zGxEPD2/examples/GxEPD2_GFX_Example/TextDisplay.cpp

// Display Library example for SPI e-paper panels from Dalian Good Display and boards from Waveshare.
// Requires HW SPI and Adafruit_GFX. Caution: the e-paper panels require 3.3V supply AND data lines!
//
// Display Library based on Demo Example from Good Display: https://www.good-display.com/companyfile/32/
//
// Author: Jean-Marc Zingg
//
// Version: see library.properties
//
// Library: https://github.com/ZinggJM/GxEPD2
//
// Purpose: show uses of GxEPD2_GFX base class for references to a display instance
//
// TextDisplay shows the use of the display instance reference as a function parameter

// note for partial update window and setPartialWindow() method:
// partial update window size and position is on byte boundary in physical x direction
// the size is increased in setPartialWindow() if x or w are not multiple of 8 for even rotation, y or h for odd rotation
// see also comment in GxEPD2_BW.h, GxEPD2_3C.h or GxEPD2_GFX.h for method setPartialWindow()

#include "TextDisplay.h"
#include <Fonts/FreeMonoBold9pt7b.h>

const char HelloWorld[] = "Hello World!";
const char HelloArduino[] = "Hello Arduino!";
const char HelloEpaper[] = "Hello E-Paper!";

void helloWorld(GxEPD2_GFX& display)
{
  //Serial.println("helloWorld");
  display.setRotation(1);
  display.setFont(&FreeMonoBold9pt7b);
  display.setTextColor(GxEPD_BLACK);
  int16_t tbx, tby; uint16_t tbw, tbh;
  display.getTextBounds(HelloWorld, 0, 0, &tbx, &tby, &tbw, &tbh);
  // center bounding box by transposition of origin:
  uint16_t x = ((display.width() - tbw) / 2) - tbx;
  uint16_t y = ((display.height() - tbh) / 2) - tby;
  display.setFullWindow();
  display.firstPage();
  do
  {
    display.fillScreen(GxEPD_WHITE);
    display.setCursor(x, y);
    display.print(HelloWorld);
  }
  while (display.nextPage());
  //Serial.println("helloWorld done");
}

void helloWorldForDummies(GxEPD2_GFX& display)
{
  //Serial.println("helloWorld");
  const char text[] = "Hello World!";
  // most e-papers have width < height (portrait) as native orientation, especially the small ones
  // in GxEPD2 rotation 0 is used for native orientation (most TFT libraries use 0 fix for portrait orientation)
  // set rotation to 1 (rotate right 90 degrees) to have enough space on small displays (landscape)
  display.setRotation(1);
  // select a suitable font in Adafruit_GFX
  display.setFont(&FreeMonoBold9pt7b);
  // on e-papers black on white is more pleasant to read
  display.setTextColor(GxEPD_BLACK);
  // Adafruit_GFX has a handy method getTextBounds() to determine the boundary box for a text for the actual font
  int16_t tbx, tby; uint16_t tbw, tbh; // boundary box window
  display.getTextBounds(text, 0, 0, &tbx, &tby, &tbw, &tbh); // it works for origin 0, 0, fortunately (negative tby!)
  // center bounding box by transposition of origin:
  uint16_t x = ((display.width() - tbw) / 2) - tbx;
  uint16_t y = ((display.height() - tbh) / 2) - tby;
  // full window mode is the initial mode, set it anyway
  display.setFullWindow();
  // here we use paged drawing, even if the processor has enough RAM for full buffer
  // so this can be used with any supported processor board.
  // the cost in code overhead and execution time penalty is marginal
  // tell the graphics class to use paged drawing mode
  display.firstPage();
  do
  {
    // this part of code is executed multiple times, as many as needed,
    // in case of full buffer it is executed once
    // IMPORTANT: each iteration needs to draw the same, to avoid strange effects
    // use a copy of values that might change, don't read e.g. from analog or pins in the loop!
    display.fillScreen(GxEPD_WHITE); // set the background to white (fill the buffer with value for white)
    display.setCursor(x, y); // set the postition to start printing text
    display.print(text); // print some text
    // end of part executed multiple times
  }
  // tell the graphics class to transfer the buffer content (page) to the controller buffer
  // the graphics class will command the controller to refresh to the screen when the last page has been transferred
  // returns true if more pages need be drawn and transferred
  // returns false if the last page has been transferred and the screen refreshed for panels without fast partial update
  // returns false for panels with fast partial update when the controller buffer has been written once more, to make the differential buffers equal
  // (for full buffered with fast partial update the (full) buffer is just transferred again, and false returned)
  while (display.nextPage());
  //Serial.println("helloWorld done");
}

