diff --git a/library/src/main/ets/downsampling/Downsampler.ets b/library/src/main/ets/downsampling/Downsampler.ets
index 6e40317..a94000f 100644
--- a/library/src/main/ets/downsampling/Downsampler.ets
+++ b/library/src/main/ets/downsampling/Downsampler.ets
@@ -29,53 +29,50 @@ export interface calculateScaleType {
 
 export class Downsampler {
   calculateScaling(
-    typeValue: string | null,
-    sourceWidth: number | undefined, //原始宽高
+    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 | undefined,
+    downsampType: DownsampleStrategy,
   ): calculateScaleType {
-    const fileType = typeValue //获取图片类型
-    let targetWidth: number | null = null;//降采样之后的宽
-    let targetHeight: number | null = null;//降采样之后的高
-    if (sourceHeight <= 0 || sourceWidth == undefined || sourceWidth == null || sourceWidth <= 0) {
-      throw new Error("Cannot found width or height")
-    }
-    if(downsampType===undefined){
-      throw new Error("Cannot found downsampType");
+
+    if (sourceHeight <= 0 || sourceWidth <= 0) {
+        throw new Error("非法宽高 sourceHeight sourceWidth")
     }
     let downsampler = this.getDownsampler(downsampType);
-    let exactScaleFactor : number = downsampler.getScaleFactor(sourceWidth, sourceHeight, requestWidth, requestHeight, downsampType);
-    let rounding: SampleSizeRounding= downsampler.getSampleSizeRounding(sourceWidth, sourceHeight, requestWidth, requestHeight, downsampType);//采样类型
-    if (exactScaleFactor==undefined|| exactScaleFactor <= 0 ) {
-      throw new Error("Cannot round with exactScaleFactor");
+    let exactScaleFactor: number =
+      downsampler.getScaleFactor(sourceWidth, sourceHeight, requestWidth, requestHeight, downsampType);
+    let rounding: SampleSizeRounding =
+      downsampler.getSampleSizeRounding(sourceWidth, sourceHeight, requestWidth, requestHeight, downsampType); //采样类型
+    //原始宽高和缩放系数的乘积
+    let outSize = {
+      width: this.round(exactScaleFactor * sourceWidth),
+      height: this.round(exactScaleFactor * sourceHeight)
     }
-    let outWidth: number = this.round(exactScaleFactor * sourceWidth);//原始宽和缩放系数的乘积
-    let outHeight: number = this.round(exactScaleFactor * sourceHeight);//原始高和缩放系数的乘积
-    let widthScaleFactor = sourceWidth / outWidth;//计算的缩放因子
-    let heightScaleFactor = sourceHeight / outHeight;//计算的缩放因子
-    let scaleFactor = rounding ==SampleSizeRounding.QUALITY ? Math.max(widthScaleFactor, heightScaleFactor) :
-    Math.min(widthScaleFactor, heightScaleFactor) //将整型的缩放因子转换为2的次幂采样大小
-    let powerOfTwoSampleSize: number = scaleFactor;
-    powerOfTwoSampleSize = Math.max(1, highestOneBit(scaleFactor))
-    if (rounding == 0 && (powerOfTwoSampleSize < (1 / exactScaleFactor))) {
-      powerOfTwoSampleSize = powerOfTwoSampleSize << 1;
+    let scaleFactor =
+      rounding == SampleSizeRounding.QUALITY ? Math.max(sourceWidth / outSize.width, sourceHeight / outSize.height) :
+      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
+    scaleFactor = Math.max(1, highestOneBit(scaleFactor))
+    if (rounding == 0 && (scaleFactor < (1 / exactScaleFactor))) {
+      scaleFactor = scaleFactor << 1;
     }
     //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 (fileType === "png") {
-      targetWidth = Math.floor(sourceWidth / powerOfTwoSampleSize);
-      targetHeight = Math.floor(sourceHeight / powerOfTwoSampleSize);
-    } else if (fileType === "webp") {
-      targetWidth = Math.round(sourceWidth / powerOfTwoSampleSize);
-      targetHeight = Math.round(sourceHeight / powerOfTwoSampleSize);
+    if (typeValue === "png") {
+      return {
+        targetWidth: Math.floor(sourceWidth / scaleFactor),
+        targetHeight: Math.floor(sourceHeight / scaleFactor)
+      }
+    } else if (typeValue === "webp") {
+      targetWidth = Math.round(sourceWidth / scaleFactor);
+      targetHeight = Math.round(sourceHeight / scaleFactor);
     } else {
-      targetWidth = sourceWidth / powerOfTwoSampleSize;
-      targetHeight = sourceHeight / powerOfTwoSampleSize;
+      targetWidth = sourceWidth / scaleFactor;
+      targetHeight = sourceHeight / scaleFactor;
     }
-    return  { targetWidth, targetHeight }
   }
-  getDownsampler(downsampType:DownsampleStrategy) {
+
+  getDownsampler(downsampType: DownsampleStrategy) {
     switch (downsampType) {
       case DownsampleStrategy.FIT_CENTER_MEMORY:
       case DownsampleStrategy.FIT_CENTER_QUALITY:
@@ -93,6 +90,7 @@ export class Downsampler {
         throw new Error('Unsupported downsampling strategy');
     }
   }
+
   round(value: number): number {
     return Math.floor(value + 0.5);
   }