更新说明：

- 补充单个图片测试demo

Signed-off-by: 明月清风 <qiufeihu1@h-partners.com>

entry/src/main/ets/pages/SingleImage.ets

@@ -29,8 +29,9 @@ struct SingleImage {
     fs.writeSync(file.fd, icon.buffer);
     fs.fsyncSync(file.fd);
     fs.closeSync(file);
-    getContext().resourceManager.getMediaContentSync( $r("app.media.aaa"))
-      .buffer as ArrayBuffer;
+    this.changePic(getContext().resourceManager.getMediaContentSync( $r("app.media.aaa"))
+      .buffer as ArrayBuffer);
+
 
   }
 
@@ -84,12 +85,12 @@ struct SingleImage {
             transformation: new BlurTransformation(10)
           }
         }).width(100).height(100)
-        Text("自定义下载")
+        Text("pixelMap加载图片")
           .fontSize(30)
           .fontWeight(FontWeight.Bold)
         ImageKnifeComponent({
           imageKnifeOption: {
-            loadSrc: this.pixelMap,
+            loadSrc: this.pixelMap!,
             placeholderSrc: $r("app.media.loading"),
             errorholderSrc: $r("app.media.app_icon"),
             objectFit: ImageFit.Contain,