rt-thread/components/rtgui/common/dc.c

/*
 * File      : dc.c
 * This file is part of RT-Thread RTOS
 * COPYRIGHT (C) 2006 - 2009, RT-Thread Development Team
 *
 * The license and distribution terms for this file may be
 * found in the file LICENSE in this distribution or at
 * http://www.rt-thread.org/license/LICENSE
 *
 * Change Logs:
 * Date           Author       Notes
 * 2009-10-16     Bernard      first version
 * 2010-09-20     richard      modified rtgui_dc_draw_round_rect
 * 2010-09-27     Bernard      fix draw_mono_bmp issue
 * 2011-04-25     Bernard      fix fill polygon issue, which found by loveic
 */
#include <rtgui/dc.h>
#include <rtgui/rtgui_system.h>

#include <string.h> /* for strlen */
#include <stdlib.h> /* fir qsort  */

/* for sin/cos etc */
#include <math.h>
#ifndef M_PI
#define M_PI    3.14159265358979323846
#endif

static int _int_compare(const void *a, const void *b)
{
    return (*(const int *) a) - (*(const int *) b);
}

void rtgui_dc_destory(struct rtgui_dc *dc)
{
    if (dc == RT_NULL) return;

    dc->engine->fini(dc);
    rtgui_free(dc);
}
RTM_EXPORT(rtgui_dc_destory);

void rtgui_dc_draw_line(struct rtgui_dc *dc, int x1, int y1, int x2, int y2)
{
    if (dc == RT_NULL) return;

    if (y1 == y2)
    {
        rtgui_dc_draw_hline(dc, x1, x2, y1);
    }
    else if (x1 == x2)
    {
        rtgui_dc_draw_vline(dc, x1, y1, y2);
    }
    else
    {
        int dx, dy, sdx, sdy, dxabs, dyabs, x, y, px, py;
        register rt_base_t i;
        /* rtgui_rect_t rect; */

        dx = x2 - x1;       /* the horizontal distance of the line */
        dy = y2 - y1;       /* the vertical distance of the line */

#define rtgui_sgn(x) ((x<0)?-1:((x>0)?1:0)) /* macro to return the sign of a number */
#define rtgui_abs(x) ((x)>=0? (x):-(x))     /* macro to return the absolute value */

        dxabs = rtgui_abs(dx);
        dyabs = rtgui_abs(dy);
        sdx = rtgui_sgn(dx);
        sdy = rtgui_sgn(dy);
        x = dyabs >> 1;
        y = dxabs >> 1;
        px = x1;
        py = y1;

        if (dxabs >= dyabs) /* the line is more horizontal than vertical */
        {
            for (i = 0; i < dxabs; i++)
            {
                y += dyabs;
                if (y >= dxabs)
                {
                    y -= dxabs;
                    py += sdy;
                }
                px += sdx;

                /* draw this point */
                rtgui_dc_draw_point(dc, px, py);
            }
        }
        else                /* the line is more vertical than horizontal */
        {
            for (i = 0; i < dyabs; i++)
            {
                x += dxabs;
                if (x >= dyabs)
                {
                    x -= dyabs;
                    px += sdx;
                }
                py += sdy;

                /* draw this point */
                rtgui_dc_draw_point(dc, px, py);
            }
        }
    }
}
RTM_EXPORT(rtgui_dc_draw_line);

void rtgui_dc_draw_horizontal_line(struct rtgui_dc *dc, int x1, int x2, int y)
{
    rtgui_color_t color;

    if (dc == RT_NULL) return ;

    /* save old color */
    color = RTGUI_DC_FC(dc);

    RTGUI_DC_FC(dc) = dark_grey;
    rtgui_dc_draw_hline(dc, x1, x2, y);

    y ++;

    RTGUI_DC_FC(dc) = high_light;
    rtgui_dc_draw_hline(dc, x1, x2, y);

    /* restore color */
    RTGUI_DC_FC(dc) = color;
}
RTM_EXPORT(rtgui_dc_draw_horizontal_line);

void rtgui_dc_draw_vertical_line(struct rtgui_dc *dc, int x, int y1, int y2)
{
    rtgui_color_t color;

    if (dc == RT_NULL) return ;

    /* save old color */
    color = RTGUI_DC_FC(dc);

    RTGUI_DC_FC(dc) = dark_grey;
    rtgui_dc_draw_vline(dc, x, y1, y2);

    x ++;

    RTGUI_DC_FC(dc) = high_light;
    rtgui_dc_draw_vline(dc, x, y1, y2);

    /* restore color */
    RTGUI_DC_FC(dc) = color;
}
RTM_EXPORT(rtgui_dc_draw_vertical_line);

void rtgui_dc_draw_rect(struct rtgui_dc *dc, struct rtgui_rect *rect)
{
    rtgui_dc_draw_hline(dc, rect->x1, rect->x2, rect->y1);
    rtgui_dc_draw_hline(dc, rect->x1, rect->x2, rect->y2 - 1);

    rtgui_dc_draw_vline(dc, rect->x1, rect->y1, rect->y2);
    rtgui_dc_draw_vline(dc, rect->x2 - 1, rect->y1, rect->y2);
}
RTM_EXPORT(rtgui_dc_draw_rect);

void rtgui_dc_fill_rect_forecolor(struct rtgui_dc *dc, struct rtgui_rect *rect)
{
    int i = 0;

