Html IMG vs CSS Background-image

Image – Useful Tips

An image can be used in a webpage for two regions,

1) Image =  for content use, on the other hand, tend to change frequently. New images are uploaded often, users change their profile images and photo galleries, etc.

2) Background Image = for design. I.e. logos, button images, links with images, etc. tend to stay the same. They’re only changed if designer want to redesign.

The way I tend to think about this is, do I want the image to appear on all screen sizes, on all devices, with CSS turned either on or off? Do I want the image to be “indexed” by Google and Facebook. If the answer is yes to all or any of these questions, then usually the image is “content” and you should use an IMG tag.

If you want a different image to display at different screen sizes (or no image at all on certain devices), or if you’re happy for the image to not appear on a print out, or you’re happy for the image to not appear if CSS is turned off, then usually the image is “design” and you should use a background image.

Note: If an HTML file contains ten images – eleven files are required to display the page right. Loading images takes time, so my best advice is: Use images carefully.

Note: When a web page is loaded, it is the browser, at that moment, that actually gets the image from a web server and inserts it into the page. Therefore, make sure that the images actually stay in the same spot in relation to the web page, otherwise your visitors will get a broken link icon. The broken link icon is shown if the browser cannot find the image.
read more @ http://www.css-jquery-design.com/…

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Proper uses of IMG & Background-image

  1. Use IMG if you intend to have people print your page and you want the image to be included by default. 
  2. Use IMG (with alt text) when the image has an important semantic meaning, such as a warning icon. This ensures that the meaning of the image can be communicated in all user-agents, including screen readers.

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Creating a Puzzle game using jQuery

Today we are making a simple puzzle game called “Doraemon Puzzle”. The purpose of the game is to slide 15 square blocks around to form an image. The goal of this tutorial is to look at this simple browser-based game and explain how it was made line by line. It’s a great way to learn jQuery. For this tutorial, We will use a 2D image of kid’s favorite cartoon “Doraemon” for square-sliding game.  I will go over each line of code to demonstrate the train of thought. I really do believe that breaking this game up into explanations on per-line basis will help you understand how to use jQuery in your own projects.

Concept about creating a Game as a jQuery Plugin

A jQuery plugin is a perfect way to create image slideshows, custom user interface controls and of course browser-based games. We won’t just write JavaScript code here, we will create a jQuery plugin.

A plugin is nothing more than our own custom jQuery method. You know how we have jQuery’s methods .css() and .animate()? Well, jQuery gives us the ability to extend its own functionality with custom methods that we create ourselves. Like the existing jQuery methods, we can apply the method we will create to a jQuery selector.

Well, the game is called “Doraemon Puzzle”, and we want to make our game “embeddable” inside an arbitrary HTML element like <div id=”game_area”>here</div> so we can move it around anywhere on the page.

creating-puzzle-game-with-jquery

The jQuery

We will actually create our own jQuery method and call it .puzzle_dg(). I have already created the plugin “puzzle_dg.min.js“.  Therefore, in order to launch the game inside an HTML element with id “#game_area” we will call this command:

$(window).load(function(){
    $('#game_area').puzzle_dg(140)
});

This will create and attach the game board to the div whose id is “game_area.” Also, each square will become 140 by 140 pixels in width and height based on the only passed parameter. You can re-size the game blocks and area easy by just changing this parameter.

In this tutorial I used the image of a Doraemon cartoon. You can replace it with any image you want.

Executing a custom method as shown in the code above will pass the selector string “#game_area” to our plugin function which grabs the DIV. Inside our custom method, we can refer to that selector/element using the this keyword. And we can also enable jQuery methods on it by passing it to the new jQuery object like so: $(this); — inside the extended function I have created.

The HTML

First, let’s prepare HTML markup for our game.  We have only call <div id="game_area"></div> for creating game area.

We have to include the awesome jQuery library. After including the jQuery library we have to include “puzzle_dg.min.js”  file as game plugin.

<!-- This is where the game will be injected -->
<div id="game_object"></div>

<script src="http://code.jquery.com/jquery-1.7.1.min.js"></script>
<script src="js/main.js"></script>
<script type="text/javascript">$(window).load(function(){
    $('#game_area').puzzle_dg(140)
});</script>

CSS

There are a few styles for our game:

#game_area {
	background-color: #ffffff;
	height: 550px;
	margin: 20px auto;
	position: relative;
	width: 550px;
}
#board div {
	background: url("images/doraemon.jpg") no-repeat scroll 0 0 #ffffff;
	cursor: pointer;
	height: 140px;
	line-height: 140px;
	position: absolute;
	text-align: center;
	width: 140px;
	/* css3 shadow */
    -moz-box-shadow: inset 0 0 20px #2caae7;
	-webkit-box-shadow: inset 0 0 20px #2caae7;
	-ms-box-shadow: inset 0 0 20px #2caae7;
	-o-box-shadow: inset 0 0 20px #2caae7;
	box-shadow: inset 0 0 20px #2caae7;
}

view demo

Conclusion

I tried to explain the code to the best of my ability here but some details were skipped because there is so much more to JavaScript. I hope you enjoyed this article. Thanks for reading!

