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+---
+title: Trying to build a New kind of terminal emulator for the modern age
+permalink: /trying-to-build-a-new-kind-of-terminal-emulator.html
+date: 2023-01-26T12:00:00+02:00
+layout: post
+type: post
+draft: false
+---
+
+Over the past few weeks, I have been really thinking about terminal emulators,
+how we interact with computers, the separation of text-based programs and GUI
+ones. To be perfectly honest, I got pissed off one evening when I was cleaning
+up files on my computer. Normally, I go into console and do `ncdu` and check
+where the junk is. Then I start deleting stuff. Without any discrimination,
+usually. But when it comes to screenshots, I have learned that it's good to keep
+them somewhere near if I need to refer to something that I was doing. I am an
+avid screenshot taker. So at that point I checked Pictures folder and also did a
+basic search `find . -type f -name "*.jpg"` for all the JPEG files in my home
+directory and immediately got pissed off. Why can’t I see thumbnails in my
+terminal? I know why, but why in the year of 2022 this is still a problem. I am
+used to traversing my disk via terminal. I am faster, and I am more comfortable
+this way. But when it comes to visualization, I then need to revert to GUI
+applications and again find the same file to see it. I know that programs like
+`feh` and `sxiv` are available, but I would just like to see the preview. Like
+[Jupyter notebook](https://jupyter.org/) or something similar.  Just having it
+inline. Part of a result.
+
+It also didn’t help that I was spending some time with the [Plan
+9](https://plan9.io/plan9/) Operating system. More specifically
+[9FRONT](http://9front.org/). The way that [ACME editor](http://acme.cat-v.org/)
+handles text editing is just wonderful. Different and fresh somehow, even though
+it’s super old.
+
+So, I went on a lookout for an interesting way of visualizing results of some
+query. I found these applications to be outstanding examples of how not to be a
+captive of a predetermined way of doing things.
+
+- [Wolfram Mathematica](https://www.wolfram.com/mathematica/)
+- [Jupyter notebooks](https://jupyter.org/)
+- [Plan 9 / 9FRONT](http://www.9front.org)
+- [Temple OS](https://templeos.org/)
+- [Emacs](https://www.gnu.org/software/emacs/)
+
+My idea is not as out there as ACME is, but it is a spin on the terminal
+emulators. I like the modes that Vi/Vim provides you with. I like the way the
+Emacs does its own `M-x` `M-c`.  Furthermore, I really like how Mathematica and
+Jupyter present the data in a free flowing form. And I love how Temple OS is
+basically a C interpreter on some level.
+
+> **Note:** This is part 1 of the journey. Nowhere finished yet. I am just 
+> tinkering with this at the moment. This whole thing can easily spectacularly 
+> fail.
+
+So I started. I knew that I wanted to have the couple of modes, but I didn’t
+like the repetition of keystrokes, so the only option was to have some sort of
+toggle and indicate to the user that they are in a special mode. Like Vi does
+for Normal and Visual mode.
+
+These modes would for the first version be:
+
+- *Preview mode* (toggle with Ctrl + P)
+    - When this mode would be enabled, the `ls` command would try to find images
+    from the results and display thumbnails from them in the terminal itself.
+    No ASCII art. Proper images. In a grid!
+- *Detach mode* (toggle with Ctrl + D)
+    - When this mode would be enabled, every command would open a new window 
+    and execute that command in it. This would be useful for starting `htop` 
+    in a separate window.
+
+The reason for having these modes togglable is to not ask for previews every
+time. You enable a mode and until you disable it, it behaves that way.  Purely
+out of ergonomic reasons.
+
+I would like to treat every terminal I open as a session mentally. When I start
+using the terminal, I start digging deeper into the issue I am trying to
+resolve.  And while I am doing this, I would like to open detached windows
+etc. A lot of these things can be done easily with something like
+[i3](https://i3wm.org/), but also that pull you out of the context of what you
+were doing. I would like to orchestrate everything from one single point.
+
+In planning for this project, I knew that I would need to use a language like C
+and a library such as [SDL2](https://www.libsdl.org/) in order to achieve the
+desired results. I had considered other options, but ultimately determined that
+[SDL2](https://www.libsdl.org/) was the best fit based on its capabilities and
+reputation in the programming community.
+
+At first, I thought the idea of a hardware accelerated terminal was a bit of a
+joke. It seemed like such a niche and unnecessary feature, especially given the
+fact that terminal emulators have been around for decades and have always relied
+on software rendering. But to be fair, [Alacritty](https://alacritty.org/) is
+doing the same thing. Well, they are doing a remarkable job at it.
+
+So, I embarked on a journey. Everything has to start somewhere. For me, it
+started with creating a window! It has to start somewhere. 🙂
+
+```c
+// Oh, Hi Mark!
+// Create the window, obviously.