    rtgui_dc_draw_rect(dc, rect);
    do
    {
        rtgui_dc_draw_hline(dc, rect->x1 + 1, rect->x2 - 1, rect->y1 + i);
        i++;
    }
    while (!(rect->y1 + i == rect->y2));
}
RTM_EXPORT(rtgui_dc_fill_rect_forecolor);

void rtgui_dc_draw_round_rect(struct rtgui_dc *dc, struct rtgui_rect *rect, int r)
{
    RT_ASSERT(((rect->x2 - rect->x1) / 2 >= r) && ((rect->y2 - rect->y1) / 2 >= r));

    if (r < 0)
    {
        return;
    }

    if (r == 0)
    {
        rtgui_dc_draw_rect(dc, rect);
        return;
    }

    if (((rect->x2 - rect->x1) / 2 >= r) && ((rect->y2 - rect->y1) / 2 >= r))
    {
        rtgui_dc_draw_arc(dc, rect->x1 + r, rect->y1 + r, r, 180, 270);
        rtgui_dc_draw_arc(dc, rect->x2 - r, rect->y1 + r, r, 270, 360);
        rtgui_dc_draw_arc(dc, rect->x1 + r, rect->y2 - r, r, 90,  180);
        rtgui_dc_draw_arc(dc, rect->x2 - r, rect->y2 - r, r, 0,   90);

        rtgui_dc_draw_hline(dc, rect->x1 + r, rect->x2 - r, rect->y1);
        rtgui_dc_draw_hline(dc, rect->x1 + r, rect->x2 - r, rect->y2);
        rtgui_dc_draw_vline(dc, rect->x1, rect->y1 + r, rect->y2 - r);
        rtgui_dc_draw_vline(dc, rect->x2, rect->y1 + r, rect->y2 - r);
    }
}
RTM_EXPORT(rtgui_dc_draw_round_rect);

void rtgui_dc_fill_round_rect(struct rtgui_dc *dc, struct rtgui_rect *rect, int r)
{
    struct rtgui_rect rect_temp;

    RT_ASSERT(((rect->x2 - rect->x1) / 2 >= r) && ((rect->y2 - rect->y1) / 2 >= r));

    if (((rect->x2 - rect->x1) / 2 >= r) && ((rect->y2 - rect->y1) / 2 >= r))
    {
        rect_temp.x1 = rect->x1 + r;
        rect_temp.y1 = rect->y1;
        rect_temp.x2 = rect->x2 - r;
        rect_temp.y2 = rect->y2;
        rtgui_dc_fill_rect_forecolor(dc, &rect_temp);//fill rect with foreground

        rect_temp.x1 = rect->x1;
        rect_temp.y1 = rect->y1 + r;
        rect_temp.x2 = rect->x1 + r;
        rect_temp.y2 = rect->y2 - r;
        rtgui_dc_fill_rect_forecolor(dc, &rect_temp);//fill rect with foreground

        rect_temp.x1 = rect->x2 - r;
        rect_temp.y1 = rect->y1 + r;
        rect_temp.x2 = rect->x2;
        rect_temp.y2 = rect->y2 - r;
        rtgui_dc_fill_rect_forecolor(dc, &rect_temp);//fill rect with foreground

        rtgui_dc_fill_circle(dc, rect->x1 + r, rect->y1 + r, r);
        rtgui_dc_fill_circle(dc, rect->x2 - r, rect->y2 - r, r);
        rtgui_dc_fill_circle(dc, rect->x2 - r, rect->y1 + r, r);
        rtgui_dc_fill_circle(dc, rect->x1 + r, rect->y2 - r, r);
    }
}
RTM_EXPORT(rtgui_dc_fill_round_rect);

void rtgui_dc_draw_shaded_rect(struct rtgui_dc *dc, rtgui_rect_t *rect,
                               rtgui_color_t c1, rtgui_color_t c2)
{
    RT_ASSERT(dc != RT_NULL);

    RTGUI_DC_FC(dc) = c1;
    rtgui_dc_draw_vline(dc, rect->x1, rect->y1, rect->y2);
    rtgui_dc_draw_hline(dc, rect->x1 + 1, rect->x2, rect->y1);

    RTGUI_DC_FC(dc) = c2;
    rtgui_dc_draw_vline(dc, rect->x2 - 1, rect->y1, rect->y2);
    rtgui_dc_draw_hline(dc, rect->x1, rect->x2, rect->y2 - 1);
}
RTM_EXPORT(rtgui_dc_draw_shaded_rect);

void rtgui_dc_draw_focus_rect(struct rtgui_dc *dc, rtgui_rect_t *rect)
{
    int x, y;

    for (x = rect->x1; x < rect->x2 - 1; x++)
    {
        if ((x + rect->y1) & 0x01)
            rtgui_dc_draw_point(dc, x, rect->y1);
        if ((x + rect->y2 - 1) & 0x01)
            rtgui_dc_draw_point(dc, x, rect->y2 - 1);
    }

    for (y = rect->y1; y < rect->y2; y++)
    {
        if ((rect->x1 + y) & 0x01)
            rtgui_dc_draw_point(dc, rect->x1, y);
        if ((rect->x2 - 1 + y) & 0x01)
            rtgui_dc_draw_point(dc, rect->x2 - 1, y);
    }
}
RTM_EXPORT(rtgui_dc_draw_focus_rect);

void rtgui_dc_draw_text(struct rtgui_dc *dc, const char *text, struct rtgui_rect *rect)
{
    rt_uint32_t len;
    struct rtgui_font *font;
    struct rtgui_rect text_rect;

