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Coverage for "ChatLayoutDelegate.swift" : 0.00%

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ChatLayout/Classes/Core/ChatLayoutDelegate.swift

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//
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// ChatLayout
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// ChatLayoutDelegate.swift
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// https://github.com/ekazaev/ChatLayout
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//
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// Created by Eugene Kazaev in 2020-2023.
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// Distributed under the MIT license.
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//
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// Become a sponsor:
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// https://github.com/sponsors/ekazaev
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//
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import Foundation
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import UIKit
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/// Represents the point in time when `CollectionViewChatLayout` asks about layout attributes modification.
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public enum InitialAttributesRequestType: Hashable {
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    /// `UICollectionView` initially asks about the layout of an item.
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    case initial
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    /// An item is being invalidated.
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    case invalidation
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}
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/// `CollectionViewChatLayout` delegate
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public protocol ChatLayoutDelegate: AnyObject {
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    /// `CollectionViewChatLayout` will call this method to ask if it should present the header in the current layout.
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    /// - Parameters:
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    ///   - chatLayout: `CollectionViewChatLayout` reference.
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    ///   - sectionIndex: Index of the section.
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    /// - Returns: `Bool`.
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    func shouldPresentHeader(_ chatLayout: CollectionViewChatLayout,
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                             at sectionIndex: Int) -> Bool
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    /// `CollectionViewChatLayout` will call this method to ask if it should present the footer in the current layout.
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    /// - Parameters:
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    ///   - chatLayout: `CollectionViewChatLayout` reference.
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    ///   - sectionIndex: Index of the section.
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    /// - Returns: `Bool`.
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    func shouldPresentFooter(_ chatLayout: CollectionViewChatLayout,
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                             at sectionIndex: Int) -> Bool
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    /// `CollectionViewChatLayout` will call this method to ask what size the item should have.
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    ///
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    /// **NB:**
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    ///
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    /// If you are trying to speed up the layout process by returning exact item sizes in this method -
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    /// do not forget to change `UICollectionReusableView.preferredLayoutAttributesFitting(...)` method and do not
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    /// call `super.preferredLayoutAttributesFitting(...)` there as it will measure the `UIView`
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    /// using Autolayout Engine anyway.
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    ///
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    /// - Parameters:
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    ///   - chatLayout: `CollectionViewChatLayout` reference.
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    ///   - kind: Type of element represented by `ItemKind`.
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    ///   - indexPath: Index path of the item.
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    /// - Returns: `ItemSize`.
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    func sizeForItem(_ chatLayout: CollectionViewChatLayout,
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                     of kind: ItemKind,
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                     at indexPath: IndexPath) -> ItemSize
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    /// `CollectionViewChatLayout` will call this method to ask what type of alignment the item should have.
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    /// - Parameters:
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    ///   - chatLayout: `CollectionViewChatLayout` reference.
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    ///   - kind: Type of element represented by `ItemKind`.
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    ///   - indexPath: Index path of the item.
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    /// - Returns: `ChatItemAlignment`.
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    func alignmentForItem(_ chatLayout: CollectionViewChatLayout,
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                          of kind: ItemKind,
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                          at indexPath: IndexPath) -> ChatItemAlignment
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    ///   Asks the delegate to modify a layout attributes instance so that it represents the initial visual state of an item
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    ///   being inserted.
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    ///
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    ///   The `originalAttributes` instance is a reference type, and therefore can be modified directly.
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    ///
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    /// - Parameters:
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    ///   - chatLayout: `CollectionViewChatLayout` reference.
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    ///   - kind: Type of element represented by `ItemKind`.
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    ///   - indexPath: Index path of the item.
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    ///   - originalAttributes: `ChatLayoutAttributes` that the `CollectionViewChatLayout` is going to use.
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    ///   - state: `InitialAttributesRequestType` instance. Represents when is this method being called.
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    func initialLayoutAttributesForInsertedItem(_ chatLayout: CollectionViewChatLayout,
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                                                of kind: ItemKind,
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                                                at indexPath: IndexPath,
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                                                modifying originalAttributes: ChatLayoutAttributes,
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                                                on state: InitialAttributesRequestType)
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    ///   Asks the delegate to modify a layout attributes instance so that it represents the final visual state of an item
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    ///   being removed via `UICollectionView.deleteSections(_:)`.
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    ///
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    ///   The `originalAttributes` instance is a reference type, and therefore can be modified directly.
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    ///
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    /// - Parameters:
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    ///   - chatLayout: `CollectionViewChatLayout` reference.
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    ///   - kind: Type of element represented by `ItemKind`.
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    ///   - indexPath: Index path of the item.
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    ///   - originalAttributes: `ChatLayoutAttributes` that the `CollectionViewChatLayout` is going to use.
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    func finalLayoutAttributesForDeletedItem(_ chatLayout: CollectionViewChatLayout,
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                                             of kind: ItemKind,
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                                             at indexPath: IndexPath,
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                                             modifying originalAttributes: ChatLayoutAttributes)
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}
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/// Default extension.
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public extension ChatLayoutDelegate {
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    /// Default implementation returns: `false`.
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    func shouldPresentHeader(_ chatLayout: CollectionViewChatLayout,
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                             at sectionIndex: Int) -> Bool {
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        false
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    }
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    /// Default implementation returns: `false`.
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    func shouldPresentFooter(_ chatLayout: CollectionViewChatLayout,
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                             at sectionIndex: Int) -> Bool {
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        false
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    }
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    /// Default implementation returns: `ItemSize.auto`.
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    func sizeForItem(_ chatLayout: CollectionViewChatLayout,
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                     of kind: ItemKind,
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                     at indexPath: IndexPath) -> ItemSize {
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        .auto
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    }
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    /// Default implementation returns: `ChatItemAlignment.fullWidth`.
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    func alignmentForItem(_ chatLayout: CollectionViewChatLayout,
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                          of kind: ItemKind,
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                          at indexPath: IndexPath) -> ChatItemAlignment {
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        .fullWidth
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    }
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    /// Default implementation sets a `ChatLayoutAttributes.alpha` to zero.
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    func initialLayoutAttributesForInsertedItem(_ chatLayout: CollectionViewChatLayout,
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                                                of kind: ItemKind,
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                                                at indexPath: IndexPath,
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                                                modifying originalAttributes: ChatLayoutAttributes,
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                                                on state: InitialAttributesRequestType) {
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        originalAttributes.alpha = 0
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    }
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    /// Default implementation sets a `ChatLayoutAttributes.alpha` to zero.
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    func finalLayoutAttributesForDeletedItem(_ chatLayout: CollectionViewChatLayout,
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                                             of kind: ItemKind,
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                                             at indexPath: IndexPath,
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                                             modifying originalAttributes: ChatLayoutAttributes) {
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        originalAttributes.alpha = 0
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    }
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}