154 lines
4.6 KiB
Swift
154 lines
4.6 KiB
Swift
//
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// IMImageContainerLogic.swift
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// Crush
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//
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// Created by Leon on 2025/8/22.
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//
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import UIKit
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/// 设计稿中的常量
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struct ImageDisplayConstants {
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var W_MAX: CGFloat
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var H_MAX: CGFloat
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var W_MIN: CGFloat
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var H_MIN: CGFloat
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var RATIO_MIN: CGFloat
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var RATIO_MAX: CGFloat
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static let `default` = ImageDisplayConstants(
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W_MAX: 372,
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H_MAX: 372,
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W_MIN: 48,
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H_MIN: 48,
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RATIO_MIN: 9.0 / 21.0,
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RATIO_MAX: 21.0 / 9.0
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)
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}
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/// 计算结果
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struct CalculatedImageSize {
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var width: CGFloat
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var height: CGFloat
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var type: ImageType
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var ratio: CGFloat
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}
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/// 图片类型
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enum ImageType: String {
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case large
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case small
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case tiny
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}
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/// 工具类
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class ImageDisplayLogic {
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/// 限制数值范围
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private static func clamp(_ value: CGFloat, min: CGFloat, max: CGFloat) -> CGFloat {
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return Swift.min(Swift.max(value, min), max)
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}
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/// 判断图片类型
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static func getImageType(originalWidth: CGFloat,
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originalHeight: CGFloat,
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constants: ImageDisplayConstants = .default) -> ImageType {
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let W_MAX = constants.W_MAX
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let H_MAX = constants.H_MAX
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let W_MIN = constants.W_MIN
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let H_MIN = constants.H_MIN
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// A. 大图
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let isLargeImage = (
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(originalWidth >= W_MAX && originalHeight > (9.0/21.0) * H_MAX) ||
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(originalHeight >= H_MAX && originalWidth > (9.0/21.0) * W_MAX)
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)
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if isLargeImage { return .large }
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// C. 超小图
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let isTinyImage = (originalWidth < W_MIN || originalHeight < H_MIN)
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if isTinyImage { return .tiny }
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// B. 小图
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return .small
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}
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/// 计算最终展示比例
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static func calculateDisplayRatio(originalWidth: CGFloat,
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originalHeight: CGFloat,
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imageType: ImageType,
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constants: ImageDisplayConstants = .default) -> CGFloat {
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let originalRatio = originalWidth / originalHeight
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if imageType == .large {
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return clamp(originalRatio, min: constants.RATIO_MIN, max: constants.RATIO_MAX)
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} else {
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return originalRatio
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}
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}
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/// 计算最终展示尺寸
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static func calculateImageDisplaySize(originalWidth: CGFloat,
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originalHeight: CGFloat,
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constants: ImageDisplayConstants = .default) -> CalculatedImageSize {
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let W_MAX = constants.W_MAX
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let H_MAX = constants.H_MAX
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let W_MIN = constants.W_MIN
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let H_MIN = constants.H_MIN
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// 1. 类型
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let imageType = getImageType(originalWidth: originalWidth, originalHeight: originalHeight, constants: constants)
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// 2. 比例
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let displayRatio = calculateDisplayRatio(originalWidth: originalWidth, originalHeight: originalHeight, imageType: imageType, constants: constants)
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// 3. 最终尺寸
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var finalWidth: CGFloat = 0
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var finalHeight: CGFloat = 0
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switch imageType {
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case .large:
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if displayRatio >= 1 {
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// 宽图
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finalWidth = W_MAX
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finalHeight = W_MAX / displayRatio
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} else {
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// 高图
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finalHeight = H_MAX
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finalWidth = H_MAX * displayRatio
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}
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case .small:
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if displayRatio >= 1 {
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finalHeight = originalHeight
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finalWidth = min(originalWidth, W_MAX)
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} else {
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finalWidth = originalWidth
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finalHeight = min(originalHeight, H_MAX)
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}
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case .tiny:
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if displayRatio >= 1 {
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finalHeight = H_MIN
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finalWidth = min(H_MIN * displayRatio, W_MAX)
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} else {
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finalWidth = W_MIN
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finalHeight = min(W_MIN / displayRatio, H_MAX)
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}
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}
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return CalculatedImageSize(
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width: round(finalWidth),
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height: round(finalHeight),
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type: imageType,
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ratio: displayRatio
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)
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}
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/// 根据容器宽度调整常量
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static func adjustConstants(for containerWidth: CGFloat) -> ImageDisplayConstants {
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let maxSize = min(containerWidth * 0.5, 372)
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var c = ImageDisplayConstants.default
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c.W_MAX = maxSize
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c.H_MAX = maxSize
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return c
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}
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}
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