FontFamilyTypefaceAdapter.kt
/*
* Copyright 2021 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.text.font
/**
* Used by [FontFamilyResolverImpl] to dispatch requests for either [FontListFontFamily] resolution
* or delegate all other [FontFamily] requests to [PlatformFontFamilyTypefaceAdapter].
*
* - [FontListFontFamily] will be resolved by [FontListFontFamilyTypefaceAdapter]
* - All other [FontFamily] will be resolved by [PlatformFontFamilyTypefaceAdapter]
*/
internal interface FontFamilyTypefaceAdapter {
/**
* Resolve a typefaceRequest to a typeface result.
*
* Results are [TypefaceResult.Async] only if a font fallback chain and reflow is required,
* otherwise return [TypefaceResult.Immutable].
*
* Immutable results may be cached forever without any potential for change.
*
* Async results must update their caller via writes to the state object, and should ensure that
* [onAsyncCompletion] is called when the font resolution completes when an immutable final
* result is available to allow caches to update.
*
* @param typefaceRequest unique description of this typeface request
* @param platformFontLoader font loader used for loading typefaces from [Font] descriptors
* @param onAsyncCompletion will be called (on an arbitrary thread) when
* [FontLoadingStrategy.Async] fonts reach their final resolved state, may be called prior to
* resolve returning
* @return result of typeface lookup.
*/
fun resolve(
typefaceRequest: TypefaceRequest,
platformFontLoader: PlatformFontLoader,
onAsyncCompletion: ((TypefaceResult.Immutable) -> Unit),
createDefaultTypeface: (TypefaceRequest) -> Any
): TypefaceResult?
}