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Flutter 124: 日常问题小结 (三) 自定义 Dialog 二三事

针对日常不同的需求,我们时常需要自定义 Dialog ,而小菜在尝试过程中遇到一些小问题,简单记录总结一下;

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小菜在自定义含有文本框的 Dialog 时,文本框获取焦点时,软键盘会部分遮挡对话框,但当小菜替换为 AlertDialog 时,文本框获取焦点时,对话框会向上浮动,避免软键盘遮挡;

对于含有文本框的自定义 Dialog ,小菜在最外层使用的是 Material 嵌套,小菜通过采用 Scaffold 来嵌套处理,默认 Scaffold 中 resizeToAvoidBottomPadding / resizeToAvoidBottomInset 为 true ,当设置为 false 时,文本框获取焦点时,依旧会被软键盘遮挡;因为在固定情景可以配合 resizeToAvoidBottomPadding 实现是否被软键盘遮挡效果;

resizeToAvoidBottomPadding 主要用于自身 Widget 是否避免被其他窗口遮挡;其中小菜查资料介绍在 Flutter 1.1.9 之后更推荐使用 resizeToAvoidBottomInset ;

小菜自定义一个可以多选 item 的 Dialog ,但 Dialog 中并没有状态更新的 State ,如何进行 Dialog 中状态更新呢?

小菜之前在 showDialog 时直接创建了 TypeListDialog ,此时是无状态的,当 WidgetBuilder 创建一个 StatefulBuilder 有状态的构造器即可,可以将 state 传递到 Dialog 中;

小菜在自定义 Dialog 时如何在一个回调方法中传递多个参数?

小菜在 Dialog 的回调方法中传递两个 List ,而在接收回调方法中匹配两个参数即可;小菜简单看作是一个函数方法;

小菜在重写 AppBar 时,如何取消默认的返回按钮?

取消 AppBar 前面的返回图标有多种方式;

自定义 Dialog 案例源码

小菜对于 Flutter 的应用还不够熟悉,很多常用的场景会处理的很不到位,小菜会对日常的小问题进行简单记录,逐步学习;如有错误,请多多指导!

Flutter入门这一篇效率文章就够了

本文面向 Flutter 初学者,旨在用易懂的方式带大家入门。除了 Flutter 代码,还会介绍到语法、原理、特性等基础知识。相信本文能帮助你学习和理解 Flutter。

我们先看一下目前的一些跨平台方案,从前端渲染的角度来分类的话,大致可以分为以下几种方案。

WebView 渲染

这种方案就很好理解,现在很多项目都会嵌入 H5 的页面。就是用 JavaScript 等前端技术进行开发,在客户端上用 WebView 来进行渲染。微信小程序目前使用的就是这种方案。

它的优点很明显,使用成熟的前端技术进行开发,学习成本低,开发效率高,并且支持动态发布代码。

但缺点也很明显,在性能体验上,和原生还是存在较大差距的。

原生控件渲染

既然 WebView 的性能不够好,于是就有了使用原生控件进行渲染的方案。这种方案,同样也是使用 JavaScript 开发,区别是它最终是调用原生控件进行渲染的。这种方案的代表是 Facebook 的 React Native。

由于使用原生控件进行渲染,性能体验也会更接近原生。但也只是更接近,和原生还是有差距的,因为它需要频繁的进行 JavaScript 和原生之间的通信,这个通信效率是比较低的。

另外,由于需要适配各个平台的控件,那就有可能出现,系统控件更新了,而框架本身还没有更新,由此产生了一些问题。换句话说,这种方案是受到原生控件限制的。

绘图引擎渲染

接下来就是主角了。

在前端,如果完全不使用原生控件,我们可以通过系统的绘图 API 绘制出一个用户界面。从这个角度出发,可以在各个平台使用一个统一接口的绘图引擎来进行界面绘制,这个引擎最终调用的是系统的 API 绘制的。这样的话,它的性能可以做到接近原生,并且又不受原生控件的限制,在不同平台上能够做到 UI 统一。

Flutter 就是这样的一个开发框架。

一个跨平台 UI 解决方案

Flutter 是由 Google 开发的,一个跨平台 UI 解决方案。换句话说,它原则上只管 UI 的问题,如果涉及到平台本身的一些功能,比如调用蓝牙、摄像头,一般还是需要原生代码去操作。但现在也会有一些第三方库帮我们解决这些问题。

绘图引擎 Skia

Flutter 使用 Skia 作为它的绘图引擎。Skia 已经被 Google 收购,目前很多 Google 旗下的产品都是用 Skia 绘制的,包括 Android。

