bonus-material-app/src/services/utils/imageUtils.js

// 图片处理工具类
class ImageUtils {
    /**
     * 将图片转换为Base64字符串（相当于Android的bitmapToString）
     * @param {string} imagePath 图片路径
     * @param {number} quality 压缩质量 0-100
     * @returns {Promise<string>} Base64字符串
     */
    static async imageToBase64(imagePath, quality = 50) {
        try {
            // 如果已经是base64格式，直接返回数据部分
            if (imagePath.startsWith("data:image/")) {
                return imagePath.split(",")[1]
            }

            // 如果是纯base64字符串，直接返回
            if (!imagePath.includes("/") && !imagePath.includes("\\")) {
                return imagePath
            }

            // 压缩图片
            const compressResult = await new Promise((resolve, reject) => {
                window.uni.compressImage({
                    src: imagePath,
                    quality: quality,
                    success: resolve,
                    fail: reject,
                })
            })

            // 读取压缩后的文件并转换为base64
            const fileManager = window.uni.getFileSystemManager()
            const base64Data = await new Promise((resolve, reject) => {
                fileManager.readFile({
                    filePath: compressResult.tempFilePath,
                    encoding: "base64",
                    success: (res) => resolve(res.data),
                    fail: reject,
                })
            })

            return base64Data
        } catch (error) {
            console.error("Image to base64 conversion failed:", error)
            throw error
        }
    }

    /**
     * 获取缩放后的图片（相当于Android的getSmallBitmap）
     * @param {string} imagePath 图片路径
     * @param {number} maxWidth 最大宽度
     * @param {number} maxHeight 最大高度
     * @returns {Promise<string>} 处理后的图片路径
     */
    static async getSmallImage(imagePath, maxWidth = 1024, maxHeight = 1024) {
        try {
            return await this.resizeImageWithCanvas(imagePath, maxWidth, maxHeight)
        } catch (error) {
            console.error("Get small image failed:", error)
            // 如果canvas方法失败，尝试使用压缩API
            return await this.fallbackCompress(imagePath, maxWidth, maxHeight)
        }
    }

    /**
     * 使用Canvas调整图片尺寸
     * @param {string} imagePath 图片路径
     * @param {number} maxWidth 最大宽度
     * @param {number} maxHeight 最大高度
     * @returns {Promise<string>} 处理后的图片路径
     */
    static async resizeImageWithCanvas(imagePath, maxWidth, maxHeight) {
        return new Promise((resolve, reject) => {
            // 获取图片信息
            window.uni.getImageInfo({
                src: imagePath,
                success: (imageInfo) => {
                    const { width, height } = imageInfo

                    // 计算缩放比例
                    const scale = this.calculateScale(width, height, maxWidth, maxHeight)
                    const newWidth = Math.floor(width * scale)
                    const newHeight = Math.floor(height * scale)

                    // 如果不需要缩放，直接返回原图
                    if (scale >= 1) {
                        resolve(imagePath)
                        return
                    }

                    // 创建canvas上下文
                    const canvasId = "imageProcessCanvas_" + Date.now()
                    const ctx = window.uni.createCanvasContext(canvasId)

                    // 绘制缩放后的图片
                    ctx.drawImage(imagePath, 0, 0, newWidth, newHeight)
                    ctx.draw(false, () => {
                        // 导出canvas为临时文件
                        window.uni.canvasToTempFilePath({
                            canvasId: canvasId,
                            fileType: "jpg",
                            quality: 0.8,
                            success: (res) => {
                                resolve(res.tempFilePath)
                            },
                            fail: reject,
                        })
                    })
                },
                fail: reject,
            })
        })
    }

    /**
     * 备用压缩方法
     * @param {string} imagePath 图片路径
     * @param {number} maxWidth 最大宽度
     * @param {number} maxHeight 最大高度
     * @returns {Promise<string>} 处理后的图片路径
     */
    static async fallbackCompress(imagePath, maxWidth, maxHeight) {
        return new Promise((resolve, reject) => {
            window.uni.compressImage({
                src: imagePath,
                quality: 80,
                compressedWidth: maxWidth,
                compressedHeight: maxHeight,
                success: (res) => resolve(res.tempFilePath),
                fail: reject,
            })
        })
    }

    /**
     * 计算缩放比例（相当于Android的calculateInSampleSize）
     * @param {number} originalWidth 原始宽度
     * @param {number} originalHeight 原始高度
     * @param {number} maxWidth 最大宽度
     * @param {number} maxHeight 最大高度
     * @returns {number} 缩放比例
     */
    static calculateScale(originalWidth, originalHeight, maxWidth, maxHeight) {
        if (originalWidth <= maxWidth && originalHeight <= maxHeight) {
            return 1 // 不需要缩放
        }

        const widthScale = maxWidth / originalWidth
        const heightScale = maxHeight / originalHeight

        // 选择较小的缩放比例，确保图片完全适应限制尺寸
        return Math.min(widthScale, heightScale)
    }

    /**
     * 批量处理图片
     * @param {string} imagePath 图片路径
     * @param {object} options 处理选项
     * @returns {Promise<string>} 处理后的Base64字符串
     */
    static async processImage(imagePath, options = {}) {
        const { maxWidth = 1024, maxHeight = 1024, quality = 50, outputFormat = "base64" } = options

        try {
            // 1. 先缩放图片
            const resizedImagePath = await this.getSmallImage(imagePath, maxWidth, maxHeight)

            // 2. 根据输出格式返回结果
            if (outputFormat === "base64") {
                return await this.imageToBase64(resizedImagePath, quality)
            } else {
                return resizedImagePath
            }
        } catch (error) {
            console.error("Process image failed:", error)
            throw error
        }
    }

    /**
     * 获取图片尺寸信息
     * @param {string} imagePath 图片路径
     * @returns {Promise<object>} 图片信息
     */
    static async getImageInfo(imagePath) {
        return new Promise((resolve, reject) => {
            window.uni.getImageInfo({
                src: imagePath,
                success: resolve,
                fail: reject,
            })
        })
    }
}

export default ImageUtils