3.x分支新增降采样功能

Signed-off-by: zgf <zenggaofeng2@h-partners.com>

CHANGELOG.md

@@ -2,6 +2,7 @@
 - Added callback information for image loading
 - Added the interface for obtaining the upper limit and size of the current cache and the number of images corresponding to the current cache
 - HTTPS custom certificate verification
+- Add downsampling function to reduces memory cache consumption
 
 ## 3.2.0-rc.1
 - Change the queue from Stack to Queue

README_zh.md

@@ -293,7 +293,17 @@ ImageKnifeComponent({ ImageKnifeOption: = new ImageKnifeOption({
               })
 }).width(100).height(100)
 ```
-
+#### 12.图片降采样 示例
+```
+ImageKnifeComponent({
+        imageKnifeOption:{
+          loadSrc:$r("app.media.pngSample"),
+          placeholderSrc:$r('app.media.loading'),
+          errorholderSrc:$r('app.media.failed'),
+          downsampleOf: DownsampleStrategy.NONE
+        }
+      }).width(300).height(300)
+```
 
 #### 复用场景
 在aboutToRecycle生命周期清空组件内容；通过watch监听触发图片的加载。
@@ -319,7 +329,7 @@ ImageKnifeComponent({ ImageKnifeOption: = new ImageKnifeOption({
 ### ImageKnifeOption参数列表
 
 | 参数名称                  | 入参内容                                                                                                                                                                                                                                                                                            | 功能简介                |
-|-----------------------|---------------------------------------------------------------------------------------------------------------------------------------|---------------|
+|-----------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------|
 | loadSrc               | string、PixelMap、Resource                                                                                                                                                                                                                                                                        | 主图展示                |
 | placeholderSrc        | PixelMap、Resource                                                                                                                                                                                                                                                                               | 占位图图展示（可选）          |
 | errorholderSrc        | PixelMap、Resource                                                                                                                                                                                                                                                                               | 错误图展示（可选）           |
@@ -336,14 +346,26 @@ ImageKnifeComponent({ ImageKnifeOption: = new ImageKnifeOption({
 | signature             | String                                                                                                                                                                                                                                                                                          | 自定义缓存关键字（可选）        | 
 | headerOption          | Array<HeaderOptions>                                                                                                                                                                                                                                                                            | 设置请求头（可选）           |
 | transformation        | PixelMapTransformation                                                                                                                                                                                                                                                                          | 图片变换（可选）            |
-| drawingColorFilter    | ColorFilter                                                                                                                           | drawing.ColorFilter                  | 图片变换（可选）        |
+| drawingColorFilter    | ColorFilter、drawing.ColorFilter                                                                                                                                                                                                                                                                 | 图片变换（可选）        |
-| onComplete            | (event:EventImage                                                                                                                     | undefined) => voi              | 颜色滤镜效果（可选）        |
+| onComplete            | (event:EventImage、undefined) => void                                                                                                                                                                                                                                                            | 颜色滤镜效果（可选）        |
 | onLoadListener        | onLoadStart?: (req?: ImageKnifeRequest) => void,onLoadSuccess?: (data: string \| PixelMap \| undefined, imageData: ImageKnifeData, req?: ImageKnifeRequest) => void,onLoadFailed?: (err: string, req?: ImageKnifeRequest) => void,onLoadCancel?: (res: string, req?: ImageKnifeRequest) => void | 监听图片加载成功与失败         |
+| downsampleOf          | DownsampleStrategy                                                                                                                                                                                                                                                                              | 降采样（可选）             |
+
+### 降采样类型
+| 类型                  | 相关描述              |
+|---------------------|-------------------|
+| NONE                | 不进行降采样            |
+| AT_MOST             | 请求尺寸大于实际尺寸不进行放大   |
+| FIT_CENTER_MEMORY          | 两边自适应内存优先             |
+| FIT_CENTER_QUALITY          | 两边自适应质量优先             |