Android 内置了 Skia,但 iOS 没有,所以在打 iOS 安装包的时候,会把 Skia 一起打进去。这就导致了,用同一份 Flutter 代码打包之后,iOS 的包要比 Android 的包大一些。

开发语言 Dart

Flutter 使用的开发语言,叫 Dart。Dart 也是 Google 自家的,它是一门面向对象的语言,从它身上会看到一些其他开发语言的影子。学习起来难度不大的。

前面讲跨平台方案的时候,可以发现别的方案基本都是用 JavaScript 作为开发语言的,但为什么 Flutter 不用?就因为 Dart 是谷歌自家的吗?这个问题先留着,我们后面会提到。

这里部分就简单点带过了,具体的搭建流程可以在官网查看:

主要的搭建步骤如下:

下载 Flutter SDK

官网下载地址:

由于在国内访问可能受限,官方为中国开发者搭建了镜像:

更新环境变量

解压后,将 flutter\bin 的全路径添加到环境变量 PATH 中。

安装开发工具

理论上,任何文本编辑器都可以用来开发 Flutter 应用,但推荐的开发工具是 Android Studio、IntelliJ 以及 VS Code。因为在这些开发工具上,可以安装官方的 Flutter 和 Dart 插件,得到更好的开发体验。文章里使用 Android Studio 来演示。

如果你打算开发 iOS 应用,则还需要安装 Xcode。

安装插件

在开发工具的插件设置中,安装上面说到的 Flutter 和 Dart 插件。Flutter 插件用于支持 Flutter 的运行、调试、热重载等功能,而 Dart 插件则提供了代码的输入校验、代码补全等功能。

万物始于 Hello World,我们先来创建一个显示 Hello World 的 Flutter 项目。

在 Android Studio 的欢迎页面选择 Start a new Flutter project ,或者通过菜单栏的 File New New Flutter Project ,创建一个新的 Flutter 项目。

创建好的项目里面包含了 android 和 ios 两个文件夹,它们是标准的 Android 和 iOS 项目。我们的 Flutter 代码,存放在 lib 文件夹里。项目创建好后,会默认带一个计数器的示例,我们不管它,把 main.dart 的代码改成 Hello World:

启动一个模拟器,或者连上真机,点击 Run 运行一下,就能看这样一个界面了:

具体代码先混个眼熟就好,具体的后面会再讲到。

在写 Flutter 之前,还要先跟大家简单介绍一下 Dart 的语法。如果你有 Java 或 JavaScript 的开发经验,以及面向对象的编程思想,学起来是很快的。

我们可以在 test 文件夹下新建一个 dart 文件,用来写测试代码。

指定类型

var

但和 JavaScript 不同的是,以下代码在 JavaScript 是不会报错的,但在 Dart 里会报错:

Object

如果非要上面这样写,那也可以。把 var 换成 Object 就不报错了:

和 Java 类似,Object 是所有对象的根基类。但是这样的话,如果想打印一下 num 的字符串长度,是会报错的:

因为 length 是属于 String 的,但系统只知道 num 是一个对象,并不知道它是一个 String。

dynamic

如果还是非要这样写,那也可以。Dart 有一个特有的关键字 dynamic,把 Object 改成 dynamic 就不报错了:

我们运行一下这个文件,可以在控制台看到正确打印出了字符串长度。

函数

dynamic

在 Dart 里,函数也是可以不写返回类型的,不写的话会被当做 dynamic 来处理。这样的话,函数的类型就是 return 的类型,如果没有 return 则是 void 类型。比如可以这样:

运行之后是能正确打印出字符串长度的。

用于传参

Dart 里的函数也是一个对象,所以可以把函数作为参数来传递,比如:

可选参数

在 Dart 的函数传参里,有一个叫可选参数的概念,我们以文字控件 Text 为例,在源码里可以看到 Text 的构造函数是这样的:

首先,在参数里有一个 data,它是要显示的文字内容,是一个必填项。而 data 后面的一堆参数,是用一个大括号括起来的,这些参数就叫做可选参数,意思是这些参数可传可不传。

假如我们要显示一个比较长的文字,又想限制它最多显示两行,就可以这样来创建一个 Text:

可选参数,在 Flutter 里面用的非常多。

异步

Future

在 Dart 里使用 Future 来处理异步任务,比如我们现在延时一秒打印 666,代码如下:

Future 的语法和 Promise 非常像。任务执行成功会调用 then,执行失败会调用 catchError,而无论成功还是失败,都会调用 whenComplete。

async/await

如果你不喜欢上面那种写法,或者是想把异步转成同步,就可以用 async 和 await 这两个关键字来转换。

我们把上面的代码转换一下,写一个 getString 方法,返回的类型是 Future,它会延时返回一个字符串。在 main 函数后面加上 async 关键字,在 getString() 前面加上 await,代码如下:

