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WDS10 - More About HTML Images

Omkar Ajnadkar
Masters in Computer Science at The University of Texas at Dallas
Originally published at thecodingexpress.blogspot.com on ・3 min read

In the last article we learned about:

  • How to use images as HTML links
  • HTML links as bookmarks on large pages
  • Advanced target attribute in links
    In this post, we will study little more about HTML images. We have seen that we can insert an image in HTML pages with the help of <img> tag and it will have following main attributes:

  • src : To represent the source of an image

  • alt : Alternate text to show if an image does not load

  • width : To represent the width

  • height : To represent the height
    We have also seen how to use images as the link in the last article. Now let's see some more stuff about images. 

Aligning/ Floating Images

Sometimes just placing images in the centre of Document does not look good. At such times we can place image left or on right and follow text on another side. For such case, we can use align attribute in <img> tag same as we use to align text. We can also do this with CSS but we will see that later when we will start learning CSS. For now, align attribute will be perfect with possible values center, left and right as before.

Image Map

  • We have seen that we can use images as links but there is one restriction in it. We have to use only one link for the complete image. We can't use separate parts of the image to link to various sources. That's where <map> tag comes to rescue.  

  • First, we will create an image with <img> tag and will add one extra attribute called usemap. Its value will be any name with # always before it.

  • Now you will create the <map> element with attribute name which will have value same as usemap attributes value in the image except #. This is sort of linkup between image and map tag so that HTML knows for which image you are applying mapping. 

  • Now inside <map> and </map> tags we will create <area> tags for various areas you want to link to various sources.

  • Before moving forward, let's see what <area> tag is.The first attribute of the <area> tag is shape. It can have any of following 3 values:

    • rect : For rectangular shape
    • circle : For the circular shape
    • poly : For polynomial shape
  • Now next attribute that we must define the coordinates of above shape with coords. It is important to note that that coordinates of the top-left corner of any specified area are 0,0. For various shapes coordinate pattern will be different:

    • If shape="rect" then coords="x1,y1,x2,y2" where x1,y1,x2,y2 specifies the coordinates of left-top and right-bottom corners of rectangle.
    • If shape="circle" then coords="x,y, radius" where x, y are coordinates of the center of the circle while radius is of course radius of the circle.
    • If shape="poly" then coords="x1,y1,x2,y2....xn,yn" where each pair of x-y is coordinate of the polygon. If the first and last pair is not same then the browser will automatically add last coordinate pair to close the polygon.
  • The last attribute will be nothing but href where you will mention the link to that part.

I think that's enough for this today as it will take more time to understand mapping part.In the next part, we will learn little more about images and will also start tables in HTML. Comment on how you think this article is, what improvements should I do and for any doubts. Share with your friends and keep coding.

 

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