void helloFullScreenPartialMode(GxEPD2_GFX& display)
{
  //Serial.println("helloFullScreenPartialMode");
  const char fullscreen[] = "full screen update";
  const char fpm[] = "fast partial mode";
  const char spm[] = "slow partial mode";
  const char npm[] = "no partial mode";
  display.setPartialWindow(0, 0, display.width(), display.height());
  display.setRotation(1);
  display.setFont(&FreeMonoBold9pt7b);
  display.setTextColor(GxEPD_BLACK);
  const char* updatemode;
  if (display.epd2.hasFastPartialUpdate)
  {
    updatemode = fpm;
  }
  else if (display.epd2.hasPartialUpdate)
  {
    updatemode = spm;
  }
  else
  {
    updatemode = npm;
  }
  // do this outside of the loop
  int16_t tbx, tby; uint16_t tbw, tbh;
  // center update text
  display.getTextBounds(fullscreen, 0, 0, &tbx, &tby, &tbw, &tbh);
  uint16_t utx = ((display.width() - tbw) / 2) - tbx;
  uint16_t uty = ((display.height() / 4) - tbh / 2) - tby;
  // center update mode
  display.getTextBounds(updatemode, 0, 0, &tbx, &tby, &tbw, &tbh);
  uint16_t umx = ((display.width() - tbw) / 2) - tbx;
  uint16_t umy = ((display.height() * 3 / 4) - tbh / 2) - tby;
  // center HelloWorld
  display.getTextBounds(HelloWorld, 0, 0, &tbx, &tby, &tbw, &tbh);
  uint16_t hwx = ((display.width() - tbw) / 2) - tbx;
  uint16_t hwy = ((display.height() - tbh) / 2) - tby;
  display.firstPage();
  do
  {
    display.fillScreen(GxEPD_WHITE);
    display.setCursor(hwx, hwy);
    display.print(HelloWorld);
    display.setCursor(utx, uty);
    display.print(fullscreen);
    display.setCursor(umx, umy);
    display.print(updatemode);
  }
  while (display.nextPage());
  //Serial.println("helloFullScreenPartialMode done");
}

void helloArduino(GxEPD2_GFX& display)
{
  //Serial.println("helloArduino");
  display.setRotation(1);
  display.setFont(&FreeMonoBold9pt7b);
  display.setTextColor(display.epd2.hasColor ? GxEPD_RED : GxEPD_BLACK);
  int16_t tbx, tby; uint16_t tbw, tbh;
  // align with centered HelloWorld
  display.getTextBounds(HelloWorld, 0, 0, &tbx, &tby, &tbw, &tbh);
  uint16_t x = ((display.width() - tbw) / 2) - tbx;
  // height might be different
  display.getTextBounds(HelloArduino, 0, 0, &tbx, &tby, &tbw, &tbh);
  uint16_t y = ((display.height() / 4) - tbh / 2) - tby; // y is base line!
  // make the window big enough to cover (overwrite) descenders of previous text
  uint16_t wh = FreeMonoBold9pt7b.yAdvance;
  uint16_t wy = (display.height() / 4) - wh / 2;
  display.setPartialWindow(0, wy, display.width(), wh);
  display.firstPage();
  do
  {
    display.fillScreen(GxEPD_WHITE);
    //display.drawRect(x, y - tbh, tbw, tbh, GxEPD_BLACK);
    display.setCursor(x, y);
    display.print(HelloArduino);
  }
  while (display.nextPage());
  delay(1000);
  //Serial.println("helloArduino done");
}

