File content as of revision 2:66a3fe0dc83a:

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

Written by Limor Fried/Ladyada for Adafruit Industries.
BSD license, check license.txt for more information.
All text above must be included in any redistribution.

*/

/*
 *  Modified by Tatsuki Fukuda 25/5/2014 for use in mbed
 */
 
 #include "mbed.h"
#include "Adafruit_GFX.h"
#include "glcdfont.h"

// 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;
    for(j=0; j<h; j++) {
        for(i=0; i<w; i++ ) {
            if(bitmap[i+(j/8)*w]& _BV(j%8) )
                drawPixel(x+i, y+j, color);
        }
    }
}

size_t Adafruit_GFX::writeChar(uint8_t c)
{
    if (c == '\n') {
        cursor_y += textsize*8;
        cursor_x  = 0;
    } else if (c == '\r') {
        cursor_x  = 0;
    } 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;
        }
    }
    return 1;
}

// 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 = 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::invertDisplay(bool i)
{
    // Do nothing, must be subclassed if supported
}