Arduino_GFX.cpp

/*
This file is modified from Uno's GFX library. The only modification 
at this time is that I've factored a conditional statement out of the tight
loop involved in line drawing, for some minor performance improvement. 
Please respect the copyright and usage notice from Adafruit below. 
--mrule 2015/12/15

This is the core graphics library for all our displays, providing a common
set of graphics primitives (points, lines, circles, etc.).  It needs to be
paired with a hardware-specific library for each display device we carry
(to handle the lower-level functions).

Adafruit invests time and resources providing this open source code, please
support Uno & open-source hardware by purchasing products from Adafruit!
 
Copyright (c) 2013 Uno Industries.  All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

- Redistributions of source code must retain the above copyright notice,
  this list of conditions and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/

#include "Arduino_GFX.h"    // Core graphics library

#include "glcdfont.c"
#ifdef __AVR__
 #include <avr/pgmspace.h>
#elif defined(ESP8266)
 #include <pgmspace.h>
#else
 #define pgm_read_byte(addr) (*(const unsigned char *)(addr))
#endif

#ifndef min
 #define min(a,b) ((a < b) ? a : b)
#endif

Arduino_GFX::Arduino_GFX(int16_t w, int16_t h):
  WIDTH(w), HEIGHT(h)
{
  _width    = WIDTH;
  _height   = HEIGHT;
  rotation  = 0;
  cursor_y  = cursor_x    = 0;
  textsize  = 1;
  textcolor = textbgcolor = 0xFFFF;
  wrap      = true;
  _cp437    = false;
}

// Draw a circle outline
void Arduino_GFX::drawCircle(int16_t x0, int16_t y0, int16_t r,
    uint16_t color) {
  int16_t f = 1 - r;
  int16_t ddF_x = 1;
  int16_t ddF_y = -2 * r;
  int16_t x = 0;
  int16_t y = r;
  drawPixel(x0  , y0+r, color);
  drawPixel(x0  , y0-r, color);
  drawPixel(x0+r, y0  , color);
  drawPixel(x0-r, y0  , color);
  while (x<y) {
    if (f >= 0) {
      y--;
      ddF_y += 2;
      f += ddF_y;
    }
    x++;
    ddF_x += 2;
    f += ddF_x;
    drawPixel(x0 + x, y0 + y, color);
    drawPixel(x0 - x, y0 + y, color);
    drawPixel(x0 + x, y0 - y, color);
    drawPixel(x0 - x, y0 - y, color);
    drawPixel(x0 + y, y0 + x, color);
    drawPixel(x0 - y, y0 + x, color);
    drawPixel(x0 + y, y0 - x, color);
    drawPixel(x0 - y, y0 - x, color);
  }
}

void Arduino_GFX::drawCircleHelper( int16_t x0, int16_t y0,
               int16_t r, uint8_t cornername, uint16_t color) {
  int16_t f     = 1 - r;
  int16_t ddF_x = 1;
  int16_t ddF_y = -2 * r;
  int16_t x     = 0;
  int16_t y     = r;
  while (x<y) {
    if (f >= 0) {
      y--;
      ddF_y += 2;
      f     += ddF_y;
    }
    x++;
    ddF_x += 2;
    f     += ddF_x;
    if (cornername & 0x4) {
      drawPixel(x0 + x, y0 + y, color);
      drawPixel(x0 + y, y0 + x, color);
    } 
    if (cornername & 0x2) {
      drawPixel(x0 + x, y0 - y, color);
      drawPixel(x0 + y, y0 - x, color);
    }
    if (cornername & 0x8) {
      drawPixel(x0 - y, y0 + x, color);
      drawPixel(x0 - x, y0 + y, color);
    }
    if (cornername & 0x1) {
      drawPixel(x0 - y, y0 - x, color);
      drawPixel(x0 - x, y0 - y, color);
    }
  }
}


void Arduino_GFX::fillCircle(int16_t x0, int16_t y0, int16_t r,
			      uint16_t color) {
  drawFastVLine(x0, y0-r, 2*r+1, color);
  fillCircleHelper(x0, y0, r, 3, 0, color);
}

