source: rtos_arduino/trunk/arduino_lib/libraries/Robot_Control/src/utility/Adafruit_GFX.cpp@ 136

/*
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 Adafruit & open-source hardware by purchasing products from Adafruit!

Copyright (c) 2013 Adafruit 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 "Adafruit_GFX.h"
#include "glcdfont.c"
#ifdef __AVR__
 #include <avr/pgmspace.h>
#else
 #define pgm_read_byte(addr) (*(const unsigned char *)(addr))
#endif

Adafruit_GFX::Adafruit_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;
}

// Draw a circle outline
void Adafruit_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 Adafruit_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 Adafruit_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 Adafruit_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;

  while (x<y) {
    if (f >= 0) {
      y--;
      ddF_y += 2;
      f     += ddF_y;
    }
    x++;
    ddF_x += 2;
    f     += ddF_x;

    if (cornername & 0x1) {
      drawFastVLine(x0+x, y0-y, 2*y+1+delta, color);
      drawFastVLine(x0+y, y0-x, 2*x+1+delta, color);
    }
    if (cornername & 0x2) {
      drawFastVLine(x0-x, y0-y, 2*y+1+delta, color);
      drawFastVLine(x0-y, y0-x, 2*x+1+delta, color);
    }
  }
}

// Bresenham's algorithm - thx wikpedia
void Adafruit_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;

  if (y0 < y1) {
    ystep = 1;
  } else {
    ystep = -1;
  }

  for (; x0<=x1; x0++) {
    if (steep) {
      drawPixel(y0, x0, color);
    } else {
      drawPixel(x0, y0, color);
    }
    err -= dy;
    if (err < 0) {
      y0 += ystep;
      err += dx;
    }
  }
}

// Draw a rectangle
void Adafruit_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 Adafruit_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 Adafruit_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 Adafruit_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 Adafruit_GFX::fillScreen(uint16_t color) {
  fillRect(0, 0, _width, _height, color);
}

// Draw a rounded rectangle
void Adafruit_GFX::drawRoundRect(int16_t x, int16_t y, int16_t w,
  int16_t h, int16_t r, uint16_t color) {
  // 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 Adafruit_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 Adafruit_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 Adafruit_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, last;

  // Sort coordinates by Y order (y2 >= y1 >= y0)
  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) { // Handle awkward all-on-same-line case as its own thing
    a = b = x0;
    if(x1 < a)      a = x1;
    else if(x1 > b) b = x1;
    if(x2 < a)      a = x2;
    else if(x2 > b) b = x2;
    drawFastHLine(a, y0, b-a+1, color);
    return;
  }

  int16_t
    dx01 = x1 - x0,
    dy01 = y1 - y0,
    dx02 = x2 - x0,
    dy02 = y2 - y0,
    dx12 = x2 - x1,
    dy12 = y2 - y1,
    sa   = 0,
    sb   = 0;

  // For upper part of triangle, find scanline crossings for segments
  // 0-1 and 0-2.  If y1=y2 (flat-bottomed triangle), the scanline y1
  // is included here (and second loop will be skipped, avoiding a /0
  // error there), otherwise scanline y1 is skipped here and handled
  // in the second loop...which also avoids a /0 error here if y0=y1
  // (flat-topped triangle).
  if(y1 == y2) last = y1;   // Include y1 scanline
  else         last = y1-1; // Skip it

  for(y=y0; y<=last; y++) {
    a   = x0 + sa / dy01;
    b   = x0 + sb / dy02;
    sa += dx01;
    sb += dx02;
    /* longhand:
    a = x0 + (x1 - x0) * (y - y0) / (y1 - y0);
    b = x0 + (x2 - x0) * (y - y0) / (y2 - y0);
    */
    if(a > b) swap(a,b);
    drawFastHLine(a, y, b-a+1, color);
  }

