[Refactor] Abstract text editing into reusable components.

client/src/terminal.cpp

@@ -1,4 +1,5 @@
 #include <cstdio>
+#include <memory>
 #include <SDL3/SDL.h>
 #include <GL/glew.h>
 #include <SDL3/SDL_events.h>
@@ -8,11 +9,10 @@
 #include "gfx/txt_renderer.h"
 #include "gfx/types.h"
 
-Terminal::Terminal(ClientNetwork* network) : _network(network) {
-  /* Placeholder welcome message to history. */
-  _should_close   = false;
-  _scroll_offset  = 0;
-  _prompt         = "";
+Terminal::Terminal(ClientNetwork* network)
+    : _network(network), _should_close(false), _scroll_offset(0),
+      _prompt("") {
+  _input_view = std::make_unique<TextView>(&_input_buffer);
 }
 
 Terminal::~Terminal(void) {}
@@ -45,8 +45,8 @@ void Terminal::set_prompt(const std::string& prompt) {
 bool Terminal::close(void) { return _should_close; }
 
 void Terminal::_on_ret_press(void) {
-  std::string command = _input_buffer;
-  _input_buffer.clear(); /* Clear the input buffer immediately. */
+  std::string command = _input_buffer.get_line(0);
+  _input_buffer.clear();
 
   /* Add the command to history. */
   _history.push_back(_prompt + "> " + command);
@@ -70,16 +70,9 @@ void Terminal::_on_ret_press(void) {
 }
 
 void Terminal::handle_input(SDL_Event* event) {
-  if(event->type == SDL_EVENT_TEXT_INPUT) {
-    /* Append chars to the input buffer. */
-    _input_buffer += event->text.text;
-  } else if(event->type == SDL_EVENT_KEY_DOWN) {
-    /* Handle special keys. */
-    if(event->key.key == SDLK_BACKSPACE && _input_buffer.length() > 0) {
-      _input_buffer.pop_back();
-    } else if(event->key.key == SDLK_RETURN) {
-      _on_ret_press();
-    }
+  /* Pass input to TextView; if true, RET was pressed. */
+  if(_input_view->handle_event(event)) {
+    _on_ret_press();
   }
 }
 
@@ -120,14 +113,16 @@ void Terminal::render(TextRenderer* renderer, int x, int y, int width, int heigh
   }
 
   /* Draw current input line. */
-  std::string line_to_render = _prompt + "> " + _input_buffer;
-  if(show_cursor) {
-    line_to_render += "_";
-  }
   float prompt_y_pos = (y+height) - padding - line_height
     - ((_history.size()-_scroll_offset)*line_height);
-  renderer->render_text(line_to_render.c_str(), x+padding, prompt_y_pos, 1.0f, green);
 
+  /* Render prompt string. */
+  std::string prompt_str = _prompt + "> ";
+  renderer->render_text(prompt_str.c_str(), x + padding, prompt_y_pos, 1.0f, green);
+
+  /* Render text view for the input right after prompt. */
+  float input_x_pos = x + padding + (prompt_str.length() * 8.5f); /* Estimate width */
+  _input_view->render(renderer, input_x_pos, prompt_y_pos, show_cursor);
   /* Disable scissor test. */
   glDisable(GL_SCISSOR_TEST);
 }

client/src/terminal.h

@@ -1,10 +1,13 @@
 #pragma once
 #include <string>
 #include <vector>
+#include <memory>
 #include <SDL3/SDL.h>
 
 #include "gfx/txt_renderer.h"
 #include "client_network.h"
+#include "ui/text_buffer.h"
+#include "ui/text_view.h"
 
 class Terminal {
 public:
@@ -22,10 +25,11 @@ public:
 private:
   void _on_ret_press(void);
 
-  std::string _input_buffer;
   bool _should_close;
   std::vector<std::string> _history;
   int _scroll_offset;
   std::string _prompt;
   ClientNetwork* _network;
+  TextBuffer _input_buffer;
+  std::unique_ptr<TextView> _input_view;
 };

client/src/ui/text_view.cpp

@@ -0,0 +1,77 @@
+#include <SDL3/SDL_events.h>
+#include "text_view.h"
+#include "gfx/txt_renderer.h"
+#include "gfx/types.h"
+#include "ui/text_buffer.h"
+
+TextView::TextView(TextBuffer* buffer) : _buffer(buffer) {}
+
+TextView::~TextView(void) {}
+
+bool TextView::handle_event(SDL_Event* event) {
+  if(!_buffer) return false;
+
+  if(event->type == SDL_EVENT_TEXT_INPUT) {
+    _buffer->insert_char(event->text.text[0]);
+  } else if(event->type == SDL_EVENT_KEY_DOWN) {
+    switch(event->key.key) {
+      case SDLK_BACKSPACE:
+        _buffer->backspace();
+        break;
+      case SDLK_RETURN:
+        /* Instead of adding newline, signal that input was submitted. */
+        return true;
+        break;
+      case SDLK_LEFT:
+        _buffer->move_cursor(-1,0);
+        break;
+      case SDLK_RIGHT:
+        _buffer->move_cursor(1,0);
+        break;
+      case SDLK_UP:
+        _buffer->move_cursor(0,-1);
+        break;
+      case SDLK_DOWN:
+        _buffer->move_cursor(0,1);
+        break;
+      case SDLK_HOME:
+        _buffer->move_cursor_home();
+        break;
+      case SDLK_END:
+        _buffer->move_cursor_end();
+        break;
+      default:
+        break;
+    }
+  }
+  return false;
+}
+
+void TextView::render(TextRenderer* renderer, int x, int y, bool show_cursor) {
+  if(!_buffer) return;
+
+  const Color text_color = { 1.0f, 1.0f, 1.0f };
+  float line_height = 20.0f; /* TODO: Get font metrics? */
+
+  /*
+   * Just render first line (for term input) for now.
+   * The code editor would need to iterate through _buffer->get_line_count()
+   */
+  std::string line = _buffer->get_line(0);
+  Point cursor_pos = _buffer->get_cursor_pos();
+
+  if(show_cursor) {
+    /*
+     * This hacky. we should calculate the text width
+     * up to the cursor pos to draw correctly.
+     * For now, just append an underscore.
+     */
+    if(cursor_pos.col == line.length()) {
+      line += "_";
+    } else {
+      line.insert(cursor_pos.col, 1, '_');
+    }
+  }
+
+  renderer->render_text(line.c_str(), x, y, 1.0f, text_color);
+}