    RT_ASSERT(dc != RT_NULL);

    font = RTGUI_DC_FONT(dc);
    if (font == RT_NULL)
    {
        /* use system default font */
        font = rtgui_font_default();
    }

    /* text align */
    rtgui_font_get_metrics(font, text, &text_rect);
    rtgui_rect_moveto_align(rect, &text_rect, RTGUI_DC_TEXTALIGN(dc));

    len = strlen((const char *)text);
    rtgui_font_draw(font, dc, text, len, &text_rect);
}
RTM_EXPORT(rtgui_dc_draw_text);

void rtgui_dc_draw_text_stroke(struct rtgui_dc *dc, const char *text, struct rtgui_rect *rect,
                               rtgui_color_t color_stroke, rtgui_color_t color_core)
{
    int x, y;
    rtgui_rect_t r;
    rtgui_color_t fc;

    RT_ASSERT(dc != RT_NULL);

    fc = RTGUI_DC_FC(dc);
    RTGUI_DC_FC(dc) = color_stroke;
    for (x = -1; x < 2; x++)
    {
        for (y = -1; y < 2; y++)
        {
            r = *rect;
            rtgui_rect_moveto(&r, x, y);
            rtgui_dc_draw_text(dc, text, &r);
        }
    }
    RTGUI_DC_FC(dc) = color_core;
    rtgui_dc_draw_text(dc, text, rect);
    RTGUI_DC_FC(dc) = fc;
}
RTM_EXPORT(rtgui_dc_draw_text_stroke);

/*
 * draw a monochrome color bitmap data
 */
void rtgui_dc_draw_mono_bmp(struct rtgui_dc *dc, int x, int y, int w, int h, const rt_uint8_t *data)
{
    int i, j, k;

    /* get word bytes */
    w = (w + 7) / 8;

    /* draw mono bitmap data */
    for (i = 0; i < h; i ++)
        for (j = 0; j < w; j++)
            for (k = 0; k < 8; k++)
                if (((data[i * w + j] >> (7 - k)) & 0x01) != 0)
                    rtgui_dc_draw_point(dc, x + 8 * j + k, y + i);
}
RTM_EXPORT(rtgui_dc_draw_mono_bmp);

void rtgui_dc_draw_byte(struct rtgui_dc *dc, int x, int y, int h, const rt_uint8_t *data)
{
    rtgui_dc_draw_mono_bmp(dc, x, y, 8, h, data);
}
RTM_EXPORT(rtgui_dc_draw_byte);

void rtgui_dc_draw_word(struct rtgui_dc *dc, int x, int y, int h, const rt_uint8_t *data)
{
    rtgui_dc_draw_mono_bmp(dc, x, y, 16, h, data);
}
RTM_EXPORT(rtgui_dc_draw_word);

void rtgui_dc_draw_border(struct rtgui_dc *dc, rtgui_rect_t *rect, int flag)
{
    rtgui_rect_t r;
    rtgui_color_t color;

    if (dc == RT_NULL) return ;

    /* save old color */
    color = RTGUI_DC_FC(dc);

    r = *rect;
    switch (flag)
    {
    case RTGUI_BORDER_RAISE:
        rtgui_dc_draw_shaded_rect(dc, &r, high_light, black);
        rtgui_rect_inflate(&r, -1);
        rtgui_dc_draw_shaded_rect(dc, &r, light_grey, dark_grey);
        break;

    case RTGUI_BORDER_SUNKEN:
        rtgui_dc_draw_shaded_rect(dc, &r, dark_grey, high_light);
        rtgui_rect_inflate(&r, -1);
        rtgui_dc_draw_shaded_rect(dc, &r, black, light_grey);
        break;

    case RTGUI_BORDER_BOX:
        rtgui_dc_draw_shaded_rect(dc, &r, dark_grey, high_light);
        rtgui_rect_inflate(&r, -1);
        rtgui_dc_draw_shaded_rect(dc, &r, high_light, dark_grey);
        break;

    case RTGUI_BORDER_STATIC:
        rtgui_dc_draw_shaded_rect(dc, &r, dark_grey, high_light);
        break;

    case RTGUI_BORDER_EXTRA:
        RTGUI_DC_FC(dc) = light_grey;
        rtgui_dc_draw_rect(dc, &r);
        break;

    case RTGUI_BORDER_SIMPLE:
        RTGUI_DC_FC(dc) = black;
        rtgui_dc_draw_rect(dc, &r);
        break;

    default:
        break;
    }

    /* restore color */
    RTGUI_DC_FC(dc) = color;
}
RTM_EXPORT(rtgui_dc_draw_border);

void rtgui_dc_draw_polygon(struct rtgui_dc *dc, const int *vx, const int *vy, int count)
{
    int i;
    const int *x1, *y1, *x2, *y2;

    /*
    * Sanity check
    */
    if (count < 3) return;

    /*
    * Pointer setup
    */
    x1 = x2 = vx;
    y1 = y2 = vy;
    x2++;
    y2++;

