Adafruit_GFX.cpp

/*
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 <cmath>

#define abs std::abs

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

#ifndef _swap_int16_t
#define _swap_int16_t(a, b) { int16_t t = a; a = b; b = t; }
#endif

/**************************************************************************/
/*!
   @brief    Instatiate a GFX context for graphics! Can only be done by a superclass
   @param    w   DisplayDriver width, in pixels
   @param    h   DisplayDriver height, in pixels
*/
/**************************************************************************/
Adafruit_GFX::Adafruit_GFX(int16_t w, int16_t h):
WIDTH(w), HEIGHT(h)
{
    _width    = WIDTH;
    _height   = HEIGHT;
    rotation  = 0;
}

/**************************************************************************/
/*!
   @brief    Write a line.  Bresenham's algorithm - thx wikpedia
    @param    x0  Start point x coordinate
    @param    y0  Start point y coordinate
    @param    x1  End point x coordinate
    @param    y1  End point y coordinate
    @param    color 16-bit 5-6-5 Color to draw with
*/
/**************************************************************************/
void Adafruit_GFX::writeLine(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_int16_t(x0, y0);
        _swap_int16_t(x1, y1);
    }

    if (x0 > x1) {
        _swap_int16_t(x0, x1);
        _swap_int16_t(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) {
            writePixel(y0, x0, color);
        } else {
            writePixel(x0, y0, color);
        }
        err -= dy;
        if (err < 0) {
            y0 += ystep;
            err += dx;
        }
    }
}

/**************************************************************************/
/*!
   @brief    Start a display-writing routine, overwrite in subclasses.
*/
/**************************************************************************/
void Adafruit_GFX::startWrite(){
}

/**************************************************************************/
/*!
   @brief    Write a pixel, overwrite in subclasses if startWrite is defined!
    @param   x   x coordinate
    @param   y   y coordinate
   @param    color 16-bit 5-6-5 Color to fill with
*/
/**************************************************************************/
void Adafruit_GFX::writePixel(int16_t x, int16_t y, uint16_t color){
    drawPixel(x, y, color);
}

/**************************************************************************/
/*!
   @brief    Write a perfectly vertical line, overwrite in subclasses if startWrite is defined!
    @param    x   Top-most x coordinate
    @param    y   Top-most y coordinate
    @param    h   Height in pixels
   @param    color 16-bit 5-6-5 Color to fill with
*/
/**************************************************************************/
void Adafruit_GFX::writeFastVLine(int16_t x, int16_t y,
        int16_t h, uint16_t color) {
    // Overwrite in subclasses if startWrite is defined!
    // Can be just writeLine(x, y, x, y+h-1, color);
    // or writeFillRect(x, y, 1, h, color);
    drawFastVLine(x, y, h, color);
}

/**************************************************************************/
/*!
   @brief    Write a perfectly horizontal line, overwrite in subclasses if startWrite is defined!
    @param    x   Left-most x coordinate
    @param    y   Left-most y coordinate
    @param    w   Width in pixels
   @param    color 16-bit 5-6-5 Color to fill with
*/
/**************************************************************************/
void Adafruit_GFX::writeFastHLine(int16_t x, int16_t y,
        int16_t w, uint16_t color) {
    // Overwrite in subclasses if startWrite is defined!
    // Example: writeLine(x, y, x+w-1, y, color);
    // or writeFillRect(x, y, w, 1, color);
    drawFastHLine(x, y, w, color);
}

/**************************************************************************/
/*!
   @brief    Write a rectangle completely with one color, overwrite in subclasses if startWrite is defined!
    @param    x   Top left corner x coordinate
    @param    y   Top left corner y coordinate
    @param    w   Width in pixels
    @param    h   Height in pixels
   @param    color 16-bit 5-6-5 Color to fill with
*/
/**************************************************************************/
void Adafruit_GFX::writeFillRect(int16_t x, int16_t y, int16_t w, int16_t h,
        uint16_t color) {
    // Overwrite in subclasses if desired!
    fillRect(x,y,w,h,color);
}

