uni-app:踩坑路---关于使用了transform导致fixed定位不生效的问题

前言：

继续记录，在上篇文章中，弹出框遮罩层在ios上没有正确的铺盖全屏，是因为机型的原因，也和我们的代码结构有相关的问题。今天再来展示另外一个奇葩的问题。

这次我使用了在本篇博客中的弹出框组件CustomDialog.vue。记录uni-app横屏项目：自定义弹出框-CSDN博客

以及在这篇博客中的CustomItem.vue组件。

uni-app：踩坑路---scroll-view内使用fixed定位，无效的问题-CSDN博客

CustomDialog.vue

<template><view class="dialog-overlay" v-if="visible" :style="{ zIndex: zIndex }" @tap="closeMask"><view class="dialog" v-if="dialogVisible" :style="[getStyle]" :class="[showAnimate ? 'bounce-enter-active' : 'bounce-leave-active']" @tap.stop><view class="close" v-if="showClose" @tap="close"><view class="iconfont icon-guanbi"></view></view><slot></slot></view></view>
</template><script>
export default {name: 'CustomDialog',props: {visible: {type: Boolean,default: false},width: {type: String,default: 'auto'},height: {type: String,default: 'auto'},radius: {type: String,default: '16rpx'},bgColor: {type: String,default: '#fff'},customStyle: {type: Object,default: () => ({})},/* 是否展示右上角关闭按钮 */showClose: {type: Boolean,default: true},/* 是否点击遮罩层可以关闭弹出框 */maskCloseAble: {type: Boolean,default: true},/* 弹出框层级 */zIndex: {type: Number,default: 999}},data() {return {dialogVisible: this.visible,showAnimate: this.visible,timer: null};},beforeDestroy() {this.clearTimeout();},watch: {visible: {handler(val) {setTimeout(() => {this.dialogVisible = val;this.showAnimate = val;}, 50);},immediate: true}},computed: {getStyle() {return {width: this.width,height: this.height,background: this.bgColor,borderRadius: this.radius,...this.customStyle};}},methods: {clearTimeout() {if (this.timer) {clearTimeout(this.timer);this.timer = null;}},closeMask() {if (!this.maskCloseAble) return;this.close();},close() {this.closeAnimate();this.timer = setTimeout(() => {this.$emit('close');this.$emit('update:visible', false);}, 500);},closeAnimate() {this.showAnimate = false;this.clearTimeout();}}
};
</script><style lang="scss" scoped>
.dialog-overlay {position: fixed;top: 0;left: 0;right: 0;bottom: 0;display: flex;align-items: center;justify-content: center;background-color: rgba(#000, 0.3);
}.dialog {position: relative;border-radius: 16px;padding: 20rpx;padding-bottom: 14rpx;margin-left: -50rpx;opacity: 0;.close {position: absolute;width: 28rpx;height: 28rpx;border-radius: 50%;background-color: rgba(#000, 0.6);top: -10rpx;right: -10rpx;.icon {width: 10rpx;height: 10rpx;}}
}/*  打开与关闭的类名 */
.bounce-enter-active {animation: bounceIn 0.5s both;
}
.bounce-leave-active {animation: bounceOut 0.5s both;
}/* 定义bounceIn动画 */
@keyframes bounceIn {0% {opacity: 0;transform: scale(0);}50% {opacity: 1;transform: scale(1.2);}70% {opacity: 1;transform: scale(0.9);}100% {opacity: 1;transform: scale(1);}
}
/* 定义 bounceOut 动画 */
@keyframes bounceOut {0% {opacity: 1;transform: scale(1);}25% {opacity: 1;transform: scale(0.95);}50% {opacity: 0;transform: scale(1.1);}100% {opacity: 0;transform: scale(0);}
}.icon-guanbi {color: #94ffd8;font-size: 16rpx;
}
</style>

CustomItem.vue

<template><view class=""><view class="item" @click="visible = true"></view><view class="mask" v-if="visible" @click="visible = false"></view></view>
</template><script>
export default {name: 'CustomItem',data() {return {visible: false};}
};
</script><style lang="scss" scoped>
.item {width: 100rpx;height: 100rpx;background-color: #00aaff;
}
.mask {position: fixed;top: 0;left: 0;right: 0;bottom: 0;background-color: rgba(#000, 0.5);
}
</style>

页面使用：

<template><view class="index"><button @click="visible = true">click</button><custom-dialog :visible.sync="visible" width="500rpx" height="200rpx"><view class="list"><custom-item class="item" v-for="i in 3" :key="i"></custom-item></view></custom-dialog></view>
</template><script>
import CustomDialog from '@/components/CustomDialog/index.vue';
import CustomItem from '@/components/CustomItem/index.vue';
export default {components: {CustomDialog,CustomItem},data() {return {visible: false};}
};
</script><style lang="scss" scoped>
.index {width: 100vw;height: 100vh;display: flex;align-items: center;justify-content: center;
}
.list {padding: 20rpx;display: flex;align-items: center;.item {margin-right: 20rpx;}
}
</style>

和上篇文章中不同的是，这次可并没有使用scroll-view组件，只是在弹出框组件内使用了另一个Item组件而已，但是效果却大大出乎了意料！

弹出框显示：一切ok

点击蓝色方块，展示一个遮罩层：没想到这个遮罩层他又又又被截断了，没有去正确的铺满全屏。。。这次又是为什么？

经过我一层层的排出，最后得出了一个惊人的结论，居然和我的弹出框组件有关，还是最让人意想不到的css的transform属性。transform对普通元素的N多渲染影响，这篇文章就说明的相当详细。

下面我把所有关于transform都给注释掉了，然后再去尝试点击蓝色方块。

/* 定义bounceIn动画 */
@keyframes bounceIn {0% {opacity: 0;// transform: scale(0);}50% {opacity: 1;// transform: scale(1.2);}70% {opacity: 1;// transform: scale(0.9);}100% {opacity: 1;// transform: scale(1);}
}
/* 定义 bounceOut 动画 */
@keyframes bounceOut {0% {opacity: 1;// transform: scale(1);}25% {opacity: 1;// transform: scale(0.95);}50% {opacity: 0;// transform: scale(1.1);}100% {opacity: 0;// transform: scale(0);}
}

ok，彻底告别地球了。。。