    /*
    * Draw
    */
    for (i = 1; i < count; i++)
    {
        rtgui_dc_draw_line(dc, *x1, *y1, *x2, *y2);
        x1 = x2;
        y1 = y2;
        x2++;
        y2++;
    }
    rtgui_dc_draw_line(dc, *x1, *y1, *vx, *vy);
}
RTM_EXPORT(rtgui_dc_draw_polygon);

void rtgui_dc_draw_regular_polygon(struct rtgui_dc *dc, int x, int y, int r, int count, rt_uint16_t angle)
{
    int i, temp_val;
    double temp;
    float angle_interval;
    int *xx;
    int *x_head;
    int *yy;
    int *y_head;

    /*
    * Sanity check
    */
    if (count < 3) return;

    angle_interval = 360.0 / count;

    /*
    * Pointer setup
    */

    x_head = xx = (int *)rtgui_malloc(sizeof(int) * count);
    y_head = yy = (int *)rtgui_malloc(sizeof(int) * count);

    for (i = 0; i < count; i++)
    {
        temp     = cos(((angle_interval * i) + angle) * M_PI / 180);
        temp     *= r;
        temp_val = (int)temp;
        *xx      = temp_val + x;

        temp     = sin(((angle_interval * i) + angle) * M_PI / 180);
        temp     *= r;
        temp_val = (int)temp;
        *yy      = temp_val + y;

        xx++;
        yy++;
    }

    rtgui_dc_draw_polygon(dc, (const int *)x_head, (const int *)y_head, count);

    rtgui_free(x_head);
    rtgui_free(y_head);

}
RTM_EXPORT(rtgui_dc_draw_regular_polygon);

void rtgui_dc_fill_polygon(struct rtgui_dc *dc, const int *vx, const int *vy, int count)
{
    int i;
    int y, xa, xb;
    int miny, maxy;
    int x1, y1;
    int x2, y2;
    int ind1, ind2;
    int ints;
    int *poly_ints = RT_NULL;

    /*
    * Sanity check number of edges
    */
    if (count < 3) return;

    /*
    * Allocate temp array, only grow array
    */
    poly_ints = (int *) rtgui_malloc(sizeof(int) * count);
    if (poly_ints == RT_NULL) return ; /* no memory, failed */

    /*
     * Determine Y maximal
     */
    miny = vy[0];
    maxy = vy[0];
    for (i = 1; (i < count); i++)
    {
        if (vy[i] < miny) miny = vy[i];
        else if (vy[i] > maxy) maxy = vy[i];
    }

    /*
    * Draw, scanning y
    */
    for (y = miny; (y <= maxy); y++)
    {
        ints = 0;
        for (i = 0; (i < count); i++)
        {
            if (!i)
            {
                ind1 = count - 1;
                ind2 = 0;
            }
            else
            {
                ind1 = i - 1;
                ind2 = i;
            }
            y1 = vy[ind1];
            y2 = vy[ind2];
            if (y1 < y2)
            {
                x1 = vx[ind1];
                x2 = vx[ind2];
            }
            else if (y1 > y2)
            {
                y2 = vy[ind1];
                y1 = vy[ind2];
                x2 = vx[ind1];
                x1 = vx[ind2];
            }
            else
            {
                continue;
            }

            if (((y >= y1) && (y < y2)) || ((y == maxy) && (y > y1) && (y <= y2)))
            {
                poly_ints[ints++] = ((65536 * (y - y1)) / (y2 - y1)) * (x2 - x1) + (65536 * x1);
            }
        }

        qsort(poly_ints, ints, sizeof(int), _int_compare);

        for (i = 0; (i < ints); i += 2)
        {
            xa = poly_ints[i] + 1;
            xa = (xa >> 16) + ((xa & 32768) >> 15);
            xb = poly_ints[i + 1] - 1;
            xb = (xb >> 16) + ((xb & 32768) >> 15);
            rtgui_dc_draw_hline(dc, xa, xb, y);
        }
    }

    /* release memory */
    rtgui_free(poly_ints);
}
RTM_EXPORT(rtgui_dc_fill_polygon);

void rtgui_dc_draw_circle(struct rtgui_dc *dc, int x, int y, int r)
{
    rt_int16_t cx = 0;
    rt_int16_t cy = r;
    rt_int16_t df = 1 - r;
    rt_int16_t d_e = 3;
    rt_int16_t d_se = -2 * r + 5;
    rt_int16_t xpcx, xmcx, xpcy, xmcy;
    rt_int16_t ypcy, ymcy, ypcx, ymcx;

    /*
     * sanity check radius
     */
    if (r < 0) return ;

    /* special case for r=0 - draw a point  */
    if (r == 0) rtgui_dc_draw_point(dc, x, y);

    /*
     * draw circle
     */
    do
    {
        ypcy = y + cy;
        ymcy = y - cy;
        if (cx > 0)
        {
            xpcx = x + cx;
            xmcx = x - cx;
            rtgui_dc_draw_point(dc, xmcx, ypcy);
            rtgui_dc_draw_point(dc, xpcx, ypcy);
            rtgui_dc_draw_point(dc, xmcx, ymcy);
            rtgui_dc_draw_point(dc, xpcx, ymcy);
        }
        else
        {
            rtgui_dc_draw_point(dc, x, ymcy);
            rtgui_dc_draw_point(dc, x, ypcy);
        }
        xpcy = x + cy;
        xmcy = x - cy;
        if ((cx > 0) && (cx != cy))
        {
            ypcx = y + cx;
            ymcx = y - cx;
            rtgui_dc_draw_point(dc, xmcy, ypcx);
            rtgui_dc_draw_point(dc, xpcy, ypcx);
            rtgui_dc_draw_point(dc, xmcy, ymcx);
            rtgui_dc_draw_point(dc, xpcy, ymcx);
        }
        else if (cx == 0)
        {
            rtgui_dc_draw_point(dc, xmcy, y);
            rtgui_dc_draw_point(dc, xpcy, y);
        }

