yii2源碼學習筆記(十九）_ZenDei技術網路在線

view剩餘代碼 ...
view剩餘代碼
  1     /**
  2      * @return string|boolean the view file currently being rendered. False if no view file is being rendered.
  3      * 當前正在渲染的視圖文件
  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，執行[renderFile()]時被調用，預設觸發[[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. 要渲染的視圖文件。
 16      * @param array $params the parameter array passed to the [[render()]] method.
 17      * 參數數組傳遞到[render()]方法。
 18      * @return boolean whether to continue rendering the view file. 是否繼續渲染視圖文件。
 19      */
 20     public function beforeRender($viewFile, $params)
 21     {
 22         $event = new ViewEvent([//實例化ViewEvent
 23             'viewFile' => $viewFile,
 24             'params' => $params,
 25         ]);
 26         $this->trigger(self::EVENT_BEFORE_RENDER, $event);//觸發[EVENT_BEFORE_RENDER]事件
 27 
 28         return $event->isValid;//判斷是否繼續渲染文件
 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      * 後置事件，在執行[renderFile()]方法後被調用，預設觸發[[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.要渲染的視圖文件。
 37      * @param array $params the parameter array passed to the [[render()]] method.
 38      * 參數數組傳遞到[render()]方法。
 39      * @param string $output the rendering result of the view file. Updates to this parameter
 40      * will be passed back and returned by [[renderFile()]].
 41      * 返回視圖渲染的結果
 42      */
 43     public function afterRender($viewFile, $params, &$output)
 44     {
 45         if ($this->hasEventHandlers(self::EVENT_AFTER_RENDER)) {//判斷[EVENT_AFTER_RENDER]事件是否存在
 46             $event = new ViewEvent([
 47                 'viewFile' => $viewFile,
 48                 'params' => $params,
 49                 'output' => $output,
 50             ]);
 51             //觸發[EVENT_AFTER_RENDER]事件
 52             $this->trigger(self::EVENT_AFTER_RENDER, $event);
 53             $output = $event->output;//返回結果
 54         }
 55     }
 56 
 57     /**
 58      * Renders a view file as a PHP script.
 59      * 返回一個視圖文件當作PHP腳本
 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      * 將傳入的參數轉換為變數，包含並執行view文件，返回執行結果
 64      * This method should mainly be called by view renderer or [[renderFile()]].
 65      *
 66      * @param string $_file_ the view file. 視圖文件
 67      * @param array $_params_ the parameters (name-value pairs) that will be extracted and made available in the view file.
 68      * @return string the rendering result 執行結果
 69      */
 70     public function renderPhpFile($_file_, $_params_ = [])
 71     {
 72         ob_start(); //打開輸出緩衝
 73         ob_implicit_flush(false); //關閉緩衝區
 74         extract($_params_, EXTR_OVERWRITE);// 將一個數組轉換為變數使用
 75         require($_file_);
 76         
 77         return ob_get_clean();//得到緩衝區的內容並清除當前輸出緩衝
 78     }
 79 
 80     /**
 81      * Renders dynamic content returned by the given PHP statements. 渲染動態內容
 82      * This method is mainly used together with content caching (fragment caching and page caching)
 83      * 用來聚合緩存的內容
 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語句返回的動態內容
 87      * @param string $statements the PHP statements for generating the dynamic content.生成動態內容的PHP語句。
 88      * @return string the placeholder of the dynamic content, or the dynamic content if there is no
 89      * active content cache currently. 動態內容占位符 如果當前沒有有效的內容緩存，調用evaluateDynamicContent輸出
 90      */
 91     public function renderDynamic($statements)
 92     {
 93         if (!empty($this->cacheStack)) {//動態內容的列表不為空
 94             $n = count($this->dynamicPlaceholders);//統計動態內容條數
 95             $placeholder = "<![CDATA[YII-DYNAMIC-$n]]>";//生成占位符
 96             $this->addDynamicPlaceholder($placeholder, $statements);//添加動態內容占位符
 97 
 98             return $placeholder;
 99         } else {//沒有有效緩存 執行傳入的PHP語句，返回執行結果
100             return $this->evaluateDynamicContent($statements);
101         }
102     }
103 
104     /**
105      * Adds a placeholder for dynamic content. 添加一個動態內容占位符
106      * This method is internally used. 內部使用
107      * @param string $placeholder the placeholder name 占位符名稱
108      * @param string $statements the PHP statements for generating the dynamic content
109      * 生成動態內容的PHP語句
110      */
111     public function addDynamicPlaceholder($placeholder, $statements)
112     {
113         foreach ($this->cacheStack as $cache) {
114             $cache->dynamicPlaceholders[$placeholder] = $statements;//添加動態內容占位符
115         }
116         $this->dynamicPlaceholders[$placeholder] = $statements;//給當前視圖添加動態內容占位符
117     }
118 
119     /**
120      * Evaluates the given PHP statements. 給定的PHP語句的值
121      * This method is mainly used internally to implement dynamic content feature.內部使用實現動態內容功能
122      * @param string $statements the PHP statements to be evaluated. PHP語句進行計算
123      * @return mixed the return value of the PHP statements. PHP語句的值
124      */
125     public function evaluateDynamicContent($statements)
126     {
127         return eval($statements);
128     }
129 
130     /**
131      * Begins recording a block.
