View繼承了component，用於渲染視圖文件：yii2\base\View.php
1 <?php
2 /**
3 * @link http://www.yiiframework.com/
4 * @copyright Copyright (c) 2008 Yii Software LLC
5 * @license http://www.yiiframework.com/license/
6 */
7
8 namespace yii\base;
9
10 use Yii;
11 use yii\helpers\FileHelper;
12 use yii\widgets\Block;
13 use yii\widgets\ContentDecorator;
14 use yii\widgets\FragmentCache;
15
16 /**
17 * View represents a view object in the MVC pattern.
18 * MVC中的視圖
19 * View provides a set of methods (e.g. [[render()]]) for rendering purpose.
20 * 視圖提供了一套渲染頁面的方法
21 * @property string|boolean $viewFile The view file currently being rendered. False if no view file is being
22 * rendered. This property is read-only.
23 *
24 * @author Qiang Xue <qiang.xue@gmail.com>
25 * @since 2.0
26 */
27 class View extends Component
28 {
29 /**
30 * @event Event an event that is triggered by [[beginPage()]].
31 * 事件被[beginPage()]觸發
32 */
33 const EVENT_BEGIN_PAGE = 'beginPage';
34 /**
35 * @event Event an event that is triggered by [[endPage()]].
36 * 事件被[endPage()]觸發
37 */
38 const EVENT_END_PAGE = 'endPage';
39 /**
40 * @event ViewEvent an event that is triggered by [[renderFile()]] right before it renders a view file.
41 * 事件被[renderFile()]觸發前呈現一個視圖文件
42 */
43 const EVENT_BEFORE_RENDER = 'beforeRender';
44 /**
45 * @event ViewEvent an event that is triggered by [[renderFile()]] right after it renders a view file.
46 * 事件被[renderFile()]觸發後呈現一個視圖文件
47 */
48 const EVENT_AFTER_RENDER = 'afterRender';
49
50 /**
51 * @var ViewContextInterface the context under which the [[renderFile()]] method is being invoked.
52 * ViewContextInterface背景下 [renderFile()]方法被調用
53 */
54 public $context;
55 /**
56 * @var mixed custom parameters that are shared among view templates.
57 * 視圖模板中共享的自定義參數
58 */
59 public $params = [];
60 /**
61 * @var array a list of available renderers indexed by their corresponding supported file extensions.
62 * Each renderer may be a view renderer object or the configuration for creating the renderer object.
63 * 一個可用的渲染索引列表。每個渲染器是一個渲染器對象或創建渲染對象配置數組
64 * For example, the following configuration enables both Smarty and Twig view renderers:
65 *
66 * ~~~
67 * [
68 * 'tpl' => ['class' => 'yii\smarty\ViewRenderer'],
69 * 'twig' => ['class' => 'yii\twig\ViewRenderer'],
70 * ]
71 * ~~~
72 *
73 * If no renderer is available for the given view file, the view file will be treated as a normal PHP
74 * and rendered via [[renderPhpFile()]].
75 */
76 public $renderers;
77 /**
78 * @var string the default view file extension. This will be appended to view file names if they don't have file extensions.
79 * 默認視圖文件擴展名，文件沒有擴展名的情況下自動加載
80 */
81 public $defaultExtension = 'php';
82 /**
83 * @var Theme|array|string the theme object or the configuration for creating the theme object.
84 * If not set, it means theming is not enabled.主題對象或創建主題對象的配置 未設置則不啟用
85 */
86 public $theme;
87 /**
88 * @var array a list of named output blocks. The keys are the block names and the values
89 * are the corresponding block content. You can call [[beginBlock()]] and [[endBlock()]]
90 * to capture small fragments of a view. They can be later accessed somewhere else
91 * through this property.
92 * 一個輸出塊列表。鍵是塊名稱值為內容。可以調用 [beginblock()]和[endblock()]捕獲視圖的小片段
93 * 可以在其他地方通過這個屬性訪問。
94 */
95 public $blocks;
96 /**
97 * @var array a list of currently active fragment cache widgets. This property
98 * is used internally to implement the content caching feature. Do not modify it directly.
99 * 當前操作片段的緩存部件列表。用於內部實現內容緩存功能。不要直接修改
100 * @internal
101 */
102 public $cacheStack = [];
103 /**
104 * @var array a list of placeholders for embedding dynamic contents. This property
105 * is used internally to implement the content caching feature. Do not modify it directly.