        /*
         * Update
         */
        if (df < 0)
        {
            df += d_e;
            d_e += 2;
            d_se += 2;
        }
        else
        {
            df += d_se;
            d_e += 2;
            d_se += 4;
            cy--;
        }
        cx++;
    }
    while (cx <= cy);
}
RTM_EXPORT(rtgui_dc_draw_circle);

void rtgui_dc_fill_circle(struct rtgui_dc *dc, rt_int16_t x, rt_int16_t y, rt_int16_t r)
{
    rt_int16_t cx = 0;
    rt_int16_t cy = r;
    rt_int16_t ocx = (rt_int16_t) 0xffff;
    rt_int16_t ocy = (rt_int16_t) 0xffff;
    rt_int16_t df = 1 - r;
    rt_int16_t d_e = 3;
    rt_int16_t d_se = -2 * r + 5;
    rt_int16_t xpcx, xmcx, xpcy, xmcy;
    rt_int16_t ypcy, ymcy, ypcx, ymcx;

    /*
     * Sanity check radius
     */
    if (r < 0) return;

    /*
     * Special case for r=0 - draw a point
     */
    if (r == 0)
    {
        rtgui_dc_draw_point(dc, x, y);
        return ;
    }

    /*
     * Draw
     */
    do
    {
        xpcx = x + cx;
        xmcx = x - cx;
        xpcy = x + cy;
        xmcy = x - cy;
        if (ocy != cy)
        {
            if (cy > 0)
            {
                ypcy = y + cy;
                ymcy = y - cy;
                rtgui_dc_draw_hline(dc, xmcx, xpcx, ypcy);
                rtgui_dc_draw_hline(dc, xmcx, xpcx, ymcy);
            }
            else
            {
                rtgui_dc_draw_hline(dc, xmcx, xpcx, y);
            }
            ocy = cy;
        }
        if (ocx != cx)
        {
            if (cx != cy)
            {
                if (cx > 0)
                {
                    ypcx = y + cx;
                    ymcx = y - cx;
                    rtgui_dc_draw_hline(dc, xmcy, xpcy, ymcx);
                    rtgui_dc_draw_hline(dc, xmcy, xpcy, ypcx);
                }
                else
                {
                    rtgui_dc_draw_hline(dc, xmcy, xpcy, y);
                }
            }
            ocx = cx;
        }
        /*
         * Update
         */
        if (df < 0)
        {
            df += d_e;
            d_e += 2;
            d_se += 2;
        }
        else
        {
            df += d_se;
            d_e += 2;
            d_se += 4;
            cy--;
        }
        cx++;
    }
    while (cx <= cy);
}
RTM_EXPORT(rtgui_dc_fill_circle);

void rtgui_dc_draw_arc(struct rtgui_dc *dc, rt_int16_t x, rt_int16_t y, rt_int16_t r, rt_int16_t start, rt_int16_t end)
{
    rt_int16_t cx = 0;
    rt_int16_t cy = r;
    rt_int16_t df = 1 - r;
    rt_int16_t d_e = 3;
    rt_int16_t d_se = -2 * r + 5;
    rt_int16_t xpcx, xmcx, xpcy, xmcy;
    rt_int16_t ypcy, ymcy, ypcx, ymcx;
    rt_uint8_t drawoct;
    int startoct, endoct, oct, stopval_start, stopval_end;
    double temp;

    stopval_start = 0;
    stopval_end = 0;
    temp = 0;

    /* Sanity check radius */
    if (r < 0) return ;
    /* Special case for r=0 - draw a point */
    if (r == 0)
    {
        rtgui_dc_draw_point(dc, x, y);
        return;
    }

    /*
    * Draw arc
    */

    // Octant labelling
    //
    //  \ 5 | 6 /
    //   \  |  /
    //  4 \ | / 7
    //     \|/
    //------+------ +x
    //     /|\
    //  3 / | \ 0
    //   /  |  \
    //  / 2 | 1 \
    //      +y

    drawoct = 0; // 0x00000000
    // whether or not to keep drawing a given octant.
    // For example: 0x00111100 means we're drawing in octants 2-5

    // 0 <= start & end < 360; note that sometimes start > end - if so, arc goes back through 0.
    while (start < 0) start += 360;
    while (end < 0) end += 360;
    /* Fixup angles */
    start = start % 360;
    end = end % 360;


    // now, we find which octants we're drawing in.
    startoct = start / 45;
    endoct = end / 45;
    oct = startoct - 1; // we increment as first step in loop

    //stopval_start, stopval_end; // what values of cx to stop at.
    do
    {
        oct = (oct + 1) % 8;

        if (oct == startoct)
        {
            // need to compute stopval_start for this octant.  Look at picture above if this is unclear
            switch (oct)
            {
            case 0:
            case 3:
                temp = sin(start * M_PI / 180);
                break;
            case 1:
            case 6:
                temp = cos(start * M_PI / 180);
                break;
            case 2:
            case 5:
                temp = -cos(start * M_PI / 180);
                break;
            case 4:
            case 7:
                temp = -sin(start * M_PI / 180);
                break;
            }
            temp *= r;
            stopval_start = (int)temp; // always round down.
            // This isn't arbitrary, but requires graph paper to explain well.
            // The basic idea is that we're always changing drawoct after we draw, so we
            // stop immediately after we render the last sensible pixel at x = ((int)temp).