+| CENTER_OUTSIDE_MEMORY       | 宽高缩放比最大的比例，进行缩放适配内存优先 |
+| CENTER_OUTSIDE_QUALITY       | 宽高缩放比最大的比例，进行缩放适配质量优先 |
+| AT_LEAST      | 根据宽高的最小的比例，进行适配   |
 
 ### ImageKnife接口
 
 | 参数名称              | 入参内容                                                                                                                                  | 功能简介             |
-|-------------------|-------------------------------------------------------------------------------------------------------|------------------|
+|-------------------|---------------------------------------------------------------------------------------------------------------------------------------|------------------|
 | initMemoryCache   | newMemoryCache: IMemoryCache                                                                                                          | 自定义内存缓存策略        |
 | initFileCache     | context: Context, size: number, memory: number                                                                                        | 初始化文件缓存数量和大小     |
 | reload            | request: ImageKnifeRequest                                                                                                            | 图片重新加载           |
@@ -354,11 +376,11 @@ ImageKnifeComponent({ ImageKnifeOption: = new ImageKnifeOption({
 | addHeader         | key: string, value: Object                                                                                                            | 全局添加http请求头      |
 | setHeaderOptions  | Array<HeaderOptions>                                                                                                                  | 全局设置http请求头      |
 | deleteHeader      | key: string                                                                                                                           | 全局删除http请求头      |
-| setCustomGetImage | customGetImage?: (context: Context, src: string、PixelMap、Resource ,headers?: Record<string, Object>) => Promise<ArrayBuffer、undefined>                                                      | PixelMap         | Resource) => Promise<ArrayBuffer | undefined>   | 全局设置自定义下载 |
+| setCustomGetImage | customGetImage?: (context: Context, src: string、PixelMap、Resource ,headers?: Record<string, Object>) => Promise<ArrayBuffer、undefined>| 全局设置自定义下载 |
 | setEngineKeyImpl  | IEngineKey                                                                                                                            | 全局配置缓存key生成策略    |
 | putCacheImage     | url: string, pixelMap: PixelMap, cacheType: CacheStrategy = CacheStrategy.Default, signature?: string                                 | 写入内存磁盘缓存         |
-| removeMemoryCache | url: string                                                                                           | ImageKnifeOption | 清理指定内存缓存      |
+| removeMemoryCache | url: string、ImageKnifeOption                                                                                                          | 清理指定内存缓存      |
-| removeFileCache   | url: string                                                                                           | ImageKnifeOption | 清理指定磁盘缓存      |
+| removeFileCache   | url: string、ImageKnifeOption                                                                                                          | 清理指定磁盘缓存      |
 | getCacheLimitSize  | cacheType?: CacheStrategy                                                                                                             | 获取指定缓存的上限大小      |
 | getCurrentCacheNum  | cacheType?: CacheStrategy                                                                                                             | 获取指定缓存的当前缓存图片个数  |
 | getCurrentCacheSize  | cacheType?: CacheStrategy                                                                                                             | 获取指定缓存的当前大小      |
@@ -366,9 +388,9 @@ ImageKnifeComponent({ ImageKnifeOption: = new ImageKnifeOption({
 
 ### 回调接口说明
 | 回调接口        | 回调字段                                                                                | 回调描述                                                                                                                                                                  |
-|----------------|-------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+|----------------|-------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | onLoadStart    | req: ImageKnifeRequest                                                              | req返回字段中包含了图片请求的信息，如图片的url及其组件的宽高，同时ImageKnifeRequest包含了ImageKnifeData，其中包含此次请求的开始及其检查内存缓存的时间点                                                                        |
-| onLoadSuccess  | data: string \| PixelMap \| undefined, imageData: ImageKnifeData, req?: ImageKnifeRequest | data:加载成功的结果数据；imageData：图片的存入缓存中的信息 ，req：图片请求的信息，同时其中的ImageKnifeData，包含此次请求中图片的原始大小、图片的解码大小、格式、图片帧、请求结束时间、磁盘检查时间、网络请求开始结束、图片解码开始结束等时间点                               |
+| onLoadSuccess  | data: string、PixelMap、undefined, imageData: ImageKnifeData, req?: ImageKnifeRequest | data:加载成功的结果数据；imageData：图片的存入缓存中的信息 ，req：图片请求的信息，同时其中的ImageKnifeData，包含此次请求中图片的原始大小、图片的解码大小、格式、图片帧、请求结束时间、磁盘检查时间、网络请求开始结束、图片解码开始结束等时间点                               |
 | onLoadFailed   | err: string, req?: ImageKnifeRequest                                                | err:错误信息描述；req：图片请求的信息，同时其中的ImageKnifeData，包含此次请求错误信息（ErrorInfo，TimeInfo），ErrorInfo其中包含了，错误阶段、错误码及其网络请求的错误码；TimeInfo中包含请求结束时间、磁盘检查时间、网络请求开始结束、图片解码开始结束等时间点            |
 | onLoadCancel   | reason: string, req?: ImageKnifeRequest                                             | reason:取消回调原因；req：图片请求的信息，同时其中的ImageKnifeData，包含此次请求错误信息（ErrorInfo，TimeInfo），ErrorInfo其中包含了，错误阶段、错误码及其网络请求的错误码；TimeInfo中包含请求结束时间、磁盘检查时间、网络请求开始结束、图片解码开始结束及其请求取消等时间点   |
 

entry/src/main/ets/common/CustomEngineKeyImpl.ets

@@ -12,7 +12,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import { IEngineKey, ImageKnifeOption, PixelMapTransformation,SparkMD5 ,ImageKnifeRequestSource} from '@ohos/libraryimageknife';