/**************************************************************************/
/*!
   @brief    End a display-writing routine, overwrite in subclasses if startWrite is defined!
*/
/**************************************************************************/
void Adafruit_GFX::endWrite(){
}

/**************************************************************************/
/*!
   @brief    Draw a perfectly vertical line (this is often optimized in a subclass!)
    @param    x   Top-most x coordinate
    @param    y   Top-most y coordinate
    @param    h   Height in pixels
   @param    color 16-bit 5-6-5 Color to fill with
*/
/**************************************************************************/
void Adafruit_GFX::drawFastVLine(int16_t x, int16_t y,
        int16_t h, uint16_t color) {
    startWrite();
    writeLine(x, y, x, y+h-1, color);
    endWrite();
}

/**************************************************************************/
/*!
   @brief    Draw a perfectly horizontal line (this is often optimized in a subclass!)
    @param    x   Left-most x coordinate
    @param    y   Left-most y coordinate
    @param    w   Width in pixels
   @param    color 16-bit 5-6-5 Color to fill with
*/
/**************************************************************************/
void Adafruit_GFX::drawFastHLine(int16_t x, int16_t y,
        int16_t w, uint16_t color) {
    startWrite();
    writeLine(x, y, x+w-1, y, color);
    endWrite();
}

/**************************************************************************/
/*!
   @brief    Fill a rectangle completely with one color. Update in subclasses if desired!
    @param    x   Top left corner x coordinate
    @param    y   Top left corner y coordinate
    @param    w   Width in pixels
    @param    h   Height in pixels
   @param    color 16-bit 5-6-5 Color to fill with
*/
/**************************************************************************/
void Adafruit_GFX::fillRect(int16_t x, int16_t y, int16_t w, int16_t h,
        uint16_t color) {
    startWrite();
    for (int16_t i=x; i<x+w; i++) {
        writeFastVLine(i, y, h, color);
    }
    endWrite();
}

/**************************************************************************/
/*!
   @brief    Fill the screen completely with one color. Update in subclasses if desired!
    @param    color 16-bit 5-6-5 Color to fill with
*/
/**************************************************************************/
void Adafruit_GFX::fillScreen(uint16_t color) {
    fillRect(0, 0, _width, _height, color);
}

/**************************************************************************/
/*!
   @brief    Draw a line
    @param    x0  Start point x coordinate
    @param    y0  Start point y coordinate
    @param    x1  End point x coordinate
    @param    y1  End point y coordinate
    @param    color 16-bit 5-6-5 Color to draw with
*/
/**************************************************************************/
void Adafruit_GFX::drawLine(int16_t x0, int16_t y0, int16_t x1, int16_t y1,
        uint16_t color) {
    // Update in subclasses if desired!
    if(x0 == x1){
        if(y0 > y1) _swap_int16_t(y0, y1);
        drawFastVLine(x0, y0, y1 - y0 + 1, color);
    } else if(y0 == y1){
        if(x0 > x1) _swap_int16_t(x0, x1);
        drawFastHLine(x0, y0, x1 - x0 + 1, color);
    } else {
        startWrite();
        writeLine(x0, y0, x1, y1, color);
        endWrite();
    }
}

/**************************************************************************/
/*!
   @brief    Draw a circle outline
    @param    x0   Center-point x coordinate
    @param    y0   Center-point y coordinate
    @param    r   Radius of circle
    @param    color 16-bit 5-6-5 Color to draw with
*/
/**************************************************************************/
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;

    startWrite();
    writePixel(x0  , y0+r, color);
    writePixel(x0  , y0-r, color);
    writePixel(x0+r, y0  , color);
    writePixel(x0-r, y0  , color);

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

        writePixel(x0 + x, y0 + y, color);
        writePixel(x0 - x, y0 + y, color);
        writePixel(x0 + x, y0 - y, color);
        writePixel(x0 - x, y0 - y, color);
        writePixel(x0 + y, y0 + x, color);
        writePixel(x0 - y, y0 + x, color);
        writePixel(x0 + y, y0 - x, color);
        writePixel(x0 - y, y0 - x, color);
    }
    endWrite();
}

