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Commit c1a22014 authored by Mike Schneider's avatar Mike Schneider
Browse files

Add ViewMotionBuilderContext (and material spring definitions) 

Exposes the standard / expressive motion theme springs, by copying the
definitions from the compose world.

Added a test to guarantee the tokens remain in sync with what Material
publishes through Android.

Bug: 389081766
Test: ViewMotionBuilderContextTest
Flag: EXEMPT not yet used
Change-Id: I60a88905f8c13805cea7ecde78367aac4aa4199d
parent 21e72d19

mechanics/src/com/android/mechanics/spec/builder/MotionBuilderContext.kt

+4 −0
Original line number Diff line number Diff line
@@ -31,6 +31,10 @@ import com.android.mechanics.spring.SpringParameters 
 * Device / scheme specific context for building motion specs.

 *

 * See go/motion-system.

 *

 * @see rememberMotionBuilderContext for Compose

 * @see standardViewMotionBuilderContext for Views

 * @see expressiveViewMotionBuilderContext for Views

 */

interface MotionBuilderContext : Density {

    /**

mechanics/src/com/android/mechanics/view/ViewMotionBuilderContext.kt

0 → 100644
+127 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2025 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.mechanics.view



import android.content.Context

import androidx.compose.ui.unit.Density

import com.android.mechanics.spec.builder.MaterialSprings

import com.android.mechanics.spec.builder.MotionBuilderContext

import com.android.mechanics.spring.SpringParameters

import com.android.mechanics.view.ViewMaterialSprings.Default



/**

 * Creates a [MotionBuilderContext] using the **standard** motion spec.

 *

 * See go/motion-system.

 *

 * @param context The context to derive the density from.

 */

fun standardViewMotionBuilderContext(context: Context): MotionBuilderContext {

    return standardViewMotionBuilderContext(context.resources.displayMetrics.density)

}



/**

 * Creates a [MotionBuilderContext] using the **standard** motion spec.

 *

 * See go/motion-system.

 *

 * @param density The density of the display, as a scaling factor for the dp to px conversion.

 */

fun standardViewMotionBuilderContext(density: Float): MotionBuilderContext {

    return with(ViewMaterialSprings.Default) {

        ViewMotionBuilderContext(Spatial, Effects, Density(density))

    }

}



/**

 * Creates a [MotionBuilderContext] using the **expressive** motion spec.

 *

 * See go/motion-system.

 *

 * @param context The context to derive the density from.

 */

fun expressiveViewMotionBuilderContext(context: Context): MotionBuilderContext {

    return expressiveViewMotionBuilderContext(context.resources.displayMetrics.density)

}



/**

 * Creates a [MotionBuilderContext] using the **expressive** motion spec.

 *

 * See go/motion-system.

 *

 * @param density The density of the display, as a scaling factor for the dp to px conversion.

 */

fun expressiveViewMotionBuilderContext(density: Float): MotionBuilderContext {

    return with(ViewMaterialSprings.Expressive) {

        ViewMotionBuilderContext(Spatial, Effects, Density(density))

    }

}



/**

 * Material motion system spring definitions.

 *

 * See go/motion-system.

 *

 * NOTE: These are only defined here since material spring parameters are not available for View

 * based APIs. There might be a delay in updating these values, should the material tokens be

 * updated in the future.

 *

 * @see rememberMotionBuilderContext for Compose

 */

object ViewMaterialSprings {

    object Default {

        val Spatial =

            MaterialSprings(

                SpringParameters(700.0f, 0.9f),

                SpringParameters(1400.0f, 0.9f),

                SpringParameters(300.0f, 0.9f),

                MotionBuilderContext.StableThresholdSpatial,

            )



        val Effects =

            MaterialSprings(

                SpringParameters(1600.0f, 1.0f),

                SpringParameters(3800.0f, 1.0f),

                SpringParameters(800.0f, 1.0f),

                MotionBuilderContext.StableThresholdEffects,

            )

    }



    object Expressive {

        val Spatial =

            MaterialSprings(

                SpringParameters(380.0f, 0.8f),

                SpringParameters(800.0f, 0.6f),

                SpringParameters(200.0f, 0.8f),

                MotionBuilderContext.StableThresholdSpatial,

            )



        val Effects =

            MaterialSprings(

                SpringParameters(1600.0f, 1.0f),

                SpringParameters(3800.0f, 1.0f),

                SpringParameters(800.0f, 1.0f),

                MotionBuilderContext.StableThresholdEffects,

            )

    }

}



internal class ViewMotionBuilderContext(

    override val spatial: MaterialSprings,

    override val effects: MaterialSprings,

    density: Density,

) : MotionBuilderContext, Density by density

mechanics/tests/src/com/android/mechanics/view/ViewMotionBuilderContextTest.kt

0 → 100644
+77 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2025 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.

 */



@file:OptIn(ExperimentalMaterial3ExpressiveApi::class)



package com.android.mechanics.view



import android.content.Context

import androidx.compose.material3.ExperimentalMaterial3ExpressiveApi

import androidx.compose.material3.MaterialTheme

import androidx.compose.material3.MotionScheme

import androidx.compose.ui.platform.LocalContext

import androidx.compose.ui.test.junit4.createComposeRule

import androidx.test.ext.junit.runners.AndroidJUnit4

import com.android.mechanics.spec.builder.MotionBuilderContext

import com.android.mechanics.spec.builder.rememberMotionBuilderContext

import com.google.common.truth.Truth

import org.junit.Rule

import org.junit.Test

import org.junit.runner.RunWith



@RunWith(AndroidJUnit4::class)

class ViewMotionBuilderContextTest {



    @get:Rule(order = 0) val rule = createComposeRule()



    @Test

    fun materialSprings_standardScheme_matchesComposeDefinition() {

        lateinit var viewContext: Context

        lateinit var composeReference: MotionBuilderContext



        rule.setContent {

            viewContext = LocalContext.current

            MaterialTheme(motionScheme = MotionScheme.standard()) {

                composeReference = rememberMotionBuilderContext()

            }

        }



        val underTest = standardViewMotionBuilderContext(viewContext)



        Truth.assertThat(underTest.density).isEqualTo(composeReference.density)

        Truth.assertThat(underTest.spatial).isEqualTo(composeReference.spatial)

        Truth.assertThat(underTest.effects).isEqualTo(composeReference.effects)

    }



    @Test

    fun materialSprings_expressiveScheme_matchesComposeDefinition() {

        lateinit var viewContext: Context

        lateinit var composeReference: MotionBuilderContext



        rule.setContent {

            viewContext = LocalContext.current

            MaterialTheme(motionScheme = MotionScheme.expressive()) {

                composeReference = rememberMotionBuilderContext()

            }

        }



        val underTest = expressiveViewMotionBuilderContext(viewContext)



        Truth.assertThat(underTest.density).isEqualTo(composeReference.density)

        Truth.assertThat(underTest.spatial).isEqualTo(composeReference.spatial)

        Truth.assertThat(underTest.effects).isEqualTo(composeReference.effects)

    }

}