在Android中实现富文本编辑器？

Question

I am wondering if there are any good options to implement a rich text editor in Android. Please note I am talking about a rich text editor that can be used in an Android application, not the one embedded in a web page using HTML and Javascript.

My requirements are:

• Basic formatting (color, fonts, highlight, bold, italic, underline, etc.)
• Hyperlinks
• Inline images
• Bullet lists and numbered lists
• Inline table (only the contents inside a cell is editable, not the table structure)

As you can see, this is pretty much something quite similar to a typical RichEdit control on Windows.

Here are some efforts (investigation & prototyping) I have made so far:

Using WebView

I have tried using a WebView control to load an HTML fragment with one . The content becomes editable and as it is HTML, I suppose it can meet most of my requirements. But it has several issues:

• (deadly) No text caret. The user will have no idea where his/her typed characters will be inserted.
• The on-screen soft keyboard is not visible by default. There is a trick that the user has to long-press the Menu button to bring up the keyboard. But I think this is a very bad user experience. Besides, the screen layout is not properly rearranged and the text inserting point sometimes will be covered by the keyboard.

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Using EditText

I have tried using the EditText control. It seems to support some level of rich text editing (color, fonts, bold, italic, underline, inline images, bullet lists). But I still cannot figure out how I can implement the following requirements:

• Control the appereance of the bullet symbol (dot, circle, dash, arrow, star, etc.)
• Numbered list (1., 2., 3., etc.)
• Table

BTW, I have seen there are several *Span classes out there but I am not sure if they can be any help... And the http://developer.android.com does not provide much useful information about them.

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So, how on earth can I implement a rich text editor on Android? Can I extends the EditText and add my new functionalities? Or should I do something from scratch - extends the View and implement everything by myself? For later option (extending View), I actually even don't know how to show a text caret and blink it, not mentionging moving the caret with user typing.

I am desperate now... Any hints?

Thanks!

-Tony

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( EDIT )

After some further investigation, it looks like extending EditText would be my best bet. I somehow figured out how to use those Span classes and guess I should be able to do most of the tricks by using (extending) them.

For example, extending the BulletSpan and overriding drawLeadingMargin should give me the control of the bullet appereances. Extending the LeadingMarginSpan should help me on the numbered list.

As to the table, my initial plan is to extend the LineBackgroundSpan and draw all the table borders in the drawBackground override. However, I still need to figure out how to layout all the text in the table cells and properly handle the caret movement and selection. Suggestions?

Answer 1

I just published my rich text editor component under the Apache 2.0 license:

https://github.com/1gravity/Android-RTEditor

Answer 2

如果需要进行足够大的更改，我可能会同时扩展EditText和TableLayout或者至少最终使用它们的大部分源代码 。

Answer 3

Can you do the following:

1. Manually hold the contents in the EditText as your own model (ie by seperating and maintaing the content document and the view attributes as seperate entities).
2. Override the render (or draw method) to do custom layout on parts of the content document (part of your model) that handle non text characters (say bullets with particular attribute).

To me seems like if you have to muck about with the layout, are you better off writing it from scratch on your own. From what I remember the Edit text (and the richt text editor) is great for anything where you the data is pure text.

Answer 4

There is an open source EditText rich text editor called android-richtexteditor but the code was inexplicably deleted in r5. The code is still there in r4 ; just use svn to check out r4 or earlier to access it. The code appears to support italics, underline, color picker, text size, and more.

Also answered in these questions: 1 , 2

Answer 5

You can make use of any of the following libraries:-

https://github.com/commonsguy/cwac-richedit

https://github.com/chinalwb/Android-Rich-text-Editor

https://github.com/wasabeef/richeditor-android

https://github.com/irshuLx/Android-WYSIWYG-Editor

Answer 6

Extend from EditText is a best choice for you, it support CharacterSpan and ParagraphSpan.

See my App on the Google Play: https://play.google.com/store/apps/details?id=com.hly.notes

Answer 7

Check this open source Wordpress mobile application for android.It has very promising Richtexteditor based on Edittext.

You can download the source from here

Thanks