106 * 嵌入動態內容占位符列表。 用於內部實現內容緩存功能。不要直接修改
107 * @internal
108 */
109 public $dynamicPlaceholders = [];
110
111 /**
112 * @var array the view files currently being rendered. There may be multiple view files being
113 * rendered at a moment because one view may be rendered within another.
114 * 正在渲染的視圖文件。可能有多個視圖文件被渲染，因為一個視圖可以在另一個視圖中呈現
115 */
116 private $_viewFiles = [];
117
118
119 /**
120 * Initializes the view component.初始化視圖組件
121 */
122 public function init()
123 {
124 parent::init(); //調用父類的方法
125 if (is_array($this->theme)) {
126 if (!isset($this->theme['class'])) {
127 $this->theme['class'] = 'yii\base\Theme';//是數組，沒有設置類名，則類名'yii\base\Theme'
128 }
129 $this->theme = Yii::createObject($this->theme);//設置了類名，調用配置創建對象
130 } elseif (is_string($this->theme)) {//以字符串參數的形式創建對象
131 $this->theme = Yii::createObject($this->theme);
132 }
133 }
134
135 /**
136 * Renders a view.
137 * 渲染一個視圖
138 * The view to be rendered can be specified in one of the following formats:
139 *
140 * - path alias (e.g. "@app/views/site/index");
141 * 路徑別名
142 * - absolute path within application (e.g. "//site/index"): the view name starts with double slashes.
143 * The actual view file will be looked for under the [[Application::viewPath|view path]] of the application.
144 * 絕對路徑，會在[Application::viewPath|view path]下查找文件
145 * - absolute path within current module (e.g. "/site/index"): the view name starts with a single slash.
146 * The actual view file will be looked for under the [[Module::viewPath|view path]] of the [[Controller::module|current module]].
147 * 模塊下的絕對路徑，會在[Module::viewPath|view path]下查找文件
148 * - relative view (e.g. "index"): the view name does not start with `@` or `/`. The corresponding view file will be
149 * looked for under the [[ViewContextInterface::getViewPath()|view path]] of the view `$context`.
150 * 相對路徑，會在[ViewContextInterface::getViewPath()|view path]下查找文件
151 * If `$context` is not given, it will be looked for under the directory containing the view currently
152 * being rendered (i.e., this happens when rendering a view within another view).
153 *
154 * @param string $view the view name. 視圖名稱
155 * @param array $params the parameters (name-value pairs) that will be extracted and made available in the view file.
156 * 視圖中應用參數
157 * @param object $context the context to be assigned to the view and can later be accessed via [[context]]
158 * in the view. If the context implements [[ViewContextInterface]], it may also be used to locate
159 * the view file corresponding to a relative view name. 對應情景
160 * @return string the rendering result
161 * @throws InvalidParamException if the view cannot be resolved or the view file does not exist.
162 * @see renderFile()
163 */
164 public function render($view, $params = [], $context = null)
165 {
166 $viewFile = $this->findViewFile($view, $context);//查找視圖文件路徑
167 return $this->renderFile($viewFile, $params, $context);//渲染視圖文件
168 }
169
170 /**
171 * Finds the view file based on the given view name.通過視圖文件名查找視圖文件
172 * @param string $view the view name or the path alias of the view file. Please refer to [[render()]]
173 * on how to specify this parameter. 視圖名稱或路徑視圖文件的別名
174 * @param object $context the context to be assigned to the view and can later be accessed via [[context]]
175 * in the view. If the context implements [[ViewContextInterface]], it may also be used to locate
176 * the view file corresponding to a relative view name. 對應情景
177 * @return string the view file path. Note that the file may not exist. 文件路徑
178 * @throws InvalidCallException if a relative view name is given while there is no active context to
179 * determine the corresponding view file.