// Used to do circles and roundrects
void Arduino_GFX::fillCircleHelper(int16_t x0, int16_t y0, int16_t r,
    uint8_t cornername, int16_t delta, uint16_t color) {
  int16_t f     = 1 - r;
  int16_t ddF_x = 1;
  int16_t ddF_y = -2 * r;
  int16_t x     = 0;
  int16_t y     = r;
  delta += 1;
  // Case 0
  switch (cornername) {
    case 0:
      while (x<y) {
        if (f >= 0) {y--; ddF_y+=2; f+=ddF_y;}
        x++; ddF_x+=2; f+=ddF_x;
      }
      return;
    case 1:
      while (x<y) {
        if (f >= 0) {y--; ddF_y+=2; f+=ddF_y;}
        x++; ddF_x+=2; f+=ddF_x;
        drawFastVLine(x0+x, y0-y, 2*y+delta, color);
        drawFastVLine(x0+y, y0-x, 2*x+delta, color);
      }
      return;
    case 2:
      while (x<y) {
        if (f >= 0) {y--; ddF_y+=2; f+=ddF_y;}
        x++; ddF_x+=2; f+=ddF_x;
        drawFastVLine(x0-x, y0-y, 2*y+delta, color);
        drawFastVLine(x0-y, y0-x, 2*x+delta, color);
      }
      return;
    case 3:
      while (x<y) {
        if (f >= 0) {y--; ddF_y+=2; f+=ddF_y;}
        x++; ddF_x+=2; f+=ddF_x;
        drawFastVLine(x0+x, y0-y, 2*y+delta, color);
        drawFastVLine(x0+y, y0-x, 2*x+delta, color);
        drawFastVLine(x0-x, y0-y, 2*y+delta, color);
        drawFastVLine(x0-y, y0-x, 2*x+delta, color);
      }
      return;
    }  
}

// Bresenham's algorithm - thx wikpedia
void Arduino_GFX::drawLine(int16_t x0, int16_t y0, int16_t x1, int16_t y1, uint16_t color) {
  int16_t steep = abs(y1 - y0) > abs(x1 - x0);
  if (steep) {
    swap(x0, y0);
    swap(x1, y1);
  }
  if (x0 > x1) {
    swap(x0, x1);
    swap(y0, y1);
  }
  int16_t dx, dy;
  dx = x1 - x0;
  dy = abs(y1 - y0);
  int16_t err = dx / 2;
  int16_t ystep;
  ystep = y0<y1?1:-1;
  if (steep) {
      for (; x0<=x1; x0++) {
        drawPixel(y0, x0, color);
        err -= dy;
        if (err < 0) {
          y0 += ystep;
          err += dx;
        }
      }
  } else {
      for (; x0<=x1; x0++) {
        drawPixel(x0, y0, color);
        err -= dy;
        if (err < 0) {
          y0 += ystep;
          err += dx;
        }
      }
  }  
}

// Draw a rectangle
void Arduino_GFX::drawRect(int16_t x, int16_t y,
			    int16_t w, int16_t h,
			    uint16_t color) {
  drawFastHLine(x, y, w, color);
  drawFastHLine(x, y+h-1, w, color);
  drawFastVLine(x, y, h, color);
  drawFastVLine(x+w-1, y, h, color);
}

void Arduino_GFX::drawFastVLine(int16_t x, int16_t y,
				 int16_t h, uint16_t color) {
  // Update in subclasses if desired!
  drawLine(x, y, x, y+h-1, color);
}

void Arduino_GFX::drawFastHLine(int16_t x, int16_t y,
				 int16_t w, uint16_t color) {
  // Update in subclasses if desired!
  drawLine(x, y, x+w-1, y, color);
}

void Arduino_GFX::fillRect(int16_t x, int16_t y, int16_t w, int16_t h,
			    uint16_t color) {
  // Update in subclasses if desired!
  for (int16_t i=x; i<x+w; i++) {
    drawFastVLine(i, y, h, color);
  }
}

void Arduino_GFX::fillScreen(uint16_t color) {
  fillRect(0, 0, _width, _height, color);
}

// Draw a rounded rectangle
void Arduino_GFX::drawRoundRect(int16_t x, int16_t y, int16_t w,
  int16_t h, int16_t r, uint16_t color) {
  if (w<=0||h<=0) return;
  // smarter version
  drawFastHLine(x+r  , y    , w-2*r, color); // Top
  drawFastHLine(x+r  , y+h-1, w-2*r, color); // Bottom
  drawFastVLine(x    , y+r  , h-2*r, color); // Left
  drawFastVLine(x+w-1, y+r  , h-2*r, color); // Right
  // draw four corners
  drawCircleHelper(x+r    , y+r    , r, 1, color);
  drawCircleHelper(x+w-r-1, y+r    , r, 2, color);
  drawCircleHelper(x+w-r-1, y+h-r-1, r, 4, color);
  drawCircleHelper(x+r    , y+h-r-1, r, 8, color);
}

// Fill a rounded rectangle
void Arduino_GFX::fillRoundRect(int16_t x, int16_t y, int16_t w,
				 int16_t h, int16_t r, uint16_t color) {
  // smarter version
  fillRect(x+r, y, w-2*r, h, color);
  // draw four corners
  fillCircleHelper(x+w-r-1, y+r, r, 1, h-2*r-1, color);
  fillCircleHelper(x+r    , y+r, r, 2, h-2*r-1, color);
}

// Draw a triangle
void Arduino_GFX::drawTriangle(int16_t x0, int16_t y0,
				int16_t x1, int16_t y1,
				int16_t x2, int16_t y2, uint16_t color) {
  drawLine(x0, y0, x1, y1, color);
  drawLine(x1, y1, x2, y2, color);
  drawLine(x2, y2, x0, y0, color);
}

