diff --git a/library/src/main/ets/downsampling/Downsampler.ets b/library/src/main/ets/downsampling/Downsampler.ets
index 033d148..6e40317 100644
--- a/library/src/main/ets/downsampling/Downsampler.ets
+++ b/library/src/main/ets/downsampling/Downsampler.ets
@@ -37,8 +37,8 @@ export class Downsampler {
     downsampType: DownsampleStrategy | undefined,
   ): calculateScaleType {
     const fileType = typeValue //获取图片类型
-    let targetWidth: number | null = null;
-    let targetHeight: number | null = null;
+    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")
     }
@@ -47,14 +47,14 @@ export class Downsampler {
     }
     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);
+    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 outWidth: number = this.round(exactScaleFactor * sourceWidth);
-    let outHeight: number = this.round(exactScaleFactor * sourceHeight);
-    let widthScaleFactor = sourceWidth / outWidth;
-    let heightScaleFactor = sourceHeight / outHeight;
+    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;