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/*
* Copyright (C) 2020 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License
*/
package com.android.systemui.util.animation
import android.annotation.SuppressLint
import android.content.Context
import android.view.View
import android.view.ViewGroup
import android.widget.FrameLayout
import com.android.systemui.R
/**
* A special view that is designed to host a single "unique object". The unique object is
* dynamically added and removed from this view and may transition to other UniqueObjectHostViews
* available in the system.
* This is useful to share a singular instance of a view that can transition between completely
* independent parts of the view hierarchy.
* If the view currently hosts the unique object, it's measuring it normally,
* but if it's not attached, it will obtain the size by requesting a measure, as if it were
* always attached.
*/
class UniqueObjectHostView(
context: Context
) : FrameLayout(context) {
lateinit var measurementManager: MeasurementManager
@SuppressLint("DrawAllocation")
override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
val paddingHorizontal = paddingStart + paddingEnd
val paddingVertical = paddingTop + paddingBottom
val width = MeasureSpec.getSize(widthMeasureSpec) - paddingHorizontal
val widthSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.getMode(widthMeasureSpec))
val height = MeasureSpec.getSize(heightMeasureSpec) - paddingVertical
val heightSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.getMode(heightMeasureSpec))
val measurementInput = MeasurementInput(widthSpec, heightSpec)
// Let's make sure the measurementManager knows about our size, to ensure that we have
// a value available. This might perform a measure internally if we don't have a cached
// size.
val (cachedWidth, cachedHeight) = measurementManager.onMeasure(measurementInput)
if (isCurrentHost()) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec)
getChildAt(0)?.requiresRemeasuring = false
}
// The goal here is that the view will always have a consistent measuring, regardless
// if it's attached or not.
// The behavior is therefore very similar to the view being persistently attached to
// this host, which can prevent flickers. It also makes sure that we always know
// the size of the view during transitions even if it has never been attached here
// before.
// We previously still measured the size when the view was attached, but this doesn't
// work properly because we can set the measuredState while still attached to the
// old host, which will trigger an inconsistency in height
setMeasuredDimension(cachedWidth + paddingHorizontal, cachedHeight + paddingVertical)
}
override fun addView(child: View?, index: Int, params: ViewGroup.LayoutParams?) {
if (child == null) {
throw IllegalArgumentException("child must be non-null")
}
if (child.measuredWidth == 0 || measuredWidth == 0 || child.requiresRemeasuring == true) {
super.addView(child, index, params)
return
}
// Suppress layouts when adding a view. The view should already be laid out with the
// right size when being attached to this view
invalidate()
addViewInLayout(child, index, params, true /* preventRequestLayout */)
// RTL properties are normally resolved in onMeasure(), which we are intentionally skipping
child.resolveRtlPropertiesIfNeeded()
val left = paddingLeft
val top = paddingTop
val paddingHorizontal = paddingStart + paddingEnd
val paddingVertical = paddingTop + paddingBottom
child.layout(left,
top,
left + measuredWidth - paddingHorizontal,
top + measuredHeight - paddingVertical)
}
private fun isCurrentHost() = childCount != 0
interface MeasurementManager {
fun onMeasure(input: MeasurementInput): MeasurementOutput
}
}
/**
* Does this view require remeasuring currently outside of the regular measure flow?
*/
var View.requiresRemeasuring: Boolean
get() {
val required = getTag(R.id.requires_remeasuring)
return required?.equals(true) ?: false
}
set(value) {
setTag(R.id.requires_remeasuring, value)
}
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