运行之后可以看到,能正常延时一秒后,把字符串打印出来。这里 getString() 返回的类型是 Future,而 await getString() 则是返回了延时之后返回的字符串。await 要在 async 的函数里面才能使用。

async 和 await 其实是一个语法糖,它最终也是转换成 Future 调用链的形式执行的。

接下来回到 Flutter,Flutter 里最重要的一个概念是 Widget(下面翻译作控件)。

在原生开发里面,我们可能会在界面上区分,这是一个 View,这是一个 Layout,这是一个 View Controller。但在 Flutter 里面,它们全都属于一个统一的模型 Widget。可以说,在 Flutter 界面里,所有东西都是 Widget。

以前学面向对象的时候,我们都听过一句话,叫万物皆对象。我这里套用一下,在 Flutter 里, 万物皆控件 。

具体有哪些控件,我做了一下简单的分类。

根控件

所有的控件都属于 StatefulWidget 或 StatelessWidget 。它们的区别是,StatefulWidget 拥有状态 State ,而 StatelessWidget 没有。

StatefulWidget

当一个控件是可变的时候,就要使用 StatefulWidget 来构建。StatefulWidget 本身不可变,但它持有的状态 State 是可变的。

StatelessWidget

当一个控件状态是固定不可变的时候,就可以使用 StatelessWidget。前面我们写的 Hello World 就是使用 StatelessWidget。

容器控件

容器类控件一般是将某些属性或配置,作用在它的子控件上,比如控件所在的宽高、背景、位置等。

常用的容器控件有 Container、Center、Padding 等。

布局控件

布局控件可以类比作原生开发中的 Layout,通常它会拥有一个 children 的属性,用于接收一个控件数组,对这些控件进行特定的排版。

常用的布局控件有 Row、Column、Stack、Flex 等。

基础控件

基础控件就是常用的文字、按钮、图片等控件。

常用的基础控件有 Text、TextField、Button、Image 等。

功能控件

在 Flutter 里还有一类控件,它们不影响 UI 布局,但带有一些特定的功能,比如页面跳转、事件监听、定义主题等。我们把这一类控件称作功能控件。

常用的功能控件有 Navigator、NotificationListener、Theme 等。

开始写 Flutter 代码了。还记不记得,在 Flutter 项目创建之后,是自带一个计数器 demo 的,现在我们用自己的代码实现一遍。代码修改成如下:

运行之后,就可以看到这样的界面了:

按钮每点击一次,数字就会加一。下面我们来分析一下这段代码,看下里面用到的一些 Widget。

StatefulWidget

由于页面中的数字是跟随状态变化的,所以该页面改用 StatefulWidget。StatefulWidget 并不会直接返回一个 Widget,而是返回状态 State,在 State 里再返回 Widget。

Scaffold

Scaffold 是一个标准的 Material Design 页面,它包含了标题栏、浮动按钮、侧滑菜单、底部导航栏等配置。我们这里用到了标题栏 appBar、页面内容 body、浮动按钮 floatingActionButton。

AppBar

AppBar 就是标题栏,通过查看控件的构造方法,我们可以知道它可配置的属性。

AppBar 的可选参数除了标题 title,还可以配置标题前的内容 leading,右侧的操作按钮 anctions,控件垂直高度 elevation 等。我们只传了 title,其他属性都用默认值。

Center

Center 是一个容器类控件,它的作用就是让它的子控件居中显示。

FloatingActionButton

熟悉安卓开发的应该对这个控件比较熟悉,它就是页面右下角一个特定样式的 Button,参数里面的 onPressed 是一个必填项,要传一个点击之后的回调函数。

根据这个例子,下面给大家介绍一下 Flutter 两个比较重要的特性。

点击 Button 之后,我们把 num 变量加一,并使用 setState 通知状态发生了改变,Flutter 会根据新的状态更新 UI。如果有接触过小程序开发,setState 就和小程序的 setData 类似。

在 Flutter 里面我们不需要用 set 方法来更新 UI,可变控件是和状态绑定的,这就是 Flutter 的响应式 UI 编程。

在 Android Q 和 iOS 13 里都加入了暗黑模式,我们也换一个暗黑主题来玩一下。MaterialApp 里有一个 theme 的属性,我们把它配置一下:

这次改完之后不点 Run 了,我们点一下闪电图标 Flutter Hot Reload ,就能看到界面发生了变化:

这就是 Flutter 的 热重载 ,在修改完代码之后,通过热重载就能马上在设备上看到修改结果,可以很大程度上增加开发效率。

下面再给大家介绍几个 Flutter 里的常见操作。

在 Flutter 里,使用 Navigator 来管理页面跳转,比如要跳转到一个 NewPage 可以这样写:

进栈使用 push,出栈则是 pop。

使用 MaterialPageRoute 会模拟出 Android 上页面跳转的过场效果。

我们来看看怎么显示一张本地图片。

先在根目录新建一个存放图片的文件夹,比如叫 images,把图片 picture.png 放进去。

找到根目录下的 pubspec.yaml 文件,这个便是 Flutter 依赖配置文件,我们需要在这里配置一下刚才的图片:

这样,我们就能使用 Image 控件把这张图片显示出来了:

和 node 的 npm 以及 Android 的 jcenter 类似,Flutter 也拥有一个公共仓库 pub.dev。pub.dev 是 Google 官方的 Dart 仓库,在上面可以找到我们需要的包和插件。

Flutter 本身没有 Toast,我们来接入一个。在 pub.dev 上搜索后,我决定使用 fluttertoast:

按照说明,在 pubspec.yaml 文件里的 dependencies 下配置:

点一下 Android Studio 右上角的 Packages get 同步之后就可以使用了:

我们上面使用的都是 Material Design 的控件,它们都是在 flutter/material.dart 包里面的。如果要使用 iOS 风格的控件,则要用到 flutter/cupertino.dart 包:

iOS 风格的控件,基本都以 Cupertino 开头。我们把计时器页面里的控件替换一下:

效果如下:

代码的部分就到这里了,接下来跟大家聊一下编译方式,编程语言的编译方式有两种。

关于它们孰优孰劣,就要看从哪个角度去对比了。JIT 的话,它的一大特点就是支持动态发布代码,也就是支持热更新。但要是从性能的角度考虑,AOT 会更好,因为在运行的时候不用再进行编译的操作的,运行的效率会更高一些。

回到我们一开始的时候留下的问题,为什么别的跨平台方案都是用 JavaScript,而 Flutter 要用 Dart 来开发。JavaScript 的编译方式是 JIT 的,它不支持 AOT。而 Dart 同时支持 JIT 和 AOT。

Flutter 在开发阶段使用 JIT,让我们用上了热重载,增加了开发效率。在打包时改用 AOT,保证了正式版应用的性能。

最后讲一下大家比较关心的一个东西,Flutter 是否支持热更新?前面说到 Dart 支持 JIT,所以从技术层面它是支持的。但是目前是不支持的,在官方的计划文档中,可以看到:

至于原因,官方在这里进行了说明。总的来说,是由于政策的限制,以及出于对性能和安全性的考虑,暂时不支持了。

到这就结束啦。由于想把 Flutter 基础在一篇内讲完,没有涉及太多细节,如果要写 Flutter 代码还需要深入学习。但相信理解之后再学,会轻松很多。

关于樱花的唯美句子简短英语

关于樱花的唯美句子简短英语

关于樱花的唯美句子简短英语,樱花品种相当繁多,数目超过三百种以上,樱花并不是一种花,而是统称, 樱花是春天特有的浪漫,也是希望美好的象征。以下关于樱花的唯美句子简短英语。

关于樱花的唯美句子简短英语1

1、When you walk to the square, the cherry blossoms come in two colors: one is white and the other is red. It looks like a piece of flower sea, flower bud and leaf one to morning and put, think elder sister and younger sister, rush to come into this world. Look, flower bud is five one, like a string of sweet and sweet cherry on the branch.

2、The cherry blossoms are usually five petals, with long stamens in the center, and usually nine to ten flowers, like beautiful yellow bean sprouts. The unborn baby, like a balloon that is about to explode, looks lovely.

3、The mountain cherry and the cherry trees are not as white as peach blossoms, nor as green as pear flowers, they are lilies grey. It is full of red and red, almost the spring of the Beijing city of haitang. In addition, there is also a pale yellow turmeric, a low-hanging branch of the branches, the "spring equinox", the first flowering of the other side, petals to more than 300 pieces of chrysanthemum... The beauty of beauty.

4、The cherry blossoms were so white that they were red, with yellow flowers clustered in five petals. Like plum flower, tree trunk looks like peach tree trunks, leaves of various is spend less, is the green leaves foil flower, blossom but Ye Shaohua, a small branches have seven or eight flower, clusters of clusters, like floating in the blue sky white cloud, and like a snow ball on the trees, this is the foil flower leaves!

