@nativescript-community/ui-canvaslabel

Alternative to the built-in NativeScript Label but uses canvas which allows extreme complexity and customization.

Table of Contents

• Installation
• Configuration
• Performances
• TODO / Limitations
  • Examples:
• Demos and Development
  • Repo Setup
  • Build
  • Demos
• Contributing
  • Update repo
  • Update readme
  • Update doc
  • Publish
  • modifying submodules
• Questions

A NativeScript Label widget. This widget takes a different approch from other label components. It is based on nativescript-canvas and allows drawing multiple labels within one single widget. It allows extreme complexity and customization.

Installation

Run the following command from the root of your project:

ns plugin add @nativescript-community/ui-canvaslabel

Configuration

It works almost like a normal label. You can create spans, just like with the {N} labels. However there is a big difference with the {N} component. CSpan do not support css class and never will! It was actually made on purpose to make to make the component much more efficient.

For now CanvasLabel do not auto size itself. I will add some way of doing it in the future but in a sense it defies the purpose of this component.

The CanvasLabel component supports most labels properties: color, fontSize,fontFamily,fontStyle, fontWeight,textAlignment. Those can be defined through css.

Now with CanvasLabel you don't set the text directly. Instead you create CSpan or CGroup

Here is a complex Vue layout as an example

<CanvasLabel id="canvaslabel" fontSize="10" color="white" backgroundColor="darkgray">
    <CGroup fontSize="18" verticalAlignment="middle" paddingLeft="20">
        <CSpan :text="item.text1" fontWeight="bold" />
        <CSpan :text="'\n' + item.text2" color="#ccc" fontSize="16" />
    </CGroup>

    <CGroup fontSize="12" verticalAlignment="bottom" paddingLeft="20" paddingBottom="1">
        <CSpan :text="item.icon1" fontSize="20" color="green" :fontFamily="mdiFontFamily" />
        <CSpan :text="' ' + item.texticon1" verticalTextAlignment="center" />
        <CSpan :text="'   ' + item.icon2" fontSize="20" color="red" :fontFamily="mdiFontFamily" />
        <CSpan :text="' ' + item.texticon2" verticalTextAlignment="center" />
        <CSpan :text="'   ' + item.icon3" fontSize="20" color="yellow" :fontFamily="mdiFontFamily" />
        <CSpan :text="' ' + item.texticon3" verticalTextAlignment="center" />
    </CGroup>

    <CGroup fontSize="12" verticalAlignment="middle" horizontalAlignment="center" textAlignment="right" paddingRight="20" color="brown" width="60">
        <CSpan :text="item.icon1" fontSize="14" :fontFamily="mdiFontFamily" />
        <CSpan :text="'\n' + item.texticon1" paddingRight="10" />
    </CGroup>
    <CSpan :text="item.text4" color="lightgray" fontSize="14" textAlignment="right" paddingRight="20" paddingTop="4" />
</CanvasLabel>

For full example / doc look at the vue demo and the typings.

Performances

CanvasLabel is made to be real fast. It was designed principaly to be used within list views. It uses the technique of drawing the text directly instead of using heavy native text components. That technique is used by many apps looking for the best performances. One of the best examples is Telegram.

TODO / Limitations

• For now there is no accessibility support (but it should be possible)
• The label can't size itself. I will add some ways of doing that. But possibly not in the way you are used to.
• no ellipsize support yet. Will come (this could be a solution)
• a lot of canvas features can be added like shadows, gradient ...
• transform supoort should be possible at least for groups and top spans.

Examples:

• Basic
  • A basic SVG example

Demos and Development

Repo Setup

The repo uses submodules. If you did not clone with --recursive then you need to call

git submodule update --init

The package manager used to install and link dependencies must be pnpm or yarn. npm wont work.

To develop and test: if you use yarn then run yarn if you use pnpm then run pnpm i

Interactive Menu:

To start the interactive menu, run npm start (or yarn start or pnpm start). This will list all of the commonly used scripts.

Build

npm run build.all

WARNING: it seems yarn build.all wont always work (not finding binaries in node_modules/.bin) which is why the doc explicitly uses npm run

Demos

npm run demo.[ng|react|svelte|vue].[ios|android]

npm run demo.svelte.ios # Example

Demo setup is a bit special in the sense that if you want to modify/add demos you dont work directly in demo-[ng|react|svelte|vue] Instead you work in demo-snippets/[ng|react|svelte|vue] You can start from the install.ts of each flavor to see how to register new demos

Contributing

Update repo

You can update the repo files quite easily

First update the submodules

npm run update

Then commit the changes Then update common files

npm run sync

Then you can run yarn|pnpm, commit changed files if any

Update readme

npm run readme

Update doc

npm run doc

Publish

The publishing is completely handled by lerna (you can add -- --bump major to force a major release) Simply run

npm run publish

modifying submodules

The repo uses https:// for submodules which means you won't be able to push directly into the submodules. One easy solution is t modify ~/.gitconfig and add

[url "ssh://[email protected]/"]
	pushInsteadOf = https://github.com/

Questions

If you have any questions/issues/comments please feel free to create an issue or start a conversation in the NativeScript Community Discord.