修改demo

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

@@ -126,16 +126,20 @@ struct DownSamplePage {
       desiredPixelFormat: 3,
     }
     let imageInfo = await imageSource.getImageInfo()
-    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
+
+    if (this.imageKnifeOption.downsampleOf !== DownsampleStrategy.NONE){
+      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()

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

@@ -28,7 +28,7 @@ export enum SampleSizeRounding {
   //（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);