| /* |
| * 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.ui.core |
| |
| import androidx.compose.Immutable |
| import androidx.compose.Stable |
| import androidx.ui.geometry.Size |
| import kotlin.math.max |
| import kotlin.math.min |
| |
| private const val OriginalScale = 1.0f |
| |
| /** |
| * Represents a rule to apply to scale a source rectangle to be inscribed into a destination |
| */ |
| @Stable |
| interface ContentScale { |
| |
| /** |
| * Computes the scale factor to apply to both dimensions in order to fit the source |
| * appropriately with the given destination size |
| */ |
| fun scale(srcSize: Size, dstSize: Size): Float |
| |
| /** |
| * Companion object containing commonly used [ContentScale] implementations |
| */ |
| companion object { |
| |
| /** |
| * Scale the source uniformly (maintaining the source's aspect ratio) so that both |
| * dimensions (width and height) of the source will be equal to or larger than the |
| * corresponding dimension of the destination. |
| * |
| * This [ContentScale] implementation in combination with usage of [Alignment.Center] |
| * provides similar behavior to [android.widget.ImageView.ScaleType.CENTER_CROP] |
| */ |
| @Stable |
| val Crop = object : ContentScale { |
| override fun scale(srcSize: Size, dstSize: Size): Float = |
| computeFillMaxDimension(srcSize, dstSize) |
| } |
| |
| /** |
| * Scale the source uniformly (maintaining the source's aspect ratio) so that both |
| * dimensions (width and height) of the source will be equal to or less than the |
| * corresponding dimension of the destination |
| * |
| * This [ContentScale] implementation in combination with usage of [Alignment.Center] |
| * provides similar behavior to [android.widget.ImageView.ScaleType.FIT_CENTER] |
| */ |
| @Stable |
| val Fit = object : ContentScale { |
| override fun scale(srcSize: Size, dstSize: Size): Float = |
| computeFillMinDimension(srcSize, dstSize) |
| } |
| |
| /** |
| * Scale the source maintaining the aspect ratio so that the bounds match the destination |
| * height. This can cover a larger area than the destination if the height is larger than |
| * the width. |
| */ |
| @Stable |
| val FillHeight = object : ContentScale { |
| override fun scale(srcSize: Size, dstSize: Size): Float = |
| computeFillHeight(srcSize, dstSize) |
| } |
| |
| /** |
| * Scale the source maintaining the aspect ratio so that the bounds match the |
| * destination width. This can cover a larger area than the destination if the width is |
| * larger than the height. |
| */ |
| @Stable |
| val FillWidth = object : ContentScale { |
| override fun scale(srcSize: Size, dstSize: Size): Float = |
| computeFillWidth(srcSize, dstSize) |
| } |
| |
| /** |
| * Scale the source to maintain the aspect ratio to be inside the destination bounds |
| * if the source is larger than the destination. If the source is smaller than or equal |
| * to the destination in both dimensions, this behaves similarly to [None]. This will |
| * always be contained within the bounds of the destination. |
| * |
| * This [ContentScale] implementation in combination with usage of [Alignment.Center] |
| * provides similar behavior to [android.widget.ImageView.ScaleType.CENTER_INSIDE] |
| */ |
| @Stable |
| val Inside = object : ContentScale { |
| override fun scale(srcSize: Size, dstSize: Size): Float = |
| if (srcSize.width <= dstSize.width && srcSize.height <= dstSize.height) { |
| OriginalScale |
| } else { |
| computeFillMinDimension(srcSize, dstSize) |
| } |
| } |
| |
| /** |
| * Do not apply any scaling to the source |
| */ |
| @Stable |
| val None = FixedScale(OriginalScale) |
| } |
| } |
| |
| /** |
| * [ContentScale] implementation that always scales the dimension by the provided |
| * fixed floating point value |
| */ |
| @Immutable |
| data class FixedScale(val value: Float) : ContentScale { |
| override fun scale(srcSize: Size, dstSize: Size): Float = value |
| } |
| |
| private fun computeFillMaxDimension(srcSize: Size, dstSize: Size): Float { |
| val widthScale = computeFillWidth(srcSize, dstSize) |
| val heightScale = computeFillHeight(srcSize, dstSize) |
| return max(widthScale, heightScale) |
| } |
| |
| private fun computeFillMinDimension(srcSize: Size, dstSize: Size): Float { |
| val widthScale = computeFillWidth(srcSize, dstSize) |
| val heightScale = computeFillHeight(srcSize, dstSize) |
| return min(widthScale, heightScale) |
| } |
| |
| private fun computeFillWidth(srcSize: Size, dstSize: Size): Float = |
| dstSize.width / srcSize.width |
| |
| private fun computeFillHeight(srcSize: Size, dstSize: Size): Float = |
| dstSize.height / srcSize.height |