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Flutter OHOS flutter_native_image

时间：2024-12-18 09:31:40浏览次数：3  
标签：fs image PropertyKey flutter let file fileName Flutter native

flutter_native_image

原生 Flutter 图片工具

此插件旨在提供原生工具来调整图像大小并通过压缩降低其质量。代码有点粗糙（尤其是 iOS 部分），但它可以满足我的需求，并且从未崩溃过。如果您愿意，请随意改进它。

用法

安装

在依赖项下的 pubspec.yaml 中添加以下几行

flutter_native_image: ^0.0.6

压缩图像

File compressedFile = await FlutterNativeImage.compressImage(file.path,
quality: quality, percentage: percentage);

您必须从文件系统中为其提供一个文件，并可选地提供质量 (1-100) 和调整大小百分比 (1-100)。每个平台都会使用其适当的工具来处理调整大小。

要将图像调整为特定尺寸，请使用以下代码：

ImageProperties properties = await FlutterNativeImage.getImageProperties(file.path);
File compressedFile = await FlutterNativeImage.compressImage(file.path, quality: 80, 
targetWidth: 600, targetHeight: 300);

保持文件的纵横比：

ImageProperties properties = await FlutterNativeImage.getImageProperties(file.path);
File compressedFile = await FlutterNativeImage.compressImage(file.path, quality: 80, 
targetWidth: 600, 
targetHeight: (properties.height * 600 / properties.width).round());

获取图像属性

ImageProperties properties = await FlutterNativeImage.getImageProperties(file.path);

它返回一个包含图像宽度和高度的 ImageProperties 对象。

裁剪图像

File croppedFile = await FlutterNativeImage.cropImage(file.path, originX, originY, width, height);

返回包含按给定尺寸裁剪的图像的文件。

鸿蒙实现代码 FlutterNativeImagePlugin.ets

/**
 * Copyright (c) 2024 Huawei Device Co., Ltd.
 * 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.
 */

import { FlutterPlugin, FlutterPluginBinding } from '@ohos/flutter_ohos/src/main/ets/embedding/engine/plugins/FlutterPlugin';
import MethodChannel, { MethodCallHandler, MethodResult } from '@ohos/flutter_ohos/src/main/ets/plugin/common/MethodChannel';
import MethodCall from '@ohos/flutter_ohos/src/main/ets/plugin/common/MethodCall';
import image from '@ohos.multimedia.image';
import fs from '@ohos.file.fs';
import common from '@ohos.app.ability.common';
import { Log } from '@ohos/flutter_ohos';
import deviceInfo from '@ohos.deviceInfo';
import  { BusinessError } from '@ohos.base';
import util from '@ohos.util';

/** FlutterNativeImagePlugin **/
export default class FlutterNativeImagePlugin implements FlutterPlugin, MethodCallHandler {
  private channel: MethodChannel | null = null;
  private context: common.Context | null = null;
  private pluginBinding: FlutterPluginBinding | null = null;

  constructor(context?: common.Context) {
if(context) {
  this.context = context
}
  }

  setUp(context: common.Context) {
this.context = context;
  }

  getUniqueClassName(): string {
return "FlutterNativeImagePlugin"
  }

  onAttachedToEngine(binding: FlutterPluginBinding): void {
this.channel = new MethodChannel(binding.getBinaryMessenger(), "flutter_native_image");
this.channel.setMethodCallHandler(this)
this.pluginBinding = binding
if(this.pluginBinding) {
  this.setUp(this.pluginBinding.getApplicationContext())
}
  }

  onDetachedFromEngine(binding: FlutterPluginBinding): void {
if (this.channel != null) {
  this.channel.setMethodCallHandler(null)
}
  }

  async onMethodCall(call: MethodCall, result: MethodResult): Promise<void> {
if(call.method == "compressImage") {
  let fileName: string = call.argument("file")
  let resizePercentage: number = call.argument("percentage")
  let targetWidth: number = call.argument("targetWidth") == null ? 0 : call.argument("targetWidth")
  let targetHeight: number = call.argument("targetHeight") == null ? 0 : call.argument("targetHeight")
  let quality: number = call.argument("quality")

  if(!fs.accessSync(fileName)) {
result.error("file does not exist", fileName, null)
return
  }

  let file: fs.File = fs.openSync(fileName);

  let contextImage: image.ImageSource = image.createImageSource(fileName)
  let contextImageInfo: image.ImageInfo = await contextImage.getImageInfo()

  let newWidth: number = targetWidth == 0 ? (contextImageInfo.size.width / 100 * resizePercentage): targetWidth
  let newHeight: number = targetHeight == 0 ? (contextImageInfo.size.height / 100 * resizePercentage): targetHeight

  let scaleX: number = newWidth / contextImageInfo.size.width
  let scaleY: number = newHeight / contextImageInfo.size.height

  let bmp: image.PixelMap = await contextImage.createPixelMap()
  const imagePackerApi = image.createImagePacker()
  let packOpts: image.PackingOption = { format: "image/jpeg", quality: quality }

  await bmp.scale(scaleX, scaleY)

  let bos: ArrayBuffer = await imagePackerApi.packing(bmp, packOpts)

  try{
if(this.context) {
  let outputFileName: string = this.context.cacheDir + "/" + this.getFilenameWithoutExtension(file).concat("_compressed" + file.fd + util.generateRandomUUID(true)) + ".jpg"

