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Canvas

website/blog/2023-04-26-canvas.md

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Unleash your inner artist 🧑‍🎨 and boost your Flet creativity with brand-new Canvas control just released in Flet 0.6.0!

Canvas enables you to draw arbitrary graphics using a set of primitives, or "shapes", such as line, circle, arc, path and text. I bet you can even implement your own version of charts using Canvas control!

Combine Canvas with GestureDetector and you get a free-hand drawing app - Flet Brush 😀!

Example source

Canvas control is located in flet.canvas package. You need another import to use it:

python
import flet.canvas as cv

Here's a simple program drawing a smiley face with Circle and Arc shapes using filled and stroke Paint:

python
import math
import flet as ft
import flet.canvas as cv

def main(page: ft.Page):
    stroke_paint = paint = ft.Paint(stroke_width=2, style=ft.PaintingStyle.STROKE)
    fill_paint = paint = ft.Paint(style=ft.PaintingStyle.FILL)
    cp = cv.Canvas(
        [
            cv.Circle(100, 100, 50, stroke_paint),
            cv.Circle(80, 90, 10, stroke_paint),
            cv.Circle(84, 87, 5, fill_paint),
            cv.Circle(120, 90, 10, stroke_paint),
            cv.Circle(124, 87, 5, fill_paint),
            cv.Arc(70, 95, 60, 40, 0, math.pi, paint=stroke_paint),
        ],
        width=float("inf"),
        expand=True,
    )

    page.add(cp)

ft.run(main)

Read more about Canvas in docs and explore Canvas examples!

Other changes

Rich text support

While working on drawing text on Canvas, as a bonus to this release, we implemented a new TextSpan control which can now be used with Text.spans to output rich text.

Check rich text examples: one, two and three.

url property for buttons

If you need to open a URL by clicking on a button or any other control with on_click event you can just provide that URL in url instead of doing that in the code with page.launch_url() method.

Instead of that:

python
ft.ElevatedButton("Go to Google", on_click=lambda e: e.page.launch_url("https://google.com"))

you can just do this:

python
ft.ElevatedButton("Go to Google", url="https://google.com")

A new url property also solves blocked window on Safari issue.

As a continuation of url property Markdown control can now be enabled to auto-follow URLs in the document:

python
import flet as ft

md = """
[Go to Google](https://www.google.com)
"""

def main(page: ft.Page):
    page.add(
        ft.Markdown(
            md,
            extension_set=ft.MarkdownExtensionSet.GITHUB_WEB,
            auto_follow_links=True,
        )
    )

ft.run(main)

Better web support

In this release we also did some improvements to web support like capturing user info in page.client_id and page.client_user_agent as well as fixing nasty #1333 and #1289 bugs related to routing.

That's all for today!

Upgrade Flet module to the latest version (pip install flet --upgrade), give canvas and rich text a try and let us know what you think!