MeshCore-Solo/src/helpers/ui/DisplayDriver.h

#pragma once

#include <stdint.h>
#include <string.h>

class DisplayDriver {
  int _w, _h;
protected:
  DisplayDriver(int w, int h) { _w = w; _h = h; }
public:
  enum Color { DARK=0, LIGHT, RED, GREEN, BLUE, YELLOW, ORANGE }; // on b/w screen, colors will be !=0 synonym of light

  int width() const { return _w; }
  int height() const { return _h; }

  virtual bool isOn() = 0;
  virtual void turnOn() = 0;
  virtual void turnOff() = 0;
  virtual void clear() = 0;
  virtual void startFrame(Color bkg = DARK) = 0;
  virtual void setTextSize(int sz) = 0;
  virtual void setColor(Color c) = 0;
  virtual void setCursor(int x, int y) = 0;
  virtual void print(const char* str) = 0;
  virtual void printWordWrap(const char* str, int max_width) { print(str); }   // fallback to basic print() if no override
  virtual void fillRect(int x, int y, int w, int h) = 0;
  virtual void drawRect(int x, int y, int w, int h) = 0;
  virtual void drawXbm(int x, int y, const uint8_t* bits, int w, int h) = 0;
  virtual uint16_t getTextWidth(const char* str) = 0;
  virtual int getCharWidth() const { return 6; }   // advance width of a typical character (xAdvance for monospace)
  virtual int getLineHeight() const { return 8; }  // pixel rows per line (cell height, not just glyph height)
  virtual void drawTextCentered(int mid_x, int y, const char* str) {   // helper method (override to optimise)
    int w = getTextWidth(str);
    setCursor(mid_x - w/2, y);
    print(str);
  }
  virtual void drawTextRightAlign(int x_anch, int y, const char* str) {
    int w = getTextWidth(str);
    setCursor(x_anch - w, y);
    print(str);
  }
  virtual void drawTextLeftAlign(int x_anch, int y, const char* str) {
    setCursor(x_anch, y);
    print(str);
  }
  
  virtual void translateUTF8ToBlocks(char* dest, const char* src, size_t dest_size) {
    size_t n = strlen(src);
    if (n >= dest_size) n = dest_size - 1;
    memcpy(dest, src, n);
    dest[n] = 0;
  }
  
  // draw text with ellipsis if it exceeds max_width
  virtual void drawTextEllipsized(int x, int y, int max_width, const char* str) {
    char temp_str[256];  // reasonable buffer size
    translateUTF8ToBlocks(temp_str, str, sizeof(temp_str));
    
    if (getTextWidth(temp_str) <= max_width) {
      setCursor(x, y);
      print(temp_str);
      return;
    }
    
    // for variable-width fonts (GxEPD), add space after ellipsis
    // for fixed-width fonts (OLED), keep tight spacing to save precious characters
    const char* ellipsis;
    // use a simple heuristic: if 'i' and 'l' have different widths, it's variable-width
    int i_width = getTextWidth("i");
    int l_width = getTextWidth("l");
    if (i_width != l_width) {
      ellipsis = "... ";  // variable-width fonts: add space
    } else {
      ellipsis = "...";   // fixed-width fonts: no space
    }
    
    int ellipsis_width = getTextWidth(ellipsis);
    int str_len = strlen(temp_str);
    
    while (str_len > 0 && getTextWidth(temp_str) > max_width - ellipsis_width) {
      temp_str[--str_len] = 0;
    }
    // Strip any orphaned UTF-8 leading byte left by the byte-at-a-time trimming above.
    // A leading byte (0xC0-0xFF, high two bits = 11) with no following continuation
    // byte renders as an invisible 6px advance, leaving a gap before the ellipsis.
    while (str_len > 0 && ((uint8_t)temp_str[str_len - 1] & 0xC0) == 0xC0) {
      temp_str[--str_len] = 0;
    }
    strcat(temp_str, ellipsis);
    
    setCursor(x, y);
    print(temp_str);
  }
  
  virtual void setBrightness(uint8_t level) { }  // level 0-4 (min to max), no-op default
  virtual void endFrame() = 0;
};