+import { IEngineKey, ImageKnifeOption, PixelMapTransformation,SparkMD5 ,ImageKnifeRequestSource,
+  DownsampleStrategy} from '@ohos/libraryimageknife';
 
 //全局自定义key demo
 @Sendable
@@ -35,6 +36,9 @@ export class CustomEngineKeyImpl implements IEngineKey {
       if (imageKnifeOption.transformation) {
         key += "transformation=" + this.getTransformation(imageKnifeOption.transformation) + ";"
       }
+      if ((imageKnifeOption.downsampleOf !== DownsampleStrategy.NONE && imageKnifeOption.downsampleOf !== undefined)) {
+        key += "downsampleOf" + imageKnifeOption.downsampleOf + "width=" + width + "height=" + height
+      }
     }
     return key
   }

entry/src/main/ets/pages/DownSamplePage.ets

@@ -0,0 +1,214 @@
+/*
+ * 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 { DownsampleStrategy, ImageKnifeOption, } from '@ohos/imageknife';
+import { ImageKnifeComponent } from '@ohos/libraryimageknife';
+import { image } from '@kit.ImageKit';
+import { BusinessError } from '@kit.BasicServicesKit';
+import { Downsampler } from '@ohos/imageknife/src/main/ets/downsampling/Downsampler';
+import { FileTypeUtil } from '@ohos/imageknife/src/main/ets/utils/FileTypeUtil';
+
+@Entry
+@Component
+struct DownSamplePage {
+  @State imageKnifeOption: ImageKnifeOption = {
+    loadSrc: $r('app.media.startIcon'),
+    placeholderSrc: $r("app.media.loading"),
+    errorholderSrc: $r("app.media.app_icon"),
+    objectFit: ImageFit.Contain
+  }
+  isBrightness: boolean = false
+  @State beforeSampling: number = 0
+  @State afterSampling: number = 0
+  @State SamplingList: SamplingType[] = [
+
+    new SamplingType(7, "AT_LEAST"),
+    new SamplingType(1, "AT_MOST"),
+
+    new SamplingType(2, "FIT_CENTER_MEMORY"),
+    new SamplingType(4, "FIT_CENTER_QUALITY"),
+    new SamplingType(5, "CENTER_OUTSIDE_MEMORY"),
+    new SamplingType(6, "CENTER_OUTSIDE_QUALITY"),
+    new SamplingType(0, "NONE"),
+
+  ]
+  @State checked: boolean = false
+
+  updateImageKnifeOption(value: string) {
+    if (value === 'NONE') {
+      this.imageKnifeOption = {
+        loadSrc: $r('app.media.pngSample'),
+        placeholderSrc: $r("app.media.loading"),
+        errorholderSrc: $r("app.media.app_icon"),
+        objectFit: ImageFit.Contain,
+        downsampleOf: DownsampleStrategy.NONE
+      }
+      this.originalPixMap($r('app.media.pngSample'))
+      this.afterSamplingFunc($r('app.media.pngSample'))
+    } else if (value === 'AT_MOST') {
+      this.imageKnifeOption = {
+        loadSrc: $r('app.media.pngSample'),
+        placeholderSrc: $r("app.media.loading"),
+        errorholderSrc: $r("app.media.app_icon"),
+        objectFit: ImageFit.Contain,
+        downsampleOf: DownsampleStrategy.AT_MOST
+      }
+      this.originalPixMap($r('app.media.pngSample'))
+      this.afterSamplingFunc($r('app.media.pngSample'))
+    } else if (value === 'FIT_CENTER_MEMORY') {
+      this.imageKnifeOption = {
+        loadSrc: $r('app.media.pngSample'),
+        placeholderSrc: $r("app.media.loading"),
+        errorholderSrc: $r("app.media.app_icon"),
+        objectFit: ImageFit.Contain,
+        downsampleOf: DownsampleStrategy.FIT_CENTER_MEMORY
+      }
+      this.originalPixMap($r('app.media.pngSample'))
+      this.afterSamplingFunc($r('app.media.pngSample'))
+    } else if (value === 'FIT_CENTER_QUALITY') {
+      this.imageKnifeOption = {
+        loadSrc: $r('app.media.pngSample'),
+        placeholderSrc: $r("app.media.loading"),
+        errorholderSrc: $r("app.media.app_icon"),
+        objectFit: ImageFit.Contain,
+        downsampleOf: DownsampleStrategy.FIT_CENTER_QUALITY
+      }
+      this.originalPixMap($r('app.media.pngSample'))
+      this.afterSamplingFunc($r('app.media.pngSample'))
+    } else if (value === 'CENTER_OUTSIDE_MEMORY') {
+      this.imageKnifeOption = {
+        loadSrc: $r('app.media.pngSample'),
+        placeholderSrc: $r("app.media.loading"),
+        errorholderSrc: $r("app.media.app_icon"),
+        objectFit: ImageFit.Contain,
+        downsampleOf: DownsampleStrategy.CENTER_OUTSIDE_MEMORY
+      }
+      this.originalPixMap($r('app.media.pngSample'))
+      this.afterSamplingFunc($r('app.media.pngSample'))
+    } else if (value === 'CENTER_OUTSIDE_QUALITY') {
+      this.imageKnifeOption = {
+        loadSrc: $r('app.media.pngSample'),
+        placeholderSrc: $r("app.media.loading"),
+        errorholderSrc: $r("app.media.app_icon"),
+        objectFit: ImageFit.Contain,
+        downsampleOf: DownsampleStrategy.CENTER_OUTSIDE_QUALITY
+      }
+      this.originalPixMap($r('app.media.pngSample'))
+      this.afterSamplingFunc($r('app.media.pngSample'))
+    } else {
+      this.imageKnifeOption = {
+        loadSrc: $r('app.media.pngSample'),
+        placeholderSrc: $r("app.media.loading"),
+        errorholderSrc: $r("app.media.app_icon"),
+        objectFit: ImageFit.Contain,
+        downsampleOf: DownsampleStrategy.AT_LEAST
+      }
+      this.originalPixMap($r('app.media.pngSample'))
+      this.afterSamplingFunc($r('app.media.pngSample'))
+    }
+  }
+
+  async afterSamplingFunc(imgs: Resource) {
+    let img: Uint8Array = await getContext(this).resourceManager.getMediaContent(imgs);
+    let imageSource: image.ImageSource = image.createImageSource(img.buffer.slice(0));
+    let fileTypeUtil = new FileTypeUtil();
+    let typeValue = fileTypeUtil.getFileType(img.buffer.slice(0)) as string;
+    let decodingOptions: image.DecodingOptions = {
+      editable: true,
+      desiredPixelFormat: 3,
+    }
+    let imageInfo = await imageSource.getImageInfo()
+
+    if (this.imageKnifeOption.downsampleOf !== DownsampleStrategy.NONE && this.imageKnifeOption.downsampleOf != undefined ) {
+      let reqSize =
+        new Downsampler().calculateScaling(typeValue, imageInfo.size.width, imageInfo.size.height, 300,
