Textarea Pointing Canvas Tutorial
With our blog posting thread last left off with yesterday’s Textarea Pointing PDF Tutorial, I know we’ve been holding out on involving …
… not for “nga, nga, nga nga, nga” reasons, but because we want to show that the starting out with “textarea character data” sets is a useful layer of information that can sit on top and easily pass onto these (last two above in particular) functionalities above in optional reporting modes of use, but still keep that “textual context” in place as well. Win, win, we’d say.
However, on non-mobile web browsers in particular, you’ve got to appreciate how the modern browsers interface to canvas elements and image data (which can be derived from that canvas element by the oft mentioned [canvasElement].toDataURL() method) with a myriad of right click (Windows or two finger gesture on Mac OS X) options, our favourites of which are …
- image – Open Image in New Tab (or Window)
- image – Save Image to Desktop
- image – Save Image As…
- image – Copy Image
- image – Share Mail (to client email (ie. your own email address is “From” email address) as image attachment)
- image – Share Message
- canvas – Save Page as Web Archive
- canvas – Print Page… Open PDF in PDF Reader
- canvas – Print Page… Save As PDF
- canvas – Print Page… Save As PostScript
- canvas – Print Page… Mail PDF (to client email (ie. your own email address is “From” email address) with a PDF attachment)
… so much so that we just want all this clientside (no PHP serverside “anything” today) to wash over you with your mind “swimming” with possibilities, perhaps?!
Take a look at today’s live run‘s textarea_pointing.htm HTML and Javascript (DOM) and CSS code changed this way as all that needed to change to involve canvas and image data and data URIs in our Textarea Pointing project.
If there is no serverside “anything” going on, what is the “glue” that holds all this clientside interfacing together? These days, more and more, it is the use of data URI portable data that can be used in, just with today’s work …
- HTML img element src attribute
- HTML img element style attribute background URL(data URI)
This is all great, but that’s it, unless you want to run that image data back through an intelligent scanning process to try to regain the “character data”? Some scanners do this, but do you really think you are going to continue getting a good result that way forever? We say, hang on to data in rawer forms and resolutions until the very last minute, and only go to these very well programmed for “graphical” forms (of final reporting) for your final reporting, or if you know that only that “blobby” “graphical” form is all that’s required anyway. If so, think about using HTML canvas from the start. It’s data capture capabilities, as we at this blog have been at pains to point out for a long time now, are also excellent.
Another Paul Kelly song seems apt!
Previous relevant Textarea Pointing PDF Tutorial is shown below.
Textarea Pointing PDF Tutorial
Yesterday’s Textarea Pointing Email Tutorial was a start to our “sharing” functionality “push” with our new Textarea Pointing project. That work involved …
- (new window) with menu
- (new window) without menu
- email with HTML attachment … and today we add to that …
- email with PDF attachment … as well as …
- PDF download to client device
- PDF display via default client PDF viewer
… that required, again, Linux diff PDF Tutorial live run‘s prediff.php PHP code integration in this changed way. This time, though, rather than $outputpdf->Cell($x, $y, $line_of_text); being the best Fpdf means of displaying of the PDF text, we found …
$outputpdf->Text($x, $y, $line_of_text);
… to be more applicable to programming like for the way vinyl records work with their stylus, in other words, at a given …
- HTML textarea element (x,y) position … we gather …
- HTML textarea element font information stored in the alt attribute … to place text …
- to be able to …
$outputpdf->SetFont($fontFamily, $fontStyle, $fontSize);
$outputpdf->SetTextColor($fontColR, $fontColG, $fontColB);
$outputpdf->Text($x, $y, $line_of_text);
… as the “work of the code” needed to transition from our “user capture with character data” (in the “textarea”s) to a graphical system (or “widget”, you might like to think of this as). It just so happens that the first (graphical) “widget” design of interest is the creation of PDF, as it is a good conduit between “character data” and a “graphical look”. A “widget” feeling thing being what it is though, expect more integrations to come, as time goes on!
Today’s live run‘s textarea_pointing.htm code changed this way.
Previous relevant Textarea Pointing Email Tutorial is shown below.
