computeraxe

Centering Slideshows with jQuery Cycle Plugin

axe — Tue, 31 Jan 2012 07:05:30 +0000

The jQuery Cycle plugin is a JavaScript plugin that will help you make beautiful slideshows. There are a ton of options for the Cycle plugin to help you make really nice-looking and functional slideshows.

This example will show the steps to take for centering slides in a slideshow using the Cycle plugin. HTML markup in this case is a group of images inside a

container. CSS is used to give some style to our slideshow and for centering everything. JavaScript is used to control the transitions of the slides and the animation of the slideshow.

HTML Markup:

A basic slideshow might have a few images that are cycled through in sequential fashion with random special effects that bring each photo into view. The JavaScript code that could be used with the jQuery Cycle plugin for such a slideshow could be as follows:

JavaScript:

jQuery(document).ready(function($) {
 $('#showy').cycle({
  fx: 'all',
  speed: 800,
  pause: 2000,
  slideExpr: 'img'
 });
});

So far, we’d get a mess if no CSS rules targeted the slideshow.

Without at least giving dimensions to the slideshow, via width and height properties, the Cycle plugin will be helpless to show the images correctly. Make sure to add width and height values to the slideshow container in the CSS rules.

Also, you’ll need to specify the position property. In this case we’re giving a value of ‘relative’ instead of ‘absolute’ for the position property as we want to center the slideshow instead of placing it at some exact location. Without specifying the position of the slideshow container, some of the transition effects won’t be seen as intended.

The trick to centering the slideshow is to set the margins. Give the right and left margins a string value of ‘auto’ to center things horizontally. The top and bottom margins are given a numerical value, 10 px in this case.

CSS:

#showy {
position:relative;
height:300px;
width: 300px;
margin: 10px auto;
}

Using these simple CSS styling rules, we get a more pleasing slideshow experience.

JavaScript Plugin: jQuery Cycle for Slideshows

axe — Tue, 24 Jan 2012 07:05:27 +0000

JavaScript plugins can definitely speed up development of a website, but unless you take the time to explore the plugins you’re using, you may not be using them to full advantage. Read on to learn more about using the jQuery Cycle plugin for slideshows. It works with jQuery v1.3.2 and later.

The jQuery Cycle Plugin offers an amazing number of transitions for your next slideshow. If any of the two dozen transitions don’t give the effect you’re looking for, the plugin can always be modified to suit. If you’re looking to make some unique transitions, check out the advanced demos on the plugin site.

Over 50 options can be implemented to show your slides in the best light. Options are available for controlling the speed of the transitions, the length of time between slides, as well as running the slideshow backwards or stopping after a certain number of slides have been shown.

Slides can be forced to fit a container and made to be manually paused and resumed. Easing transitions can be specified as can random showing of slides. Options in Cycle are plentiful and definitely worth investigating.

Command strings can be used to pause or resume the slideshow or advance to the next or previous slides. Tie these commands to a click event to let your visitors see the show as they wish.

The Cycle plugin works with two assumptions in creating slideshows. First, it assumes that a container object has been identified, usually via a class or id identifier, that will contain the slides for the slideshow. All children of the containing parent will become a slide.

Second, the slides must all be children of the container. Any object can be a child here, so textual content, images, anchors and divs can all be manipulated and viewed as slides in your slideshow. Don’t put anything else in the slideshow container unless you want it to become part of the slideshow.

Here’s the HTML markup that could be used for a simple slideshow of images:

The images are contained in a specific container, div#show, which can be styled with CSS. Giving the container and the slides fixed dimensions works best, so make sure to specify the widths and heights.

