >= 11)
            setLayerType(View.LAYER_TYPE_SOFTWARE, null);
        setupPaint();
    }
    public RoundedImageView(Context context, AttributeSet attrs)
    {
        super(context, attrs);
        if (Build.VERSION.SDK_INT >= 11)
            setLayerType(View.LAYER_TYPE_SOFTWARE, null);
        setupPaint();
    }
    public RoundedImageView(Context context, AttributeSet attrs, int defStyleAttr)
    {
        super(context, attrs, defStyleAttr);
        if (Build.VERSION.SDK_INT >= 11)
            setLayerType(View.LAYER_TYPE_SOFTWARE, null);
        setupPaint();
    }
    @TargetApi(21)
    public RoundedImageView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)
    {
        super(context, attrs, defStyleAttr, defStyleRes);
        if (Build.VERSION.SDK_INT >= 11)
            setLayerType(View.LAYER_TYPE_SOFTWARE, null);
        setupPaint();
    }
    private Paint setupPaint()
    {
        mPaint = new Paint();
        mPaint.setColor(Color.TRANSPARENT);
        mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
        mPaint.setAntiAlias(true);
        mPaint.setDither(true);
        mPaint.setStrokeWidth(1);
        mPaint.setStrokeJoin(Paint.Join.ROUND);
        mPaint.setStrokeCap(Paint.Cap.ROUND);
        mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
        return mPaint;
    }
    @Override
    protected void onDraw(Canvas canvas)
    {
        super.onDraw(canvas);
        Path path = RoundedRect(0, 0, getWidth(), getHeight(), mCornerRadius, mCornerRadius,
                mRoundedTopLeft, mRoundedTopRight, mRoundedBottomRight, mRoundedBottomLeft);
        canvas.drawPath(path, mPaint);
    }
    public static Path RoundedRect(
            float left, float top, float right, float bottom, float rx, float ry,
            boolean tl, boolean tr, boolean br, boolean bl)
    {
        Path path = new Path();
        if (rx < 0) rx = 0;
        if (ry < 0) ry = 0;
        float width = right - left;
        float height = bottom - top;
        if (rx > width / 2) rx = width / 2;
        if (ry > height / 2) ry = height / 2;
        float widthMinusCorners = (width - (2 * rx));
        float heightMinusCorners = (height - (2 * ry));
        path.moveTo(right, top + ry);
        if (tr)
            path.rQuadTo(0, -ry, -rx, -ry);//top-right corner
        else
        {
            path.rLineTo(0, -ry);
            path.rLineTo(-rx, 0);
        }
        path.rLineTo(-widthMinusCorners, 0);
        if (tl)
            path.rQuadTo(-rx, 0, -rx, ry); //top-left corner
        else
        {
            path.rLineTo(-rx, 0);
            path.rLineTo(0, ry);
        }
        path.rLineTo(0, heightMinusCorners);
        if (bl)
            path.rQuadTo(0, ry, rx, ry);//bottom-left corner
        else
        {
            path.rLineTo(0, ry);
            path.rLineTo(rx, 0);
        }
        path.rLineTo(widthMinusCorners, 0);
        if (br)
            path.rQuadTo(rx, 0, rx, -ry); //bottom-right corner
        else
        {
            path.rLineTo(rx, 0);
            path.rLineTo(0, -ry);
        }
        path.rLineTo(0, -heightMinusCorners);
        path.close();//Given close, last lineto can be removed.
        path.setFillType(Path.FillType.INVERSE_EVEN_ODD);
        return path;
    }
}

我已经尝试过： - 在视图持有人中设置可回收假

• 在绘画中设置不同的波特达夫模式

• 此视图的LAYER_TYPE_HARDWARE（硬件加速）

• 构造函数中的setDrawingCacheBackgroundColor(0x00000000);

• setLayerType(View.LAYER_TYPE_SOFTWARE, paint);在此函数中传递油漆

• 尝试在super.onDraw()之前使画布透明

更新：

经过大量的摆弄，我得出结论，每当我的视图持有人的视图超出屏幕时。所有的阿尔法通道都变成了黑色。我有一种感觉，它必须与setLayerType(View.LAYER_TYPE_SOFTWARE, null);

Answer 1

通过加速父软件来工作。

我通过把它解决了

if (Build.VERSION.SDK_INT >= 11)
                view.setLayerType(View.LAYER_TYPE_SOFTWARE, null);

在我的视图持有人的构造函数中。即使我为任何父容器视图启用了软件加速，它也能正常工作。

现在我不知道为什么会这样。