5、The contrast between the flowering cherry blossoms is very small, but in the same tree, you can also see the various forms of flowers. Some of them are budding, the flowers are different from the branches, and they seem to have an unspoken fear of the outside world. Some have just blossomed, like babys smiling face, sweet and pure, can not stand any wind and rain, but still lovable; The blossoming cherry blossoms, like a group of lively and lovely children, make up a rich and full happy paradise, and many generations live together. It is like a young girl standing tall and erect, but she is full of vitality and graceful.

6、Spring came, and the branches of the cherry trees were brightly colored. The flowers were small and small, and the five or six gathered together to form a flower ball, clustered in clusters on the branches, stretching the long, narrow petals and the flowers wrapped in them.

7、The varieties of sakura are different, its leaves are different, some are green and smooth, some are red and rough, others are green inside, but the edges are red... The sakura bark is dark brown, which is exactly the way it is decorated with pink cherry blossoms, but it doesnt seem to be able to hide its own qualities or qualities. The petals of the cherry blossom have three or five flowers each, which are in the form of umbrella-shaped inflorescences, which are carried out at the level of sepals, giving off a faint scent of flowers...

8、On both sides of the road are beautiful cherry blossoms. There are two varieties, one of which was opened in February, and the red cherry blossom of the double flaps, and we can see a little bit more sporadically. While the flowers are blooming with sweet pink blossoms, we often see them in the pictures. I stand under the tree and look at them carefully, looking at them as if they were the flowers. I dont know if peach blossoms are related to cherry blossoms, but they are as indistinguishable as twin sisters. Of course, as long as you observe carefully, you will find that their branches are different, and the peach tree trunks are darker and brighter. According to the introduction, there are more than 10,000 cherry trees here.

9、Springs favorite flower is cherry blossom. Often overnight, its open. Sudden, overwhelming. Then fall in the wind. There is no nostalgia. The Japanese call it flowers blowing snow. At dusk, walking through the cherry trees, the white petals are still fluttering. It suddenly occurred to me that this was the most extravagant flower. Because it dies early.

10、The cherry blossoms have blossomed into beautiful cherry blossoms, and they have blossomed into a beautiful and sad love. Love will eventually fall, which is the unchangeable fate of beautiful things. Good and short, like cherry blossoms.

11、The leaves of the cherry blossoms are water droplets, with tiny little pubescent hairs on the edges, and the leaves of the stem are glimmering, just when the green light is shining. The red flower needs a foil, which is true. Although it has always been a supporting role, it still brings a green meaning to people. The thick trunk was brown and the surface was waxy and smooth.

12、The cherry blossom is dark red, a bit like a single pink peach blossom, but the flower is smaller than peach blossom, and the flower shape is not as beautiful as peach blossom. I dont know whether I was bullied by the cold rain last night, and every flower was drooping, like the little girl who was angry.

13、Cherry blossoms, will be allergic to the spring season, open-minded heaven, smoothing out the blundering heart, be familiar with simple words said to people will understand, silly childish tomorrow, dancing like you hair, allow me to cherish not small rely on silent in uproar, want to meet spring flowers and plants leave will have new harvest, waiting for the spring the filar silk like subtle miracles will happen, I heard that day there is cloud in nestle, and found that the accumulation of change, faintly see the tail of a lion, believe think again beautiful also learn the scene ahead in the dawn of the garden Yang, I feel special, I understand you have a window, you will see the melting love, no plan no adventure, happy every day, a warm glow.

14、Looking at the cherry blossoms, they are very disappointed. The cherry blossom is dark red, a bit like a single pink peach blossom, but the flower is smaller than peach blossom, and the flower shape is not as beautiful as peach blossom. I dont know whether I was bullied by the cold rain last night, and every flower was bowed down, like a little girl in anger, more like a Japanese womans bow and a smile. I think this is the origin of the Japanese national flower, and may also be able to say why the Japanese women are so bent over a shallow smile.

15、I proud, never make public, I want to, but never say, I just like to see cherry blossoms flutter sinks down, quietly watching the clouds drift in the feet, see the wind blowing hair, I want to sleep in parents arms, in brother Xiao Sheng piano company, however, all this is nothing but just desire, they who also can not give, I can only be a person lonely wandering, like abandoned.

16、We do not have to admire her beauty, just to be able to quietly smell her fragrance, the thin ice, and enjoy the dreamlike cherry blossoms. I gently walked to a cherry tree, unable to resist the impulse of the heart, tiptoe, carefully folding a cherry tree, sitting on the lake on the lakeside stone bench, carefully studied. The petals of the petals of the petals are so that they are not vulgar, but the subtle aroma of the heart.

