/*
* 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
import androidx.compose.runtime.Immutable
import androidx.compose.runtime.Stable
import androidx.compose.ui.graphics.RectangleShape
import androidx.compose.ui.graphics.Shape
import androidx.compose.ui.platform.InspectableValue
import androidx.compose.ui.platform.ValueElement
import androidx.compose.ui.util.annotation.FloatRange
import androidx.compose.ui.util.packFloats
import androidx.compose.ui.util.unpackFloat1
import androidx.compose.ui.util.unpackFloat2
/**
* Constructs a [TransformOrigin] from the given fractional values from the Layer's
* width and height
*/
@Suppress("NOTHING_TO_INLINE")
inline fun TransformOrigin(pivotFractionX: Float, pivotFractionY: Float): TransformOrigin =
TransformOrigin(packFloats(pivotFractionX, pivotFractionY))
/**
* A two-dimensional position represented as a fraction of the Layer's width and height
*/
@OptIn(ExperimentalUnsignedTypes::class)
@Immutable
inline class TransformOrigin(@PublishedApi internal val packedValue: Long) {
/**
* Return the position along the x-axis that should be used as the
* origin for rotation and scale transformations. This is represented as a fraction
* of the width of the content. A value of 0.5f represents the midpoint between the left
* and right bounds of the content
*/
val pivotFractionX: Float
get() = unpackFloat1(packedValue)
/**
* Return the position along the y-axis that should be used as the
* origin for rotation and scale transformations. This is represented as a fraction
* of the height of the content. A value of 0.5f represents the midpoint between the top
* and bottom bounds of the content
*/
val pivotFractionY: Float
get() = unpackFloat2(packedValue)
/**
* Returns a copy of this TransformOrigin instance optionally overriding the
* pivotFractionX or pivotFractionY parameter
*/
fun copy(
pivotFractionX: Float = this.pivotFractionX,
pivotFractionY: Float = this.pivotFractionY
) = TransformOrigin(pivotFractionX, pivotFractionY)
companion object {
/**
* [TransformOrigin] constant to indicate that the center of the content should
* be used for rotation and scale transformations
*/
val Center = TransformOrigin(0.5f, 0.5f)
}
}
/**
* A [Modifier.Element] that makes content draw into a draw layer. The draw
* layer can be invalidated separately from parents. A [drawLayer] should be used when the content
* updates independently from anything above it to minimize the invalidated content.
*
* A [DrawLayerModifier] can also be used to apply effects to content, such as
* scaling ([scaleX], [scaleY]), rotation ([rotationX], [rotationY], [rotationZ]),
* opacity ([alpha]), shadow ([shadowElevation], [shape]), and clipping ([clip], [shape]).
* Changes to most properties will not invalidate the contents. If set up correctly,
* animating these properties can avoid composition, layout, and drawing.
*
* @sample androidx.compose.ui.samples.AnimateFadeIn
* @see drawLayer
*/
interface DrawLayerModifier : Modifier.Element {
/**
* The horizontal scale of the drawn area. This would typically default to `1`.
*/
val scaleX: Float get() = 1f
/**
* The vertical scale of the drawn area. This would typically default to `1`.
*/
val scaleY: Float get() = 1f
/**
* The alpha of the drawn area. Setting this to something other than `1`
* will cause the drawn contents to be translucent and setting it to `0` will
* cause it to be fully invisible.
*/
@get:FloatRange(from = 0.0, to = 1.0)
val alpha: Float
get() = 1f
/**
* Horizontal pixel offset of the layer relative to its left bound
*/
val translationX: Float get() = 0f
/**
* Vertical pixel offset of the layer relative to its top bound
*/
val translationY: Float get() = 0f
/**
* Sets the elevation for the shadow in pixels. With the [shadowElevation] > 0f and
* [shape] set, a shadow is produced.
*/
@get:FloatRange(from = 0.0, to = 3.4e38 /* POSITIVE_INFINITY */)
val shadowElevation: Float
get() = 0f
/**
* The rotation of the contents around the horizontal axis in degrees.