+          300, this.imageKnifeOption.downsampleOf)
+      decodingOptions = {
+        editable: true,
+        desiredSize: {
+          width: reqSize.width,
+          height: reqSize.height
+        }
+      }
+    }
+
+    // 创建pixelMap
+    imageSource.createPixelMap(decodingOptions).then((pixelMap: image.PixelMap) => {
+      this.afterSampling = pixelMap.getPixelBytesNumber()
+    }).catch((err: BusinessError) => {
+      console.error("Failed to create PixelMap")
+    });
+  }
+
+  async originalPixMap(imgs: Resource,) {
+    let img: Uint8Array = await getContext(this).resourceManager.getMediaContent(imgs);
+    let imageSource: image.ImageSource = image.createImageSource(img.buffer.slice(0));
+    let decodingOptions: image.DecodingOptions = {
+      editable: true,
+      desiredPixelFormat: 3,
+    }
+    // 创建pixelMap
+    imageSource.createPixelMap(decodingOptions).then((pixelMap: image.PixelMap) => {
+      this.beforeSampling = pixelMap.getPixelBytesNumber()
+    }).catch((err: BusinessError) => {
+      console.error("Failed to create PixelMap")
+    });
+  }
+  getResourceString(res:Resource){
+    return getContext().resourceManager.getStringSync(res.id)
+  }
+  build() {
+    Scroll() {
+      Column() {
+        ForEach(this.SamplingList, (item: SamplingType, index) => {
+          Flex({ justifyContent: FlexAlign.Center, alignItems: ItemAlign.Center }) {
+            Radio({ value: item.value + 'radio', group: 'radioGroup' })
+              .height(50)
+              .width(50)
+              .checked(this.checked)
+              .onClick(() => {
+                this.updateImageKnifeOption(item.value)
+              })
+            Text(this.getResourceString($r('app.string.Sampling_pecification'))+ item.value).fontSize(20)
+          }
+        }, (item: SamplingType) => JSON.stringify(item))
+        Column() {
+          Text(`${this.getResourceString($r('app.string.Unreal_samples'))}：${this.beforeSampling}`).fontSize(20)
+          Text(`${ this.getResourceString($r('app.string.After_the_sampling'))}：${this.afterSampling}`).fontSize(20)
+        }
+
+        ImageKnifeComponent({
+          imageKnifeOption: this.imageKnifeOption
+        })
+          .height(300)
+          .width(300)
+          .borderWidth(1)
+          .borderColor(Color.Pink)
+      }
+
+    }
+    .height('100%')
+    .width('100%')
+  }
+}
+
+class SamplingType {
+  key: number
+  value: string
+
+  constructor(key: number, value: string) {
+    this.key = key
+    this.value = value
+  }
+}

entry/src/main/ets/pages/Index.ets

@@ -95,6 +95,11 @@ struct Index {
 
           });
         })
+        Button($r('app.string.Image_Downsampling_Functionality')).margin({top:10}).onClick(()=>{
+          router.push({
+            uri: 'pages/DownSamplePage',
+          });
+        })
         Button($r('app.string.Display_long_image')).margin({top:10}).onClick(()=>{
           router.push({
             uri: 'pages/LongImagePage',

entry/src/main/resources/base/element/string.json

@@ -631,6 +631,22 @@
     {
       "name": "render_time",
       "value": "render successful time:%s "
+    },
+    {
+      "name": "Image_Downsampling_Functionality",
+      "value": "Downsampling function"
+    },
+    {
+      "name": "Sampling_pecification",
+      "value": "Downsampling specification"
+    },
+    {
+      "name": "Unreal_samples",
+      "value": "Unsampled size"
+    },
+    {
+      "name": "After_the_sampling",
+      "value": "Size after downsampling"
     }
   ]
 }

entry/src/main/resources/base/profile/main_pages.json

@@ -38,6 +38,7 @@
     "pages/MaxRequest2",
     "pages/MaxRequest3",
     "pages/TestImageKnifeCallbackPage",
-    "pages/TestListImageKnifeCallbackPage"
+    "pages/TestListImageKnifeCallbackPage",
+    "pages/DownSamplePage"
   ]
 }

entry/src/main/resources/zh_CN/element/string.json

@@ -627,6 +627,22 @@
     {
       "name": "render_time",
       "value": "渲染成功的时间:%s "
+    },
+    {
+      "name": "Image_Downsampling_Functionality",
+      "value": "降采样功能"
+    },
+    {
+      "name": "Sampling_pecification",
+      "value": "降采样规格"
+    },
+    {
+      "name": "Unreal_samples",
+      "value": "未降采样大小"
+    },
+    {
+      "name": "After_the_sampling",
+      "value": "降采样后大小"
     }
   ]
 }

entry/src/ohosTest/ets/test/List.test.ets

@@ -20,6 +20,7 @@ import ImageKnifeTest from './ImageKnife.test';
 import Transform from './transform.test';
 import imageFormatAndSize from  './imageFormatAndSize.test'
 import loadCallBackData from  './loadCallBackData.test'
+import SamplingTest from './SamplingTest.test';
 
 export default function testsuite() {
   MemoryLruCacheTest();
@@ -28,6 +29,7 @@ export default function testsuite() {
   ImageKnifeOptionTest();
   ImageKnifeTest();
   Transform();
+  SamplingTest()
   imageFormatAndSize();
   loadCallBackData();
 }

entry/src/ohosTest/ets/test/SamplingTest.test.ets

@@ -0,0 +1,86 @@
+/*
+ * 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 { describe, beforeAll, beforeEach, afterEach, afterAll, it, expect } from '@ohos/hypium'
+import { image } from '@kit.ImageKit'
+import { BusinessError } from '@kit.BasicServicesKit'
+import { Downsampler } from '@ohos/imageknife/src/main/ets/downsampling/Downsampler'
+import { DownsampleStrategy } from '@ohos/imageknife'
+
+export default function SamplingTest() {
+  describe('SamplingTest', () => {
+    // Defines a test suite. Two parameters are supported: test suite name and test suite function.
+    beforeAll(() => {
+      // Presets an action, which is performed only once before all test cases of the test suite start.
+      // This API supports only one parameter: preset action function.
+    })
+    beforeEach(() => {
+      // Presets an action, which is performed before each unit test case starts.
+      // The number of execution times is the same as the number of test cases defined by **it**.
