Android：ViewGroup.MarginLayoutParams 不起作用

Question

我用它来以编程方式设置边距，但它不起作用，不应用边距。在构造函数中：

public TimeWindow(Context context, int pixels, int left, int top){
    super(context);
    ViewGroup.MarginLayoutParams params = new ViewGroup.MarginLayoutParams(pixels, pixels);
    params.setMargins(left, top, 0, 0);
    this.setLayoutParams(params);
}

Answer 1

View从您的评论中推断，当您尚未设置参数时，您正在设置参数，并且当您将参数附加到布局LayoutParams时，它们将被覆盖。View我建议您做的是将您的设置移至LayoutParams该onAttachedToWindow方法。然后您就可以获取LayoutParams并getLayoutParams()修改它们。

private final int mPixelSize;
private final int mLeftMargin;
private final int mTopMargin;

public TimeWindow(Context context, int pixels, int left, int top){
    super(context);
    mPixelSize = pixels;
    mLeftMargin = left;
    mTopMargin = top;
}

@Override
protected void onAttachedToWindow() {
    super.onAttachedToWindow();
    if (getLayoutParams() instanceof MarginLayoutParams){ 
        //if getLayoutParams() returns null, the if condition will be false
        MarginLayoutParams layoutParams = (MarginLayoutParams) getLayoutParams();
        layoutParams.width = mPixelSize;
        layoutParams.height = mPixelSize;
        layoutParams.setMargins(mLeftMargin, mTopMargin, 0, 0);
        requestLayout();
    }
}