*/
@get:FloatRange(from = 0.0, to = 360.0)
val rotationX: Float
get() = 0f
/**
* The rotation of the contents around the vertical axis in degrees.
*/
@get:FloatRange(from = 0.0, to = 360.0)
val rotationY: Float
get() = 0f
/**
* The rotation of the contents around the Z axis in degrees.
*/
@get:FloatRange(from = 0.0, to = 360.0)
val rotationZ: Float
get() = 0f
/**
* Offset percentage along the x and y axis for which contents are rotated and scaled.
* The default value of 0.5f, 0.5f indicates the pivot point will be at the midpoint of the
* left and right as well as the top and bottom bounds of the layer
*/
val transformOrigin: TransformOrigin get() = TransformOrigin.Center
/**
* The [Shape] of the layer. When [shadowElevation] is non-zero a shadow is produced using
* this [shape]. When [clip] is `true` contents will be clipped to this [shape].
* When clipping, the content will be redrawn when the [shape] changes.
*/
val shape: Shape get() = RectangleShape
/**
* Set to `true` to clip the content to the [shape].
*/
val clip: Boolean get() = false
}
private data class SimpleDrawLayerModifier(
override val scaleX: Float,
override val scaleY: Float,
override val alpha: Float,
override val translationX: Float,
override val translationY: Float,
override val shadowElevation: Float,
override val rotationX: Float,
override val rotationY: Float,
override val rotationZ: Float,
override val transformOrigin: TransformOrigin,
override val shape: Shape,
override val clip: Boolean
) : DrawLayerModifier, InspectableValue {
override val nameFallback: String = "drawLayer"
override val inspectableElements: Sequence<ValueElement>
get() = sequenceOf(
ValueElement("scaleX", scaleX),
ValueElement("scaleY", scaleY),
ValueElement("alpha", alpha),
ValueElement("translationX", translationX),
ValueElement("translationY", translationY),
ValueElement("shadowElevation", shadowElevation),
ValueElement("rotationX", rotationX),
ValueElement("rotationY", rotationY),
ValueElement("rotationZ", rotationZ),
ValueElement("transformOrigin", transformOrigin),
ValueElement("shape", shape),
ValueElement("clip", clip)
)
}
/**
* Creates a [DrawLayerModifier] to have all content will be drawn into a new draw layer. The draw
* layer can be invalidated separately from parents. A [drawLayer] should be used when the content
* updates independently from anything above it to minimize the invalidated content.
*
* [drawLayer] can also be used to apply effects to content, such as scaling ([scaleX], [scaleY]),
* rotation ([rotationX], [rotationY], [rotationZ]), opacity ([alpha]), shadow
* ([shadowElevation], [shape]), and clipping ([clip], [shape]).
*
* @sample androidx.compose.ui.samples.ChangeOpacity
*
* @param scaleX [DrawLayerModifier.scaleX]
* @param scaleY [DrawLayerModifier.scaleY]
* @param alpha [DrawLayerModifier.alpha]
* @param shadowElevation [DrawLayerModifier.shadowElevation]
* @param rotationX [DrawLayerModifier.rotationX]
* @param rotationY [DrawLayerModifier.rotationY]
* @param rotationZ [DrawLayerModifier.rotationZ]
* @param shape [DrawLayerModifier.shape]
* @param clip [DrawLayerModifier.clip]
*/
@Stable
fun Modifier.drawLayer(
scaleX: Float = 1f,
scaleY: Float = 1f,
alpha: Float = 1f,
translationX: Float = 0f,
translationY: Float = 0f,
shadowElevation: Float = 0f,
rotationX: Float = 0f,
rotationY: Float = 0f,
rotationZ: Float = 0f,
transformOrigin: TransformOrigin = TransformOrigin.Center,
shape: Shape = RectangleShape,
clip: Boolean = false
) = this.then(
SimpleDrawLayerModifier(
scaleX = scaleX,
scaleY = scaleY,
alpha = alpha,
translationX = translationX,
translationY = translationY,
shadowElevation = shadowElevation,
rotationX = rotationX,
rotationY = rotationY,
rotationZ = rotationZ,
transformOrigin = transformOrigin,
shape = shape,
clip = clip
)
)