  let newFile = fs.openSync(outputFileName, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE)
  fs.write(newFile.fd, bos, (err: BusinessError, writeLen: number) => {
if(err) {
  console.error("write data to file failed with error message: " + err.message + ",error code:" + err.code)
} else {
  console.info("write data to file succeed and size is:" + writeLen)
}
fs.closeSync(newFile)
  })

  this.copyExif(fileName, outputFileName)

  result.success(outputFileName)
}

result.error("context initialization failed", fileName, null)
return
  } catch (e) {
e.printStackTrace();
  }

  return
}
if(call.method == "getImageProperties") {
  let fileName: string = call.argument("file")

  if(!fs.accessSync(fileName)) {
result.error("file does not exist", fileName, null)
return
  }

  let imageInfo: image.ImageInfo = await image.createImageSource(fileName).getImageInfo()
  let properties: Map<string, number> = new Map<string, number>()
  properties.set("width", imageInfo.size.width)
  properties.set("height", imageInfo.size.height)

  let orientation: number = 1
  try{
let imageOrientation: string = await image.createImageSource(fileName).getImageProperty(image.PropertyKey.ORIENTATION)
if(imageOrientation != null && imageOrientation != "") {
  switch (imageOrientation){
case "Top-left":
  orientation = 1
  break
case "Top-right":
  orientation = 2
  break
case "Bottom-right":
  orientation = 3
  break
case "Bottom-left":
  orientation = 4
  break
case "Left-top":
  orientation = 5
  break
case "Right-top":
  orientation = 6
  break
case "Right-bottom":
  orientation = 7
  break
case "Left-bottom":
  orientation = 8
  break
default:
  orientation = 0
  break
  }
}
  } catch (e) {

  }

  properties.set("orientation", orientation)

  result.success(properties)
  return
}
if(call.method == "cropImage") {
  let fileName: string = call.argument("file")
  let originX: number = call.argument("originX")
  let originY: number = call.argument("originY")
  let widthNumber: number = call.argument("width")
  let heightNumber: number = call.argument("height")

  if(!fs.accessSync(fileName)) {
result.error("file does not exist", fileName, null)
return
  }

  let file: fs.File = fs.openSync(fileName)

  let contextImage: image.ImageSource = image.createImageSource(fileName)
  let bmp: image.PixelMap = await contextImage.createPixelMap()

  try{
await bmp.crop({x: originX, y: originY, size: { height: heightNumber, width: widthNumber}})
  } catch (e) {
e.printStackTrace()
result.error("bounds are outside of the dimensions of the source image", fileName, null)
  }

  const imagePackerApi = image.createImagePacker()
  let packOpts: image.PackingOption = { format: "image/jpeg", quality: 100 }
  let bos: ArrayBuffer = await imagePackerApi.packing(bmp, packOpts)

  try{
if(this.context) {
  let outputFileName: string = this.context.cacheDir + "/" + this.getFilenameWithoutExtension(file).concat("_cropImage" + file.fd + util.generateRandomUUID(true)) + ".jpg"

  let newFile = fs.openSync(outputFileName, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE)
  fs.write(newFile.fd, bos, (err: BusinessError, writeLen: number) => {
if(err) {
  console.error("write data to file failed with error message: " + err.message + ",error code:" + err.code)
} else {
  console.info("write data to file succeed and size is:" + writeLen)
}
fs.closeSync(newFile)
  })

  this.copyExif(fileName, outputFileName)

  result.success(outputFileName)
}

result.error("context initialization failed", fileName, null)
return
  } catch (e) {
e.printStackTrace()
result.error(e + " went wrong", fileName, null)
  }

  return
}
if(call.method == "getPlatformVersion") {
  result.success("ohos: " + deviceInfo.buildVersion)
} else {
  result.notImplemented()
}
  }

  private getFilenameWithoutExtension(_file: fs.File) {
let fileName: string = _file.name

if(fileName.indexOf(".") > 0){
return fileName.substring(0, fileName.lastIndexOf("."))
} else {
return fileName
}
  }

  async copyExif(filePathOri: string, filePathDest: string): Promise<void> {
try {
  let oldExif: image.ImageSource = image.createImageSource(filePathOri)
  let newExif: image.ImageSource = image.createImageSource(filePathDest)
  let propertyKey: image.PropertyKey[] = [
image.PropertyKey.F_NUMBER,
image.PropertyKey.EXPOSURE_TIME,
image.PropertyKey.ISO_SPEED,
image.PropertyKey.FOCAL_LENGTH,
image.PropertyKey.GPS_DATE_STAMP,
image.PropertyKey.WHITE_BALANCE,
image.PropertyKey.GPS_TIME_STAMP,
image.PropertyKey.DATE_TIME,
image.PropertyKey.FLASH,
image.PropertyKey.GPS_LATITUDE,
image.PropertyKey.GPS_LATITUDE_REF,
image.PropertyKey.GPS_LONGITUDE,
image.PropertyKey.GPS_LONGITUDE_REF,
image.PropertyKey.MAKE,
image.PropertyKey.MODEL,
image.PropertyKey.ORIENTATION,
  ]

  propertyKey.forEach(async (value) => {
let keyValue: string = await oldExif.getImageProperty(value)
await newExif.modifyImageProperty(value, keyValue)
  })
} catch (e) {
  Log.e("FlutterNativeImagePlugin", "Error preserving exif data on selected image: " + e)
}
  }
}

标签：fs,image,PropertyKey,flutter,let,file,fileName,Flutter,native
From： https://www.cnblogs.com/hongmengos/p/18613895

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