180 */
181 protected function findViewFile($view, $context = null)
182 {
183 if (strncmp($view, '@', 1) === 0) {
184 // e.g. "@app/views/main" 判斷是否是別名路徑，是則獲取真實路徑
185 $file = Yii::getAlias($view);
186 } elseif (strncmp($view, '//', 2) === 0) {
187 // e.g. "//layouts/main" 以//開始，查找文件路徑，拼接視圖文件路徑
188 $file = Yii::$app->getViewPath() . DIRECTORY_SEPARATOR . ltrim($view, '/');
189 } elseif (strncmp($view, '/', 1) === 0) {
190 // e.g. "/site/index"
191 if (Yii::$app->controller !== null) {
192 //以/開始，且控制器存在，查找控制器對應的文件目錄，拼接路徑
193 $file = Yii::$app->controller->module->getViewPath() . DIRECTORY_SEPARATOR . ltrim($view, '/');
194 } else {
195 throw new InvalidCallException("Unable to locate view file for view '$view': no active controller.");
196 }
197 } elseif ($context instanceof ViewContextInterface) {
198 //對應情景存在 查找文件路徑，拼接視圖文件路徑
199 $file = $context->getViewPath() . DIRECTORY_SEPARATOR . $view;
200 } elseif (($currentViewFile = $this->getViewFile()) !== false) {
201 //當前渲染文件存在，拼接路徑
202 $file = dirname($currentViewFile) . DIRECTORY_SEPARATOR . $view;
203 } else {
204 throw new InvalidCallException("Unable to resolve view file for view '$view': no active view context.");
205 }
206
207 if (pathinfo($file, PATHINFO_EXTENSION) !== '') {
208 return $file;//視圖文件的擴展名不為空，返回擴展名
209 }
210 $path = $file . '.' . $this->defaultExtension; //給視圖文件添加擴展名
211 if ($this->defaultExtension !== 'php' && !is_file($path)) {
212 $path = $file . '.php';
213 }
214
215 return $path;//返回路徑
216 }
217
218 /**
219 * Renders a view file.
220 * 渲染一個視圖文件。
221 * If [[theme]] is enabled (not null), it will try to render the themed version of the view file as long
222 * as it is available.
223 * 如果[theme]可用，將渲染視圖文件的主題版本直到[theme]不可用
224 * The method will call [[FileHelper::localize()]] to localize the view file.
225 * 調用[FileHelper::localize()]方法本地化視圖文件
226 * If [[renderers|renderer]] is enabled (not null), the method will use it to render the view file.
227 * Otherwise, it will simply include the view file as a normal PHP file, capture its output and
228 * return it as a string.
229 * 如果[[renderers|renderer]]啟用，該方法將用它來渲染視圖文件。否則，將視圖文件作為一個正常的PHP文件包含進來，獲取其輸出並返回一個字符串。
230 * @param string $viewFile the view file. This can be either an absolute file path or an alias of it.
231 * 視圖文件。可以是絕對路徑或它的別名。
232 * @param array $params the parameters (name-value pairs) that will be extracted and made available in the view file.
233 * 視圖文件執行的參數
234 * @param object $context the context that the view should use for rendering the view. If null,
235 * existing [[context]] will be used.
236 * 用於渲染視圖的上下文
237 * @return string the rendering result
238 * @throws InvalidParamException if the view file does not exist
239 */
240 public function renderFile($viewFile, $params = [], $context = null)
241 {
242 $viewFile = Yii::getAlias($viewFile);//處理輸入的視圖文件名
243
244 if ($this->theme !== null) {
245 $viewFile = $this->theme->applyTo($viewFile);//如果theme非空，應用到視圖文件
246 }
247 if (is_file($viewFile)) {
248 $viewFile = FileHelper::localize($viewFile);//本地化視圖文件
249 } else {
250 throw new InvalidParamException("The view file does not exist: $viewFile");
251 }
252
253 $oldContext = $this->context;
254 if ($context !== null) {
255 $this->context = $context;
256 }
257 $output = '';
258 $this->_viewFiles[] = $viewFile;//記錄當前渲染文件
259
260 if ($this->beforeRender($viewFile, $params)) {//如果前置事件執行成功
261 Yii::trace("Rendering view file: $viewFile", __METHOD__);//記錄trace信息
262 $ext = pathinfo($viewFile, PATHINFO_EXTENSION);//視圖文件擴展名
263 if (isset($this->renderers[$ext])) {//視圖文件的擴展名是否支持
264 if (is_array($this->renderers[$ext]) || is_string($this->renderers[$ext])) {
265 $this->renderers[$ext] = Yii::createObject($this->renderers[$ext]);
266 }
267 /* @var $renderer ViewRenderer */
268 $renderer = $this->renderers[$ext];//賦值view渲染器對象
269 $output = $renderer->render($this, $viewFile, $params);//渲染視圖文件
270 } else {//視圖文件不是支持的類型，以普通php文件處理
271 $output = $this->renderPhpFile($viewFile, $params);
272 }
273 $this->afterRender($viewFile, $params, $output);
274 }
275
276 array_pop($this->_viewFiles);
277 $this->context = $oldContext;
278
279 return $output;
280 }