            // and whether to draw in this octant initially
            if (oct % 2) drawoct |= (1 << oct); // this is basically like saying drawoct[oct] = true, if drawoct were a bool array
            else         drawoct &= 255 - (1 << oct); // this is basically like saying drawoct[oct] = false
        }

        if (oct == endoct)
        {
            // need to compute stopval_end for this octant
            switch (oct)
            {
            case 0:
            case 3:
                temp = sin(end * M_PI / 180);
                break;
            case 1:
            case 6:
                temp = cos(end * M_PI / 180);
                break;
            case 2:
            case 5:
                temp = -cos(end * M_PI / 180);
                break;
            case 4:
            case 7:
                temp = -sin(end * M_PI / 180);
                break;
            }
            temp *= r;
            stopval_end = (int)temp;

            // and whether to draw in this octant initially
            if (startoct == endoct)
            {
                // note:      we start drawing, stop, then start again in this case
                // otherwise: we only draw in this octant, so initialize it to false, it will get set back to true
                if (start > end)
                {
                    // unfortunately, if we're in the same octant and need to draw over the whole circle,
                    // we need to set the rest to true, because the while loop will end at the bottom.
                    drawoct = 255;
                }
                else
                {
                    drawoct &= 255 - (1 << oct);
                }
            }
            else if (oct % 2) drawoct &= 255 - (1 << oct);
            else              drawoct |= (1 << oct);
        }
        else if (oct != startoct)     // already verified that it's != endoct
        {
            drawoct |= (1 << oct); // draw this entire segment
        }
    }
    while (oct != endoct);

    // so now we have what octants to draw and when to draw them.  all that's left is the actual raster code.
    do
    {
        ypcy = y + cy;
        ymcy = y - cy;
        if (cx > 0)
        {
            xpcx = x + cx;
            xmcx = x - cx;
            // always check if we're drawing a certain octant before adding a pixel to that octant.
            if (drawoct & 4)  rtgui_dc_draw_point(dc, xmcx, ypcy); // drawoct & 4 = 22; drawoct[2]
            if (drawoct & 2)  rtgui_dc_draw_point(dc, xpcx, ypcy);
            if (drawoct & 32) rtgui_dc_draw_point(dc, xmcx, ymcy);
            if (drawoct & 64) rtgui_dc_draw_point(dc, xpcx, ymcy);
        }
        else
        {
            if (drawoct & 6)  rtgui_dc_draw_point(dc, x, ypcy); // 4 + 2; drawoct[2] || drawoct[1]
            if (drawoct & 96) rtgui_dc_draw_point(dc, x, ymcy); // 32 + 64
        }

        xpcy = x + cy;
        xmcy = x - cy;
        if (cx > 0 && cx != cy)
        {
            ypcx = y + cx;
            ymcx = y - cx;
            if (drawoct & 8)   rtgui_dc_draw_point(dc, xmcy, ypcx);
            if (drawoct & 1)   rtgui_dc_draw_point(dc, xpcy, ypcx);
            if (drawoct & 16)  rtgui_dc_draw_point(dc, xmcy, ymcx);
            if (drawoct & 128) rtgui_dc_draw_point(dc, xpcy, ymcx);
        }
        else if (cx == 0)
        {
            if (drawoct & 24)  rtgui_dc_draw_point(dc, xmcy, y); // 8 + 16
            if (drawoct & 129) rtgui_dc_draw_point(dc, xpcy, y); // 1 + 128
        }

        /*
        * Update whether we're drawing an octant
        */
        if (stopval_start == cx)
        {
            // works like an on-off switch because start & end may be in the same octant.
            if (drawoct & (1 << startoct)) drawoct &= 255 - (1 << startoct);
            else drawoct |= (1 << startoct);
        }
        if (stopval_end == cx)
        {
            if (drawoct & (1 << endoct)) drawoct &= 255 - (1 << endoct);
            else drawoct |= (1 << endoct);
        }

        /*
        * Update pixels
        */
        if (df < 0)
        {
            df += d_e;
            d_e += 2;
            d_se += 2;
        }
        else
        {
            df += d_se;
            d_e += 2;
            d_se += 4;
            cy--;
        }

        cx++;
    }
    while (cx <= cy);
}
RTM_EXPORT(rtgui_dc_draw_arc);

void rtgui_dc_draw_annulus(struct rtgui_dc *dc, rt_int16_t x, rt_int16_t y, rt_int16_t r1, rt_int16_t r2, rt_int16_t start, rt_int16_t end)
{
    rt_int16_t start_x, start_y;
    rt_int16_t end_x, end_y;
    double temp;
    rt_int16_t temp_val = 0;

