richtext-120502110238-phpapp02

Copyright 2012CommonsWare, LLC

Rich Text Editing... And

Beyond


Whadaya Mean, Rich?

Things Like Bold, Italics, Underline, Etc. Other Terms

Styled Text Formatted Text WYSIWYG


Is Android Rich?

Native Rich Text Rendering in TextView Available to all subclasses of TextView (e.g.,

Button) Reasonable (but not immense) range of available

styles to apply Differing fonts, colors Vertical & horizontal alignments Bullets Etc.


Where Did All the Strings Go?

CharSequence In traditional Java, an inheritance artifact

Mostly the superclass of StringBuilder

In Android, used as basis for rich text Hence, lots of CharSequence parameters and

return values, in places where Android supports rich text


Spanning the Globe

Spanned Interface for CharSequences with inline

formatting Spannable

Sub-interface where the spans can be modified Editable

Sub-sub-interface where the text can be modified


Getting More Concrete

SpannedString String with markup

SpannableString String with mutable markup

SpannableStringBuilder String with mutable text and markup


We Are Stylin'

CharacterStyle Base class for all styles that can be applied to a

portion of a Spanned 21 total subclasses, each applying some effect

BackgroundColorSpan StyleSpan TypefaceSpan StrikethroughSpan


Our Resources Are Low

String Resources Can have inline markup (, , ) Retrieving the SpannedString

getText() (as opposed to getString()) Applying the resource directly to a widget in a layout

via @string/...


Oh, Those Angle Brackets

HTML Use Html.fromHtml() to convert into SpannedString

Modest, undocumented set of tags supported Optional, largely undocumented TagHandler for

trying to add support for other tags

Put the resulting SpannedString in a TextView (or subclass)


Tag! You're It?


Mark It Down

Anything You Can Convert to HTML Example: Markdown

Popular wikitext format Used by StackOverflow, GitHub, etc. Various parsers available Example: AndDown

Wrapper around sundown C parser


Format This, Buddy

Step #1: Get a SpannableString (or subclass)

Step #2: Manipulate the Formatting setSpan() applies formatting to a particular

region removeSpan() removes a particular span getSpans() retrieves applied spans for a given

region


The End of Style

SPAN_EXCLUSIVE_EXCLUSIVE Anything added at either end is considered

outside the span SPAN_INCLUSIVE_INCLUSIVE

Anything added at either end is considered inside the span

SPAN_EXCLUSIVE_INCLUSIVE SPAN_INCLUSIVE_EXCLUSIVE


CharSequence: Rich Yet Not

Most Utility Methods On String, Not CharSequence Example: indexOf()

TextUtils Offers a subset of those utility methods as static

methods that can be applied to a CharSequence


Hello? Didn't You Say Editing?

EditText Supports Editable

Reason why you keep calling toString() to get the plain text back

Users Edit Prose in Existing Spans You supply something with spans, and user types in

the middle of one, gets formatted

No UI for Users to Set Own Spans


RichEditText

Open Source Component Easy: Automatic FORMAT Action Mode

One method to enable Works on Android 2.1+ (ActionBarSherlock!) Works great on tablets (and not so hot on phones...)

Harder: Roll Your Own UI E.g., toolbar


RichEditText: Innards

Action Mode Items Set or Toggle Effects Effect = Wrapper Around CharacterStyle

Awareness of current selection Manages idiosyncrasies of different style classes

Toggle Logic See what's in the selection now of this particular

effect Invert current setting


RichEditText: The Future!

Better Support for Phones ...somehow...

Full Range of CharacterStyle Support Colors (foreground/background) Line alignment Bullets Links

Ragnark


A Little Bit Persistent

SpannableString Not Serializable Best Native Bet: Convert into HTML

Need to test that the formatting you apply will survive the round-trip conversion

Alternative: DIY More complete HTML conversion Convert into something else (byte array?

Markdown?)


What Would Be Handy...

More In, More Out Better HTML Conversion More wikitext support

Other flavors Bi-directional

Word processing formats (ODT, DOC/DOCX) Legacy formats

RTF


What Would Be Handy...

More CharacterStyles? Theoretically an extensible system, based on

interfaces More Reusable Editing Widgets

EditStyledText?

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