+SDL_Window *window = SDL_CreateWindow(
+  WINDOW_TITLE, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
+  WINDOW_WIDTH, WINDOW_HEIGHT,
+  SDL_WINDOW_RESIZABLE | SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);
+```
+
+I continued like this to get some text displayed on the screen.
+
+I noted that
+[`TTF_RenderText_Solid`](https://wiki.libsdl.org/SDL_ttf/TTF_RenderText_Solid)
+rendered text really poorly. There were no antialiasing at all. In my wisdom, I
+never checked the documentation. Well, that was a fail. To uneducated like me:
+`TTF_RenderText_Solid` renders Latin1 text at fast quality to a new 8-bit
+surface. So, that's why the texts looked like shit. No wonder.
+
+Remarks on `TTF_RenderText_Solid`: This function will allocate a new 8-bit,
+palettized surface. The surface's 0 pixel will be the colorkey, giving a
+transparent background. The 1 pixel will be set to the text color.
+
+After I replaced it with
+[`TTF_RenderText_LCD`](https://wiki.libsdl.org/SDL_ttf/TTF_RenderText_LCD) which
+renders Latin1 text at LCD subpixel quality to a new ARGB surface, the text
+started looking good. Really make sure you read the documentation. It’s actually
+good. As a side note, you can find all the documentation regarding [SDL2 on
+their Wiki](https://wiki.libsdl.org/).
+
+After that was done, I started working on displaying other things like `Preview`
+and `Detach` modes. This wasn’t really that hard. In SDL2 you can check all the
+available events with `while (SDL_PollEvent(&event) > 0)` and have a bunch of
+switch statements to determine which key is currently being pressed. More about
+keys, [SDLKey](https://documentation.help/SDL/sdlkey.html) and mroe about
+pooling the events on
+[SDL_PollEvent](https://documentation.help/SDL/sdlpollevent.html).
+
+```c
+while (SDL_PollEvent(&event) > 0)
+{
+  switch (event.type)
+  {
+  case SDL_QUIT:
+    running = false;
+    break;
+
+  case SDL_TEXTINPUT:
+    if (!meta_key_pressed)
+    {
+      strncat(input_prompt_text, event.text.text, 1);
+      update_input_prompt = true;
+    }
+    break;
+        }
+}
+```
+
+After that was somewhat working correctly, I started creating a struct that
+would hold all the commands and results and I call them Cells. Yes, I stole that
+naming idea from Jupyter.
+
+```c
+typedef struct
+{
+  char *command;
+  char *result;
+  SDL_Surface *surface;
+  SDL_Texture *texture;
+  SDL_Rect rect;
+} Cell;
+```
+
+I am at a place now where I am starting to implement scrolling. This will for
+sure be fun to code. Memory management in C is super easy. 😂
+
+I have also added a simple [INI file like
+configuration](https://en.wikipedia.org/wiki/INI_file) support. It is done in an
+[STB style of
+header](https://github.com/nothings/stb/blob/master/docs/stb_howto.txt) and maps
+to specific options supported by the terminal. It is not universal, and the code
+below demonstrates how I will use it in the future.
+
+```c
+#ifndef CONFIG_H
+#define CONFIG_H
+
+/*
+# This is a comment
+
+# This is the first configuration option
+dettach=value11111
+
+# This is the second configuration option
+preview=value22222
+
+# This is the third configuration option
+debug=value33333
+*/
+
+// Define a struct to hold the configuration options
+typedef struct
+{
+    char dettach[256];
+    char preview[256];
+    char debug[256];
+} Config;
+
+// Read the configuration file and return the options as a struct
+extern Config read_config_file(const char *filename)
+{
+  // Create a struct to hold the configuration options
+  Config config = {0};
+
+  // Open the configuration file
+  FILE *file = fopen(filename, "r");
+
+  // Read each line from the file
+  char line[256];
+  while (fgets(line, sizeof(line), file))
+  {
+    // Check if this line is a comment or empty
+    if (line[0] == '#' || line[0] == '\n')
+      continue;
+
+    // Parse the line to get the option and value
+    char option[128], value[128];
+    if (sscanf(line, "%[^=]=%s", option, value) != 2)
+      continue;
+
+    // Set the value of the appropriate option in the config struct
+    if (strcmp(option, "dettach") == 0)
+    {
+      strncpy(config.option1, value, sizeof(config.option1));
+    }
+    else if (strcmp(option, "preview") == 0)
+    {
+      strncpy(config.option2, value, sizeof(config.option2));
+    }
+    else if (strcmp(option, "debug") == 0)
+    {
+      strncpy(config.option3, value, sizeof(config.option3));
+    }
+  }
+
+  // Close the configuration file
+  fclose(file);
+
+  // Return the configuration options
+  return config;
+}
+
+#endif
+```
+
+This is as far as I managed to get for now. I have a daily job and this
+prohibits me to work on these things full time. But I should probably get back
+and finish this. At least have a simple version working out, so I can start
+testing it on my machines. Fingers crossed. 🕵️‍♂️
+