欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  php教程

yii2源码学习笔记(十九),yii2源码学习笔记

程序员文章站 2022-05-06 13:42:44
...

yii2源码学习笔记(十九),yii2源码学习笔记

view剩余代码

  1     /**
  2      * @return string|boolean the view file currently being rendered. False if no view file is being rendered.
  3      * 当前正在渲染的视图文件
  4      */
  5     public function getViewFile()
  6     {
  7         return end($this->_viewFiles);
  8     }
  9 
 10     /**
 11      * This method is invoked right before [[renderFile()]] renders a view file.
 12      * The default implementation will trigger the [[EVENT_BEFORE_RENDER]] event.
 13      * 前置事件,执行[renderFile()]时被调用,默认触发[[EVENT_BEFORE_RENDER]]事件
 14      * If you override this method, make sure you call the parent implementation first.
 15      * @param string $viewFile the view file to be rendered. 要渲染的视图文件。
 16      * @param array $params the parameter array passed to the [[render()]] method.
 17      * 参数数组传递到[render()]方法。
 18      * @return boolean whether to continue rendering the view file. 是否继续渲染视图文件。
 19      */
 20     public function beforeRender($viewFile, $params)
 21     {
 22         $event = new ViewEvent([//实例化ViewEvent
 23             'viewFile' => $viewFile,
 24             'params' => $params,
 25         ]);
 26         $this->trigger(self::EVENT_BEFORE_RENDER, $event);//触发[EVENT_BEFORE_RENDER]事件
 27 
 28         return $event->isValid;//判断是否继续渲染文件
 29     }
 30 
 31     /**
 32      * This method is invoked right after [[renderFile()]] renders a view file.
 33      * The default implementation will trigger the [[EVENT_AFTER_RENDER]] event.
 34      * 后置事件,在执行[renderFile()]方法后被调用,默认触发[[EVENT_AFTER_RENDER]]事件
 35      * If you override this method, make sure you call the parent implementation first.
 36      * @param string $viewFile the view file being rendered.要渲染的视图文件。
 37      * @param array $params the parameter array passed to the [[render()]] method.
 38      * 参数数组传递到[render()]方法。
 39      * @param string $output the rendering result of the view file. Updates to this parameter
 40      * will be passed back and returned by [[renderFile()]].
 41      * 返回视图渲染的结果
 42      */
 43     public function afterRender($viewFile, $params, &$output)
 44     {
 45         if ($this->hasEventHandlers(self::EVENT_AFTER_RENDER)) {//判断[EVENT_AFTER_RENDER]事件是否存在
 46             $event = new ViewEvent([
 47                 'viewFile' => $viewFile,
 48                 'params' => $params,
 49                 'output' => $output,
 50             ]);
 51             //触发[EVENT_AFTER_RENDER]事件
 52             $this->trigger(self::EVENT_AFTER_RENDER, $event);
 53             $output = $event->output;//返回结果
 54         }
 55     }
 56 
 57     /**
 58      * Renders a view file as a PHP script.
 59      * 返回一个视图文件当作PHP脚本
 60      * This method treats the view file as a PHP script and includes the file.
 61      * It extracts the given parameters and makes them available in the view file.
 62      * The method captures the output of the included view file and returns it as a string.
 63      * 将传入的参数转换为变量,包含并执行view文件,返回执行结果
 64      * This method should mainly be called by view renderer or [[renderFile()]].
 65      *
 66      * @param string $_file_ the view file. 视图文件
 67      * @param array $_params_ the parameters (name-value pairs) that will be extracted and made available in the view file.
 68      * @return string the rendering result 执行结果
 69      */
 70     public function renderPhpFile($_file_, $_params_ = [])
 71     {
 72         ob_start(); //打开输出缓冲
 73         ob_implicit_flush(false); //关闭缓冲区
 74         extract($_params_, EXTR_OVERWRITE);// 将一个数组转换为变量使用
 75         require($_file_);
 76         
 77         return ob_get_clean();//得到缓冲区的内容并清除当前输出缓冲
 78     }
 79 
 80     /**
 81      * Renders dynamic content returned by the given PHP statements. 渲染动态内容
 82      * This method is mainly used together with content caching (fragment caching and page caching)
 83      * 用来聚合缓存的内容
 84      * when some portions of the content (called *dynamic content*) should not be cached.
 85      * The dynamic content must be returned by some PHP statements.
 86      * 渲染某些被PHP语句返回的动态内容
 87      * @param string $statements the PHP statements for generating the dynamic content.生成动态内容的PHP语句。
 88      * @return string the placeholder of the dynamic content, or the dynamic content if there is no
 89      * active content cache currently. 动态内容占位符 如果当前没有有效的内容缓存,调用evaluateDynamicContent输出
 90      */
 91     public function renderDynamic($statements)
 92     {
 93         if (!empty($this->cacheStack)) {//动态内容的列表不为空
 94             $n = count($this->dynamicPlaceholders);//统计动态内容条数
 95             $placeholder = "";//生成占位符
 96             $this->addDynamicPlaceholder($placeholder, $statements);//添加动态内容占位符
 97 
 98             return $placeholder;
 99         } else {//没有有效缓存 执行传入的PHP语句,返回执行结果
100             return $this->evaluateDynamicContent($statements);
101         }
102     }
103 
104     /**
105      * Adds a placeholder for dynamic content. 添加一个动态内容占位符
106      * This method is internally used. 内部使用
107      * @param string $placeholder the placeholder name 占位符名称
108      * @param string $statements the PHP statements for generating the dynamic content