Textarea Pointing Email Tutorial
Yesterday’s Textarea Pointing Primer Tutorial was a little too localised in its application in our books. Not if a web application is not of generic use, but this one could be of generic use, in our pamphlettes books.
Our favourite “sharing” idea is email, by far, as today, as far as that goes, we are going to offer email “services” via a “client pre-emptive iframe” determination of whether where you have placed today’s live run‘s textarea_pointing.htm code (changed this way) has, relative to it, an existant ../PHP/Geographicals/prediff.php PHP code source (that we left to go on our Textarea Pointing project) of Linux diff PDF Tutorial (live run‘s prediff.php PHP code’s last changes were used to cater for the Textarea Pointing HTML email attachment requirement).
We like to use a “client pre-emptive iframe” technique initial check for whether the HTML finds prediff.php because the email functionality is optional after all. If prediff.php is not found, then the Email button is never shown, simple as that. But the other two displays of the HTML in new popup windows …
- with menu
- without menu … as well as …
- email with HTML attachment
… complete the scope of the new “Sharing” functionalities today, and this year, on this!
So … Happy New Year!
Previous relevant Textarea Pointing Primer Tutorial is shown below.
Textarea Pointing Primer Tutorial
Completely new idea today, so hoping this does not put some of you “episodic” users off. We’ll get back to incomplete recent “threads” at a later date. This is because we had pause for thought, due to yesterday’s PDF textual data positioning work, regarding one of our favourite HTML fundamental element types of interest (that we are always comparing) …
To quote HTML Textarea and Div Talents Primer Tutorial (as it was addressing the textarea HTML element) …
It’s crucial for getting HTML or non-caretted Text (that is internally turned into HTML behind the scenes) … via those wonderful tabs … off the user and onto the MySql database, and then out to the client user as part of a webpage. Out at that webpage, though, we’ve no doubt this content is embedded in an HTML div element, the other “talent” here.
But their strengths and weaknesses go like this, at least to us, in the limited HTML text view of things …
Text Functionality Issue HTML Element Type Strength Weakness (where a “Yes” is like … “Oh No!”) Display Monocolour Text Textarea Yes Div Yes Display Editable Text Textarea Yes Div Yes Display Multicolour Text Textarea Yes Div Yes
Nothing there above gives much encouragement about the HTML textarea‘s “positioning” talents. But what if we were to create a “posse”, or perhaps a “phalanx”, of “textarea”s to bank up with “bits and pieces” of the positioning “issue” (under the auspices of an HTML form element, for later accountability)?
What do we mean by “issue” here? Well, something like a letter, as with the end product of a scanning process involving a hardcopy letter, is that much more useful if what we end up with is the “characters” that go to make up that letter (or report, or essay), not some graphic (or totally visual) encapsulation of it, which can be what happens when you involve as your HTML “capture” element the “canvas” element. No, we want that “posse” of “textarea”s be that “character” source, which later, we can present as an overall graphic at a later date, for sharing purposes for instance, and maintain the “letter” (or report or essay) data continuously as the user edits.
How to do? We click/touch with a base “textarea” and that is enough to arrange for an “overlay” “textarea” (via CSS position:absolute and z-index properties, some background-color:transparent styling, along with div id=dscript (innerHTML) appended dynamic CSS styling making use of CSS calc‘ing <style> .mboard2 { width: calc(85% – 56px); } </style> type syntax (where the 56px would have been derived via the onclick event logic, the 85% is to allow for a 15% width menu at the right, and the 2 in mboard2 refers to the second textarea in question)) to follow (ironically an HTML div element is by far the best “container” in a (Javascript DOM controlled) linked list fashion for this, rather than appending to the HTML form element’s innerHTML (which seems to wipe out previous textarea values)), like a linked list of “textarea”s. Along the way we allow for font information to be collected and kept as well (for now, via the textarea‘s alt attribute), to add to the chances for variety with our overall “letter” (or report or essay) reporting end product.
Which leaves us to talk about the “textarea pointing” live run‘s underlying HTML and Javascript and CSS textarea_pointing.html code for your perusal.
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