December 2014
Intermediate to advanced
274 pages
6h 8m
English
Content preview from Programming Chrome AppsBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Chapter 5. Graphics and Imaging
Many Chrome Apps don’t just display text and forms; they display graphics of all sorts, both those drawn by the app and those brought into the app, such as photographs. Many of the related APIs are part of HTML5 and aren’t unique to Chrome Apps, but their use in Chrome Apps does have its peculiarities, as I’ll describe in this chapter. I’ll also show you how to use the mediaGalleries API that is (as of this writing) unique to Chrome Apps.
Outputting Graphics
Until now, all of our examples showed fairly mundane user interfaces, built up from simple HTML objects, mostly text areas and buttons. However, desktop apps need to be much snazzier, with more-advanced GUIs.
The next few sections describe six different ways to create a user interface: simple text, HTML tables, positioned HTML, drawing on a canvas, Scalable Vector Graphics (SVG), and creating a PDF. Next, we’ll look at how to display images, chiefly JPEGs. Finally, we’ll investigate the Chrome mediaGalleries API, which makes it straightforward for your app to access media files stored on the local computer.
Calendar Example
To show all the different ways of displaying graphics from a Chrome App, we’ll implement the same calendar example each way. The calendar-related part of the app, which calculates the months and days, will stay the same; only the output code will change as we go through all six variations. Figure 5-1 shows the first variation, a plain-vanilla calendar that displays as just text. ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.