17、The teacher took us to the cherry garden, looking at the pink one, like a large pink cloud, floating, floating, tired, just stop there. Close look, pink petals and green leaves all the oval, the blossom in yellow white, is white, under the above is yellow, very small, like a touch will be broken, so we just cant touch. The flowers are blooming in all shapes and shapes; Some of them are half open, trying hard; Some of them, like the shy little girl, dare not to appear. But flowers or flowers, they are crowded, dense layers. And the charming fragrance, refreshing and refreshing.

18、Look at the peach blossom standing next to the cherry blossoms. They smiled at me and looked away, like the golden red sun shining in the sky. The peach blossom after the rain is so sweet, it makes one feel drunk with its fragrance. A good sentence: yingying lotus wind before falling, a piece of peach blossom rain after the jiao ah! These peach blossoms, you do not let me, I do not let you, there are clusters of, there is a single one, is really a thousand shapes, no wonder! Peach blossom is like apricot blossom, it is light red, they are fighting every day!

19、In the evening the rosy clouds dyed red window lattice, the evening breeze with a couple of YingHuaBan, children pick up petals, there took petals, gently toss up, cherry blossoms flying in the sky, like the beautiful butterflies, dancing in the bosom of nature. The childrens laughter and the breeze, drifting far, far away...

20、Remember the first time to see the cherry blossom, a spring rain like a date, the petals rain wind blowing. The flowering period is just over a week, so brief and so gorgeous.

21、The petals of sakura are from the edge to the center, from pale pink to pure white; Pink, like a babys innocent smile, white, like the worlds snow. I cant help but gently stroke it, soft as the silk of the jiangnan. The edges of the petals are microwaves, like microwaves on a pink ocean, and the real thing is the "waves" of flowers. The stems are slender and soft, as thin as a green silver thread, as soft as a girls fair figure, from top to bottom, from thick to thin, from brown to green, supporting delicate flowers.

22、Cherry blossoms are a natural reward, but they are also a spectacle. In the cherry blossom, even if it is not for the flowers, but also unconsciously do the flower.

23、Close to see, each cherry blossom tree is like a tall girl, the cherry blossom on the tree is the adornment of the girl head. The cherry blossoms are still water droplets: some are just open, fragile as if the touch will fall off; The others are in full bloom.

24、Goodbye the cherry blossoms, again in the rain. In that day, the rainy spring, floating and sprinkling, the luojiashan mountain also appears particularly vacant. In sakura, on sakura avenue, full of people holding umbrellas. But I am thin standing in the crowd outside, the mood like this rain of cherry blossoms, strangely calm and peaceful. Not so long ago. Always in such a moment, with a piece of rain, gliding through the edge of the cherry blossoms in the paths of my soul. Cherry blossoms are in the rain. The cherry blossoms in the rain, but when we are not casual, tranquility becomes a profound commemoration, yes, in the days of luojiashan, it is our luckiest time, the most pure desire.

25、When we go out, we have a thick spring. We "traveled through the mountains and rivers" and came to yuyuantan. As soon as you enter the door, there are countless petals fluttering in the air, flying in front of our eyes. Standing in the thick shade of trees, the feeling of weariness of the day seemed to vanish, and the breeze lifted my heavy mouth. Walking forward, there was open water. The golden sun was shining on the water, as if it had covered the smooth surface of the lake with gold.

26、Area has come to cafe DE jack cherry blossoms, maybe this time missed the cherry blossom the most splendid time, a lot of cherry blossoms fade, falling slope, steps on the flower piece, formed the strips trail was paved with flowers, people walk while watching the cherry blossom, also another scenery! Although there are a lot of flowers, but there are still a lot of cherry trees, still bright, they spread a beautiful smile, welcome guests.

27、The cherry blossom is a beautiful flower. Between open in the spring and summer, extremely beautiful flowers, the white petals slightly tinged pink, the golden flowers like gold in the clustered together, is so delicate that bursting lovely little face in the breeze, look lively.

28、Cherry blossoms are beautiful and beautiful. They are important ornamental plants for early spring. They are often used in garden viewing, and they can be planted in groups or in front of roadside buildings in hillside courtyards. Blooming time flowers are gorgeous, full of trees, like clouds, extremely spectacular. The landscape of flowers and sea can be planted in large areas, and the three or five clusters of trees can be planted in the green space to form a brocade, which can also be isolated to form a little red color among the green clusters. Cherry trees can also be used as path trees and hedges or bonsai. In addition, bark and fresh tender leaves can be used medicinally. Some people make jam and condiments in Japan by grinding the flowers of cherry blossoms into nectar.

