update readme

README.md

@@ -8,19 +8,52 @@ We should know that in order to achieve Gif in flutter, we can use Image, but we
 ![](arts/gif.gif)
 
 # Usage(Simple)
+  add in pubspec
+
+   ```dart
+
+        flutter_gifimage: ^1.0.0
+
+   ```
+
+ simple usage
 
  ```dart
-     controller4= GifController(vsync: this);
+     GifController controller= GifController(vsync: this);
 
 
      GifImage(
           controller: controller,
-          image: MemoryImage(base64Decode(base64_url)),
+          image: AssetImage("images/animate.gif"),
      )
 
  ```
- GifController is just a AnimationController, usage is the same with AnimationController,If you want to play animate Between two frames ,you just called 'repeat(min: max:)','period' can change the repeat speed
- ,If you want to stop in one frame ,  call 'controller.value = .. '
+
+ list the most common operate in GifController:
+
+
+ ```dart
+ // loop from 0 frame to 29 frame
+ controller.repeat(min:0,max:29,period:Duration(millseconds:300));
+
+ // jumpTo thrid frame(index from 0)
+ controller.value = 0;
+
+ // from current frame to 26 frame
+ controller.animateTo(26);
+
+ ```
+
+ If you need to preCache gif,try this
+
+ ```dart
+ // put imageProvider
+ fetchGif(AssetImage("images/animate.gif"));
+
+ ```
+
+
+
 
 # Thanks
 * [gif_ani](https://github.com/hyz1992/gif_ani)  (thanks for giving me idea)

lib/flutter_gifimage.dart

@@ -13,10 +13,10 @@ import 'dart:ui';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 
+/// cache gif fetched image
 class GifCache{
   final Map<String,List<ImageInfo>> caches= Map();
 
-
   void clear() {
     caches.clear();
   }
@@ -28,8 +28,8 @@ class GifCache{
     }
     return false;
   }
-
 }
+
 /// controll gif
 class GifController extends AnimationController{
 
@@ -46,8 +46,15 @@ class GifController extends AnimationController{
       animationBehavior:animationBehavior??AnimationBehavior.normal,
       vsync:vsync);
 
+  @override
+  void reset() {
+    // TODO: implement reset
+    value = 0.0;
+  }
+
 }
 
+
 class GifImage extends StatefulWidget{
   GifImage({
     @required this.image,