Pixels_Antialiasing.h

/*
    Pixels. Graphics library for TFT displays.

    Copyright (C) 2012-2013  Igor Repinetski

    The code is written in C/C++ for Arduino and can be easily ported to any microcontroller by rewritting the low level pin access functions.

    Text output methods of the library rely on Pixelmeister's font data format. See: http://pd4ml.com/pixelmeister

    This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/

    Commercial use of the library is possible for licensees of "Pixelmeister (for industry)" product.

    This library includes some code portions and algoritmic ideas derived from works of
    - Andreas Schiffler -- aschiffler at ferzkopp dot net (SDL_gfx Project)
    - K. Townsend http://microBuilder.eu (lpc1343codebase Project)
*/

#include "Pixels.h"

#ifdef PIXELS_MAIN
#error Pixels_Antialiasing.h must be included before Pixels_<CONTROLLER>.h
#endif

#ifndef PIXELS_ANTIALIASING_H
#define PIXELS_ANTIALIASING_H

class PixelsAntialiased : public PixelsBase
{
  protected:
    virtual void drawCircleAntialiaced(int16_t x, int16_t y, int16_t radius, boolean bordermode);
    virtual void drawFatLineAntialiased(int16_t x1, int16_t y1, int16_t x2, int16_t y2);
    virtual void drawLineAntialiased(int16_t x1, int16_t y1, int16_t x2, int16_t y2);
    virtual void drawRoundRectangleAntialiased(int16_t x, int16_t y, int16_t width, int16_t height, int16_t rx, int16_t ry, boolean bordermode);

  public:
    virtual void enableAntialiasing(boolean enable) {
        antialiasing = enable;
    }

    PixelsAntialiased(uint16_t width, uint16_t height) : PixelsBase(width, height) {
    }
};

void PixelsAntialiased::drawLineAntialiased(int16_t x1, int16_t y1, int16_t x2, int16_t y2)
{

    boolean steep = (y2 > y1 ? y2 - y1 : y1 - y2) > (x2 > x1 ? x2 - x1 : x1 - x2);
    if (steep)
    {
        int16_t tmp = x1;
        x1 = y1;
        y1 = tmp;
        tmp = x2;
        x2 = y2;
        y2 = tmp;
    }
    if (x1 > x2)
    {
        int16_t tmp = x1;
        x1 = x2;
        x2 = tmp;
        tmp = y1;
        y1 = y2;
        y2 = tmp;
    }
    int16_t deltax = x2 - x1;
    int16_t deltay = y2 - y1;
    double gradient = 1.0 * deltay / deltax;

    int16_t xend = x1; // round(x1);
    double yend = y1 + gradient * (xend - x1);
    double xgap = rfpart(x1 + 0.5);
    int16_t xpxl1 = xend;
    int16_t ypxl1 = ipart(yend);
    putColor(xpxl1, ypxl1, steep, rfpart(yend)*xgap);
    putColor(xpxl1, ypxl1 + 1, steep, fpart(yend)*xgap);
    double intery = yend + gradient;

    xend = x2; // round(x2);
    yend = y2 + gradient * (xend - x2);
    xgap = rfpart(x2 + 0.5);
    int16_t xpxl2 = xend;
    int16_t ypxl2 = ipart(yend);
    putColor(xpxl2, ypxl2, steep, rfpart(yend)*xgap);
    putColor(xpxl2, ypxl2 + 1, steep, fpart(yend)*xgap);

    for (int16_t x = xpxl1 + 1; x < xpxl2 - 1; x++)
    {
        putColor(x, ipart(intery), steep, rfpart(intery));
        putColor(x, ipart(intery) + 1, steep, fpart(intery));
        intery += gradient;
    }
}

void PixelsAntialiased::drawFatLineAntialiased(int16_t x1, int16_t y1, int16_t x2, int16_t y2)
{
#ifdef ENABLE_FAT_LINES
// the code still needs to be completed. Problems by line caps

    double wd = lineWidth;

    int16_t dx = abs(x2 - x1);
    int16_t sx = x1 < x2 ? 1 : -1;
    int16_t dy = abs(y2 - y1);
    int16_t sy = y1 < y2 ? 1 : -1;
    int16_t err = dx - dy;

    int16_t e2;
    int16_t x;
    int16_t y;

    double ed = dx + dy == 0 ? 1 : sqrt((double) dx * dx + (double) dy * dy);

    wd = (wd + 1) / 2;
    while (true)
    {
        putColor(x1, y1, false, 1 - max(0, abs(err - dx + dy) / ed - wd + 1));
        e2 = err;
        x = x1;
        boolean out = false;
        if (2 * e2 >= -dx)   /* x step */
        {
            for (e2 += dy, y = y1; e2 < ed * wd && (y2 != y || dx > dy); e2 += dx)
            {
                putColor(x1, y += sy, false, 1 - max(0, abs(e2) / ed - wd + 1));
            }
            if (x1 == x2)
            {
                out = true;
            }
            e2 = err;
            err -= dy;
            x1 += sx;
        }
        if (2 * e2 <= dy)   /* y step */
        {
            for (e2 = dx - e2; e2 < ed * wd && (x2 != x || dx < dy); e2 += dy)
            {
                putColor(x += sx, y1, false, 1 - max(0, abs(e2) / ed - wd + 1));
            }
            if (y1 == y2)
            {
                out = true;
            }
            err += dx;
            y1 += sy;
        }
        if (out)
        {
            break;
        }
    }
#else
    drawLineAntialiased(x1, y1, x2, y2);
#endif
}

