ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

setting up jquery for drawing with Javascript - part 1 in a series

Updated on March 29, 2011

marking where the user has clicked

introduction

For the next thing, I want to demonstrate, I want to use a mouse for my program to receive input from the user. While handling mouse events is possible in native Javascript, javascript libraries make the task a lot easier. So, I will use one. JQuery seems to have the most momemtum. So, I will use that one.

This will be the first hub in another series. In this first hub, I will just get things, setup.

Putting a dot where the user clicks should be sufficient to get the mechanics I will want for the
next hub, in place.

jQuery setup is covered in lots of other places. The only twist I am adding is to merge it in with the graphing calculator application I developed and explained in my last series. Later I will expand how the user interacts with the graph using jQuery.

style sheet stuff

First I add a style for the target of mouse events.

.mousetarget { position: absolute; top:50; left:50; z-index: 2; opacity: "0%"; cursor:pointer; }

including jquery

Next, I include the jQuery library.  The commented out inclusion is to retrieve the jQuery library from a public server, but I want to be able to work while off-line.  So, I made a local copy.  The 1.4.4 and 1.4.2 are version numbers.  The latest is 1.5.1, as of this writing, but I doubt it will matter for what I want to do.

the hand-rolled javascript

<!--<script type="text/javascript" 

src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js"></script>-->
<script type="text/javascript" src="./js/jquery-1.4.2.min.js"></script>

I add a container for the mouse target style.

<div id="mousetarget" class="mousetarget" ></div>

Finally, I add some script to do what I want; put a dot where the user clicks:

<script type="text/javascript" >
$( document ).ready( function () {
	alert( "hello jquery world!" );
	$( "#mousetarget" ).css( "top", unitsquare.screeny1 );
	$( "#mousetarget" ).css( "left", unitsquare.screenx0 );
	$( "#mousetarget" ).height( unitsquare.screeny0 - unitsquare.screeny1 );
	$( "#mousetarget" ).width( unitsquare.screenx1 - unitsquare.screenx0 );
	$( "#mousetarget" ).bind( "click", function (e) {
		drawrectangle( "blackrectangle", e.clientY + 2, e.clientX - 2, 4, 4 );
	});
});
</script>

jquery usage explained

The alert just lets me know everything is setup ok.  No typos that keep javascript from running, etc.  $ is the cryptic version of the jQuery function.  "#mousetarget" is an id based selector, that describes what DOM element I want jQuery to opperate on.

The jQuery function includes lots of methods that do useful things.  I only used four of them: css, height, width and bind.  I'm not sure why the "top" and "left" style properties don't have their own functions, like height and width do.  bind associates a function with mouse-click events, if the mouse is over my target object when it is clicked.  drawrectangle is a function I wrote and explained in my previous series of hubs.  Anyway, it is what puts a black square where the user clicked.

Comments

    0 of 8192 characters used
    Post Comment

    No comments yet.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)