Gregory's Blog

Kendo Responsive Panel


I ran into someone posting the same scrolling question as I was looking to solve on stack overflow, but could not find anything else on the web. The responsive panel is used to provide a slide-out menu on mobile devices when you click on what is commonly known as a 'hamburger. The panel is used in responsive web design and is triggered when the device reaches a certain minimum screen width. Here is the code that I developed for this blog:

<nav id="sidebarPanel" class="k-content">
	<!---Suppply the sideBarType argument before loading the side bar--->
	<cfset sideBarType = "panel">
	<cfinclude template="includes/layers/sidebar.cfm">
</nav><!---<nav id="sidebar">--->
			
<!--- This script must be placed underneath the layer that is being used in order to effectively work as a flyout menu.--->
<script>
$("#sidebarPanel").kendoResponsivePanel({
	breakpoint: 1280,
	orientation: "left",
	autoClose: true
})
.on("click", "a", function(e) {
	$("#sidebarPanel").kendoResponsivePanel("close");
});
</script>

There were several challenges that I ran into when developing this. First, I tried to use the same div element that I use on the right side of the page to hold the various widgets, such as the calendar, subscribe, recent posts, etc. However, I noticed that if I tried to use the same div for the responsive menu, I could no longer apply certain css properties to the panel, and it was stuck at the top of the page. To solve this, I used a different div at the end of the application to serve as the responsive panel, duplicated the logic from the right column, and put it into the new panel at the end of the page. I also created a script to show the new responsive panel when the screen size hit the breakpoint setting (1280 pixels), and hid the original div that is on the right column. Here is the relevant portions of the code:

// Handle the sidebar and the sideBarPanels
if (windowWidth <= 1280){
	// Hide the sidepanel (the responsive panel will takeover here).
	$( "#sidebar" ).hide();
	// Show the responsive panel
	$( "#sidebarPanel" ).show();
} else {
	// Show the sidebar, and hide the responsive panel
	$( "#sidebar" ).show();
	$( "#sidebarPanel" ).hide();
}

Second, the hamburger showed up, but it closed as soon as I tried to open it. I found the following solution while searching the web:

// Important note: this is a workaround with a google chrome bug and mobile devices. 
// This prevents the following error: "Intervention] Unable to preventDefault inside passive event listener due to target being treated as passive."
// See https://github.com/telerik/kendo-ui-core/issues/3556
$(".k-rpanel-toggle").on("touchend", function(e) { 
	 e.preventDefault();
});

Third, I ran into problems where to put the resonsivePanel initiation script. I found out that it must be at underneath the actual element that it will be placed into. It now works, however, there is a big problem. I could not scroll down the responsive panel when it was triggered. It just stayed in a fixed position and only showed the top part of the page. I looked everywhere in the Kendo site, and then on the internet, looking for some arcane argument that I could use, such as scrollable: true, but couldn't find any. I then looked at the similar jQuery UI menu, and inspected Telerik's production page which has a responsive panel and found that they both used the css declaration: position: absolute;

position: absolute;

Fourth. Ok, that fixed that problem, but now the div layer disappeared at the bottom of the page. I tried setting height to 100%, but that failed too. So I looked at both jQuery and Kendo's panels again, and noticed that they also used: height: auto;

height: auto;

Also, use the autoclose argument to be false on the responsive panel widget, otherwise you won't be able to able to keep the layer open when scrolling past the bottom of the first page. That worked! The panel can be scrolled now. The final working code is pasted below: CSS:

/* The side bar panel is essentially a duplicate of the sidebar div, however, it is a responsive panel used when the screen size gets small. */
#sidebarPanel {
/* We are going to eliminate this sidebar for larger devices, and activate it when the screen size gets to a certain size. */
display: none;
/* Note: the panel will not scroll with the blog content unless there is a css position: absolute. */
position: absolute;
margin: 0;
/* Apply more padding to the right to keep things uniform. */
padding: 20px 40px 20px 20px;
width: 45%;
/* Note: if you don't set 'height: auto', the panel will not be displayed below the bottom of the page. */
height: auto;
vertical-align: top;
overflow: visible;
border-right: thin;
		
/* Put a drop shadow on the panel when it is expanded. */
#sidebarPanel.k-rpanel-expanded {
         box-shadow: 0 0 10px rgba(0,0,0,.3);
 }

CFML:

<!---This is the sidebar responsive navigation panel that is triggered when the screen gets to a certain size. It is a duplicated of the sidebar div above, however, I can't properly style the sidebar the way that I want to within the blog content, so it is duplicated without the styles here.--->
						
