(c) Cleuton Sampaio 2021
User Interface (UI) is always a big problem in applications.You can use web development in most applications, but there may always be a need to create a Desktop application.
And you have to work it out to be multiplatform (Linux, Windows or MacOS). There are several frameworks for this, such as Qt, which is multiplatform, but its can be an impediment.
And why not use Web technology as a frontend, keeping your business rules compiled within your Golang code? This is what the WebView component provides. A thin layer of web Ui that you can interface with your Golang code, in two ways: Web-> Golang and Golang-> Web.
Unfortunately, the project is poorly documented and lacks functional examples, but I tested it for you and created a very simple demo that solves 99.99% of your problems.
What do you need in a UI? Send messages and components to the user and get the result of events.
The source code of this project exemplifies this:
package main
import (
"github.com/webview/webview"
)
var w webview.WebView
func acerta() {
w.Eval("document.getElementById('txt01').value = '*****'")
}
func main() {
debug := true
page := `data:text/html,
<!DOCTYPE html>
<html>
<body>
<label for="txt01">Nome</label>
<input type="text" id="txt01">
<button onclick="tratar()">Enviar</button>
<script>
function tratar() {
go_click(document.getElementById("txt01").value)
.then(function (campo) {
window.alert(campo)
})
}
</script>
</body>
</html>
`
w = webview.New(debug)
defer w.Destroy()
w.SetTitle("Minimal webview example")
w.SetSize(800, 600, webview.HintNone)
w.Bind("go_click", func(x string) string {
acerta()
return "Digitou: " + x
})
w.Init("window.alert('teste')")
w.Navigate(page)
w.Run()
}
To run it, install:
go get github.com/webview/webview
On Linux systems you may have to install the GTK3 (or 4), GtkWebkit2 and Build Essentials packages.
The code is self-explanatory, but I will talk about some relevant methods:
- New: Instantiates the WebView;
- Set..: Change its properties (title, size, etc.);
- Bind: Associates a Golang object to an object in the Javascript global context. In this case, I am associating an anonymous function;
- Eval: Run Javascript in the web context. You can use it to change elements' properties;
- Init: Send Javascript code to be executed directly on the page;
- Navigate: Navigate to the URI. It can be an external file, an external website or, using the "data" protocol, a string generated inside the golang code, as in this example;
In this case, I send a page and a script to be executed in the interface. When entering a name and clicking the button, the fields are sent to the code Golang.
[This article] (https://medium.com/@master.rta/golang-create-a-web-view-app-for-any-platform-54917dea397) shows you how to package your app and distribute.