void PixelsAntialiased::drawRoundRectangleAntialiased(int16_t x, int16_t y, int16_t width, int16_t height, int16_t rx, int16_t ry, boolean bordermode)
{

    int16_t i;
    int32_t a2, b2, ds, dt, dxt, t, s, d;
    int16_t xp, yp, xs, ys, dyt, od, xx, yy, xc2, yc2;
    float cp;
    double sab;
    double weight, iweight;

    if ((rx < 0) || (ry < 0))
    {
        return;
    }

    if (rx == 0)
    {
        vLine(x, y - ry, y + ry);
        return;
    }

    if (ry == 0)
    {
        hLine(x - rx, y, x + rx);
        return;
    }

    a2 = rx * rx;
    b2 = ry * ry;

    ds = a2 << 1;
    dt = b2 << 1;

    xc2 = x << 1;
    yc2 = y << 1;

    sab = sqrt((double)(a2 + b2));
    od = (int)round(sab * 0.01) + 1;
    dxt = (int)round((double)a2 / sab) + od;

    t = 0;
    s = -2 * a2 * ry;
    d = 0;

    xp = x + rx;
    yp = y;

    hLine(x + rx, y + height, x + width - rx);
    hLine(x + rx, y, x + width - rx);
    vLine(x + width, y + ry, y + height - ry);
    vLine(x, y + ry, y + height - ry);

    for (i = 1; i <= dxt; i++)
    {
        xp--;
        d += t - b2;

        if (d >= 0)
        {
            ys = yp - 1;
        }
        else if ((d - s - a2) > 0)
        {
            if (((d << 1) - s - a2) >= 0)
            {
                ys = yp + 1;
            }
            else
            {
                ys = yp;
                yp++;
                d -= s + a2;
                s += ds;
            }
        }
        else
        {
            yp++;
            ys = yp + 1;
            d -= s + a2;
            s += ds;
        }

        t -= dt;

        if (s != 0)
        {
            cp = (float) abs(d) / (float) abs(s);
            if (cp > 1.0)
            {
                cp = 1.0f;
            }
        }
        else
        {
            cp = 1.0f;
        }

        weight = cp;
        iweight = 1 - weight;

        if (bordermode)
        {
            iweight = yp > ys ? 1 : iweight;
            weight = ys > yp ? 1 : weight;
        }

        /* Upper half */
        xx = xc2 - xp;
        putColor(xp, yp, false, iweight);
        putColor(xx + width, yp, false, iweight);

        putColor(xp, ys, false, weight);
        putColor(xx + width, ys, false, weight);

        /* Lower half */
        yy = yc2 - yp;
        putColor(xp, yy + height, false, iweight);
        putColor(xx + width, yy + height, false, iweight);

        yy = yc2 - ys;
        putColor(xp, yy + height, false, weight);
        putColor(xx + width, yy + height, false, weight);
    }

    /* Replaces original approximation code dyt = abs(yp - yc); */
    dyt = (int)round((double)b2 / sab) + od;

    for (i = 1; i <= dyt; i++)
    {
        yp++;
        d -= s + a2;

        if (d <= 0)
        {
            xs = xp + 1;
        }
        else if ((d + t - b2) < 0)
        {
            if (((d << 1) + t - b2) <= 0)
            {
                xs = xp - 1;
            }
            else
            {
                xs = xp;
                xp--;
                d += t - b2;
                t -= dt;
            }
        }
        else
        {
            xp--;
            xs = xp - 1;
            d += t - b2;
            t -= dt;
        }

        s += ds;

        if (t != 0)
        {
            cp = (float) abs(d) / (float) abs(t);
            if (cp > 1.0)
            {
                cp = 1.0f;
            }
        }
        else
        {
            cp = 1.0f;
        }

        weight = cp;
        iweight = 1 - weight;

        /* Left half */
        xx = xc2 - xp;
        yy = yc2 - yp;
        putColor(xp, yp, false, iweight);
        putColor(xx + width, yp, false, iweight);

        putColor(xp, yy + height, false, iweight);
        putColor(xx + width, yy + height, false, iweight);

        /* Right half */
        xx = xc2 - xs;
        putColor(xs, yp, false, weight);
        putColor(xx + width, yp, false, weight);

        putColor(xs, yy + height, false, weight);
        putColor(xx + width, yy + height, false, weight);
    }
}

void PixelsAntialiased::drawCircleAntialiaced(int16_t x, int16_t y, int16_t radius, boolean bordermode)
{
    drawRoundRectangleAntialiased(x - radius, y - radius, radius << 1, radius << 1, radius, radius, bordermode);
}
#endif