+      // This API supports only one parameter: preset action function.
+    })
+    afterEach(() => {
+      // Presets a clear action, which is performed after each unit test case ends.
+      // The number of execution times is the same as the number of test cases defined by **it**.
+      // This API supports only one parameter: clear action function.
+    })
+    afterAll(() => {
+      // Presets a clear action, which is performed after all test cases of the test suite end.
+      // This API supports only one parameter: clear action function.
+    })
+    it('AT_MOST', 0, () => {
+      let reqSize: Size =
+        new Downsampler().calculateScaling('jpg', 1024, 1024, 200,
+          200, DownsampleStrategy.AT_MOST)
+      let req = (reqSize.width < 1024 && reqSize.height < 1024)
+      expect(req).assertEqual(true);
+    })
+    it('FIT_CENTER_MEMORY', 1, () => {
+      let reqSize: Size =
+        new Downsampler().calculateScaling('jpg', 1024, 1024, 200,
+          200, DownsampleStrategy.FIT_CENTER_MEMORY)
+      let req = (reqSize.width < 1024 && reqSize.height < 1024)
+      expect(req).assertEqual(true);
+    })
+    it('FIT_CENTER_QUALITY', 2, () => {
+      let reqSize: Size =
+        new Downsampler().calculateScaling('jpg', 1024, 1024, 200,
+          200, DownsampleStrategy.FIT_CENTER_QUALITY)
+      let req = (reqSize.width < 1024 && reqSize.height < 1024)
+      expect(req).assertEqual(true);
+    })
+    it('CENTER_OUTSIDE_MEMORY', 3, () => {
+      let reqSize: Size =
+        new Downsampler().calculateScaling('jpg', 1024, 1024, 200,
+          200, DownsampleStrategy.CENTER_OUTSIDE_MEMORY)
+      let req = (reqSize.width < 1024 && reqSize.height < 1024)
+      expect(req).assertEqual(true);
+    })
+    it('CENTER_OUTSIDE_QUALITY', 4, () => {
+      let reqSize: Size =
+        new Downsampler().calculateScaling('jpg', 1024, 1024, 200,
+          200, DownsampleStrategy.CENTER_OUTSIDE_QUALITY)
+      let req = (reqSize.width < 1024 && reqSize.height < 1024)
+      expect(req).assertEqual(true);
+    })
+    it('AT_LEAST', 5, () => {
+      let reqSize: Size =
+        new Downsampler().calculateScaling('jpg', 1024, 1024, 200,
+          200, DownsampleStrategy.AT_LEAST)
+      let req = (reqSize.width < 1024 && reqSize.height < 1024)
+      expect(req).assertEqual(true);
+    })
+
+  })
+}

library/index.ets

@@ -30,6 +30,8 @@ export { IEngineKey } from './src/main/ets/key/IEngineKey'
 
 export { ImageKnifeData , CacheStrategy , ImageKnifeRequestSource} from "./src/main/ets/model/ImageKnifeData"
 
+export { DownsampleStrategy } from './src/main/ets/downsampling/DownsampleStartegy'
+
 export { PixelMapTransformation } from './src/main/ets/transform/PixelMapTransformation'
 
 export { MultiTransTransformation } from './src/main/ets/transform/MultiTransTransformation'

library/oh-package-lock.json5

@@ -1,6 +1,19 @@
 {
+  "meta": {
+    "stableOrder": false
+  },
   "lockfileVersion": 3,
   "ATTENTION": "THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.",
-  "specifiers": {},
+  "specifiers": {
-  "packages": {}
+    "@ohos/gpu_transform@^1.0.2": "@ohos/gpu_transform@1.0.4"
+  },
+  "packages": {
+    "@ohos/gpu_transform@1.0.4": {
+      "name": "@ohos/gpu_transform",
+      "version": "1.0.4",
+      "integrity": "sha512-PrKlOK66kzObw/ANIzt55YMrOLLmtrhmAZIE2c/60GBoTl7+NLxONeHA2NsDZuiW+A0KnD4QylDYWH4/yo8T0w==",
+      "resolved": "https://ohpm.openharmony.cn/ohpm/@ohos/gpu_transform/-/gpu_transform-1.0.4.har",
+      "registryType": "ohpm"
+    }
+  }
 }

library/src/main/ets/ImageKnifeDispatcher.ets

@@ -35,6 +35,7 @@ import {
 } from './model/ImageKnifeData'
 import { BusinessError } from '@kit.BasicServicesKit';
 import { ImageKnifeLoader } from './ImageKnifeLoader'
+import { DownsampleStrategy } from './downsampling/DownsampleStartegy';
 
 
 export class ImageKnifeDispatcher {
@@ -256,6 +257,9 @@ export class ImageKnifeDispatcher {
       moduleName: moduleName == "" ? undefined : moduleName,
       resName: resName == "" ? undefined : resName,
       caPath: currentRequest.imageKnifeOption.caPath,
+      targetWidth: currentRequest.componentWidth,
+      targetHeight: currentRequest.componentHeight,
+      downsampType: currentRequest.imageKnifeOption.downsampleOf == undefined ? DownsampleStrategy.NONE : currentRequest.imageKnifeOption.downsampleOf
     }
 
     if(request.customGetImage == undefined) {