void helloEpaper(GxEPD2_GFX& display)
{
  //Serial.println("helloEpaper");
  display.setRotation(1);
  display.setFont(&FreeMonoBold9pt7b);
  display.setTextColor(display.epd2.hasColor ? GxEPD_RED : GxEPD_BLACK);
  int16_t tbx, tby; uint16_t tbw, tbh;
  // align with centered HelloWorld
  display.getTextBounds(HelloWorld, 0, 0, &tbx, &tby, &tbw, &tbh);
  uint16_t x = ((display.width() - tbw) / 2) - tbx;
  // height might be different
  display.getTextBounds(HelloEpaper, 0, 0, &tbx, &tby, &tbw, &tbh);
  uint16_t y = (display.height() * 3 / 4) + tbh / 2; // y is base line!
  // make the window big enough to cover (overwrite) descenders of previous text
  uint16_t wh = FreeMonoBold9pt7b.yAdvance;
  uint16_t wy = (display.height() * 3 / 4) - wh / 2;
  display.setPartialWindow(0, wy, display.width(), wh);
  display.firstPage();
  do
  {
    display.fillScreen(GxEPD_WHITE);
    display.setCursor(x, y);
    display.print(HelloEpaper);
  }
  while (display.nextPage());
  //Serial.println("helloEpaper done");
}

#if defined(ESP8266) || defined(ESP32)
#include <StreamString.h>
#define PrintString StreamString
#else
class PrintString : public Print, public String
{
  public:
    size_t write(uint8_t data) override
    {
      return concat(char(data));
    };
};
#endif

void helloValue(GxEPD2_GFX& display, double v, int digits)
{
  //Serial.println("helloValue");
  display.setRotation(1);
  display.setFont(&FreeMonoBold9pt7b);
  display.setTextColor(display.epd2.hasColor ? GxEPD_RED : GxEPD_BLACK);
  PrintString valueString;
  valueString.print(v, digits);
  int16_t tbx, tby; uint16_t tbw, tbh;
  display.getTextBounds(valueString, 0, 0, &tbx, &tby, &tbw, &tbh);
  uint16_t x = ((display.width() - tbw) / 2) - tbx;
  uint16_t y = (display.height() * 3 / 4) + tbh / 2; // y is base line!
  // show what happens, if we use the bounding box for partial window
  uint16_t wx = (display.width() - tbw) / 2;
  uint16_t wy = (display.height() * 3 / 4) - tbh / 2;
  display.setPartialWindow(wx, wy, tbw, tbh);
  display.firstPage();
  do
  {
    display.fillScreen(GxEPD_WHITE);
    display.setCursor(x, y);
    display.print(valueString);
  }
  while (display.nextPage());
  delay(2000);
  // make the partial window big enough to cover the previous text
  uint16_t ww = tbw; // remember window width
  display.getTextBounds(HelloEpaper, 0, 0, &tbx, &tby, &tbw, &tbh);
  // adjust, because HelloEpaper was aligned, not centered (could calculate this to be precise)
  ww = max(ww, uint16_t(tbw + 12)); // 12 seems ok
  wx = (display.width() - tbw) / 2;
  // make the window big enough to cover (overwrite) descenders of previous text
  uint16_t wh = FreeMonoBold9pt7b.yAdvance;
  wy = (display.height() * 3 / 4) - wh / 2;
  display.setPartialWindow(wx, wy, ww, wh);
  // alternately use the whole width for partial window
  //display.setPartialWindow(0, wy, display.width(), wh);
  display.firstPage();
  do
  {
    display.fillScreen(GxEPD_WHITE);
    display.setCursor(x, y);
    display.print(valueString);
  }
  while (display.nextPage());
  //Serial.println("helloValue done");
}

void showFont(GxEPD2_GFX& display, const char name[], const GFXfont* f)
{
  display.setFullWindow();
  display.setRotation(0);
  display.setTextColor(GxEPD_BLACK);
  display.firstPage();
  do
  {
    drawFont(display, name, f);
  }
  while (display.nextPage());
}

void drawFont(GxEPD2_GFX& display, const char name[], const GFXfont* f)
{
  //display.setRotation(0);
  display.fillScreen(GxEPD_WHITE);
  display.setTextColor(GxEPD_BLACK);
  display.setFont(f);
  display.setCursor(0, 0);
  display.println();
  display.println(name);
  display.println(" !\"#$%&'()*+,-./");
  display.println("0123456789:;<=>?");
  display.println("@ABCDEFGHIJKLMNO");
  display.println("PQRSTUVWXYZ[\\]^_");
  if (display.epd2.hasColor)
  {
    display.setTextColor(GxEPD_RED);
  }
  display.println("`abcdefghijklmno");
  display.println("pqrstuvwxyz{|}~ ");
}