删除可绘制对象只有在取消滑动后点击后才会被清除

Question

在回收器视图中，只有在轻cancellation轻扫时点击后，删除可绘制对象才会被清除。

我不知道我在代码上做错了什么。我正在使用CLEAR模式清除canvas，但在取消滑动后可见。有关更多详细信息，请找到GIF文件。

abstract public class SwipeToDeleteHelper extends ItemTouchHelper.Callback {
Context context;
private Paint paint;
private ColorDrawable Background;
private int BackgroundColour;
private Drawable DeleteDrawable;
private int intrinsicWidth;
private int intrinsicHeight;
public SwipeToDeleteHelper(Context context) {
    this.context = context;
    Background = new ColorDrawable();
    BackgroundColour = Color.parseColor("#ff3d00");
    DeleteDrawable = ContextCompat.getDrawable(context,R.drawable.ic_delete);
    intrinsicHeight = DeleteDrawable.getIntrinsicHeight();
    intrinsicWidth = DeleteDrawable.getIntrinsicHeight(); }
@Override
public int getMovementFlags(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder) {
    return makeMovementFlags(0,ItemTouchHelper.LEFT );
}
@Override
public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {
    return false;}
@Override
public void onChildDraw(@NonNull Canvas c, @NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {
    super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
    View view = viewHolder.itemView;
    int itemHeight = view.getHeight();
    Boolean isCancelled = dX==0 && isCurrentlyActive;
    if(isCancelled)
    {
        clearCanvas(c,view.getRight()+dX,(float)view.getTop(),(float)view.getRight(),(float)view.getBottom());
        super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
        return;}
        Background.setColor(BackgroundColour);
        Background.setBounds(view.getRight() + (int) dX, view.getTop(), view.getRight(), view.getBottom());
        Background.draw(c);
        int DeleteIconTop = view.getTop() + (itemHeight - intrinsicHeight) / 2;
        int DeleteIconMargin = (itemHeight - intrinsicHeight) / 2;
        int DeleteIconLeft = view.getRight() - DeleteIconMargin - intrinsicWidth;
        int DeleteIconRight = view.getRight() - DeleteIconMargin;
        int DeleteIconBottom = DeleteIconTop + intrinsicHeight;
        DeleteDrawable.setBounds(DeleteIconLeft, DeleteIconTop, DeleteIconRight, DeleteIconBottom);
        DeleteDrawable.draw(c);
    super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
}
private void clearCanvas(Canvas c, float left, float top, float right, float bottom) {
    Paint clearPaint = new Paint();
    clearPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
    c.drawRect(left,top,right,bottom,clearPaint);
}
@Override
public float getSwipeThreshold(@NonNull RecyclerView.ViewHolder viewHolder) {
    return 0.7f; //super.getSwipeThreshold(viewHolder);
}
}

Answer 1

这一行避免了我的错误。c.clipRect((， c.save(( 和 c.restore((

DeleteSwipe.setBounds(myItem.getLeft(),myItem.getTop(),(int)dX,myItem.getBottom());
DeleteIcon = ContextCompat.getDrawable(getActivity(),R.drawable.ic_delete);
DeleteIcon.setBounds(IconLeft,IconTop,IconRight,IconBottom);
DeleteSwipe.draw(c);
c.save();
c.clipRect(myItem.getLeft(),myItem.getTop(),(int)dX,myItem.getBottom());
DeleteIcon.draw(c);