[new feature] NumberKeyboard add custom theme (#472)

packages/number-keyboard/Key.vue

@@ -0,0 +1,49 @@
+<template>
+  <i
+    v-text="text"
+    @touchstart.stop.prevent="onFocus"
+    @touchmove="onBlur"
+    @touchend="onBlur"
+    @touchcancel="onBlur"
+    class="van-hairline van-key"
+    :class="className"
+  />
+</template>
+
+<script>
+export default {
+  props: {
+    text: [String, Number],
+    type: {
+      type: Array,
+      default: () => []
+    }
+  },
+
+  data() {
+    return {
+      active: false
+    };
+  },
+
+  computed: {
+    className() {
+      const types = this.type.slice(0);
+      this.active && types.push('active');
+
+      return types.map(type => `van-key--${type}`);
+    }
+  },
+
+  methods: {
+    onFocus() {
+      this.active = true;
+      this.$emit('press', this.text);
+    },
+
+    onBlur() {
+      this.active = false;
+    }
+  }
+};
+</script>