LayoutParams - NOT WORKING !！ ！

需要使用类型:MarginLayoutParams

MarginLayoutParams params = (MarginLayoutParams) vector8.getLayoutParams();
params.width = 200; params.leftMargin = 100; params.topMargin = 200;

MarginLayoutParams的代码示例:

http://www.codota.com/android/classes/android.view.ViewGroup.MarginLayoutParams

简单的Kotlin扩展方案

单独设置所有/任何边:

fun View.setMargin(left: Int? = null, top: Int? = null, right: Int? = null, bottom: Int? = null) {
    val params = (layoutParams as? MarginLayoutParams)
    params?.setMargins(
            left ?: params.leftMargin,
            top ?: params.topMargin,
            right ?: params.rightMargin,
            bottom ?: params.bottomMargin)
    layoutParams = params
}

myView.setMargin(10, 5, 10, 5)
// or just any subset
myView.setMargin(right = 10, bottom = 5)

直接引用资源值:

fun View.setMarginRes(@DimenRes left: Int? = null, @DimenRes top: Int? = null, @DimenRes right: Int? = null, @DimenRes bottom: Int? = null) {
    setMargin(
            if (left == null) null else resources.getDimensionPixelSize(left),
            if (top == null) null else resources.getDimensionPixelSize(top),
            if (right == null) null else resources.getDimensionPixelSize(right),
            if (bottom == null) null else resources.getDimensionPixelSize(bottom),
    )
}

myView.setMarginRes(top = R.dimen.my_margin_res)

直接将所有方面平等地设置为属性:

var View.margin: Int
    get() = throw UnsupportedOperationException("No getter for property")
    set(@Px margin) = setMargin(margin, margin, margin, margin)
   
myView.margin = 10 // px

// or as res
var View.marginRes: Int
    get() = throw UnsupportedOperationException("No getter for property")
    set(@DimenRes marginRes) {
        margin = resources.getDimensionPixelSize(marginRes)
    }

myView.marginRes = R.dimen.my_margin_res

为了直接设置一个特定的边，你可以像这样创建一个属性扩展:

var View.leftMargin
    get() = marginLeft
    set(@Px leftMargin) = setMargin(left = leftMargin)

var View.leftMarginRes: Int
    get() = throw UnsupportedOperationException("No getter for property")
    set(@DimenRes leftMarginRes) {
        leftMargin = resources.getDimensionPixelSize(leftMarginRes)
    }

这也允许你做出水平或垂直的变化:

var View.horizontalMargin
    get() = throw UnsupportedOperationException("No getter for property")
    set(@Px horizontalMargin) = setMargin(left = horizontalMargin, right = horizontalMargin)

var View.horizontalMarginRes: Int
    get() = throw UnsupportedOperationException("No getter for property")
    set(@DimenRes horizontalMarginRes) {
        horizontalMargin = resources.getDimensionPixelSize(horizontalMarginRes)
    }

注意:如果margin设置失败，你可能在渲染之前太早了，这意味着params == null。尝试用myView包装修改。Post {margin = 10}

以下是最新更新的综合答案:

第一步，更新页边距

基本思想是获取边缘，然后更新它。更新将自动应用，您不需要设置它。要获得布局参数，只需调用这个方法:

LayoutParams layoutParams = (LayoutParams) yourView.findViewById(R.id.THE_ID).getLayoutParams();

LayoutParams来自于视图的布局。如果视图来自线性布局，你需要导入LinearLayout.LayoutParams。如果你使用相对布局，导入线性布局。LayoutParams等等。

现在，如果你使用Layout_marginLeft, Right等来设置边距，你需要以这种方式更新边距

layoutParams.setMargins(left, top, right, bottom);

如果您使用新的layout_marginStart设置边缘，则需要以这种方式更新边缘

layoutParams.setMarginStart(start);
layoutParams.setMarginEnd(end);

步骤2，在dp中更新边缘

上面两种更新边缘的方法都是以像素为单位更新的。你需要把dp转换成像素。

float dpRatio = context.getResources().getDisplayMetrics().density;
int pixelForDp = (int)dpValue * dpRatio;

现在把计算出来的值放到上面的边距更新函数中，你应该都设置好了

就像今天一样，最好的办法可能是使用AirBnB提供的巴黎图书馆。

然后可以像这样应用样式:

Paris.style(myView).apply(R.style.MyStyle);

它还支持使用注释的自定义视图(如果你扩展了一个视图):

@Styleable and @Style

使用此方法设置dp中的边距

private void setMargins (View view, int left, int top, int right, int bottom) {
    if (view.getLayoutParams() instanceof ViewGroup.MarginLayoutParams) {
        ViewGroup.MarginLayoutParams p = (ViewGroup.MarginLayoutParams) view.getLayoutParams();

        final float scale = getBaseContext().getResources().getDisplayMetrics().density;
        // convert the DP into pixel
        int l =  (int)(left * scale + 0.5f);
        int r =  (int)(right * scale + 0.5f);
        int t =  (int)(top * scale + 0.5f);
        int b =  (int)(bottom * scale + 0.5f);

        p.setMargins(l, t, r, b);
        view.requestLayout();
    }
}

调用方法:

setMargins(linearLayout,5,0,5,0);

在Kotlin中，它看起来像这样:

val layoutParams = (yourView?.layoutParams as? MarginLayoutParams)
layoutParams?.setMargins(40, 40, 40, 40)
yourView?.layoutParams = layoutParams