/**************************************************************************/
/*!
    @brief    Quarter-circle drawer, used to do circles and roundrects
    @param    x0   Center-point x coordinate
    @param    y0   Center-point y coordinate
    @param    r   Radius of circle
    @param    cornername  Mask bit #1 or bit #2 to indicate which quarters of the circle we're doing
    @param    color 16-bit 5-6-5 Color to draw with
*/
/**************************************************************************/
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) {
            writePixel(x0 + x, y0 + y, color);
            writePixel(x0 + y, y0 + x, color);
        }
        if (cornername & 0x2) {
            writePixel(x0 + x, y0 - y, color);
            writePixel(x0 + y, y0 - x, color);
        }
        if (cornername & 0x8) {
            writePixel(x0 - y, y0 + x, color);
            writePixel(x0 - x, y0 + y, color);
        }
        if (cornername & 0x1) {
            writePixel(x0 - y, y0 - x, color);
            writePixel(x0 - x, y0 - y, color);
        }
    }
}

/**************************************************************************/
/*!
   @brief    Draw a circle with filled color
    @param    x0   Center-point x coordinate
    @param    y0   Center-point y coordinate
    @param    r   Radius of circle
    @param    color 16-bit 5-6-5 Color to fill with
*/
/**************************************************************************/
void Adafruit_GFX::fillCircle(int16_t x0, int16_t y0, int16_t r,
        uint16_t color) {
    startWrite();
    writeFastVLine(x0, y0-r, 2*r+1, color);
    fillCircleHelper(x0, y0, r, 3, 0, color);
    endWrite();
}


/**************************************************************************/
/*!
    @brief  Quarter-circle drawer with fill, used for circles and roundrects
    @param  x0       Center-point x coordinate
    @param  y0       Center-point y coordinate
    @param  r        Radius of circle
    @param  corners  Mask bits indicating which quarters we're doing
    @param  delta    Offset from center-point, used for round-rects
    @param  color    16-bit 5-6-5 Color to fill with
*/
/**************************************************************************/
void Adafruit_GFX::fillCircleHelper(int16_t x0, int16_t y0, int16_t r,
  uint8_t corners, 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;
    int16_t px    = x;
    int16_t py    = y;

    delta++; // Avoid some +1's in the loop

    while(x < y) {
        if (f >= 0) {
            y--;
            ddF_y += 2;
            f     += ddF_y;
        }
        x++;
        ddF_x += 2;
        f     += ddF_x;
        // These checks avoid double-drawing certain lines, important
        // for the SSD1306 library which has an INVERT drawing mode.
        if(x < (y + 1)) {
            if(corners & 1) writeFastVLine(x0+x, y0-y, 2*y+delta, color);
            if(corners & 2) writeFastVLine(x0-x, y0-y, 2*y+delta, color);
        }
        if(y != py) {
            if(corners & 1) writeFastVLine(x0+py, y0-px, 2*px+delta, color);
            if(corners & 2) writeFastVLine(x0-py, y0-px, 2*px+delta, color);
            py = y;
        }
        px = x;
    }
}

/**************************************************************************/
/*!
   @brief   Draw a rectangle with no fill color
    @param    x   Top left corner x coordinate
    @param    y   Top left corner y coordinate
    @param    w   Width in pixels
    @param    h   Height in pixels
    @param    color 16-bit 5-6-5 Color to draw with
*/
/**************************************************************************/
void Adafruit_GFX::drawRect(int16_t x, int16_t y, int16_t w, int16_t h,
        uint16_t color) {
    startWrite();
    writeFastHLine(x, y, w, color);
    writeFastHLine(x, y+h-1, w, color);
    writeFastVLine(x, y, h, color);
    writeFastVLine(x+w-1, y, h, color);
    endWrite();
}

