frontend-learn | : books : 前端知识学习整理 | State Container library

I want to call a method from a child Component and I have this code

AppState:

I've been trying to implement a custom keyboard solution for one of my projects, so I created a custom component for this. Each time a key is pressed on this component, a javascript function is called and receives the id of the input that has currently the focus.

In my Blazor server app, I have a page called Home that is basically a search page. On the Home page (the "parent") there is a form with controls to filter the data stored in a backend database. Each row of the search results has an Edit button that displays a bootstrap dialog allowing one to edit the data. After the Save button on the UpdateDocumentNumber (grandchild) component is clicked I want to refresh the search results in the Home page (parent).

• Parent: Home (page) with search results grid; embeds a DisplayDocumentNumber component for each item
• Child: DisplayDocumentNumber component, which has its own (child) UpdateDocumentNumber component
• Grandchild: UpdateDocumentNumber component - bootstrap dialog

My understanding is I can use Event Callback to do this; however, while I can raise/invoke the Event Callback from grandchild to child, I cannot seem to then inform the parent from the child.

Some more details...

As the Home ("parent" page) iterates over the returned list of items it inserts a component (the "child"), and then the component has a component to reference the Edit dialog. Here's the Home page iterating over the search results:

Solved - Solution by @Henk Holterman

By making the method async and adding a Task.Delay into the method, you can execute both by calling the second method from the first after the delay.

I am building a simple React-native app with Expo for rating Github repositories and ran into a nasty issue. When I am trying to render a list of the repositories with Flatlist it throws me the following error: undefined is not an object (evaluating 'repository.fullName'); although my code is pretty much identical to the one in React-native docs. Here is the RepositoryList.jsx where the Flatlist is being rendered:

As everyone knows, we can use docker start [dockerID] to start a closed container.

But, If this container exits immediately after startup. What should I do?

For example, I have a MySQL container, it runs without any problems. But the system is down. At next time I start this container. It tell me a file is worry so that this container immediately exit.
Now I want to delete this file, but this container can not be activated, so I can't enter this container to delete this file. What should I do?

And if I want to open bash in this state container, What should I do?

Im currently using redux to manage my state. The scenario is as such , Upon successful creation of a new object , i would like to append the response data into my existing state container as i don't wish to make a new API call to render it.

I write a server-side blazor app. You can create sensors with states (Good, warning, error...) with a little API for reporting new states.

Now I want to refetch the new state (or all sensors) on a blazor client from the DB if the API gets called.

I tried to apply "3. State Container" from this guide: https://chrissainty.com/3-ways-to-communicate-between-components-in-blazor/

How I can force the site to refetch the sensors after a API request? The Sensor and Blazor Client are different devices.

I have a number of medical pictures presented on canvas, as an example below.

I’m trying to make a tool that allows you to select any area of ​​the image with the tool in the form of an expandable circle, and fill in only that part of it that doesn't go beyond the outline in which the original click pixel was located. A filled outline is drawn on a separate canvas layer.

Now I use the most common iterative stack implementation of flood fill with variable tolerance (comparison function). You can familiarize yourself with it here. Everything doesn't work very well, especially in pictures where there are no strong contrast differences and in high-resolution images, everything else is pretty slow.

I had the idea to create a state container and look for whether the desired filled outline exists there and if so, then just replace the canvas pixel array (though, again, I will have to resort to some additional processing, the canvas pixel array contains 4 channel, while at the output of the algorithm only 1 is obtained and just replacing the content doesn't work, you need to replace each pixel with a pixel divided into 4 channels) instead of a slow flood fill each time. But this approach has one significant problem: memory consumption. As you might guess, a filled outline, especially of a decent resolution alone, can take up quite a lot of space, and their set becomes a real problem of memory consumption.

It was decided to store the finished contours in the form of polygons and extracting them from the container simply fill them with faster context fill. The algorithm used allows me to output a set of boundaries, but due to the features of the algorithm, this array is unordered and connecting the vertices in this order, we get only a partially filled outline (right picture). Is there a way to sort them in such a way that I could only connect them and get a closed path (the holes that are in the filled outline in the left picture shouldn't be a priori, so we don’t have to worry about them)?

Summing up, due to the not-so-best fill job, I think to use a different algorithm / implementation, but I don’t know which one. Here are some of my ideas:

1. Use a different implementation, for example, a line scanning method. As far as I know, here is one of the fastest and most effective implementations of the algorithm among open sources. Pros: possible efficiency and speed. Cons: I need to somehow convert the result to a polygon, rewrite the algorithm to javascript (probably emscripten, can do it well, but in any case I will have to rewrite a considerable part of the code).

2. Use a completely different approach.

   a) I don’t know, but maybe the Canny detector can be useful for extracting the polygon. But as far as the use of the program is meant on the client side, it will be unprofitable to extract all the boundaries, it is necessary to figure out how to process only the necessary section, and not the entire picture.

   b) Then, knowing the border, use any sufficiently fast fill algorithm that simply won't go beyond the boundaries found.

I'll be glad to know about some other ways, and even better to see ready-made implementations in javascript

UPD:

For a better understanding, the tool cursor and the expected result of the algorithm are presented below.