49 lines
2.9 KiB
Markdown
49 lines
2.9 KiB
Markdown
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What is the `Context` all about? This `Context` has several reasons why it is introduced into `crossterm version 0.2.3`.
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These points are related to the features like `Alternatescreen` and managing the terminal state.
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- At first `Terminal state`:
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Because this is a terminal manipulating library there will be made changes to terminal when running an process.
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If you stop the process you want the terminal back in its original state.
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Therefore, I need to track the changes made to the terminal.
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- At second `Handle to the console`
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In Rust we can call `stdout()` to get an handle to the current default console handle.
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For example when in unix systems you want to print something to the main screen you can use the following code:
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write!(std::io::stdout(), "{}", "some text").
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But things change when we are in alternate screen modes.
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We can not simply use `stdout()` to get a handle to the alternate screen, since this call returns the current default console handle (mainscreen).
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Instead we need to store an handle to the screen output.
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This handle could be used to put into alternate screen modes and back into main screen modes.
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Through this stored handle Crossterm can execute its command on the current screen whether it be alternate screen or main screen.
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For unix systems we store the handle gotten from `stdout()` for windows systems that are not supporting ANSI escape codes we store WinApi `HANDLE` struct witch will provide access to the current screen.
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So to recap this `Context` struct is a wrapper for a type that manges terminal state changes.
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When this `Context` goes out of scope all changes made will be undone.
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Also is this `Context` is a wrapper for access to the current console screen.
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Because Crossterm needs access to the above to types quite often I have chosen to add those two in one struct called `Context` so that this type could be shared throughout library.
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Check this link for more info: [cleanup of the changes](https://stackoverflow.com/questions/48732387/how-can-i-run-clean-up-code-in-a-rust-library).
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Now the user has to pass an context type to the modules of Crossterm like this:
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let context = Context::new();
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let cursor = cursor(&context);
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let terminal = terminal(&context);
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let color = color(&context);
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Check the documentation of `AlternateScreen` for more info about how to properly manage the `Context` of the terminal.
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If you don't use alternate screen functionalist's please checkout the `Crossterm` documentation whits will make things easier for you.
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Because this looks a little odd I will provide a type withs will manage the `Context` for you. You can call the different modules like the following:
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let crossterm = Crossterm::new();
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let color = envoirment.color();
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let cursor = envoirment.cursor();
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let terminal = envoirment.terminal();
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