[Adaptive] Add calculateWindowSize methods

[alexvanyo]

Adds three methods (with each other as implementations):

• calculateWindowSize
• calculateWindowBounds
• calculateWindowMetrics

calculateWindowSize provides a direct replacement for LocalConfiguration.current.screenWidthDp and LocalConfiguration.screenHeightDp that is more accurate and more useful, using the variant of WindowMetricsCalculator.computeCurrentWindowMetrics that takes a @UiContext Context introduced in 1.1.x.

[alexvanyo]

This requires a @UiContext Context, and it's not clear if LocalContext.current is guaranteed to be a @UiContext, although I suspect it should be.

[Dramaga11]

/*

• Copyright 2023 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

•  https://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.google.accompanist.adaptive

import android.content.res.Configuration
import androidx.annotation.UiContext
import androidx.compose.runtime.Composable
import androidx.compose.ui.graphics.toComposeIntRect
import androidx.compose.ui.platform.LocalConfiguration
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.platform.LocalDensity
import androidx.compose.ui.unit.DpRect
import androidx.compose.ui.unit.DpSize
import androidx.compose.ui.unit.size
import androidx.window.layout.WindowMetrics
import androidx.window.layout.WindowMetricsCalculator

/**

• Calculates the current window size from the underlying [LocalContext].
• The value of [LocalContext] must be a [UiContext] (or unwrappable to a [UiContext]), to properly
• retrieve the window metrics values. For example, if there are multiple displayed windows
• across 1 or more physical displays, there could be multiple possible window sizes.
• This method is preferred over using LocalConfiguration.current.screenWidthDp and
• LocalConfiguration.current.screenHeightDp to retrieve the window size for multiple reasons:
• • [Configuration.screenWidthDp] and [Configuration.screenHeightDp] are integers. However, the
• density may be non-integral, which means that the true width and height of the window (in dps)
• can be non-integral. When this occurs, the reported [Configuration.screenWidthDp] and
• [Configuration.screenHeightDp] are necessarily rounded from the true width and height of the
• window. If these values are then used to size some component, the second rounding to pixels
• can result in accumulated rounding errors, and the size can be off by one or more pixels.
• • [Configuration.screenWidthDp] and [Configuration.screenHeightDp] do not correspond to the
• width and height of the window directly. Instead, they can be smaller than the width and height
• by a certain amount of insets.
  */
  @composable
  public fun calculateWindowSize(): DpSize = calculateWindowBounds().size

/**

• Calculates the current window bounds from the underlying [LocalContext].
• The value of [LocalContext] must be a [UiContext] (or unwrappable to a [UiContext]), to properly
• retrieve the window metrics values.
  */
  @composable
  public fun calculateWindowBounds(): DpRect {
  val density = LocalDensity.current
  val metrics = calculateWindowMetrics()
  val bounds = metrics.bounds.toComposeIntRect()
  return with(density) {
  DpRect(
  bounds.left.toDp(),
  bounds.top.toDp(),
  bounds.right.toDp(),
  bounds.bottom.toDp(),
  )
  }
  }

/**

• Calculates the current window metrics from the underlying [LocalContext].
• The value of [LocalContext] must be a [UiContext] (or unwrappable to a [UiContext]), to properly
• retrieve the window metrics values.
  */
  @composable
  public fun calculateWindowMetrics(): WindowMetrics {
  // Observe view configuration changes and recalculate the size class on each change. We can't
  // use Activity#onConfigurationChanged as this will sometimes fail to be called on different
  // API levels, hence why this function needs to be @composable so we can observe the
  // ComposeView's configuration changes.
  LocalConfiguration.current
  val context = LocalContext.current
  return WindowMetricsCalculator.getOrCreate().computeCurrentWindowMetrics(context)