    /* Sanity check radius */
    if ((r1 < 0) || (r2 < 0)) return ;
    /* Special case for r=0 - draw a point */
    if ((r1 == 0) && (r2 == 0))
    {
        rtgui_dc_draw_point(dc, x, y);
        return;
    }

    while (start < 0) start += 360;
    while (end < 0) end += 360;

    rtgui_dc_draw_arc(dc, x, y, r1, start, end);
    rtgui_dc_draw_arc(dc, x, y, r2, start, end);

    temp     = cos(start * M_PI / 180);
    temp_val = (int)(temp * r1);
    start_x  = x + temp_val;
    temp_val = (int)(temp * r2);
    end_x    = x + temp_val;

    temp     = sin(start * M_PI / 180);
    temp_val = (int)(temp * r1);
    start_y  = y + temp_val;
    temp_val = (int)(temp * r2);
    end_y    = y + temp_val;

    rtgui_dc_draw_line(dc, start_x, start_y, end_x, end_y);

    temp     = cos(end * M_PI / 180);
    temp_val = (int)(temp * r1);
    start_x  = x + temp_val;
    temp_val = (int)(temp * r2);
    end_x    = x + temp_val;

    temp     = sin(end * M_PI / 180);
    temp_val = (int)(temp * r1);
    start_y  = y + temp_val;
    temp_val = (int)(temp * r2);
    end_y    = y + temp_val;

    rtgui_dc_draw_line(dc, start_x, start_y, end_x, end_y);
}
RTM_EXPORT(rtgui_dc_draw_annulus);

void rtgui_dc_draw_sector(struct rtgui_dc *dc, rt_int16_t x, rt_int16_t y, rt_int16_t r, rt_int16_t start, rt_int16_t end)
{
    int start_x, start_y;
    int end_x, end_y;

    /* Sanity check radius */
    if (r < 0) return ;
    /* Special case for r=0 - draw a point */
    if (r == 0)
    {
        rtgui_dc_draw_point(dc, x, y);
        return;
    }

    while (start < 0) start += 360;
    while (end < 0) end += 360;

    /* Fixup angles */
    start = start % 360;
    end = end % 360;

    rtgui_dc_draw_arc(dc, x, y, r, start, end);

    start_x = x + r * cos(start * M_PI / 180);
    start_y = y + r * sin(start * M_PI / 180);

    end_x = x + r * cos(end * M_PI / 180);
    end_y = y + r * sin(end * M_PI / 180);

    rtgui_dc_draw_line(dc, x, y, start_x, start_y);
    rtgui_dc_draw_line(dc, x, y, end_x, end_y);
}
RTM_EXPORT(rtgui_dc_draw_sector);

void rtgui_dc_fill_sector(struct rtgui_dc *dc, rt_int16_t x, rt_int16_t y, rt_int16_t r, rt_int16_t start, rt_int16_t end)
{
    int start_x, start_y;
    int end_x, end_y;

    /* Sanity check radius */
    if (r < 0) return ;
    /* Special case for r=0 - draw a point */
    if (r == 0)
    {
        rtgui_dc_draw_point(dc, x, y);
        return;
    }

    while (start < 0) start += 360;
    while (end < 0) end += 360;

    /* Fixup angles */
    start = start % 360;
    end = end % 360;

    end_x = x + r * cos(end * M_PI / 180);
    end_y = y + r * sin(end * M_PI / 180);

    do
    {
        start_x = x + r * cos(start * M_PI / 180);
        start_y = y + r * sin(start * M_PI / 180);
        start ++;

        rtgui_dc_draw_line(dc, x, y, start_x, start_y);
    }
    while (!((start_x == end_x) && (start_y == end_y)));
}
RTM_EXPORT(rtgui_dc_fill_sector);

void rtgui_dc_draw_ellipse(struct rtgui_dc *dc, rt_int16_t x, rt_int16_t y, rt_int16_t rx, rt_int16_t ry)
{
    int ix, iy;
    int h, i, j, k;
    int oh, oi, oj, ok;
    int xmh, xph, ypk, ymk;
    int xmi, xpi, ymj, ypj;
    int xmj, xpj, ymi, ypi;
    int xmk, xpk, ymh, yph;

    /*
     * Sanity check radii
     */
    if ((rx < 0) || (ry < 0))  return;

    /*
     * Special case for rx=0 - draw a vline
     */
    if (rx == 0)
    {
        rtgui_dc_draw_vline(dc, x, y - ry, y + ry);
        return;
    }

    /*
     * Special case for ry=0 - draw a hline
     */
    if (ry == 0)
    {
        rtgui_dc_draw_hline(dc, x - rx, x + rx, y);
        return;
    }

    /*
     * Init vars
     */
    oh = oi = oj = ok = 0xFFFF;

    if (rx > ry)
    {
        ix = 0;
        iy = rx * 64;

        do
        {
            h = (ix + 32) >> 6;
            i = (iy + 32) >> 6;
            j = (h * ry) / rx;
            k = (i * ry) / rx;

            if (((ok != k) && (oj != k)) || ((oj != j) && (ok != j)) || (k != j))
            {
                xph = x + h;
                xmh = x - h;
                if (k > 0)
                {
                    ypk = y + k;
                    ymk = y - k;
                    rtgui_dc_draw_point(dc, xmh, ypk);
                    rtgui_dc_draw_point(dc, xph, ypk);
                    rtgui_dc_draw_point(dc, xmh, ymk);
                    rtgui_dc_draw_point(dc, xph, ymk);
                }
                else
                {
                    rtgui_dc_draw_point(dc, xmh, y);
                    rtgui_dc_draw_point(dc, xph, y);
                }
                ok = k;
                xpi = x + i;
                xmi = x - i;
                if (j > 0)
                {
                    ypj = y + j;
                    ymj = y - j;
                    rtgui_dc_draw_point(dc, xmi, ypj);
                    rtgui_dc_draw_point(dc, xpi, ypj);
                    rtgui_dc_draw_point(dc, xmi, ymj);
                    rtgui_dc_draw_point(dc, xpi, ymj);
                }
                else
                {
                    rtgui_dc_draw_point(dc, xmi, y);
                    rtgui_dc_draw_point(dc, xpi, y);
                }
                oj = j;
            }