29、Look, so many dye color cotton candy to float in the air, that is tall, the cherry blossom on the cherry trees, let people see the couldnt help thinking the school gate at the bound on the stick to sell cotton candy, really want to eat a few mouth snack; Come a little closer, the cherry blossoms are in clusters, clusters, more like a branch of melting ice cream; A little closer to see it, flying in the air, still white with pink, just like the snow in the winter makeup general beauty.

30、Beautiful cherry blossoms, white pink, in the breeze, sometimes embracing; Sometimes crooning; Now and then he lowers his head and whispers; Or head laughed, this beautiful scene, touches everyones nerves, they at the same time of ornamental, keep out of the cell phone camera take pictures, posing a variety of poss, leave this happy and beautiful scene good memories!

关于樱花的唯美句子简短英语2

1、关于樱花的英语句子、段子、短文任意,有翻译

In Japan cherry blossoms also symbolize clouds due to their nature of blooming en masse, besides being an enduring metaphor for the ephemeral nature of life, an aspect of Japanese cultural tradition that is often associated with Buddhistic influence, and which is embodied in the concept of mono no aware.

The association of the cherry blossom with mono no aware dates back to 18th-century scholar Motoori Norinaga. The transience of the blossoms, the extreme beauty and quick death, has often been associated with mortality; for this reason, cherry blossoms are richly symbolic, and have been utilized often in Japanese art, manga, anime, and film, as well as at musical performances for ambient effect. There is at least one popular folk song, originally meant for the shakuhachi (bamboo flute), titled "Sakura", and several pop songs. The flower is also represented on all manner of consumer goods in Japan, including kimono, stationery, and dishware.

在日本,樱花也象征着云,由于其性质盛开的集体,除了是一个持久的比喻为生命的短暂性质,一方面,日本的文化传统,往往是与佛教的影响,并体现在概念的单不知道。协会的'樱花与单不知道可以追溯到18世纪的学者本居宣长。短暂的樱花,极端的美和快速死亡,往往是相关的死亡率;为此,樱花是丰富的象征,并已用于经常在日本艺术,漫画,动画,电影,以及在音乐表演对周围环境的影响。至少有一个流行的民歌,原本是为了尺八,名为“樱花”,和一些流行歌曲。花也代表所有消费品的方式在日本,包括和服,文具,和餐具。

2、日本樱花英文介绍,10句话就行

Prunus serrulata or Japanese Cherry; also called Hill Cherry, Oriental Cherry or East Asian Cherry, is a species of cherry native to Japan, Korea and China. It is known for its spring cherry blossom displays and festivals.Prunus serrulata is a small deciduous tree with a short single trunk, with a dense crown reaching a height of 8–12 metres (26–39 ft). The smooth bark is chestnut-brown, with prominent horizontal lenticels. The leaves are arranged alternately, simple, ovate-lanceolate, 5–13 cm long and 2.5–6.5 cm broad, with a short petiole and a serrate or doubly serrate margin. At the end of autumn, the green leaves turn yellow, red or crimson.。

3、Sometimes you need to look back, otherwise you will never know what you have lost in the way of forever searching.

偶尔要回头看看,否则永远都在追寻,而不知道自己失去了什么. Miracles sometimes occur, but you have to work terribly for them.奇迹有时候是会发生的,但是你得为之拼命的努力。

关于樱花的唯美句子简短英语3

关于赏樱花的说说

1、阳春三月,在温暖的春风里,看一场浪漫樱花。

2、又是一年樱花烂漫时,一起相约赏樱花美,好的人和事总是特别短暂,要珍惜当下。

3、粉色的樱花,充满着春天的精彩,洋溢着春天的热闹,散播着春天的朝气。

4、如果樱花常开 如果故人常在。

5、空气新酿的清新,是樱花味的。

6、神明把光风交给霁月,把樱花交给春天,把黑夜交给星光,把心跳交给脸红,把你交给我。

7、樱花盛开,花瓣徐徐吹落,如烟花般易逝,把刹那的芳华留存在人们心里。

8、樱花已经悄悄盛开,温暖的春风带走了冬天的尾巴,为春天带来活力。

9、阳光如此明媚、陪我赏樱花可好……

10、樱花和我,都想见你。

11、你看,城南的樱花都开了,一切都会好起来的。

12、春天到了,樱花树的枝条上裹上一层斑斓的色彩。只见花朵小巧玲珑,五六朵聚集在一起组成了一个花球,一簇一簇地拥挤在枝头上,舒展着狭长的花瓣和被包裹在其中的花蕊。