132      * This method is a shortcut to beginning [[Block]]
133      * 數據塊開始的標記，該方法是開始[Block]的快捷方式
134      * 數據塊可以在一個地方指定視圖內容在另一個地方顯示，通常和佈局一起使用
135      * @param string $id the block ID. 數據塊標識
136      * @param boolean $renderInPlace whether to render the block content in place. 是否渲染塊內容。
137      * Defaults to false, meaning the captured block will not be displayed.
138      * @return Block the Block widget instance 數據塊部件實例
139      */
140     public function beginBlock($id, $renderInPlace = false)
141     {
142         return Block::begin([
143             'id' => $id,//數據塊唯一標識
144             'renderInPlace' => $renderInPlace,//是否顯示標識
145             'view' => $this,
146         ]);
147     }
148 
149     /**
150      * Ends recording a block. 數據塊結束標識
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      * 開始指定的view渲染內容，用來實現嵌套佈局，傳入的第一個參數為佈局文件的路徑
162      * ~~~
163      * <?php $this->beginContent('@app/views/layouts/base.php'); ?>
164      * ...layout content here...
165      * <?php $this->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.佈局文件的路徑或路徑別名。
170      * @param array $params the variables (name => value) to be extracted and made available in the decorative view.
171      * 可以在視圖中運用的參數
172      * @return ContentDecorator the ContentDecorator widget instance 部件實例
173      * @see ContentDecorator
174      */
175     public function beginContent($viewFile, $params = [])
176     {
177         return ContentDecorator::begin([
178             'viewFile' => $viewFile,
179             'params' => $params,
180             'view' => $this,
181         ]);
182     }
183 
184     /**
185      * Ends the rendering of content.結束渲染內容
186      */
187     public function endContent()
188     {
189         ContentDecorator::end();
190     }
191 
192     /**
193      * Begins fragment caching. 開始片段緩存
194      * This method will display cached content if it is available.
195      * If not, it will start caching and would expect an [[endCache()]]
196      * call to end the cache and save the content into cache.
197      * 展示可用的緩存內容，否則將開始緩存內容直到出現[endCache()]方法
198      * A typical usage of fragment caching is as follows,
199      *
200      * ~~~
201      * if ($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.緩存片段的唯一標識
208      * @param array $properties initial property values for [[FragmentCache]]初始屬性[FragmentCache]
209      * @return boolean whether you should generate the content for caching. 是否生成緩存的內容。
210      * False if the cached version is available.
211      */
212     public function beginCache($id, $properties = [])
213     {
214         $properties['id'] = $id;    //片段標識
215         $properties['view'] = $this;    //調用初始化屬性
216         /* @var $cache FragmentCache */
217         $cache = FragmentCache::begin($properties); 
218         if ($cache->getCachedContent() !== false) {
219             $this->endCache();//從緩存中讀取到了緩存的內容，則渲染內容並返回 false，不再進行緩存
220 
221             return false;
222         } else {
223             return true;
224         }
225     }
226 
227     /**
228      * Ends fragment caching. 結束片段緩存
229      */
230     public function endCache()
231     {
232         FragmentCache::end();
233     }
234 
235     /**
236      * Marks the beginning of a page.頁面開始標記
237      */
238     public function beginPage()
239     {
240         ob_start(); //打開輸出緩衝
241         ob_implicit_flush(false);//關閉緩衝區
242 
243         $this->trigger(self::EVENT_BEGIN_PAGE);
244     }
245 
246     /**
247      * Marks the ending of a page. 頁面結束標記
248      */
249     public function endPage()
250     {
251         $this->trigger(self::EVENT_END_PAGE);
252         ob_end_flush();//關閉輸出緩衝區
253     }