| /* |
| * Copyright 2019 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.ui.core |
| |
| import androidx.ui.unit.Density |
| import androidx.ui.unit.IntPx |
| import androidx.ui.unit.IntPxPosition |
| import androidx.ui.unit.IntPxSize |
| |
| /** |
| * A [Modifier.Element] that changes the way a UI component is measured and laid out. |
| */ |
| interface LayoutModifier : Modifier.Element { |
| /** |
| * Modifies [constraints] for performing measurement of the modified layout element. |
| */ |
| fun Density.modifyConstraints(constraints: Constraints): Constraints = constraints |
| |
| /** |
| * Returns the container size of a modified layout element given the original container |
| * measurement [constraints] and the measured [childSize]. |
| */ |
| fun Density.modifySize(constraints: Constraints, childSize: IntPxSize): IntPxSize = |
| childSize |
| |
| /** |
| * Determines the modified minimum intrinsic width of [measurable]. |
| * See [Measurable.minIntrinsicWidth]. |
| */ |
| fun Density.minIntrinsicWidthOf(measurable: Measurable, height: IntPx): IntPx { |
| val constraints = Constraints(maxHeight = height) |
| val layoutWidth = measurable.minIntrinsicWidth(modifyConstraints(constraints).maxHeight) |
| return modifySize(constraints, IntPxSize(layoutWidth, height)).width |
| } |
| |
| /** |
| * Determines the modified maximum intrinsic width of [measurable]. |
| * See [Measurable.maxIntrinsicWidth]. |
| */ |
| fun Density.maxIntrinsicWidthOf(measurable: Measurable, height: IntPx): IntPx { |
| val constraints = Constraints(maxHeight = height) |
| val layoutWidth = measurable.maxIntrinsicWidth(modifyConstraints(constraints).maxHeight) |
| return modifySize(constraints, IntPxSize(layoutWidth, height)).width |
| } |
| |
| /** |
| * Determines the modified minimum intrinsic height of [measurable]. |
| * See [Measurable.minIntrinsicHeight]. |
| */ |
| fun Density.minIntrinsicHeightOf(measurable: Measurable, width: IntPx): IntPx { |
| val constraints = Constraints(maxWidth = width) |
| val layoutHeight = measurable.minIntrinsicHeight(modifyConstraints(constraints).maxWidth) |
| return modifySize(constraints, IntPxSize(width, layoutHeight)).height |
| } |
| |
| /** |
| * Determines the modified maximum intrinsic height of [measurable]. |
| * See [Measurable.maxIntrinsicHeight]. |
| */ |
| fun Density.maxIntrinsicHeightOf(measurable: Measurable, width: IntPx): IntPx { |
| val constraints = Constraints(maxWidth = width) |
| val layoutHeight = measurable.maxIntrinsicHeight(modifyConstraints(constraints).maxWidth) |
| return modifySize(constraints, IntPxSize(width, layoutHeight)).height |
| } |
| |
| /** |
| * Returns the position of a modified child of size [childSize] within a container of |
| * size [containerSize]. |
| */ |
| fun Density.modifyPosition( |
| childSize: IntPxSize, |
| containerSize: IntPxSize |
| ): IntPxPosition = IntPxPosition.Origin |
| |
| /** |
| * Returns the modified position of [line] given its unmodified [value]. |
| */ |
| fun Density.modifyAlignmentLine( |
| line: AlignmentLine, |
| value: IntPx? |
| ): IntPx? = value |
| } |