  // For lower part of triangle, find scanline crossings for segments
  // 0-2 and 1-2.  This loop is skipped if y1=y2.
  sa = dx12 * (y - y1);
  sb = dx02 * (y - y0);
  for(; y<=y2; y++) {
    a   = x1 + sa / dy12;
    b   = x0 + sb / dy02;
    sa += dx12;
    sb += dx02;
    /* longhand:
    a = x1 + (x2 - x1) * (y - y1) / (y2 - y1);
    b = x0 + (x2 - x0) * (y - y0) / (y2 - y0);
    */
    if(a > b) swap(a,b);
    drawFastHLine(a, y, b-a+1, color);
  }
}

void Adafruit_GFX::drawBitmap(int16_t x, int16_t y,
                              const uint8_t *bitmap, int16_t w, int16_t h,
                              uint16_t color) {

  int16_t i, j, byteWidth = (w + 7) / 8;

  for(j=0; j<h; j++) {
    for(i=0; i<w; i++ ) {
      if(pgm_read_byte(bitmap + j * byteWidth + i / 8) & (128 >> (i & 7))) {
        drawPixel(x+i, y+j, color);
      }
    }
  }
}

#if ARDUINO >= 100
size_t Adafruit_GFX::write(uint8_t c) {
#else
void Adafruit_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 Adafruit_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;

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

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

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

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

uint8_t Adafruit_GFX::getRotation(void) {
  return rotation;
}

void Adafruit_GFX::setRotation(uint8_t x) {
  rotation = (x & 3);
  switch(rotation) {
   case 0:
   case 2:
    _width  = WIDTH;
    _height = HEIGHT;
    break;
   case 1:
   case 3:
    _width  = HEIGHT;
    _height = WIDTH;
    break;
  }
}

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

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

uint16_t Adafruit_GFX::newColor(uint8_t r, uint8_t g, uint8_t b) {
  return ((r & 0xF8) << 8) | ((g & 0xFC) << 3) | (b >> 3);
}

void Adafruit_GFX::background(uint8_t red, uint8_t green, uint8_t blue) {
  background(newColor(red, green, blue));
}

void Adafruit_GFX::background(color c) {
  fillScreen(c);
}

void Adafruit_GFX::stroke(uint8_t red, uint8_t green, uint8_t blue) {
  stroke(newColor(red, green, blue));
}

void Adafruit_GFX::stroke(color c) {
  useStroke = true;
  strokeColor = c;
  setTextColor(c);
}

void Adafruit_GFX::noStroke() {
  useStroke = false;
}

void Adafruit_GFX::noFill() {
  useFill = false;
}

void Adafruit_GFX::fill(uint8_t red, uint8_t green, uint8_t blue) {
  fill(newColor(red, green, blue));
}

void Adafruit_GFX::fill(color c) {
  useFill = true;
  fillColor = c;
}

void Adafruit_GFX::text(int value, uint8_t x, uint8_t y){
  if (!useStroke)
    return;
  
  setTextWrap(false);
  setTextColor(strokeColor);
  setCursor(x, y);
  print(value);
}
void Adafruit_GFX::text(long value, uint8_t x, uint8_t y){
  if (!useStroke)
    return;
  
  setTextWrap(false);
  setTextColor(strokeColor);
  setCursor(x, y);
  print(value);
}
void Adafruit_GFX::text(char value, uint8_t x, uint8_t y){
  if (!useStroke)
    return;
  
  setTextWrap(false);
  setTextColor(strokeColor);
  setCursor(x, y);
  print(value);
}

void Adafruit_GFX::text(const char * text, int16_t x, int16_t y) {
  if (!useStroke)
    return;
  
  setTextWrap(false);
  setTextColor(strokeColor);
  setCursor(x, y);
  print(text);
}

void Adafruit_GFX::textWrap(const char * text, int16_t x, int16_t y) {
  if (!useStroke)
    return;
  
  setTextWrap(true);
  setTextColor(strokeColor);
  setCursor(x, y);
  print(text);
}


void Adafruit_GFX::textSize(uint8_t size) {
  setTextSize(size);
}

void Adafruit_GFX::point(int16_t x, int16_t y) {
  if (!useStroke)
    return;
  