// Fill a triangle
void Arduino_GFX::fillTriangle ( 
    int16_t x0, int16_t y0,
    int16_t x1, int16_t y1,
    int16_t x2, int16_t y2, uint16_t color) {
  int16_t a, b, y;
  if (y0 > y1) {swap(y0, y1); swap(x0, x1);}
  if (y1 > y2) {swap(y2, y1); swap(x2, x1);}
  if (y0 > y1) {swap(y0, y1); swap(x0, x1);}
  if(y0 == y2)  return;
  int16_t
    dx01 = x1 - x0,
    dy01 = y1 - y0,
    dx02 = x2 - x0,
    dy02 = y2 - y0,
    dx12 = x2 - x1,
    dy12 = y2 - y1;
  int32_t
    sa   = 0,
    sb   = 0;
  int16_t last = y1==y2? y1:y1-1;
  // Skip the first line to avoid triangle overlap in meshes
  sa += dx01;
  sb += dx02;
  for(y=y0+1; y<=last; y++) {
    a   = x0 + sa / dy01;
    b   = x0 + sb / dy02;
    sa += dx01;
    sb += dx02;
    if(a > b) swap(a,b);
    drawFastHLine(a, y, b-a, color);
  }
  sa = dx12 * (y - y1);
  sb = dx02 * (y - y0);
  for(; y<y2; y++) {
    a   = x1 + sa / dy12;
    b   = x0 + sb / dy02;
    sa += dx12;
    sb += dx02;
    if(a > b) swap(a,b);
    drawFastHLine(a, y, b-a, color);
  }
}

#if ARDUINO >= 100
size_t Arduino_GFX::write(uint8_t c) {
#else
void Arduino_GFX::write(uint8_t c) {
#endif
  if (c == '\n') {
    cursor_y += textsize*8;
    cursor_x  = 0;
  } else if (c == '\r') {
    // skip em
  } else {
    drawChar(cursor_x, cursor_y, c, textcolor, textbgcolor, textsize);
    cursor_x += textsize*6;
    if (wrap && (cursor_x > (_width - textsize*6))) {
      cursor_y += textsize*8;
      cursor_x = 0;
    }
  }
#if ARDUINO >= 100
  return 1;
#endif
}

// Draw a character
void Arduino_GFX::drawChar(int16_t x, int16_t y, unsigned char c,
			    uint16_t color, uint16_t bg, uint8_t size) {

  if((x >= _width)            || // Clip right
     (y >= _height)           || // Clip bottom
     ((x + 6 * size - 1) < 0) || // Clip left
     ((y + 8 * size - 1) < 0))   // Clip top
    return;

  if(!_cp437 && (c >= 176)) c++; // Handle 'classic' charset behavior

  for (int8_t i=0; i<6; i++ ) {
    uint8_t line;
    if (i == 5) 
      line = 0x0;
    else 
      line = pgm_read_byte(font+(c*5)+i);
    for (int8_t j = 0; j<8; j++) {
      if (line & 0x1) {
        if (size == 1) // default size
          drawPixel(x+i, y+j, color);
        else {  // big size
          fillRect(x+(i*size), y+(j*size), size, size, color);
        } 
      } else if (bg != color) {
        if (size == 1) // default size
          drawPixel(x+i, y+j, bg);
        else {  // big size
          fillRect(x+i*size, y+j*size, size, size, bg);
        }
      }
      line >>= 1;
    }
  }
}

void Arduino_GFX::setCursor(int16_t x, int16_t y) {
  cursor_x = x;
  cursor_y = y;
}

int16_t Arduino_GFX::getCursorX(void) const {
  return cursor_x;
}

int16_t Arduino_GFX::getCursorY(void) const {
  return cursor_y;
}

void Arduino_GFX::setTextSize(uint8_t s) {
  textsize = (s > 0) ? s : 1;
}

void Arduino_GFX::setTextColor(uint16_t c) {
  // For 'transparent' background, we'll set the bg 
  // to the same as fg instead of using a flag
  textcolor = textbgcolor = c;
}

void Arduino_GFX::setTextColor(uint16_t c, uint16_t b) {
  textcolor   = c;
  textbgcolor = b; 
}

void Arduino_GFX::setTextWrap(boolean w) {
  wrap = w;
}

// Enable (or disable) Code Page 437-compatible charset.
// There was an error in glcdfont.c for the longest time -- one character
// (#176, the 'light shade' block) was missing -- this threw off the index
// of every character that followed it.  But a TON of code has been written
// with the erroneous character indices.  By default, the library uses the
// original 'wrong' behavior and old sketches will still work.  Pass 'true'
// to this function to use correct CP437 character values in your code.
void Arduino_GFX::cp437(boolean x) {
  _cp437 = x;
}

// Return the size of the display (per current rotation)
int16_t Arduino_GFX::width(void) const {
  return _width;
}
 
int16_t Arduino_GFX::height(void) const {
  return _height;
}

void Arduino_GFX::invertDisplay(boolean i) {
  // Do nothing, must be subclassed if supported
}