Add custom hotkeys. (#2340)

Co-authored-by: LosFarmosCTL <80157503+LosFarmosCTL@users.noreply.github.com>
Co-authored-by: Paweł <zneix@zneix.eu>
Co-authored-by: Felanbird <41973452+Felanbird@users.noreply.github.com>
Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

src/controllers/hotkeys/README.md

@@ -0,0 +1,95 @@
+# Custom Hotkeys
+
+## Table of Contents
+
+- [Glossary](#Glossary)
+- [Adding new hotkeys](#Adding_new_hotkeys)
+- [Adding new hotkey categories](#Adding_new_hotkey_categories)
+
+## Glossary
+
+| Word                    | Meaning                                                                                   |
+| ----------------------- | ----------------------------------------------------------------------------------------- |
+| Shortcut                | `QShortcut` object created from a hotkey.                                                 |
+| Hotkey                  | Template for creating shortcuts in the right categories. See [Hotkey object][hotkey.hpp]. |
+| Category                | Place where hotkeys' actions are executed.                                                |
+| Action                  | Code that makes a hotkey do something.                                                    |
+| Keybinding or key combo | The keys you press on the keyboard to do something.                                       |
+
+## Adding new hotkeys
+
+Adding new hotkeys to a widget that already has hotkeys is quite easy.
+
+### Add an action
+
+1.  Locate the call to `getApp()->hotkeys->shortcutsForCategory(...)`, it is located in the `addShortcuts()` method
+2.  Above that should be a `HotkeyController::HotkeyMap` named `actions`
+3.  Add your new action inside that map, it should return a non-empty QString only when configuration errors are found.
+4.  Go to `ActionNames.hpp` and add a definition for your hotkey with a nice user-friendly name. Be sure to double-check the argument count.
+
+### Add a default
+
+Defaults are stored in `HotkeyController.cpp` in the `resetToDefaults()` method. To add a default just add a call to `tryAddDefault` in the appropriate section. Make sure that the name you gave the hotkey is unique.
+
+```cpp
+void HotkeyController::tryAddDefault(std::set<QString> &addedHotkeys,
+                                     HotkeyCategory category,
+                                     QKeySequence keySequence, QString action,
+                                     std::vector<QString> args, QString name)
+```
+
+- where `action` is the action you added before,
+- `category` — same category that is in the `shortcutsForCategory` call
+- `name` — **unique** name of the default hotkey
+- `keySequence` - key combo for the hotkey
+
+## Adding new hotkey categories
+
+If you want to add hotkeys to new widget that doesn't already have them it's a bit more work.
+
+### Add the `HotkeyCategory` value
+
+Add a value for the `HotkeyCategory` enum in [`HotkeyCategory.hpp`][hotkeycategory.hpp]. If you widget is a popup, it's best to use the existing `PopupWindow` category.
+
+### Add a nice name for the category
+
+Add a string name and display name for the category in [`HotkeyController.hpp`][hotkeycontroller.hpp] to `hotkeyCategoryNames` and `hotkeyCategoryDisplayNames`.
+
+### Add a shortcut context
+
+To make sure shortcuts created from your hotkeys are only executed in the right places, you need to add a shortcut context for Qt. This is done in `Hotkey.cpp` in `Hotkey::getContext()`.
+See the [ShortcutContext enum docs for possible values](https://doc.qt.io/qt-5/qt.html#ShortcutContext-enum)
+
+### Override `addShortcuts`
+
+If the widget you're adding Hotkeys is a `BaseWidget` or a `BaseWindow`. You can override the `addShortcuts()` method. You should also add a call to it in the constructor. Here is some template/example code:
+
+```cpp
+void YourWidget::addShortcuts()
+{
+    HotkeyController::HotkeyMap actions{
+        {"barrelRoll", // replace this with your action code
+         [this](std::vector<QString> arguments) -> QString {
+             // DO A BARREL ROLL
+             return ""; // only return text if there is a configuration error.
+         }},
+    };
+    this->shortcuts_ = getApp()->hotkeys->shortcutsForCategory(HotkeyCategory::PopupWindow /* or your category name */,
+                                                            actions, this);
+}
+```
+
+## Renaming defaults
+
+Renaming defaults is currently not possible. If you were to rename one, it would get recreated for everyone probably leading to broken shortcuts, don't do this until a proper mechanism has been made.
+
+<!-- big list of links -->
+
+[actionnames.hpp]: https://github.com/Chatterino/chatterino2/blob/custom_hotkeys/src/controllers/hotkeys/ActionNames.hpp
+[hotkey.cpp]: https://github.com/Chatterino/chatterino2/blob/custom_hotkeys/src/controllers/hotkeys/Hotkey.cpp
+[hotkey.hpp]: https://github.com/Chatterino/chatterino2/blob/custom_hotkeys/src/controllers/hotkeys/Hotkey.hpp
+[hotkeycontroller.cpp]: https://github.com/Chatterino/chatterino2/blob/custom_hotkeys/src/controllers/hotkeys/HotkeyController.cpp
+[hotkeycontroller.hpp]: https://github.com/Chatterino/chatterino2/blob/custom_hotkeys/src/controllers/hotkeys/HotkeyController.hpp
+[hotkeymodel.cpp]: https://github.com/Chatterino/chatterino2/blob/custom_hotkeys/src/controllers/hotkeys/HotkeyModel.cpp
+[hotkeymodel.hpp]: https://github.com/Chatterino/chatterino2/blob/custom_hotkeys/src/controllers/hotkeys/HotkeyModel.hpp
+[hotkeycategory.hpp]: https://github.com/Chatterino/chatterino2/blob/custom_hotkeys/src/controllers/hotkeys/HotkeyCategory.hpp