<template>
    <div class="tm-image" :style="style" @click="onClick">
        <img :src="src"
             :alt="alt"
             :style="{'object-fit': mode}"
             @load="onLoad"
             @error="onError">
        <div v-if="this.loading" class="tm-image-load">
            <slot name="loading">加载中</slot>
        </div>
        <div v-if="this.error" class="tm-image-error">
            <slot name="error">加载出错</slot>
        </div>
    </div>
</template>

<script>
    import suffixPx from '../../utils/suffixPx.js';

    export default {
        name: "tm-image",
        data() {
            return {
                loading: true,
                error: false
            }
        },
        props: {
            src: String,
            alt: String,
            mode: {  // 模式：https://developer.mozilla.org/zh-CN/docs/Web/CSS/object-fit
                type: String,
                default: "fill",
                validator(value) {
                    return ['contain', 'cover', 'fill', 'none', 'scale-down'].includes(value);
                }
            },
            width: [String, Number],
            height: [String, Number]
        },
        computed: {
            style() {
                return {
                    width: suffixPx(this.width),
                    height: suffixPx(this.height)
                }
            }
        },
        methods: {
            onClick(event) {
                this.$emit('click', event);   // 向父节点传递一个自定义事件
            },
            onLoad(event) {
                this.loading = false;
                this.$emit('loading', event); // 向父节点传递一个自定义事件
            },
            onError(event) {
                this.loading = false;
                this.error = true;
                this.$emit('error', event); // 向父节点传递一个自定义事件
            }
        }
    }
</script>

<style scoped>
    .tm-image{
        position: relative;
        overflow: hidden;
    }
    .tm-image .tm-image-load,
    .tm-image .tm-image-error{
        position: absolute;
        top:0;
        left: 0;
        width: 100%;
        height: 100%;
        background: #f2f2f2;
        color: #666;
        display: flex;
        align-items: center;
        justify-content: center;
    }
    .tm-image img {
        width: 100%;
        height: 100%;
    }
</style>