Android布局优化

<!-- 优化前 -->
<LinearLayout>
    <LinearLayout>
        <LinearLayout>
            <TextView/>
        </LinearLayout>
    </LinearLayout>
</LinearLayout>
 
<!-- 优化后 -->
<ConstraintLayout>
    <TextView
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent"/>
</ConstraintLayout>

<androidx.constraintlayout.widget.ConstraintLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    
    <ImageView
        android:id="@+id/image"
        app:layout_constraintDimensionRatio="1:1"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent"/>
        
    <TextView
        android:layout_width="0dp"
        app:layout_constraintStart_toEndOf="@id/image"
        app:layout_constraintTop_toTopOf="@id/image"
        app:layout_constraintEnd_toEndOf="parent"/>
        
</androidx.constraintlayout.widget.ConstraintLayout>

<!-- layout_item.xml -->
<merge xmlns:android="http://schemas.android.com/apk/res/android">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
</merge>

<ViewStub
    android:id="@+id/stub"
    android:layout="@layout/error_view"
    android:inflatedId="@+id/error"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"/>

// 按需加载布局
viewStub.inflate()

<include
    layout="@layout/common_toolbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"/>

// 在开发者选项中启用
// 使用Android Studio的Layout Inspector工具
// 分析视图层级和布局性能

// 使用Systrace分析布局性能
TraceCompat.beginSection("Layout Performance")
// 布局操作
TraceCompat.endSection()

// 预加载布局
val layoutInflater = LayoutInflater.from(context)
val view = layoutInflater.inflate(R.layout.item_view, null, false)
 
// 缓存View
viewCache.put("key", view)

class AsyncLayoutInflater(context: Context) {
    fun inflate(@LayoutRes layoutRes: Int, parent: ViewGroup?, 
                callback: (View) -> Unit) {
        coroutineScope.launch(Dispatchers.IO) {
            val view = withContext(Dispatchers.Main) {
                layoutInflater.inflate(layoutRes, parent, false)
            }
            callback(view)
        }
    }
}

// 使用TransitionManager平滑更新布局
TransitionManager.beginDelayedTransition(viewGroup)
 
// 更新布局参数
val params = view.layoutParams
params.width = newWidth
view.layoutParams = params

class LayoutPerformanceMonitor {
    fun startMonitor() {
        val startTime = System.nanoTime()
        // 布局操作
        val endTime = System.nanoTime()
        val duration = (endTime - startTime) / 1_000_000 // 转换为毫秒
        Log.d("Performance", "Layout time: $duration ms")
    }
}

class OverdrawMonitor {
    fun checkOverdraw(view: View) {
        view.getLocationInWindow(location)
        val isOverdraw = // 检查重叠区域
        if (isOverdraw) {
            Log.w("Performance", "Overdraw detected")
        }
    }
}