The default behavior is to fade slides in and out of the container in a continuous and sequential manner, in a cyclical way. So, we’re going to ‘cycle’ through the slides in this slideshow. The javascript for a slideshow using default behavior is simple:

$('#show').cycle();

With Cycle plugin default settings the slideshow starts with the first image or slide and each slide takes one second, or 1000 milliseconds, to be faded in. Each slide is then paused for 4 seconds and then faded out in one second. The slideshow wraps around so that the first slide will be shown after the last one. The fading in and out action occurs continuously and indefinitely with the default settings, as below:

To alter the slideshow behavior pass an effect, other than fade, as a string to the cycle method, like so:

$('#show2').cycle('shuffle');

Check out all the effects that can be used to transition slides: blindX, blindY, blindZ, cover, curtainX, curtainY, fade, fadeZoom, growX, growY, scrollUp, scrollDown, scrollLeft, scrollRight, scrollHorz, scrollVert, shuffle, slideX, slideY, toss, turnUp, turnDown, turnLeft, turnRight, uncover, wipe, and zoom.

Several transitions can be combined in a comma-separated list if you can’t choose just one. Or, use the string ‘all’ to see all the slide transition effects in a random manner.

Alternatively, you can use an options object to set the fx option among others. The code below specifies fade, zoom and curtainY effects to bring the slides in and out of the container. Each slide will be brought in slowly (800 ms) and taken out quickly (400 ms) taking a total of 3 seconds for each complete transition. This is the code for the slideshow (#show3) at the top of this post.

$('#show3').cycle({
  fx: 'fade,zoom,curtainY',
    speedIn: 800,
    speedOut: 400,
    slideExpr: 'img'
    timeout: 3000,
    nowrap: true
});

The parameter slideExpr is given a string value of ‘img’ in order to produce a slideshow without long blank pauses in between slides when using WordPress. WordPress and other content management systems may introduce extraneous markup when preparing webpages. The markup may be incorrectly interpreted by different browsers used to view slideshows created with Cycle, so it’s become important to specify the elements that are supposed to be cycled in the slideshow. Thus, the addition of slideExpr: ‘img’ as an optional parameter is necessary for image slideshows in WordPress.

The slideshow just above will be shown only one time and end with the last slide because the nowrap option is set to true. This might be a good thing to remember for leaving a textual message on the screen with your last slide instead of having the slideshow run indefinitely.

If you get stuck or need a little help with figuring out how to work the Cycle plugin, visit the jQuery Forum.

jQuery Stop Action Improves InnerFade Plugin

axe — Tue, 17 Jan 2012 07:05:11 +0000

When animations go wrong it’s usually in the timing. Perhaps the browser can’t keep up with all that it’s asked to do or the operating system is bogged down by other tasks. In any case the lack of enough working memory or CPU cycles will have animations stacking up until there are enough resources to do all those fancy moves.

Some animations run continuously and others may be controlled by setting timers or stopping the animations at predetermined times. Other animations happen after some event has occurred, like when a user mouses over an element on the page or clicks a button.

Animations created with the jQuery InnerFade plugin run continuously, which may create a problem if the users’ computer resources aren’t up to the job.

It was noted that an InnerFade news ticker animation of links worked fine and as expected when the browser tab was left open and running. Working with another tab open and going back to the news ticker site, the news items got stacked onto one another so that the text was unreadable and the timing was double time.

Reloading the page or waiting for a couple of seconds to pass brought the expected behavior back. The animations caught up to where they should have been and the behavior continued as expected.

I’m not exactly sure why the animations stacked up in my page and not in the demo page by the plugin author, but I found a solution to this stacking problem.

jQuery lets us use a stop() action to clear the previously requested animations that haven’t finished yet. Optional parameters for the stop() action are clearQueue and gotoEnd, which are false by default.

To use the stop() action in this case, set both parameters to true. This will clear all animations in the queue and jump to the place where the action should be at now.

If it were important to catch up to the latest animation, use true for the optional gotoEnd parameter. When set to true, the gotoEnd parameter figures out what the screen should look like at the end of the present set of animations in the queue and goes there.