<!--- Side bar is to the right of the main panel container. It is also used as a responsive panel below when the screen size is small. --->
<nav id="sidebarPanel" class="k-content">
<!---Suppply the sideBarType argument before loading the side bar--->
<cfset sideBarType = "panel">
<cfinclude template="includes/layers/sidebar.cfm">
</nav><!---<nav id="sidebar">--->

Javascript:

<!-- This script must be placed underneath the layer that is being used in order to effectively work as a flyout menu.--->
$("#sidebarPanel").kendoResponsivePanel({
	breakpoint: 1280,
	orientation: "left",
	autoClose: false // set this to false if you want the layer to stay up when you want to sroll down.
})
.on("click", "a", function(e) {
	$("#sidebarPanel").kendoResponsivePanel("close");
});

// Important note: this is a workaround with a google chrome bug and mobile devices. 
// This prevents the following error: "Intervention] Unable to preventDefault inside passive event listener due to target being treated as passive."
// See https://github.com/telerik/kendo-ui-core/issues/3556
$(".k-rpanel-toggle").on("touchend", function(e) { 
	e.preventDefault();
});

This entry was posted on February 10, 2019 at 12:38 AM and has received 1906 views.

Needed to develop a new proxy function


First, we can't get session vars in the main blog.cfc. Raymond (and et-al) had another application.cfm in the org/cambden/blog folder that prevented this component from having access to the session variables set on the /blogCfc/application.cfm template. Cfc's should have access to the session scope unless it finds another application.cfm (or cfc) template, and here, this is the case. This poses some problems with ajax. I do not want to have to hard code authentication variables, like the isAdmin, in a javascript ajax post. This is quite insecure. I tried in vain to get the blog.cfc component to work for my purposes. After finding and eliminating the 'other' application.cfm template which caused problems accessing the session scope, I was able to obtain session variables, but the elimination of the application.cfm template in the same directory caused new problems. One example is that the isUserInRole function is now erroring out with an 'You have attempted to dereference a scalar variable of type class java.lang.String as a structure with members.'. This new error was raised throughout the blog.cfc template. Another issue is that I suspect that the /blogCfc/org/delmore/coldfishconfig.xml file is not working when the application.cfm template is disabled. This file most likely deals with the cfauthentication tag. In order to have the session scope, and in order to potentially cache the code after an ajax operation, I had to develop a new template to act as a proxy. I am not using a .cfc component for ajax post operations as I need the session variables and need to perform client side operations, such as setting form values, and caching the output of the page. Goals: The proxy template will use Raymond's blog.cfc to perform all database operations. Whenever possible, I will perform server side business logic using Raymonds Blog.cfc.

This entry was posted on November 10, 2018 at 12:42 AM and has received 742 views.

Introductory purpose


I have been using ColdFusion since 1998? It was version 2.5 I believe... I started off using ColdFusion's built in UI, and quickly became disappointed. It was fine for beginners, but problematic when using it for enterprise web applications. The ColdFusion UI was brittle, you could not expand the functionality, and you had to purchase a new version of ColdFusion in order to update it- if you could at all. The overall consensus among serious developers was to use something other than ColdFusion's built in UI. I personally settled on using Telerik's Kendo library with jQuery. I found this UI to be powerful, and beautiful. One of the problems with current front end design is that the method in which to beautify the page requires very long and complex style sheets. Often, the style sheets are almost as complex as the server side code. I wanted to use a library that was powerful, looked really good, but did not require a lot of fuss in the UI. Kendo offers me dozens of predefined themes that I can use for generic enterprise class web applications, and allows the front end to look really good with minimal fuss. Kendo also offers rich HTML5 web widgets, such as a beautiful grid that supports editing data sets with millions of rows. It also forces the developer to use modern HTML5 code. Kendo is not without issues though. As we will see, it is complex, and getting it to work can be tedious at times. I hope to annotate some of the challenges using Kendo, but it is in my opinion, one of the most powerful and elegant UI libraries around. In regards to ColdFusion, another major issue with Kendo is that It is also completely absent among ColdFusion developers. I can't find any body of information to go to when things go astray. Telerik does not offer any ColdFusion wrappers, and Telerik only markets and supports its product for .Net, PHP, and JSP. If at all possible, I hope that this blog can be a resource to ColdFusion developers to use Kendo, even if exploratively. I have admired the original author of the code base that powers this blog, and use his own blog examples of ColdFusion and code for my own professional use. Raymond Camden is a legend in the ColdFusion community. His posts on the internet have literally saved my professional bacon many times. I am happy to try to re-engineer one of his own older applications to fulfill this purpose. I'm going to make decisions with his original open source code, and hope to thoroughly rewrite it. And ironically, I will likely use his new blogging layout at https://www.raymondcamden.com/ as an example how to best re-design his older original code.

This entry was posted on October 30, 2018 at 2:13 AM and has received 608 views.




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