library/src/main/ets/ImageKnifeLoader.ets

@@ -33,6 +33,8 @@ import image from '@ohos.multimedia.image';
 import { RequestJobResult } from './model/ImageKnifeData'
 import util from '@ohos.util';
 import { FileTypeUtil } from './utils/FileTypeUtil';
+import { DownsampleStrategy } from './downsampling/DownsampleStartegy';
+import { Downsampler } from './downsampling/Downsampler';
 
 class RequestData {
   receiveSize: number = 2000
@@ -124,6 +126,16 @@ export class ImageKnifeLoader {
     let size = (await imageSource.getImageInfo()).size
     callBackData.imageWidth = size.width;
     callBackData.imageHeight = size.height;
+    try {
+      if ((request.downsampType !== DownsampleStrategy.NONE) &&
+        request.requestSource == ImageKnifeRequestSource.SRC) {
+        decodingOptions =
+          ImageKnifeLoader.getDownsamplerDecodingOptions(typeValue, request, size, ImageKnifeRequestSource.SRC)
+      }
+    } catch (err) {
+      ImageKnifeLoader.makeEmptyResult(request, err)
+      return
+    }
     timeInfo.decodeStartTime = Date.now();
 
     await imageSource.createPixelMap(decodingOptions)
@@ -186,9 +198,6 @@ export class ImageKnifeLoader {
     let scale = size.height / size.width
     let hValue = Math.round(request.componentHeight);
     let wValue = Math.round(request.componentWidth);
-    callBackData.imageWidth = size.width;
-    callBackData.imageHeight = size.height;
-    timeInfo.decodeStartTime = Date.now();
     let defaultSize: image.Size = {
       height: vp2px(wValue) * scale,
       width: vp2px(wValue)
@@ -197,6 +206,18 @@ export class ImageKnifeLoader {
       editable: true,
       desiredSize: defaultSize
     };
+    callBackData.imageWidth = size.width;
+    callBackData.imageHeight = size.height;
+    try {
+      if ((request.downsampType !== DownsampleStrategy.NONE) &&
+        request.requestSource == ImageKnifeRequestSource.SRC) {
+        opts = ImageKnifeLoader.getDownsamplerDecodingOptions(typeValue, request, size)
+      }
+    } catch (err) {
+      ImageKnifeLoader.makeEmptyResult(request,err)
+      return
+    }
+    timeInfo.decodeStartTime = Date.now();
     await imageSource.createPixelMap(opts)
       .then((pixelmap: PixelMap) => {
         timeInfo.decodeEndTime = Date.now();
@@ -541,4 +562,29 @@ export class ImageKnifeLoader {
     }
     ImageKnifeLoader.parseImage(resBuf,fileKey,request, callBackData)
   }
+
+  static getDownsamplerDecodingOptions(typeValue: string, request: RequestJobRequest, size: Size,
+    SRC?: ImageKnifeRequestSource):image.DecodingOptions {
+    let reqSize =
+      new Downsampler().calculateScaling(typeValue, size.width, size.height, request.targetWidth, request.targetHeight,
+        request.downsampType)
+    if (typeValue == "svg") {
+      return {
+        editable: true,
+        desiredSize: {
+          height: vp2px(reqSize.height),
+          width: vp2px(reqSize.width)
+        }
+
+      }
+    } else {
+      return {
+        editable: request.requestSource === SRC && request.transformation !== undefined ? true : false,
+        desiredSize:{
+          width: reqSize.width,
+          height: reqSize.height
+        }
+      }
+    }
+  }
 }

library/src/main/ets/downsampling/BaseDownsampling.ets

@@ -0,0 +1,21 @@
+/*
+ * 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 { DownsampleStrategy } from './DownsampleStartegy';
+
+export interface BaseDownsampling {
+  getName(): string
+
+  getScaleFactor(sourceWidth: number, sourceHeight: number, requestWidth: number, requestHeight: number,downsampType?:DownsampleStrategy): number
+}

library/src/main/ets/downsampling/DownsampleStartegy.ets

@@ -0,0 +1,148 @@
+/*
+ * 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 { BaseDownsampling } from './BaseDownsampling';
+import { getScale, highestOneBit, round, SampleSizeRounding } from './DownsampleUtils';
+
+export class FitCenter implements BaseDownsampling {
+  getName() {
+    return "FitCenter"
+  }
+
+  getScaleFactor(sourceWidth: number, sourceHeight: number, requestedWidth: number, requestedHeight: number,
+    downsampType: DownsampleStrategy
+  ): number {
+    //重新计算宽高比;
+    let outSize: Size = {
+      width: round(getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType) * sourceWidth),
+      height:round(getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType) * sourceHeight)
+    }
+    let scaleFactor = downsampType === DownsampleStrategy.FIT_CENTER_QUALITY?
