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<?php
/**
 * TLinkButton class file
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.pradosoft.com/
 * @copyright Copyright &copy; 2005-2008 PradoSoft
 * @license http://www.pradosoft.com/license/
 * @version $Id: TLinkButton.php 2541 2008-10-21 15:05:13Z qiang.xue $
 * @package System.Web.UI.WebControls
 */

/**
 * TLinkButton class
 *
 * TLinkButton creates a hyperlink style button on the page.
 * TLinkButton has the same appearance as a hyperlink. However, it is mainly
 * used to submit data to a page. Like {@link TButton}, you can create either
 * a <b>submit</b> button or a <b>command</b> button.
 *
 * A <b>command</b> button has a command name (specified by
 * the {@link setCommandName CommandName} property) and and a command parameter
 * (specified by {@link setCommandParameter CommandParameter} property)
 * associated with the button. This allows you to create multiple TLinkButton
 * components on a Web page and programmatically determine which one is clicked
 * with what parameter. You can provide an event handler for
 * {@link onCommand OnCommand} event to programmatically control the actions performed
 * when the command button is clicked. In the event handler, you can determine
 * the {@link setCommandName CommandName} property value and
 * the {@link setCommandParameter CommandParameter} property value
 * through the {@link TCommandParameter::getName Name} and
 * {@link TCommandParameter::getParameter Parameter} properties of the event
 * parameter which is of type {@link TCommandEventParameter}.
 *
 * A <b>submit</b> button does not have a command name associated with the button
 * and clicking on it simply posts the Web page back to the server.
 * By default, a TLinkButton component is a submit button.
 * You can provide an event handler for the {@link onClick OnClick} event
 * to programmatically control the actions performed when the submit button is clicked.
 *
 * Clicking on button can trigger form validation, if
 * {@link setCausesValidation CausesValidation} is true.
 * And the validation may be restricted within a certain group of validator
 * controls by setting {@link setValidationGroup ValidationGroup} property.
 * If validation is successful, the data will be post back to the same page.
 *
 * TLinkButton will display the {@link setText Text} property value
 * as the hyperlink text. If {@link setText Text} is empty, the body content
 * of TLinkButton will be displayed. Therefore, you can use TLinkButton
 * as an image button by enclosing an &lt;img&gt; tag as the body of TLinkButton.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @version $Id: TLinkButton.php 2541 2008-10-21 15:05:13Z qiang.xue $
 * @package System.Web.UI.WebControls
 * @since 3.0
 */
class TLinkButton extends TWebControl implements IPostBackEventHandler, IButtonControl, IDataRenderer
{
        /**
         * @return string tag name of the button
         */
        protected function getTagName()
        {
                return 'a';
        }

        /**
         * @return boolean whether to render javascript.
         */
        public function getEnableClientScript()
        {
                return $this->getViewState('EnableClientScript',true);
        }

        /**
         * @param boolean whether to render javascript.
         */
        public function setEnableClientScript($value)
        {
                $this->setViewState('EnableClientScript',TPropertyValue::ensureBoolean($value),true);
        }

        /**
         * Adds attribute name-value pairs to renderer.
         * This overrides the parent implementation with additional button specific attributes.
         * @param THtmlWriter the writer used for the rendering purpose
         */
        protected function addAttributesToRender($writer)
        {
                $page=$this->getPage();
                $page->ensureRenderInForm($this);

                $writer->addAttribute('id',$this->getClientID());

                // We call parent implementation here because some attributes
                // may be overwritten in the following
                parent::addAttributesToRender($writer);

                if($this->getEnabled(true) && $this->getEnableClientScript())
                {
                        $this->renderLinkButtonHref($writer);
                        $this->renderClientControlScript($writer);
                }
                else if($this->getEnabled()) // in this case, parent will not render 'disabled'
                        $writer->addAttribute('disabled','disabled');
        }

        /**
         * Renders the client-script code.
         * @param THtmlWriter renderer
         */
        protected function renderClientControlScript($writer)
        {
                $cs = $this->getPage()->getClientScript();
                $cs->registerPostBackControl($this->getClientClassName(),$this->getPostBackOptions());
        }

        /**
         * @param boolean set by a panel to register this button as the default button for the panel.
         */
        public function setIsDefaultButton($value)
        {
                $this->setViewState('IsDefaultButton', TPropertyValue::ensureBoolean($value),false);
        }

        /**
         * @return boolean true if this button is registered as a default button for a panel.
         */
        public function getIsDefaultButton()
        {
                return $this->getViewState('IsDefaultButton', false);
        }

        /**
         * Renders the Href for link button.
         * @param THtmlWriter renderer
         */
        protected function renderLinkButtonHref($writer)
        {
                //create unique no-op url references
                $nop = "javascript:;//".$this->getClientID();
                $writer->addAttribute('href', $nop);
        }