In the section of the code that responds to the slide or fade settings, I used the stop() action to clear the queue and catch up. The InnerFade plugin was altered on lines 93 and 96 (of the original script) by inserting .stop(true,true) just before the fadeOut() or slideUp() methods.

line 93...$(elements[last]).stop(true,true).slideUp(settings.speed);
line 96...$(elements[last]).stop(true,true).fadeOut(settings.speed);

Below is the portion of the original script that has been modified (on lines 3 and 6 here):

$.innerfade.next = function(elements, settings, current, last) {
        if (settings.animationtype == 'slide') {
            $(elements[last]).stop(true,true).slideUp(settings.speed);
            $(elements[current]).slideDown(settings.speed);
        } else if (settings.animationtype == 'fade') {
            $(elements[last]).stop(true,true).fadeOut(settings.speed);
            $(elements[current]).fadeIn(settings.speed, function() {
							removeFilter($(this)[0]);
						});

The script now works even better!

When two separate link lists were animated with the InnerFade plugin on the same page, the first one stacked up and the second list went blank when the stop() action was used with only the first parameter set to true, so it was important to set both the clearQueue and gotoEnd parameters to true.

The stop() action also comes in handy to clear the queue when event-driven animations get backed up from too much user input, like mousing over and out too fast.

An oddity in all this is that I couldn’t replicate the bad behavior (of the original plugin) inside of WordPress. The stacking up of animations was noticed in a static page outside of WordPress. To see the original and improved InnerFade plugins in action, go to the Good Ideas static page.

Is there some way that WordPress manages the scripts differently? I dunno, but the take away message here is to make sure and test your scripts to see how they act in various circumstances.

Javascript Plugin: InnerFade with jQuery

axe — Tue, 10 Jan 2012 07:05:03 +0000

Fade elements in and out with the InnerFade javascript plugin. Its purpose is to fade “any element inside a container in and out” and it relies on jQuery to do its magic. InnerFade is a lightweight plugin of only 8 kb, so it won’t bog down your pages.

Any group of elements can be faded in and out with the InnerFade plugin as long as they are inside a container that is targeted by the first line of the script. Example elements that can be faded in and out are links in an unordered or ordered list, textual list items, or paragraphs in a div.

A. Eat Right – It’s the easiest medicine to take.
B. Buy Less Stuff – You don’t really need it, do you?
C. Recycle Everything – Save the Earth from humans.
D. Laugh Every Day – It helps to keep things in perspective.
E. Help One Another – Some day you’ll need a little help, so spread good karma.
F. Keep Smiling – It releases happy endorphins and makes you look great, too!

Target specific classes or ids for the right effect. Using the InnerFade plugin with jQuery is a simple way to show a countdown clock where one number fades out and the next one in the sequence fades in.

A news ticker, like the one above, can be created by fading in and out headlines for each news item. Each headline could be a link to the complete story. The headlines could be marked up as list items, like this list of good ideas:


A. Eat Right - It's the easiest medicine to take.
B. Buy Less Stuff - You don't really need it, do you?
C. Recycle Everything - Save the Earth from humans.
D. Laugh Every Day - It helps to keep things in perspective.
E. Help One Another - Some day you'll need a little help, so spread good karma.
F. Keep Smiling - It releases happy endorphins and makes you look great, too!

The easiest way to use the InnerFade plug is to accept the default settings, as we did above, and call it with a minimum of effort like so:

jQuery(document).ready(function($) {
    $('#good_ideas').innerfade();
  });

There are only a handful of options and changing them is fairly simple. The type of animation can be set to ‘fade’ or ‘slide’. The speed of the fading or sliding effects is set in milliseconds or with the strings ‘slow’, ‘normal’, or ‘fast’. Timeout is the time between animations in milliseconds. The type of slideshow is set using the strings ‘sequence’, ‘random’, or ‘random_start’. The height of the container element can be set in px, em, %.

Default Settings:

animationtype: fade
speed: normal
timeout: 2000
type: sequence
containerheight: auto
runningclass: innerfade

Now that you know you can call the javascript plugin and use it with the default settings, try changing the settings for different effects. For example, try sliding the elements slowly in and out of the 45px tall container in random order with a 3 second pause.

$(document).ready(
  function() {
    $('.group2fade').innerfade({
      animationtype: slide,
      speed: 'slow',
      timeout: 3000,
      type: 'random',
      containerheight: '45px'
    });
  }
);

The InnerFade plugin handles all the hiding of elements until viewed, so without javascript enabled, the visitor will see everything on the page. Use a