+    Math.max(1, highestOneBit(Math.max(sourceWidth / outSize.width, sourceHeight / outSize.height))) :
+    Math.max(1, highestOneBit(Math.min(sourceWidth / outSize.width, sourceHeight / outSize.height)))//将整型的缩放因子转换为2的次幂采样大小
+
+    if (downsampType === DownsampleStrategy.FIT_CENTER_MEMORY
+      && (scaleFactor < (1 / getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType)))) {
+      scaleFactor = scaleFactor << 1;
+    }
+    return scaleFactor
+  }
+}
+
+
+/*宽高进行等比缩放宽高里面最小的比例先放进去
+然后再更据原图的缩放比去适配另一边*/
+
+export class AtLeast implements BaseDownsampling {
+  getName() {
+    return "AtLeast"
+  }
+
+  getScaleFactor(sourceWidth: number, sourceHeight: number, requestedWidth: number, requestedHeight: number): number {
+    const widthPercentage = requestedWidth / sourceWidth;
+    const heightPercentage = requestedHeight / sourceHeight;
+    //返回宽度和高度比例中最大的值
+    let outSize: Size = {
+      width: round(Math.max(widthPercentage, heightPercentage) * sourceWidth),
+      height:round(Math.max(widthPercentage, heightPercentage) * sourceHeight)
+    }
+    let scaleFactor = Math.max(1, highestOneBit(Math.max(sourceWidth / outSize.width, sourceHeight / outSize.height)))
+
+    return scaleFactor
+  }
+}
+
+/*请求尺寸大于实际尺寸不进行放大,按照原图展示*/
+
+export class AtMost implements BaseDownsampling {
+  getName() {
+    return "AtMost"
+  }
+
+
+  getScaleFactor(sourceWidth: number, sourceHeight: number, requestedWidth: number, requestedHeight: number): number {
+    const maxIntegerFactor = Math.ceil(Math.max(sourceHeight / requestedHeight, sourceWidth / requestedWidth));
+    let lesserOrEqualSampleSize = Math.max(1, highestOneBit(maxIntegerFactor));
+    let greaterOrEqualSampleSize = lesserOrEqualSampleSize
+    if (lesserOrEqualSampleSize < maxIntegerFactor) {
+      greaterOrEqualSampleSize = lesserOrEqualSampleSize <<= 1;
+    }
+    greaterOrEqualSampleSize = lesserOrEqualSampleSize << (lesserOrEqualSampleSize < maxIntegerFactor ? 1 : 0)
+
+    let outSize: Size = {
+      width: round((1 / greaterOrEqualSampleSize) * sourceWidth),
+      height:round((1 / greaterOrEqualSampleSize) * sourceHeight)
+    }
+    let scaleFactor = Math.max(1, highestOneBit(Math.min(sourceWidth / outSize.width, sourceHeight / outSize.height)))
+    if ((scaleFactor < greaterOrEqualSampleSize)) {
+      scaleFactor = scaleFactor << 1;
+    }
+    return scaleFactor
+  }
+}
+
+/*宽高进行等比缩放宽高里面最大的比例先放进去
+然后再更据原图的缩放比去适配另一边*/
+export class CenterInside implements BaseDownsampling {
+  getName() {
+    return "CenterInside"
+  }
+  getScaleFactor(sourceWidth: number, sourceHeight: number, requestedWidth: number, requestedHeight: number,
+    downsampType: DownsampleStrategy
+  ): number {
+    let outSize: Size = {
+      width: round(Math.min(1, getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType)) * sourceWidth),
+      height:round(Math.min(1, getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType)) * sourceHeight)
+    }
+    //将整型的缩放因子转换为2的次幂采样大小
+    let scaleFactor = this.getSampleSizeType(sourceWidth, sourceHeight, requestedWidth, requestedHeight,
+      downsampType) == SampleSizeRounding.QUALITY ?
+    Math.max(1, highestOneBit(Math.max(sourceWidth / outSize.width, sourceHeight / outSize.height))) :
+    Math.max(1, highestOneBit(Math.min(sourceWidth / outSize.width, sourceHeight / outSize.height)))
+    if (this.getSampleSizeType(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType)
+      == SampleSizeRounding.MEMORY  && (scaleFactor < (1 / Math.min(1, getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType))))) {
+      scaleFactor = scaleFactor << 1;
+    }
+    return scaleFactor
+
+  }
+
+  getSampleSizeType(sourceWidth: number, sourceHeight: number, requestedWidth: number, requestedHeight: number,
+    downsampType: DownsampleStrategy
+  ): SampleSizeRounding {
+    //如果缩放因子为 1，表示没有缩放，优先选择质量
+    if (Math.min(1, getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType)) === 1) {
+      return SampleSizeRounding.QUALITY
+    }
+    //否则，使用 FIL_CENTER 的 SampleSizeRounding 值
+    return downsampType === DownsampleStrategy.CENTER_OUTSIDE_MEMORY?SampleSizeRounding.MEMORY:SampleSizeRounding.QUALITY
+  }
+}
+
+export enum DownsampleStrategy {
+  //请求尺寸大于实际尺寸不进行放大
+  AT_MOST,
+  //两边自适应内存优先
+  FIT_CENTER_MEMORY,
+  //两边自适应质量优先
+  FIT_CENTER_QUALITY,
+  //按照宽高比的最大比进行适配内存优先
+  CENTER_OUTSIDE_MEMORY,
+  //按照宽高比的最大比进行适配质量优先
+  CENTER_OUTSIDE_QUALITY,
+  //宽高进行等比缩放宽高里面最小的比例先放进去，然后再根据原图的缩放比去适配
+  AT_LEAST,
+  //不进行降采样
+  NONE,
+}

library/src/main/ets/downsampling/DownsampleUtils.ets

@@ -0,0 +1,58 @@
+/*
+ * 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 { DownsampleStrategy } from './DownsampleStartegy';
+
+export enum SampleSizeRounding {
+  /**
+   * Prefer to round the sample size up so that the image is downsampled to smaller than the
+   * requested size to use less memory.
+   */
+  //（内存优先）
+  MEMORY,
+  /**
+   * Prefer to round the sample size down so that the image is downsampled to larger than the
+   * requested size to maintain quality at the expense of extra memory usage.
