KristofferStrube.Blazor.SVGAnimation 0.2.0

Introduction

A Blazor WASM wrapper for the SVG Animation browser API.

With the wrapper, we can listen to the begin, end, and repeat events, see the status of SVG Animations, and start and stop animations at specific times from Blazor.

The specs for the API can be found at https://svgwg.org/specs/animations/#IDL

Demo

The sample project can be demoed at https://kristofferstrube.github.io/Blazor.SVGAnimation/

On each page, you can find the corresponding code for the example in the top right corner.

Getting Started

Prerequisites

You need to install .NET 7.0 or newer to use the library.

Download .NET 7

Installation

You can install the package via Nuget with the Package Manager in your IDE or using the command line:

dotnet add package KristofferStrube.Blazor.SVGAnimation

Usage

The package can be used in all Blazor projects.

Import

You also need to reference the package in order to use it in your pages. This can be done in _Import.razor by adding the following.

@using KristofferStrube.Blazor.SVGAnimation

Creating wrapper instances

The primary part of this library is a wrapper class for SVGAnimationElements which can be instantiated from your code using the static CreateAsync methods on the wrapper class.

@inject IJSRuntime JSRuntime

<svg width="100px" height="100px">
    <rect @onclick="SquareClicked"
          width="100"
          height="100"
          fill="red">
        <animate @ref="colorAnimationElementReference"
                 attributeName="fill"
                 values="red;yellow;red"
                 begin="indefinite"
                 dur="3s" />
    </rect>
</svg>

@code {
    private ElementReference colorAnimationElementReference = default!;

    private async void SquareClicked()
    {
        SVGAnimationElement colorAnimationElement = await SVGAnimationElement.CreateAsync(JSRuntime, colorAnimationElementReference);
        await colorAnimationElement.BeginElementAsync();
    }
}

You can also use a SVGAnimationElement to listen for the beginEvent, endEvent, and repeatEvent events. The following is an example of listening for when a repeat event happens.

@using KristofferStrube.Blazor.DOM
@implements IAsyncDisposable
@inject IJSRuntime JSRuntime

<b>Number of repeats: </b> @repeats
<br />
<svg width="100px" height="100px">
    <rect @onclick="SquareClicked"
          width="100"
          height="100"
          fill="red">
        <animate @ref="colorAnimationElementReference"
                 attributeName="fill"
                 values="red;yellow;red"
                 begin="indefinite"
                 repeatCount="indefinite"
                 dur="1s" />
    </rect>
</svg>

@code {
    private ElementReference colorAnimationElementReference = default!;
    private SVGAnimationElement colorAnimationElement = default!;
    private EventListener<Event> repeatListener = default!;
    private int repeats = 0;

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (!firstRender) return;
        colorAnimationElement = await SVGAnimationElement.CreateAsync(JSRuntime, colorAnimationElementReference);
        repeatListener = await colorAnimationElement.AddOnRepeatEventListenerAsync(_ =>
        {
            repeats++;
            StateHasChanged();
            return Task.CompletedTask;
        });
    }

    private async void SquareClicked()
    {
        await colorAnimationElement.BeginElementAsync();
    }

    public async ValueTask DisposeAsync()
    {
        await colorAnimationElement.RemoveOnRepeatEventListenerAsync(repeatListener);
    }
}

Issues

Feel free to open issues on the repository if you find any errors with the package or have wishes for features.

Related articles

This repository was built with inspiration and help from the following series of articles:

• Wrapping JavaScript libraries in Blazor WebAssembly/WASM
• Call anonymous C# functions from JS in Blazor WASM
• Using JS Object References in Blazor WASM to wrap JS libraries
• Blazor WASM 404 error and fix for GitHub Pages
• How to fix Blazor WASM base path problems