  drawPixel(x, y, strokeColor);
}

void Adafruit_GFX::line(int16_t x1, int16_t y1, int16_t x2, int16_t y2) {
  if (!useStroke)
    return;
  
  if (x1 == x2) {
    drawFastVLine(x1, y1, y2 - y1, strokeColor);
  }
  else if (y1 == y2) {
    drawFastHLine(x1, y1, x2 - x1, strokeColor);
  }
  else {
    drawLine(x1, y1, x2, y2, strokeColor);
  }
}

void Adafruit_GFX::rect(int16_t x, int16_t y, int16_t width, int16_t height) {
  if (useFill) {
    fillRect(x, y, width, height, fillColor);
  }
  if (useStroke) {
    drawRect(x, y, width, height, strokeColor);
  }
}

void Adafruit_GFX::rect(int16_t x, int16_t y, int16_t width, int16_t height, int16_t radius) {
  if (radius == 0) {
    rect(x, y, width, height);
  }
  if (useFill) {
    fillRoundRect(x, y, width, height, radius, fillColor);
  }
  if (useStroke) {
    drawRoundRect(x, y, width, height, radius, strokeColor);
  }
}

void Adafruit_GFX::circle(int16_t x, int16_t y, int16_t r) {
  if (r == 0)
    return;
  
  if (useFill) {
    fillCircle(x, y, r, fillColor);
  }
  if (useStroke) {
    drawCircle(x, y, r, strokeColor);
  }
}

void Adafruit_GFX::triangle(int16_t x1, int16_t y1, int16_t x2, int16_t y2, int16_t x3, int16_t y3) {
  if (useFill) {
    fillTriangle(x1, y1, x2, y2, x3, y3, fillColor);
  }
  if (useStroke) {
    drawTriangle(x1, y1, x2, y2, x3, y3, strokeColor);
  }
}

#define BUFFPIXEL 20
/*
void Adafruit_GFX::image(PImage & img, uint16_t x, uint16_t y) {
  int      w, h, row, col;
  uint8_t  r, g, b;
  uint32_t pos = 0;
  uint8_t  sdbuffer[3*BUFFPIXEL]; // pixel buffer (R+G+B per pixel)
  uint8_t  buffidx = sizeof(sdbuffer); // Current position in sdbuffer

  // Crop area to be loaded
  w = img._bmpWidth;
  h = img._bmpHeight;
  if((x+w-1) >= width())  w = width()  - x;
  if((y+h-1) >= height()) h = height() - y;

  
  // Set TFT address window to clipped image bounds
  //setAddrWindow(x, y, x+w-1, y+h-1);
  
  
  for (row=0; row<h; row++) { // For each scanline...
    // Seek to start of scan line.  It might seem labor-
    // intensive to be doing this on every line, but this
    // method covers a lot of gritty details like cropping
    // and scanline padding.  Also, the seek only takes
    // place if the file position actually needs to change
    // (avoids a lot of cluster math in SD library).
    if(img._flip) // Bitmap is stored bottom-to-top order (normal BMP)
      pos = img._bmpImageoffset + (img._bmpHeight - 1 - row) * img._rowSize;
    else     // Bitmap is stored top-to-bottom
      pos = img._bmpImageoffset + row * img._rowSize;
    if(img._bmpFile.position() != pos) { // Need seek?
      img._bmpFile.seek(pos);
      buffidx = sizeof(sdbuffer); // Force buffer reload
    }

    for (col=0; col<w; col++) { // For each pixel...
      // Time to read more pixel data?
      if (buffidx >= sizeof(sdbuffer)) { // Indeed
        img._bmpFile.read(sdbuffer, sizeof(sdbuffer));
        buffidx = 0; // Set index to beginning
      }

      // Convert pixel from BMP to TFT format, push to display
      b = sdbuffer[buffidx++];
      g = sdbuffer[buffidx++];
      r = sdbuffer[buffidx++];
      //pushColor(tft.Color565(r,g,b));
      drawPixel(x + col, y + row, newColor(r, g, b));
      
    } // end pixel
  } // end scanline

}*/