109      * 生成动态内容的PHP语句
110      */
111     public function addDynamicPlaceholder($placeholder, $statements)
112     {
113         foreach ($this->cacheStack as $cache) {
114             $cache->dynamicPlaceholders[$placeholder] = $statements;//添加动态内容占位符
115         }
116         $this->dynamicPlaceholders[$placeholder] = $statements;//给当前视图添加动态内容占位符
117     }
118 
119     /**
120      * Evaluates the given PHP statements. 给定的PHP语句的值
121      * This method is mainly used internally to implement dynamic content feature.内部使用实现动态内容功能
122      * @param string $statements the PHP statements to be evaluated. PHP语句进行计算
123      * @return mixed the return value of the PHP statements. PHP语句的值
124      */
125     public function evaluateDynamicContent($statements)
126     {
127         return eval($statements);
128     }
129 
130     /**
131      * Begins recording a block.
132      * This method is a shortcut to beginning [[Block]]
133      * 数据块开始的标记,该方法是开始[Block]的快捷方式
134      * 数据块可以在一个地方指定视图内容在另一个地方显示,通常和布局一起使用
135      * @param string $id the block ID. 数据块标识
136      * @param boolean $renderInPlace whether to render the block content in place. 是否渲染块内容。
137      * Defaults to false, meaning the captured block will not be displayed.
138      * @return Block the Block widget instance 数据块部件实例
139      */
140     public function beginBlock($id, $renderInPlace = false)
141     {
142         return Block::begin([
143             'id' => $id,//数据块唯一标识
144             'renderInPlace' => $renderInPlace,//是否显示标识
145             'view' => $this,
146         ]);
147     }
148 
149     /**
150      * Ends recording a block. 数据块结束标识
151      */
152     public function endBlock()
153     {
154         Block::end();
155     }
156 
157     /**
158      * Begins the rendering of content that is to be decorated by the specified view.
159      * This method can be used to implement nested layout. For example, a layout can be embedded
160      * in another layout file specified as '@app/views/layouts/base.php' like the following:
161      * 开始指定的view渲染内容,用来实现嵌套布局,传入的第一个参数为布局文件的路径
162      * ~~~
163      * beginContent('@app/views/layouts/base.php'); ?>
164      * ...layout content here...
165      * endContent(); ?>
166      * ~~~
167      *
168      * @param string $viewFile the view file that will be used to decorate the content enclosed by this widget.
169      * This can be specified as either the view file path or path alias.布局文件的路径或路径别名。
170      * @param array $params the variables (name => value) to be extracted and made available in the decorative view.
171      * 可以在视图中运用的参数
172      * @return ContentDecorator the ContentDecorator widget instance 部件实例
173      * @see ContentDecorator
174      */
175     public function beginContent($viewFile, $params = [])
176     {
177         return ContentDecorator::begin([
178             'viewFile' => $viewFile,
179             'params' => $params,
180             'view' => $this,
181         ]);
182     }
183 
184     /**
185      * Ends the rendering of content.结束渲染内容
186      */
187     public function endContent()
188     {
189         ContentDecorator::end();
190     }
191 
192     /**
193      * Begins fragment caching. 开始片段缓存
194      * This method will display cached content if it is available.
195      * If not, it will start caching and would expect an [[endCache()]]
196      * call to end the cache and save the content into cache.
197      * 展示可用的缓存内容,否则将开始缓存内容直到出现[endCache()]方法
198      * A typical usage of fragment caching is as follows,
199      *
200      * ~~~
201      * if ($this->beginCache($id)) {
202      *     // ...generate content here
203      *     $this->endCache();
204      * }
205      * ~~~
206      *
207      * @param string $id a unique ID identifying the fragment to be cached.缓存片段的唯一标识
208      * @param array $properties initial property values for [[FragmentCache]]初始属性[FragmentCache]
209      * @return boolean whether you should generate the content for caching. 是否生成缓存的内容。
210      * False if the cached version is available.
211      */
212     public function beginCache($id, $properties = [])
213     {
214         $properties['id'] = $id;    //片段标识
215         $properties['view'] = $this;    //调用初始化属性
216         /* @var $cache FragmentCache */
217         $cache = FragmentCache::begin($properties); 
218         if ($cache->getCachedContent() !== false) {
219             $this->endCache();//从缓存中读取到了缓存的内容,则渲染内容并返回 false,不再进行缓存
220 
221             return false;
222         } else {
223             return true;
224         }
225     }
226 
227     /**
228      * Ends fragment caching. 结束片段缓存
229      */
230     public function endCache()
231     {
232         FragmentCache::end();
233     }
234 
235     /**
236      * Marks the beginning of a page.页面开始标记
237      */
238     public function beginPage()
239     {
240         ob_start(); //打开输出缓冲
241         ob_implicit_flush(false);//关闭缓冲区
242 
243         $this->trigger(self::EVENT_BEGIN_PAGE);
244     }
245 
246     /**
247      * Marks the ending of a page. 页面结束标记
248      */
249     public function endPage()
250     {
251         $this->trigger(self::EVENT_END_PAGE);
252         ob_end_flush();//关闭输出缓冲区
253     }