scroll/src/common/editor/editor.ts

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JavaScript
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import Ansi, { KeyCommand } from './ansi.ts';
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import Buffer from './buffer.ts';
import { ctrl_key, IPoint, ITerminalSize, truncate, VERSION } from '../mod.ts';
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export class Editor {
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#buffer: Buffer;
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#screen: ITerminalSize;
#cursor: IPoint;
constructor(terminalSize: ITerminalSize) {
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this.#buffer = new Buffer();
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this.#screen = terminalSize;
this.#cursor = {
x: 0,
y: 0,
};
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}
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// --------------------------------------------------------------------------
// Command/input mapping
// --------------------------------------------------------------------------
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/**
* Determine what to do based on input
* @param input - the decoded chunk of stdin
*/
public processKeyPress(input: string): boolean {
switch (input) {
case ctrl_key('q'):
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this.clearScreen().then(() => {});
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return false;
case KeyCommand.ArrowUp:
case KeyCommand.ArrowDown:
case KeyCommand.ArrowRight:
case KeyCommand.ArrowLeft:
this.moveCursor(input);
break;
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}
return true;
}
private moveCursor(char: string): void {
switch (char) {
case KeyCommand.ArrowLeft:
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this.#cursor.x--;
break;
case KeyCommand.ArrowRight:
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this.#cursor.x++;
break;
case KeyCommand.ArrowUp:
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this.#cursor.y--;
break;
case KeyCommand.ArrowDown:
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this.#cursor.y++;
break;
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}
}
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// --------------------------------------------------------------------------
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// Terminal Output / Drawing
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// --------------------------------------------------------------------------
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/**
* Clear the screen and write out the buffer
*/
public async refreshScreen(): Promise<void> {
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this.#buffer.append(Ansi.HideCursor);
this.#buffer.append(Ansi.ResetCursor);
this.drawRows();
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this.#buffer.append(
Ansi.moveCursor(this.#cursor.y, this.#cursor.x),
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);
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this.#buffer.append(Ansi.ShowCursor);
await this.#buffer.flush();
}
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private async clearScreen(): Promise<void> {
this.#buffer.append(Ansi.ClearScreen);
this.#buffer.append(Ansi.ResetCursor);
await this.#buffer.flush();
}
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private drawRows(): void {
this.drawPlaceholderRows();
}
private drawPlaceholderRows(): void {
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for (let y = 0; y < this.#screen.rows; y++) {
if (y === Math.trunc(this.#screen.rows / 2)) {
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const message = `Kilo editor -- version ${VERSION}`;
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const messageLen = (message.length > this.#screen.cols)
? this.#screen.cols
: message.length;
let padding = Math.trunc((this.#screen.cols - messageLen) / 2);
if (padding > 0) {
this.#buffer.append('~');
padding -= 1;
this.#buffer.append(' '.repeat(padding));
}
this.#buffer.append(truncate(message, messageLen));
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} else {
this.#buffer.append('~');
}
this.#buffer.append(Ansi.ClearLine);
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if (y < this.#screen.rows - 1) {
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this.#buffer.appendLine('');
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}
}
}
}