            ix = ix + iy / rx;
            iy = iy - ix / rx;
        }
        while (i > h);
    }
    else
    {
        ix = 0;
        iy = ry * 64;

        do
        {
            h = (ix + 32) >> 6;
            i = (iy + 32) >> 6;
            j = (h * rx) / ry;
            k = (i * rx) / ry;

            if (((oi != i) && (oh != i)) || ((oh != h) && (oi != h) && (i != h)))
            {
                xmj = x - j;
                xpj = x + j;
                if (i > 0)
                {
                    ypi = y + i;
                    ymi = y - i;
                    rtgui_dc_draw_point(dc, xmj, ypi);
                    rtgui_dc_draw_point(dc, xpj, ypi);
                    rtgui_dc_draw_point(dc, xmj, ymi);
                    rtgui_dc_draw_point(dc, xpj, ymi);
                }
                else
                {
                    rtgui_dc_draw_point(dc, xmj, y);
                    rtgui_dc_draw_point(dc, xpj, y);
                }
                oi = i;
                xmk = x - k;
                xpk = x + k;
                if (h > 0)
                {
                    yph = y + h;
                    ymh = y - h;
                    rtgui_dc_draw_point(dc, xmk, yph);
                    rtgui_dc_draw_point(dc, xpk, yph);
                    rtgui_dc_draw_point(dc, xmk, ymh);
                    rtgui_dc_draw_point(dc, xpk, ymh);
                }
                else
                {
                    rtgui_dc_draw_point(dc, xmk, y);
                    rtgui_dc_draw_point(dc, xpk, y);
                }
                oh = h;
            }

            ix = ix + iy / ry;
            iy = iy - ix / ry;
        }
        while (i > h);
    }
}
RTM_EXPORT(rtgui_dc_draw_ellipse);

void rtgui_dc_fill_ellipse(struct rtgui_dc *dc, rt_int16_t x, rt_int16_t y, rt_int16_t rx, rt_int16_t ry)
{
    int ix, iy;
    int h, i, j, k;
    int oh, oi, oj, ok;
    int xmh, xph;
    int xmi, xpi;
    int xmj, xpj;
    int xmk, xpk;

    /*
     * Special case for rx=0 - draw a vline
     */
    if (rx == 0)
    {
        rtgui_dc_draw_vline(dc, x, y - ry, y + ry);
        return;
    }

    /* special case for ry=0 - draw a hline  */
    if (ry == 0)
    {
        rtgui_dc_draw_hline(dc, x - rx, x + rx, y);
        return;
    }

    /*
     * Init vars
     */
    oh = oi = oj = ok = 0xFFFF;

    /*
     * Draw
     */
    if (rx > ry)
    {
        ix = 0;
        iy = rx * 64;

        do
        {
            h = (ix + 32) >> 6;
            i = (iy + 32) >> 6;
            j = (h * ry) / rx;
            k = (i * ry) / rx;

            if ((ok != k) && (oj != k))
            {
                xph = x + h;
                xmh = x - h;
                if (k > 0)
                {
                    rtgui_dc_draw_hline(dc, xmh, xph, y + k);
                    rtgui_dc_draw_hline(dc, xmh, xph, y - k);
                }
                else
                {
                    rtgui_dc_draw_hline(dc, xmh, xph, y);
                }
                ok = k;
            }
            if ((oj != j) && (ok != j) && (k != j))
            {
                xmi = x - i;
                xpi = x + i;
                if (j > 0)
                {
                    rtgui_dc_draw_hline(dc, xmi, xpi, y + j);
                    rtgui_dc_draw_hline(dc, xmi, xpi, y - j);
                }
                else
                {
                    rtgui_dc_draw_hline(dc, xmi, xpi, y);
                }
                oj = j;
            }

            ix = ix + iy / rx;
            iy = iy - ix / rx;

        }
        while (i > h);
    }
    else
    {
        ix = 0;
        iy = ry * 64;

        do
        {
            h = (ix + 32) >> 6;
            i = (iy + 32) >> 6;
            j = (h * rx) / ry;
            k = (i * rx) / ry;

            if ((oi != i) && (oh != i))
            {
                xmj = x - j;
                xpj = x + j;
                if (i > 0)
                {
                    rtgui_dc_draw_hline(dc, xmj, xpj, y + i);
                    rtgui_dc_draw_hline(dc, xmj, xpj, y - i);
                }
                else
                {
                    rtgui_dc_draw_hline(dc, xmj, xpj, y);
                }
                oi = i;
            }
            if ((oh != h) && (oi != h) && (i != h))
            {
                xmk = x - k;
                xpk = x + k;
                if (h > 0)
                {
                    rtgui_dc_draw_hline(dc, xmk, xpk, y + h);
                    rtgui_dc_draw_hline(dc, xmk, xpk, y - h);
                }
                else
                {
                    rtgui_dc_draw_hline(dc, xmk, xpk, y);
                }
                oh = h;
            }
            ix = ix + iy / ry;
            iy = iy - ix / ry;
        }
        while (i > h);
    }
}
RTM_EXPORT(rtgui_dc_fill_ellipse);