106 lines
3.0 KiB
PHP
106 lines
3.0 KiB
PHP
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/*adapted from :
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* http://rosettacode.org/wiki/Xiaolin_Wu%27s_line_algorithm#C
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*/
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#define plot_(X, Y, D) \
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p.x = (X); \
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p.y = (Y); \
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if (p.x >= xmin && p.x <= xmax && p.y >= ymin && p.y <= ymax) { \
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color->rgba.a = (D)*0xff; \
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lcd_draw_points(lcd, &p, 1); \
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}
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#define ipart_(X) ((int)(X))
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#define round_(X) ((int)(((double)(X)) + 0.5))
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#define fpart_(X) (((double)(X)) - (double)ipart_(X))
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#define rfpart_(X) (1.0 - fpart_(X))
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#define fabs(xx) ((xx) < 0 ? -(xx) : (xx))
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#define swap_(a, b) \
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do { \
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unsigned int tmp = a; \
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a = b; \
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b = tmp; \
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} while (0)
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void draw_line(canvas_t* c, int x1, int y1, int x2, int y2) {
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rect_t r;
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point_t p;
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lcd_t* lcd = c->lcd;
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xy_t xmin, xmax, ymin, ymax;
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color_t* color = &(c->lcd->stroke_color);
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double dx = (double)x2 - (double)x1;
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double dy = (double)y2 - (double)y1;
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canvas_get_clip_rect(c, &r);
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xmin = r.x;
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xmax = r.x + r.w - 1;
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ymin = r.y;
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ymax = r.y + r.h - 1;
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if (fabs(dx) > fabs(dy)) {
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if (x2 < x1) {
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swap_(x1, x2);
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swap_(y1, y2);
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}
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double gradient = dy / dx;
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double xend = round_(x1);
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double yend = y1 + gradient * (xend - x1);
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double xgap = rfpart_(x1 + 0.5);
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int xpxl1 = xend;
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int ypxl1 = ipart_(yend);
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plot_(xpxl1, ypxl1, rfpart_(yend) * xgap);
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plot_(xpxl1, ypxl1 + 1, fpart_(yend) * xgap);
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double intery = yend + gradient;
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xend = round_(x2);
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yend = y2 + gradient * (xend - x2);
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xgap = fpart_(x2 + 0.5);
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int xpxl2 = xend;
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int ypxl2 = ipart_(yend);
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plot_(xpxl2, ypxl2, rfpart_(yend) * xgap);
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plot_(xpxl2, ypxl2 + 1, fpart_(yend) * xgap);
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int x;
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for (x = xpxl1 + 1; x <= (xpxl2 - 1); x++) {
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plot_(x, ipart_(intery), rfpart_(intery));
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plot_(x, ipart_(intery) + 1, fpart_(intery));
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intery += gradient;
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}
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} else {
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if (y2 < y1) {
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swap_(x1, x2);
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swap_(y1, y2);
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}
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double gradient = dx / dy;
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double yend = round_(y1);
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double xend = x1 + gradient * (yend - y1);
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double ygap = rfpart_(y1 + 0.5);
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int ypxl1 = yend;
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int xpxl1 = ipart_(xend);
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plot_(xpxl1, ypxl1, rfpart_(xend) * ygap);
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plot_(xpxl1, ypxl1 + 1, fpart_(xend) * ygap);
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double interx = xend + gradient;
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yend = round_(y2);
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xend = x2 + gradient * (yend - y2);
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ygap = fpart_(y2 + 0.5);
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int ypxl2 = yend;
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int xpxl2 = ipart_(xend);
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plot_(xpxl2, ypxl2, rfpart_(xend) * ygap);
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plot_(xpxl2, ypxl2 + 1, fpart_(xend) * ygap);
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int y;
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for (y = ypxl1 + 1; y <= (ypxl2 - 1); y++) {
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plot_(ipart_(interx), y, rfpart_(interx));
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plot_(ipart_(interx) + 1, y, fpart_(interx));
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interx += gradient;
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}
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}
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}
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#undef swap_
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#undef plot_
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#undef ipart_
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#undef fpart_
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#undef round_
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#undef rfpart_
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