我必须在 Android 中构建一个更复杂的自定义 View 。最终布局应如下所示:
<RelativeLayout>
<SomeView />
<SomeOtherView />
<!-- maybe more layout stuff here later -->
<LinearLayout>
<!-- the children -->
</LinearLayout>
</RelativeLayout>
但是,我只想在 XML 文件中定义这个(不定义 SomeView、SomeOtherView 等):
<MyCustomView>
<!-- the children -->
</MyCustomView>
这在 Android 中是否可行,如果可以:最干净的方法是什么? 我想到的可能解决方案是“覆盖 addView() 方法”和“删除所有 View 并稍后再添加”,但我不确定该走哪条路……
非常感谢您的帮助! :)
最佳答案
创建自定义容器 View 是绝对可行的,并且受到鼓励。这就是 Android 所说的复合控件。所以:
public class MyCustomView extends RelativeLayout {
private LinearLayout mContentView;
public MyCustomView(Context context) {
this(context, null);
}
public MyCustomView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public MyCustomView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
//Inflate and attach your child XML
LayoutInflater.from(context).inflate(R.layout.custom_layout, this);
//Get a reference to the layout where you want children to be placed
mContentView = (LinearLayout) findViewById(R.id.content);
//Do any more custom init you would like to access children and do setup
}
@Override
public void addView(View child, int index, ViewGroup.LayoutParams params) {
if(mContentView == null){
super.addView(child, index, params);
} else {
//Forward these calls to the content view
mContentView.addView(child, index, params);
}
}
}
您可以覆盖任意多个版本的 addView()
你觉得有必要,但最后他们都回调到我放在示例中的版本。仅覆盖此方法将使框架将在其 XML 标记中找到的所有子容器传递给特定的子容器。
然后像这样修改XML:
res/layout/custom_layout.xml
<merge>
<SomeView />
<SomeOtherView />
<!-- maybe more layout stuff here later -->
<LinearLayout
android:id="@+id/content" />
</merge>
使用<merge>
的原因是为了简化层次结构。所有 subview 都将附加到您的自定义类,即 RelativeLayout
.如果你不使用 <merge>
, 你最终得到一个 RelativeLayout
附加到另一个 RelativeLayout
依附于所有 child ,这可能会导致问题。
Kotlin 版本:
private fun expand(view: View) {
val parentWidth = (view.parent as View).width
val matchParentMeasureSpec = MeasureSpec.makeMeasureSpec(parentWidth, MeasureSpec.EXACTLY)
val wrapContentMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)
view.measure(matchParentMeasureSpec, wrapContentMeasureSpec)
val targetHeight = view.measuredHeight
view.isVisible = true
val animation: Animation = getExpandAnimation(view, targetHeight)
view.startAnimation(animation)
}
private fun getExpandAnimation(
view: View,
targetHeight: Int
): Animation = object : Animation() {
override fun applyTransformation(
interpolatedTime: Float,
transformation: Transformation
) {
view.layoutParams.height =
if (interpolatedTime == 1f) {
LayoutParams.WRAP_CONTENT
} else {
(targetHeight * interpolatedTime).toInt()
}
view.requestLayout()
}
override fun willChangeBounds(): Boolean {
return true
}
}.apply {
duration = getDuration(targetHeight, view)
}
private fun collapse(view: View) {
val initialHeight = view.measuredHeight
val animation: Animation = getCollapseAnimation(view, initialHeight)
view.startAnimation(animation)
}
private fun getCollapseAnimation(
view: View,
initialHeight: Int
): Animation = object : Animation() {
override fun applyTransformation(
interpolatedTime: Float,
transformation: Transformation
) {
if (interpolatedTime == 1f) {
view.isVisible = false
} else {
view.layoutParams.height =
initialHeight - (initialHeight * interpolatedTime).toInt()
view.requestLayout()
}
}
override fun willChangeBounds(): Boolean = true
}.apply {
duration = getDuration(initialHeight, view)
}
/**
* Speed = 1dp/ms
*/
private fun getDuration(initialHeight: Int, view: View) =
(initialHeight / view.context.resources.displayMetrics.density).toLong()
关于java - Android:具有现有布局的自定义 View 的多个 View 子项,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/11198026/