        /**
         * Gets the name of the javascript class responsible for performing postback for this control.
         * This method overrides the parent implementation.
         * @return string the javascript class name
         */
        protected function getClientClassName()
        {
                return 'Prado.WebUI.TLinkButton';
        }

        /**
         * Returns postback specifications for the button.
         * This method is used by framework and control developers.
         * @return array parameters about how the button defines its postback behavior.
         */
        protected function getPostBackOptions()
        {
                $options['ID'] = $this->getClientID();
                $options['EventTarget'] = $this->getUniqueID();
                $options['CausesValidation'] = $this->getCausesValidation();
                $options['ValidationGroup'] = $this->getValidationGroup();
                $options['StopEvent'] = true;

                return $options;
        }

        /**
         * Renders the body content enclosed between the control tag.
         * If {@link getText Text} is not empty, it will be rendered. Otherwise,
         * the body content enclosed in the control tag will be rendered.
         * @param THtmlWriter the writer used for the rendering purpose
         */
        public function renderContents($writer)
        {
                if(($text=$this->getText())==='')
                        parent::renderContents($writer);
                else
                        $writer->write($text);
        }

        /**
         * @return string the text caption of the button
         */
        public function getText()
        {
                return $this->getViewState('Text','');
        }

        /**
         * @param string the text caption to be set
         */
        public function setText($value)
        {
                $this->setViewState('Text',$value,'');
        }

        /**
         * Returns the caption of the button.
         * This method is required by {@link IDataRenderer}.
         * It is the same as {@link getText()}.
         * @return string caption of the button.
         * @see getText
         * @since 3.1.0
         */
        public function getData()
        {
                return $this->getText();
        }

        /**
         * Sets the caption of the button.
         * This method is required by {@link IDataRenderer}.
         * It is the same as {@link setText()}.
         * @param string caption of the button
         * @see setText
         * @since 3.1.0
         */
        public function setData($value)
        {
                $this->setText($value);
        }

        /**
         * @return string the command name associated with the {@link onCommand OnCommand} event.
         */
        public function getCommandName()
        {
                return $this->getViewState('CommandName','');
        }

        /**
         * @param string the command name associated with the {@link onCommand OnCommand} event.
         */
        public function setCommandName($value)
        {
                $this->setViewState('CommandName',$value,'');
        }

        /**
         * @return string the parameter associated with the {@link onCommand OnCommand} event
         */
        public function getCommandParameter()
        {
                return $this->getViewState('CommandParameter','');
        }

        /**
         * @param string the parameter associated with the {@link onCommand OnCommand} event.
         */
        public function setCommandParameter($value)
        {
                $this->setViewState('CommandParameter',$value,'');
        }

        /**
         * @return boolean whether postback event trigger by this button will cause input validation
         */
        public function getCausesValidation()
        {
                return $this->getViewState('CausesValidation',true);
        }

        /**
         * Sets the value indicating whether postback event trigger by this button will cause input validation.
         * @param string the text caption to be set
         */
        public function setCausesValidation($value)
        {
                $this->setViewState('CausesValidation',TPropertyValue::ensureBoolean($value),true);
        }

        /**
         * @return string the group of validators which the button causes validation upon postback
         */
        public function getValidationGroup()
        {
                return $this->getViewState('ValidationGroup','');
        }

        /**
         * @param string the group of validators which the button causes validation upon postback
         */
        public function setValidationGroup($value)
        {
                $this->setViewState('ValidationGroup',$value,'');
        }

        /**
         * Raises the postback event.
         * This method is required by {@link IPostBackEventHandler} interface.
         * If {@link getCausesValidation CausesValidation} is true, it will
         * invoke the page's {@link TPage::validate validate} method first.
         * It will raise {@link onClick OnClick} and {@link onCommand OnCommand} events.
         * This method is mainly used by framework and control developers.
         * @param TEventParameter the event parameter
         */
        public function raisePostBackEvent($param)
        {
                if($this->getCausesValidation())
                        $this->getPage()->validate($this->getValidationGroup());
                $this->onClick(null);
                $this->onCommand(new TCommandEventParameter($this->getCommandName(),$this->getCommandParameter()));
        }

        /**
         * This method is invoked when the button is clicked.
         * The method raises 'OnClick' event to fire up the event handlers.
         * If you override this method, be sure to call the parent implementation
         * so that the event handler can be invoked.
         * @param TEventParameter event parameter to be passed to the event handlers
         */
        public function onClick($param)
        {
                $this->raiseEvent('OnClick',$this,$param);
        }

        /**
         * This method is invoked when the button is clicked.
         * The method raises 'OnCommand' event to fire up the event handlers.
         * If you override this method, be sure to call the parent implementation
         * so that the event handlers can be invoked.
         * @param TCommandEventParameter event parameter to be passed to the event handlers
         */
        public function onCommand($param)
        {
                $this->raiseEvent('OnCommand',$this,$param);
                $this->raiseBubbleEvent($this,$param);
        }
}