+   */
+  //（质量优先）
+  QUALITY
+}
+//找出给定整数 i 中最高位的1（即最左边的1）所代表的值
+export function highestOneBit(i: number): number {
+  i |= (i >> 1);
+  i |= (i >> 2);
+  i |= (i >> 4);
+  i |= (i >> 8);
+  i |= (i >> 16);
+  return i - (i >>> 1);
+}
+
+
+export function getScale(sourceWidth: number, sourceHeight: number, requestedWidth: number, requestedHeight: number,
+  downsampType: DownsampleStrategy
+): number {
+  if (downsampType === DownsampleStrategy.FIT_CENTER_MEMORY) {
+    const widthPercentage = requestedWidth / sourceWidth
+    const heightPercentage = requestedHeight / sourceHeight
+    return Math.min(widthPercentage, heightPercentage)
+  } else {
+    const maxIntegerFactor = Math.max(sourceHeight / requestedHeight, sourceWidth / requestedWidth);
+    return maxIntegerFactor === 0 ? 1 : 1 / highestOneBit(maxIntegerFactor);
+
+  }
+}
+//四舍五入
+export function  round(value: number): number {
+  return Math.floor(value + 0.5);
+}

library/src/main/ets/downsampling/Downsampler.ets

@@ -0,0 +1,73 @@
+/*
+ * 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 {
+  AtMost,
+  CenterInside,
+  AtLeast,
+  DownsampleStrategy,
+  FitCenter,
+} from './DownsampleStartegy';
+export class Downsampler {
+  calculateScaling(
+    typeValue: string,
+    sourceWidth: number, //原始宽高
+    sourceHeight: number, //原始宽高
+    requestWidth: number, //请求宽高
+    requestHeight: number, //请求宽高
+    downsampType: DownsampleStrategy,
+  ): Size {
+
+    if (sourceHeight <= 0 || sourceWidth <= 0) {
+      throw new Error(`Invalid width and height, sourceHeight:${sourceHeight}+ sourceWidth:${sourceWidth}`)
+    }
+    let downsampler = this.getDownsampler(downsampType);
+    let scaleFactor: number =
+      downsampler.getScaleFactor(sourceWidth, sourceHeight, requestWidth, requestHeight, downsampType);//缩放比
+    //基于上一步得出的采样大小，根据不同的图片类型，计算采样后的图片尺寸
+    if (typeValue === "png") {
+      return {
+        width: Math.floor(sourceWidth / scaleFactor),
+        height: Math.floor(sourceHeight / scaleFactor)
+      }
+    } else if (typeValue === "webp") {
+      return {
+        width: Math.round(sourceWidth / scaleFactor),
+        height: Math.round(sourceHeight / scaleFactor)
+      }
+    } else {
+      return {
+        width: sourceWidth / scaleFactor,
+        height: sourceHeight / scaleFactor
+
+      }
+    }
+  }
+  getDownsampler(downsampType: DownsampleStrategy) {
+    switch (downsampType) {
+      case DownsampleStrategy.FIT_CENTER_MEMORY:
+      case DownsampleStrategy.FIT_CENTER_QUALITY:
+        return new FitCenter();
+      case DownsampleStrategy.AT_MOST:
+        return new AtMost();
+      case DownsampleStrategy.CENTER_OUTSIDE_MEMORY:
+      case DownsampleStrategy.CENTER_OUTSIDE_QUALITY:
+        return new CenterInside();
+      case DownsampleStrategy.AT_LEAST:
+        return new AtLeast();
+      default:
+        throw new Error('Unsupported downsampling strategy');
+    }
+  }
+}

library/src/main/ets/key/DefaultEngineKey.ets

@@ -17,6 +17,7 @@ import { ImageKnifeOption } from '../model/ImageKnifeOption';
 import { IEngineKey } from './IEngineKey';
 import { PixelMapTransformation } from '../transform/PixelMapTransformation';
 import { ImageKnifeRequestSource } from '../model/ImageKnifeData';
+import { DownsampleStrategy } from '../downsampling/DownsampleStartegy';
 
 @Sendable
 export class DefaultEngineKey implements IEngineKey {
@@ -31,6 +32,9 @@ export class DefaultEngineKey implements IEngineKey {
       if (imageKnifeOption.transformation) {
         key += "transformation=" + this.getTransformation(imageKnifeOption.transformation) + ";"
       }
+      if ((imageKnifeOption.downsampleOf !== DownsampleStrategy.NONE && imageKnifeOption.downsampleOf !== undefined)) {
+        key += "downsampleOf" + imageKnifeOption.downsampleOf + "width=" + width + "height=" + height
+      }
     }
     return key
   }

library/src/main/ets/model/ImageKnifeData.ets

@@ -18,6 +18,7 @@ import { IEngineKey } from '../key/IEngineKey'
 import { PixelMapTransformation } from '../transform/PixelMapTransformation'
 import common from '@ohos.app.ability.common';
 import { Size } from '@kit.ArkUI'
+import { DownsampleStrategy } from '../downsampling/DownsampleStartegy'
 
 export interface ImageKnifeData {
   source: PixelMap | string, // url
@@ -147,5 +148,8 @@ export interface RequestJobRequest {
   moduleName?:string,
   resName?: string
   caPath?: string,
+  targetWidth: number
+  targetHeight: number
+  downsampType: DownsampleStrategy
 }
 

library/src/main/ets/model/ImageKnifeOption.ets

@@ -18,6 +18,7 @@ import { CacheStrategy, ImageKnifeData,EventImage } from './ImageKnifeData';
 import { PixelMapTransformation } from '../transform/PixelMapTransformation';
 import { drawing } from '@kit.ArkGraphics2D';
 import { ImageKnifeRequest } from './ImageKnifeRequest';
+import { DownsampleStrategy } from '../downsampling/DownsampleStartegy';
 
 export interface HeaderOptions {
   key: string;
@@ -78,6 +79,7 @@ export class ImageKnifeOption {
   onLoadListener?: OnLoadCallBack | undefined;
   onComplete?:(event:EventImage | undefined) => void
   drawingColorFilter?: ColorFilter | drawing.ColorFilter
+  downsampleOf?: DownsampleStrategy // 降采样
   // 自定义证书路径
   caPath?: string
   constructor() {

sharedlibrary/Index.ets

@@ -24,6 +24,8 @@ export { ImageKnife } from '@ohos/imageknife'
 
 export { ImageKnifeOption,AnimatorOption } from '@ohos/imageknife'
 
+export { DownsampleStrategy } from "@ohos/imageknife"
+
 export { ImageKnifeRequest } from '@ohos/imageknife'
 
 export { FileUtils } from '@ohos/imageknife'