client/src/ui/text_view.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <SDL3/SDL_events.h>
+
+#include "ui/text_buffer.h"
+
+class TextRenderer;
+
+class TextView {
+public:
+  TextView(TextBuffer* buffer);
+  ~TextView(void);
+
+  bool handle_event(SDL_Event* event);
+  void render(TextRenderer* renderer, int x, int y, bool show_cursor);
+
+private:
+  TextBuffer* _buffer;
+};

common/src/ui/text_buffer.cpp

@@ -0,0 +1,86 @@
+#include <algorithm>
+#include <sstream>
+
+#include "ui/text_buffer.h"
+
+TextBuffer::TextBuffer(void) : _cursor_row(0), _cursor_col(0) {
+  _lines.emplace_back(""); /* Start with a single empty line. */
+}
+
+TextBuffer::~TextBuffer(void) {}
+
+void TextBuffer::insert_char(char c) {
+  _lines[_cursor_row].insert(_cursor_col, 1, c);
+  _cursor_col++;
+}
+
+void TextBuffer::backspace(void) {
+  if(_cursor_col > 0) {
+    _lines[_cursor_row].erase(_cursor_col - 1, 1);
+    _cursor_col--;
+  } else if(_cursor_row > 0) {
+    /* If start of line, merge with previous. */
+    _cursor_col = _lines[_cursor_row-1].length();
+    _lines[_cursor_row-1] += _lines[_cursor_row];
+    _lines.erase(_lines.begin() + _cursor_row);
+    _cursor_row--;
+  }
+}
+
+void TextBuffer::newline(void) {
+  std::string current_line = _lines[_cursor_row];
+  std::string new_line = current_line.substr(_cursor_col);
+  _lines[_cursor_row] = current_line.substr(0, _cursor_col);
+
+  _cursor_row++;
+  _lines.insert(_lines.begin() + _cursor_row, new_line);
+  _cursor_col = 0;
+}
+
+void TextBuffer::move_cursor(int dx, int dy) {
+  _cursor_col += dx;
+  _cursor_row += dy;
+
+  /* Clamp cursor row. */
+  _cursor_row = std::max(0, std::min((int)_lines.size()-1, _cursor_row));
+  /* Clamp cursor col. */
+  _cursor_col = std::max(0, std::min((int)_lines[_cursor_row].length(), _cursor_col));
+}
+
+void TextBuffer::move_cursor_home(void) {
+  _cursor_col = 0;
+}
+
+void TextBuffer::move_cursor_end(void) {
+  _cursor_col = _lines[_cursor_row].length();
+}
+
+const std::string& TextBuffer::get_line(int row) const {
+  return _lines[row];
+}
+
+size_t TextBuffer::get_line_count(void) const {
+  return _lines.size();
+}
+
+Point TextBuffer::get_cursor_pos(void) const {
+  return { _cursor_row, _cursor_col };
+}
+
+std::string TextBuffer::get_text(void) const {
+  std::stringstream ss;
+  for(size_t i = 0; i < _lines.size(); ++i) {
+    ss << _lines[i];
+    if(i < _lines.size()-1) {
+      ss << "\n"; /* Or another separator? */
+    }
+  }
+  return ss.str();
+}
+
+void TextBuffer::clear(void) {
+  _lines.clear();
+  _lines.emplace_back("");
+  _cursor_row = 0;
+  _cursor_col = 0;
+}

common/src/ui/text_buffer.h

@@ -0,0 +1,33 @@
+#pragma once
+
+#include <string>
+#include <vector>
+
+struct Point {
+  int row;
+  int col;
+};
+
+class TextBuffer {
+public:
+  TextBuffer(void);
+  ~TextBuffer(void);
+
+  void insert_char(char c);
+  void backspace(void);
+  void newline(void);
+  void move_cursor(int dx, int dy);
+  void move_cursor_home(void);
+  void move_cursor_end(void);
+
+  const std::string& get_line(int row) const;
+  size_t get_line_count(void) const;
+  Point get_cursor_pos(void) const;
+  std::string get_text(void) const;
+  void clear(void);
+
+private:
+  std::vector<std::string> _lines;
+  int _cursor_row;
+  int _cursor_col;
+};