Tooltip add maxWidth prop

examples/routers/tooltip.vue

@@ -1,9 +1,9 @@
 <template>
-    <div>
-        <Tooltip always placement="top" transfer :content="text" :delay="1000" theme="light">
+    <div style="margin: 200px;">
+        <Tooltip always placement="top-end" transfer :content="text" :delay="1000" theme="light">
             <Button @click="disabled = true">延时1秒显示</Button>
         </Tooltip>
-        <Tooltip placement="top" transfer :content="text">
+        <Tooltip always transfer :max-width="200" content="我的文本超级无敌长我的文本超级无敌长我的文本超级无敌长我的文本超级无敌长我的文本超级无敌长我的文本超级无敌长">
             <Button @click="handleChange">change</Button>
         </Tooltip>
         <Button @click="handleChange">change</Button>

src/components/tooltip/tooltip.vue

@@ -14,7 +14,7 @@
                 v-transfer-dom>
                 <div :class="[prefixCls + '-content']">
                     <div :class="[prefixCls + '-arrow']"></div>
-                    <div :class="[prefixCls + '-inner']"><slot name="content">{{ content }}</slot></div>
+                    <div :class="innerClasses" :style="innerStyles"><slot name="content">{{ content }}</slot></div>
                 </div>
             </div>
         </transition>
@@ -67,6 +67,9 @@
                     return oneOf(value, ['dark', 'light']);
                 },
                 default: 'dark'
+            },
+            maxWidth: {
+                type: Number
             }
         },
         data () {
@@ -74,6 +77,21 @@
                 prefixCls: prefixCls
             };
         },
+        computed: {
+            innerStyles () {
+                const styles = {};
+                if (this.maxWidth) styles['max-width'] = `${this.maxWidth}px`;
+                return styles;
+            },
+            innerClasses () {
+                return [
+                    `${prefixCls}-inner`,
+                    {
+                        [`${prefixCls}-inner-with-width`]: !!this.maxWidth
+                    }
+                ];
+            }
+        },
         watch: {
             content () {
                 this.updatePopper();

src/styles/components/tooltip.less

@@ -71,6 +71,11 @@
         border-radius: @border-radius-small;
         box-shadow: @shadow-base;
         white-space: nowrap;
+
+        &-with-width{
+            white-space: pre-wrap;
+            text-align: justify;
+        }
     }
 
     &-light &-inner{