diff --git a/library/src/main/ets/downsampling/DownsampleStartegy.ets b/library/src/main/ets/downsampling/DownsampleStartegy.ets
index e42861b..8fe9694 100644
--- a/library/src/main/ets/downsampling/DownsampleStartegy.ets
+++ b/library/src/main/ets/downsampling/DownsampleStartegy.ets
@@ -28,50 +28,16 @@ export class FitCenter implements BaseDownsampling {
       width: round(getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType) * sourceWidth),
       height:round(getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType) * sourceHeight)
     }
-    let scaleFactor = this.getSampleSizeType(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType)===
-    SampleSizeRounding.QUALITY? Math.max(1, highestOneBit(Math.max(sourceWidth / outSize.width, sourceHeight / outSize.height))) :
+    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 (this.getSampleSizeType(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType)===
-    SampleSizeRounding.MEMORY && (scaleFactor < (1 / getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType)))) {
+    if (downsampType === DownsampleStrategy.FIT_CENTER_MEMORY
+      && (scaleFactor < (1 / getScale(sourceWidth, sourceHeight, requestedWidth, requestedHeight, downsampType)))) {
       scaleFactor = scaleFactor << 1;
     }
     return scaleFactor
   }
-
-  getSampleSizeType(sourceWidth: number, sourceHeight: number, requestedWidth: number, requestedHeight: number,
-    downsampType: DownsampleStrategy
-  ): number {
-    if (downsampType === DownsampleStrategy.FIT_CENTER_QUALITY) {
-      return SampleSizeRounding.QUALITY;
-    } else {
-      return SampleSizeRounding.MEMORY;
-    }
-
-  }
-}
-
-export class None implements BaseDownsampling {
-  getName(): string {
-    return "DownsampleNone"
-  }
-
-  public getScaleFactor(sourceWidth: number, sourceHeight: number, requestedWidth: number,
-    requestedHeight: number): number {
-    let outSize: Size = {
-      width: round(sourceWidth),
-      height:round(sourceHeight)
-    }
-    let scaleFactor =
-      Math.max(1, highestOneBit(Math.max(sourceWidth / outSize.width, sourceHeight / outSize.height)))
-    return scaleFactor
-  }
-
-  //实现 getSampleSizeType 方法
-  public getSampleSizeType(sourceWidth: number, sourceHeight: number, requestedWidth: number,
-    requestedHeight: number): SampleSizeRounding {
-    return SampleSizeRounding.QUALITY
-  }
 }
 
 
@@ -95,11 +61,6 @@ export class CenterOutside implements BaseDownsampling {
 
     return scaleFactor
   }
-
-  getSampleSizeType(sourceWidth: number, sourceHeight: number, requestedWidth: number,
-    requestedHeight: number): SampleSizeRounding {
-    return SampleSizeRounding.QUALITY;
-  }
 }
 
 /*请求尺寸大于实际尺寸不进行放大,按照原图展示*/
@@ -129,13 +90,6 @@ export class AtMost implements BaseDownsampling {
     }
     return scaleFactor
   }
-
-
-  getSampleSizeType(sourceWidth: number, sourceHeight: number, requestedWidth: number,
-    requestHeight: number): SampleSizeRounding {
-    //根据 AtMost 的逻辑，总是返回 MEMORY
-    return SampleSizeRounding.MEMORY
-  }
 }
 
 /*宽高进行等比缩放宽高里面最大的比例先放进去