/**************************************************************************/
/*!
   @brief   Draw a rounded rectangle with no fill color
    @param    x   Top left corner x coordinate
    @param    y   Top left corner y coordinate
    @param    w   Width in pixels
    @param    h   Height in pixels
    @param    r   Radius of corner rounding
    @param    color 16-bit 5-6-5 Color to draw with
*/
/**************************************************************************/
void Adafruit_GFX::drawRoundRect(int16_t x, int16_t y, int16_t w,
  int16_t h, int16_t r, uint16_t color) {
    int16_t max_radius = ((w < h) ? w : h) / 2; // 1/2 minor axis
    if(r > max_radius) r = max_radius;
    // smarter version
    startWrite();
    writeFastHLine(x+r  , y    , w-2*r, color); // Top
    writeFastHLine(x+r  , y+h-1, w-2*r, color); // Bottom
    writeFastVLine(x    , y+r  , h-2*r, color); // Left
    writeFastVLine(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);
    endWrite();
}

/**************************************************************************/
/*!
   @brief   Draw a rounded rectangle with fill color
    @param    x   Top left corner x coordinate
    @param    y   Top left corner y coordinate
    @param    w   Width in pixels
    @param    h   Height in pixels
    @param    r   Radius of corner rounding
    @param    color 16-bit 5-6-5 Color to draw/fill with
*/
/**************************************************************************/
void Adafruit_GFX::fillRoundRect(int16_t x, int16_t y, int16_t w,
  int16_t h, int16_t r, uint16_t color) {
    int16_t max_radius = ((w < h) ? w : h) / 2; // 1/2 minor axis
    if(r > max_radius) r = max_radius;
    // smarter version
    startWrite();
    writeFillRect(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);
    endWrite();
}

/**************************************************************************/
/*!
   @brief   Draw a triangle with no fill color
    @param    x0  Vertex #0 x coordinate
    @param    y0  Vertex #0 y coordinate
    @param    x1  Vertex #1 x coordinate
    @param    y1  Vertex #1 y coordinate
    @param    x2  Vertex #2 x coordinate
    @param    y2  Vertex #2 y coordinate
    @param    color 16-bit 5-6-5 Color to draw with
*/
/**************************************************************************/
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);
}

/**************************************************************************/
/*!
   @brief     Draw a triangle with color-fill
    @param    x0  Vertex #0 x coordinate
    @param    y0  Vertex #0 y coordinate
    @param    x1  Vertex #1 x coordinate
    @param    y1  Vertex #1 y coordinate
    @param    x2  Vertex #2 x coordinate
    @param    y2  Vertex #2 y coordinate
    @param    color 16-bit 5-6-5 Color to fill/draw with
*/
/**************************************************************************/
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_int16_t(y0, y1); _swap_int16_t(x0, x1);
    }
    if (y1 > y2) {
        _swap_int16_t(y2, y1); _swap_int16_t(x2, x1);
    }
    if (y0 > y1) {
        _swap_int16_t(y0, y1); _swap_int16_t(x0, x1);
    }

    startWrite();
    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;
        writeFastHLine(a, y0, b-a+1, color);
        endWrite();
        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;

    // 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_int16_t(a,b);
        writeFastHLine(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_int16_t(a,b);
        writeFastHLine(a, y, b-a+1, color);
    }
    endWrite();
}


/**************************************************************************/
/*!
    @brief      Get rotation setting for display
    @returns    0 thru 3 corresponding to 4 cardinal rotations
*/
/**************************************************************************/
uint8_t Adafruit_GFX::getRotation(void) const {
    return rotation;
}

/**************************************************************************/
/*!
    @brief      Set rotation setting for display
    @param  x   0 thru 3 corresponding to 4 cardinal rotations
*/
/**************************************************************************/
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;
    }
}



/**************************************************************************/
/*!
    @brief      Get width of the display, accounting for the current rotation
    @returns    Width in pixels
*/
/**************************************************************************/
int16_t Adafruit_GFX::width(void) const {
    return _width;
}

/**************************************************************************/
/*!
    @brief      Get height of the display, accounting for the current rotation
    @returns    Height in pixels
*/
/**************************************************************************/
int16_t Adafruit_GFX::height(void) const {
    return _height;
}

/**************************************************************************/
/*!
    @brief      Invert the display (ideally using built-in hardware command)
    @param   i  True if you want to invert, false to make 'normal'
*/
/**************************************************************************/
void Adafruit_GFX::invertDisplay(boolean i) {
    // Do nothing, must be subclassed if supported by hardware
}

/***************************************************************************/