13、美丽的樱花,开在初春三月里,想着这年年岁岁的真情实感就似这樱花般的热烈和赤诚。

14、樱之夭夭,灼灼其华,四季初始,花信已至,春日的天光落于街边的樱花树,是今年春季的粉色限定,樱花樱花,我想在温柔的春日见你。

15、在樱花树下慢走,枝头的樱花灿灿的绽放,一枝枝,一朵朵,簇着拥着,如云朵般,轻柔、素雅,醉在了这最美的花季,繁杂的心也终于安静下来。

16、樱花开了,那粉嫩的花瓣随着轻风慢慢的抖动,清香随着微风轻轻的洒满了整个院子,让人神清气爽。

17、一阵微风轻拂而起,带来了远方不知名的醉人花香,却也将树枝上的樱花带离枝头,无数的樱花瓣在风中翩然起舞,像是粉色的轻纱随风浮动,令人不禁怀疑自己是在梦中。

Flutter Button(按钮)

在 Flutter 里有很多的 Button,包括了:MaterialButton、RaisedButton、FloatingActionButton、FlatButton、IconButton、ButtonBar、DropdownButton 等。

一般常用的 Button 是 MaterialButton、IconButton、FloatingActionButton。

MaterialButton 是一个 Materia 风格的按钮。

一般来说,如果需要点击事件,就要嵌套一个 Button,因为 Container、Text 等组件都没有点击事件。

RaisedButton 与 MaterialButton 类似。

FlatButton 与 MaterialButton 类似,不同的是它是透明背景的。如果一个 Container 想要点击事件时,可以使用 FlatButton 包裹,而不是 MaterialButton。因为 MaterialButton 默认带背景,而 FlatButton 默认不带背景。

IconButton 顾名思义就是 Icon + Button 的复合体,当某个 Icon 需要点击事件时,使用 IconButton 最好不过。

其外,还有已经定义好的 Icon Button:CloseButton、BackButton。他们都有导航返回的能力。

FloatingActionButton 是一个浮动在页面右下角的浮动按钮。

在 Scaffold 里使用的时候,它是一个浮动状态的按钮,在其他地方使用,就不会浮动了。

ButtonBar 是一个布局组件,可以让 Button 排列在一行。

flutter怎么把一个outlinebutton按钮放在底部

我要做的是用BottomNavigationBarItem移除/替换FAB(浮动操作按钮),并将其放在BottomNavigationBar的中心,并为其创建样式。

为了按钮能够根据屏幕宽度进行延伸变宽,用了row和expanded,expanded多大面积,按钮就有多大面积。如果不用row,expanded会向下延伸,就不是我们要的效果了。

OutlineButton控件的child和onPressed是必须的属性,borderSide用来自定义边框颜色和样式。

Flutter 之 Sliver 系列控件

SliverAppBar 控件,一个 MD 的 AppBar 。属性和 AppBar 类似,但做的效果比 AppBar 更加强大。相同的属性具体可以看 Flutter 之 Scaffold 控件 , 里面有 AppBar 控件的介绍。那么还有些没有的属性:

结合 elevation 使用,当elevation 不为 0 的时候,是否显示阴影

AppBar 展开时候的高度

true 的时候下滑AppBar优先滑动展示,展示完成后才给滑动控件滑动

snap 为 true, 则 floating 也要为 true 。true 的时候根据手指松开的位置展开或者收缩AppBar

appBar 收缩到最小高度的时候 appBar 是否可见

SliverAppBar 往往做为 CustomScrollView 的第一个子元素,根据滚动控件的偏移量或者浮动的位置来改变 SliverAppBar 的高度。所以具体用法如下

另外在上面设计到 FlexibleSpaceBar 控件,FlexibleSpaceBar 有个 collapseMode 属性

为 Sliver 系列控件添加一个 padding 。如给上面 SliverAppBar 添加一个 Padding 。

多行多列的列表控件,相当于 Android 的 GridView,有两个属性

SliverChildDelegate,这里有两种方式创建

SliverGridDelegate,也是有两种方式创建

结合上面展示效果

和上面 delegate 属性一样,需要创建一个 SliverChildDelegate 。

比 SliverList 多一个 itemExtent 属性,设置 item 的高度 。item 里面的子控件无法再改动高度。

上面 SliverAppBar 就是结合 SliverPersistentHeader 实现的效果,SliverPersistentHeader 需要一个 SliverPersistentHeaderDelegate 。 实现 SliverPersistentHeaderDelegate 有 4 个方法需要重写

至于效果,具体效果具体分析。

有一个 Widget 属性,主要作用是在 CustomScrollView 里面添加多种不同布局的样式。

占满一屏或者比一屏更多的布局,

滑动剩余部分展示的布局


本文标题:flutter浮动,flutter浮动组件
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