Shadow.kt
/*
* Copyright 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 androidx.compose.ui.draw
import androidx.compose.runtime.Stable
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.RectangleShape
import androidx.compose.ui.graphics.Shape
import androidx.compose.ui.graphics.graphicsLayer
import androidx.compose.ui.platform.debugInspectorInfo
import androidx.compose.ui.platform.inspectable
import androidx.compose.ui.unit.Dp
import androidx.compose.ui.unit.dp
/**
* Creates a [graphicsLayer] that draws a shadow. The [elevation] defines the visual
* depth of the physical object. The physical object has a shape specified by [shape].
*
* If the passed [shape] is concave the shadow will not be drawn on Android versions less than 10.
*
* Note that [elevation] is only affecting the shadow size and doesn't change the drawing order.
* Use a [androidx.compose.ui.zIndex] modifier if you want to draw the elements with larger
* [elevation] after all the elements with a smaller one.
*
* Usage of this API renders this composable into a separate graphics layer
* @see graphicsLayer
*
* Example usage:
*
* @sample androidx.compose.ui.samples.ShadowSample
*
* @param elevation The elevation for the shadow in pixels
* @param shape Defines a shape of the physical object
* @param clip When active, the content drawing clips to the shape.
*/
@Stable
fun Modifier.shadow(
elevation: Dp,
shape: Shape = RectangleShape,
clip: Boolean = elevation > 0.dp
) = if (elevation > 0.dp || clip) {
inspectable(
inspectorInfo = debugInspectorInfo {
name = "shadow"
properties["elevation"] = elevation
properties["shape"] = shape
properties["clip"] = clip
}
) {
graphicsLayer {
this.shadowElevation = elevation.toPx()
this.shape = shape
this.clip = clip
}
}
} else {
this
}