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@@ -0,0 +1,99 @@
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+export default class ImageCompress {
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+ constructor(file, fileSize, maxWH = 1920) {
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+ this.file = file
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+ this.fileSize = fileSize
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+ this.maxWH = maxWH // 最大长宽
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+ }
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+
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+ compress() {
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+ // 压缩
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+ const fileType = this.file.type
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+ const fileSize = this.file.size / 1024
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+ return new Promise(resolve => {
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+ const reader = new FileReader();
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+ reader.readAsDataURL(this.file);
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+ reader.onload = () => {
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+ const canvas = document.createElement('canvas');
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+ const img = document.createElement('img');
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+ img.src = reader.result;
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+ img.onload = () => {
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+ const ctx = canvas.getContext('2d');
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+ let _dWH = this.dWH(img.width, img.height, this.maxWH)
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+ canvas.width = _dWH.width
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+ canvas.height = _dWH.height
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+
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+ // 清空后, 重写画布
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+ ctx.clearRect(0, 0, canvas.width, canvas.height)
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+ ctx.drawImage(img, 0, 0, canvas.width, canvas.height)
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+
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+ let newImgData = canvas.toDataURL(fileType, 0.90)
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+
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+ // 压缩宽高后的图像大小
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+ let newImgSize = this.fileSizeKB(newImgData)
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+
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+ if (newImgSize > this.fileSize) {
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+ console.log('图片尺寸太大!' + fileSize + " >> " + newImgSize)
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+ reject(`图片尺寸太大!`)
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+ }
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+
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+ let blob = this.dataURLtoBlob(newImgData, fileType)
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+ let nfile = new File([blob], this.file.name);
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+ resolve(nfile)
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+ };
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+ };
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+ });
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+ }
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+
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+ /*
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+ * 长宽等比缩小
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+ * 图像的一边(长或宽)为最大目标值
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+ * */
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+ dWH(srcW, srcH, dMax) {
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+
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+ let defaults = {
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+ width: srcW,
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+ height: srcH
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+ }
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+ if (Math.max(srcW, srcH) > dMax) {
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+ if (srcW > srcH) {
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+ defaults.width = dMax
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+ defaults.height = Math.round(srcH * (dMax / srcW))
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+ return defaults
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+ } else {
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+ defaults.height = dMax
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+ defaults.width = Math.round(srcW * (dMax / srcH))
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+ return defaults
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+ }
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+ } else {
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+ return defaults
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+ }
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+ }
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+
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+ fileSizeKB(dataURL) {
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+ let self = this
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+
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+ let sizeKB = 0
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+ sizeKB = Math.round((dataURL.split(',')[1].length * 3 / 4) / 1024)
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+ return sizeKB
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+ }
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+
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+ /*
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+ * 转为Blob
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+ * */
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+ dataURLtoBlob(dataURL, fileType) {
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+ let self = this
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+
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+ let byteString = atob(dataURL.split(',')[1])
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+ let mimeString = dataURL.split(',')[0].split(':')[1].split(';')[0]
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+ let ab = new ArrayBuffer(byteString.length)
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+ let ia = new Uint8Array(ab)
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+ for (let i = 0; i < byteString.length; i++) {
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+ ia[i] = byteString.charCodeAt(i)
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+ }
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+ if (fileType) {
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+ mimeString = fileType
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+ }
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+ return new Blob([ab], { type: mimeString, lastModifiedDate: new Date() })
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+ }
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+
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+}
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QM303176530