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Posted by: Dhiraj kumar

Image Sprites – How to merge multiple images, and how to split them

An Image Sprites is a single image which is merged with multiple images. The reason why Image Sprites are needed instead of inserting multiple images into a page is to SAVE network bandwidth as well as reduce the number of server requests. Since inserting many images into a page will take longer time to load the pages, merging images into a single will help reduce loading time. For these reasons, I would recommend to use “CSS Image Sprites” function instead of inserting multiple images. Unfortunately, most of designers/developers not support this function as default, but through this tutorial, you would be able to merge multiple images into a single image as well as manipulating CSS.

“Image Sprites” is strongly recommended for Web, because Web themes have many graphics as default. Therefore, reducing the number of images is necessary to let people as well as search engines visit your sites faster than before. Some times ago, I have already posted an example of a cartoon type animation with help of Image Sprites.

Let me give you an example for easier understandings. Here is lots of avatars I have to put into a page. Without Image Sprites, I have to insert 24 individual avatars into a page. It will generate 24 requests of your web server so that it will take a long time to load.

24 image files to load / 24 requests

Just 1 image file to load / 1 request

With using “Image Sprites”, Only one request and one loading time will be generated. Which one do you think better?

In addition, with the help of “Image Sprites”, you can make use of hover effect more easily. In this tutorial, I will describe how to use Image Sprites with hover effects (View Demo).

To get started (Preparation)

  1. You may need to prepare more than two same size images to be inserted into a page like the avatar image file above.
  2. For this tutorial, I will use these 6 images below as an example. All six buttons’ sizes are equal as 33×33.

3 left images will be used for normal links, and the rest of images will be used for hover effects.

This single image below will be used for “Image Sprites”.

Instruction

  1. Download .zip file or View Demo.
  2. Extract the compressed file onto your hard drive.
  3. Open “imagesprites.html” file using any TextEditor (Notepad/Dreamweaver).
  4. I will let you know some parts you need to replace so that you better modify some codes using text editor.
  5. This code is for this example so that your code will be different. You can refer to this code about how it works.
  6. Take a look at this part of the source code below:
.prev-button {
    width: 33px; height: 33px; border: 0px; background:url('/images/controllers.png') 0 0
}
a:hover .prev-button {
    width: 33px; height: 33px; border: 0px; background: url('/images/controllers.png') 0px -33px
}
.play-button  {
    width: 33px; height: 33px; border: 0px; background:url('/images/controllers.png') -33px 0
}
a:hover .play-button  {
    width: 33px; height: 33px; border: 0px; background: url('/images/controllers.png') -33px -33px
}
.next-button  {
    width: 33px; height: 33px; border: 0px; background:url('/images/controllers.png') -66px 0
}
a:hover .next-button  {
    width: 33px; height: 33px; border: 0px; background: url('/images/controllers.png') -66px -33px
}
image sprite
 As you can see, the first image’s position is “0 0” (.prev-button). The second image (.play-button) position is “-33px 0”. Because each width is set to 33px. Hence, the next image’s position should be “-66px 0”. On the other hand, for hover images, their Y position should be “-33px”, because each height is set to 33px.
  1. If you have set all, the next is to insert HTML codes for each image class like below:
<body style="background: transparent; margin: 0pt; ">
<div>
<a href="URL" target="_top"><img class="prev-button" src="/images/spacer.gif" /></a>
</div>

<div>
<a href="URL" target="_top"><img class="play-button" src="/images/spacer.gif" /></a>
</div>

<div>
<a href="URL" target="_top"><img class="next-button" src="/images/spacer.gif" /></a>
</div>
</body>
  1. If you don’t want an image to be linked, remove href= “URL” target= “_top” tag.
  2. Replace class names such as “prev-button”, “play-button”, and “next-button” to yours.
  3. Make sure the classes doesn’t have “.” at the very front.
  4. Modifying codes is done. You can apply this technique to other merged images.
  5. Make sure “spacer.gif” as well as your merged image file are also uploaded to the right place such as “/images/”.
  6. You are ready to check how “Image Sprites” works correctly. You will reduce the number of server requests as well as save network bandwidth with this CSS technique.

Posted by: Dhiraj kumar