This requires a canvas and an external package. Thus we need to to an intermediate conversion to a rendered image. What’s important to remember, though: directly accessing pixels of Widgets is not possible. You don’t need to understand every single step. There are a more steps in between which make it a rather complex conversion chain, so let’s visualize what’s going on there: The conversion chain Good news: our good old friend, the Canvas class in combination with PictureRecorder is able to create a Picture with a toImage() function. How is that going to help? Well, if we manage to convert a text into an image, we can access its pixels from there. Okay, we now know how to access a pixel in some format of a third party package. This package has a getPixelSafe() method, allowing the caller to access a pixel given the x and y arguments. Instead of directly accessing the pixels of a rendered widget, we should rather take note of the Image package. So there are no APIs that let us access that. Anti-aliasing also makes it appear so smooth that pixels don’t come to one’s mind.īut how can we access the pixels of a widget in Flutter? Well that’s not that easy, because this is a rather low-level part of the rendering engine the developer is not supposed to access. Today’s displays have such a high resolution that the viewer does not really notice that. That doesn’t only happen to images, of course, but also to text. No matter how good the resolution of an image is and even if it’s a vector image, at the time of being displayed, the image needs to be mapped on a discrete dimension that is limited by physics. That’s because every display is based on pixels. ![]() So basically something you see every day millions of times, whether you know it or not. What we are doing here, is a classic rasterisation. Above that we display the very same text on a simulated LED display. So let’s implement a screen that has a TextField in which the user can input text. We want an LED display that can display every text with every font. ![]() We don’t want to create our own LED font in which the “LED combination” of every letter is statically stored. The simulated LED display should display text dynamically. Let’s find out! The goal The screen we want to create It made me wonder if it’s possible to simulate that in Flutter. I had a closer look at the LED display that shows the current station, the destination and the current time. I have recently taken a ride with a train.
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