<template>
  <!-- #ifdef APP -->
  <scroll-view style="flex:1">
  <!-- #endif -->
    <view>
      <!-- 测试iOS平台宽高为0时，设置渐变色会不会导致闪退 -->
      <view style="width: 0px; height: 0px; background-image: linear-gradient(to bottom,#f5f5f5,#eff2f5);"></view>
      <text>不支持背景图片，仅支持linear-gradient方法</text>
      <view v-for="(direction) in directionData">
        <text>background-image: linear-gradient({{direction}}, red, yellow)</text>
        <view class="common"
          :style="{'background-image': backgroundSelect ?'linear-gradient('+direction+', red, yellow)':''}"></view>
      </view>
      <view>
        <text>style 动态切换 background</text>
        <view @click='changeBgStyle' class="common" :style='testStyle'>{{ testStyle}}</view>
      </view>
      <view>
        <text>class 动态切换 background</text>
        <view @click='changeBgClass' class="common" :class='testClass'>{{testClass}}</view>
      </view>
    </view>
  <!-- #ifdef APP -->
  </scroll-view>
  <!-- #endif -->
</template>

<script>
  export default {
    data() {
      return {
        backgroundSelect: true,
        directionData: ['to right', 'to left', 'to bottom', 'to top', 'to bottom left', 'to bottom right', 'to top left', 'to top right'],
        testStyle: "background:linear-gradient(to right, red, yellow)",
        testClass: "bg-color"
      }
    },
    methods: {
      //供自动化测试使用
      updateBackgroundSelect() {
        this.backgroundSelect = !this.backgroundSelect
      },
      changeBgStyle() {
        const isColor = this.testStyle == "background:blue"
        if (isColor) {
          this.setBackgroundImage()
        } else {
          this.setBackgroundColor()
        }
      },
      setBackgroundColor() {
        this.testStyle = "background:blue"
      },
      setBackgroundImage() {
        this.testStyle = "background:linear-gradient(to right, red, yellow)"
      },
      changeBgClass() {
        this.testClass = this.testClass == "bg-color" ? "bg-image" : "bg-color"
      }
    }
  }
</script>

<style>
  .common {
    width: 250px;
    height: 250px;
  }
  .bg-color {
    background: blue;
  }
  .bg-image {
    background: linear-gradient(to right, red, yellow);
  }
</style>