fix: swipe sometimes will change to drag image (#81)

* swipe forbid dragstart

docs/examples-docs/swipe.md

@@ -64,6 +64,33 @@ export default {
 ```
 :::
 
+#### 隐藏指示器
+
+需要设置`show-indicators`属性为`false`，即会隐藏指示器。
+
+:::demo 隐藏指示器
+```html
+<van-swipe :show-indicators="false">
+  <van-swipe-item v-for="(img, index) in autoImages" :key="index">
+    <img v-lazy="img" alt="">
+  </van-swipe-item>
+</van-swipe>
+
+<script>
+export default {
+  data() {
+    return {
+      autoImages: [
+        'https://img.yzcdn.cn/upload_files/2017/03/09/FvkZahKoq1vkxLQFdVWeLf2UCqDz.png',
+        'https://img.yzcdn.cn/upload_files/2017/03/09/Fk0rpe_svu9d5Xk3MUCWd1QeMXOu.png'
+      ]
+    };
+  }
+};
+</script>
+```
+:::
+
 #### 自动轮播
 
 需要设置`auto-play`属性为`true`，即会自动轮播。

package.json

@@ -73,6 +73,8 @@
     "friendly-errors-webpack-plugin": "^1.6.1",
     "gh-pages": "^1.0.0",
     "gulp": "^3.9.1",
+    "gulp-cssmin": "^0.2.0",
+    "gulp-postcss": "^7.0.0",
     "gulp-util": "^3.0.8",
     "highlight.js": "^9.12.0",
     "html-webpack-plugin": "^2.29.0",

packages/swipe/src/input.js

@@ -26,6 +26,7 @@ Input.prototype = Object.create(new EventEmitter());
 extend(Input.prototype, {
   bind: function(host) {
     if (Vue.prototype.$isServer) return;
+    bindEvents(host, 'dragstart', e => e.preventDefault());
     bindEvents(host, 'touchstart mousedown', this.onTouchStart);
     if (this.options.listenMoving) {
       bindEvents(window, 'touchmove mousemove', this.onTouchMove);