Let’s build a browser!

Although it’s possible to build complex GUI layouts, you can get a lot of functionality with very little code, utilizing the rich components that are native on modern platforms.

So - let’s build a tool that lets our pet yak graze the web - a primitive web browser, in less than 40 lines of code!

Here’s the source code:

import toga
from toga.style.pack import CENTER, COLUMN, ROW, Pack


class Graze(toga.App):
    def startup(self):
        self.main_window = toga.MainWindow()

        self.webview = toga.WebView(
            on_webview_load=self.on_webview_loaded, style=Pack(flex=1)
        )
        self.url_input = toga.TextInput(
            value="https://beeware.org/", style=Pack(flex=1)
        )

        box = toga.Box(
            children=[
                toga.Box(
                    children=[
                        self.url_input,
                        toga.Button(
                            "Go",
                            on_press=self.load_page,
                            style=Pack(width=50, padding_left=5),
                        ),
                    ],
                    style=Pack(
                        direction=ROW,
                        alignment=CENTER,
                        padding=5,
                    ),
                ),
                self.webview,
            ],
            style=Pack(direction=COLUMN),
        )

        self.main_window.content = box
        self.webview.url = self.url_input.value

        # Show the main window
        self.main_window.show()

    def load_page(self, widget):
        self.webview.url = self.url_input.value

    def on_webview_loaded(self, widget):
        self.url_input.value = self.webview.url


def main():
    return Graze("Graze", "org.beeware.tutorial")


if __name__ == "__main__":
    main().main_loop()

In this example, you can see an application being developed as a class, rather than as a build method. You can also see boxes defined in a declarative manner - if you don’t need to retain a reference to a particular widget, you can define a widget inline, and pass it as an argument to a box, and it will become a child of that box.