这听起来可能很愚蠢,但是我为此感到挣扎,所以请耐心等待几秒钟。
因此,我想将一个简单的TextView
放在屏幕中央:
<TextView
android:id="@+id/helloTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:includeFontPadding="false"
android:text="Hello!"
android:textSize="50sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.464" />
我使用wrap_content
和match_constraint
进行了尝试,但无法使它居中。当我执行wrap_content
时,框会正确居中,但其中的文本却无法如您在此处看到:
当我做match_constraint
时,它只是垂直居中,而不是水平居中:
我错过了什么?
答案 0 :(得分:2)
在您发布的TextView的xml中添加:
function observe(obj) {
Object.keys(obj).forEach(key => {
let internalValue = obj[key]
let dep = new Dep()
Object.defineProperty(obj, key, {
get() {
dep.depend()
return internalValue
},
set(newValue) {
const isChanged = internalValue !== newValue
if (isChanged) {
internalValue = newValue
dep.notify()
}
}
})
})
}
class Dep {
constructor() {
this.subscribers = new Set()
}
depend() {
if (activeUpdate) {
// register the current active update as a subscriber
this.subscribers.add(activeUpdate)
}
}
notify() {
// run all subscriber functions
this.subscribers.forEach(subscriber => subscriber())
}
}
let activeUpdate
function autorun(update) {
function wrappedUpdate() {
activeUpdate = wrappedUpdate
update()
activeUpdate = null
}
wrappedUpdate()
}
const state = {
count: 0
}
observe(state)
state.count;
autorun(() => {
console.log(`count is: ${state.count}`)
})
state.count++
答案 1 :(得分:0)
<div id="map" style="position:absolute; width:100%; height:100%; background:grey;z-index:0">
<div style="position:absolute;">
<div class="forbut">
<button onclick="myFunction()" class="btn-danger">edf</button>
</div>
<div id="list" style=" width:100px; left:0; background-color: red; z-index:1">
</div>
<div style="position:absolute; left:600px;top:0">
<div class="forbut1">
<button onclick="myFunction1()" class="btn-danger">edf</button>
</div>
<div id="list1" style=" width:100px; left:600px; background-color: red; z-index:1">
</div>
</div>
</div>
</div>