927176bc16
Add code to draw simple graphics, namely lines(solid or dashed) and circles. Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
200 lines
3.9 KiB
C
200 lines
3.9 KiB
C
#include <common.h>
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#include <fb.h>
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#include <gui/graphic_utils.h>
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#include <linux/stat.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <fs.h>
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#include <malloc.h>
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static void __illuminate(struct fb_info *info,
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int x, int y,
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u8 r, u8 g, u8 b, u8 a)
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{
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void *pixel;
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pixel = fb_get_screen_base(info);
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pixel += y * info->line_length + x * (info->bits_per_pixel >> 3);
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gu_set_rgba_pixel(info, pixel, r, g, b, a);
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}
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static void illuminate(struct fb_info *info,
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bool invert,
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int x, int y,
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u8 r, u8 g, u8 b, u8 a)
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{
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if (invert)
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__illuminate(info, y, x,
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r, g, b, a);
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else
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__illuminate(info, x, y,
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r, g, b, a);
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}
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static void draw_simple_line(struct screen *sc,
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int x1, int y1,
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int x2, int y2,
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u8 r, u8 g, u8 b, u8 a,
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unsigned int dash)
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{
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int x;
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bool invert = false;
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unsigned int pixel = 0;
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BUG_ON(x1 != x2 &&
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y1 != y2);
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if (x1 == x2) {
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swap(x1, y1);
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swap(x2, y2);
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invert = true;
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}
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if (x1 > x2) {
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swap(x1, x2);
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swap(y1, y2);
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}
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for (x = x1; x < x2 - 1; x++) {
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if (!dash ||
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(++pixel % (2 * dash)) < dash)
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illuminate(sc->info,
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invert,
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x, y1,
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r, g, b, a);
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}
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}
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/**
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* gl_draw_line - draw a 2D dashed line between (x1, y1) and (x2,y2)
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*
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* @sc: screen to draw on
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* @x1, @y1: first point defining the line
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* @x2, @y2: second point defining the line
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* @r, @g, @b, @a: line's color
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* @dash: dash length (0 denotes solid line)
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*
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* gl_draw_line() implements integer version of Bresenham's algoritm
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* as can be found here:
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*
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* http://www.idav.ucdavis.edu/education/GraphicsNotes/Bresenhams-Algorithm.pdf
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*/
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void gu_draw_line(struct screen *sc,
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int x1, int y1,
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int x2, int y2,
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u8 r, u8 g, u8 b, u8 a,
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unsigned int dash)
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{
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int dx;
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int dy;
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int i, j, eps;
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bool invert = false;
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unsigned int pixel = 0;
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BUG_ON(x1 < 0 || y1 < 0 ||
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x2 < 0 || y2 < 0);
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if (x1 == x2 || y1 == y2) {
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draw_simple_line(sc,
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x1, y1,
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x2, y2,
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r, g, b, a, dash);
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return;
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}
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dx = abs(x2 - x1);
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dy = abs(y2 - y1);
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/*
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* First thing we need to determine "Driving Axis", as can be
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* seen below if Y-axis projection of the line is bigger than
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* X-axis projection we swap axes and pretend the X is Y and
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* vice versa
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*/
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if (dy > dx) {
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swap(x1, y1);
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swap(x2, y2);
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swap(dx, dy);
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invert = true;
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}
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/*
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* Second, we need to make sure that we will be traversing
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* driving axis in the direction of increment so we swap point
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* 1 with point 2 if x1 is greater than x2
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*/
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if (x1 > x2) {
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swap(x1, x2);
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swap(y1, y2);
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}
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j = y1;
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eps = dy - dx;
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for (i = x1; i <= x2 - 1; i++) {
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if (!dash ||
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(++pixel % (2 * dash)) > dash) {
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illuminate(sc->info,
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invert,
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j, i,
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r, g, b, a);
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} else {
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printf("NOT illuminating pixel: %d\n", pixel);
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}
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if (eps >= 0) {
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j += 1;
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eps -= dx;
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}
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eps += dy;
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}
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}
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/**
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* gl_draw_circle - draw a 2D circle with center at (x0, y0)
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*
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* @sc: screen to draw on
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* @x0, @y0: coordinates of circle's center
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* @radius: circle's radius
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* @r, @g, @b, @a: circle's color
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*
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* gu_draw_circle() implements midpoint circle algorithm as can be
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* found here:
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*
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* https://en.wikipedia.org/wiki/Midpoint_circle_algorithm
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*/
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void gu_draw_circle(struct screen *sc,
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int x0, int y0, int radius,
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u8 r, u8 g, u8 b, u8 a)
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{
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int x = radius;
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int y = 0;
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int e = 0;
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BUG_ON(x0 < 0 || y0 < 0 || radius < 0);
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while (x >= y) {
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__illuminate(sc->info, x0 + x, y0 + y, r, g, b, a);
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__illuminate(sc->info, x0 + y, y0 + x, r, g, b, a);
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__illuminate(sc->info, x0 - y, y0 + x, r, g, b, a);
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__illuminate(sc->info, x0 - x, y0 + y, r, g, b, a);
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__illuminate(sc->info, x0 - x, y0 - y, r, g, b, a);
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__illuminate(sc->info, x0 - y, y0 - x, r, g, b, a);
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__illuminate(sc->info, x0 + y, y0 - x, r, g, b, a);
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__illuminate(sc->info, x0 + x, y0 - y, r, g, b, a);
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y += 1;
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e += 1 + 2 * y;
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if (2 * (e - x) + 1 > 0) {
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x -= 1;
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e += 1 - 2 * x;
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}
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}
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}
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