diff options
Diffstat (limited to 'util')
| -rw-r--r-- | util/region.c | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/util/region.c b/util/region.c index 38f84c5e..76df71f3 100644 --- a/util/region.c +++ b/util/region.c @@ -1,5 +1,8 @@ +#include <assert.h> #include <math.h> +#include <limits.h> #include <stdlib.h> +#include <wlr/types/wlr_box.h> #include <wlr/util/region.h> void wlr_region_scale(pixman_region32_t *dst, pixman_region32_t *src, @@ -177,3 +180,71 @@ void wlr_region_rotated_bounds(pixman_region32_t *dst, pixman_region32_t *src, pixman_region32_init_rects(dst, dst_rects, nrects); free(dst_rects); } + +static void region_confine(pixman_region32_t *region, double x1, double y1, double x2, + double y2, double *x2_out, double *y2_out, pixman_box32_t box) { + double x_clamped = fmax(fmin(x2, box.x2 - 1), box.x1); + double y_clamped = fmax(fmin(y2, box.y2 - 1), box.y1); + + // If the target coordinates are above box.{x,y}2 - 1, but less than + // box.{x,y}2, then they are still within the box. + if (floor(x_clamped) == floor(x2) && floor(y_clamped) == floor(y2)) { + *x2_out = x2; + *y2_out = y2; + return; + } + + double dx = x2 - x1; + double dy = y2 - y1; + + // We use fabs to avoid negative zeroes and thus avoid a bug + // with negative infinity. + double delta = fmin(fabs(x_clamped - x1) / fabs(dx), fabs(y_clamped - y1) / fabs(dy)); + + // We clamp it again due to precision errors. + double x = fmax(fmin(delta * dx + x1, box.x2 - 1), box.x1); + double y = fmax(fmin(delta * dy + y1, box.y2 - 1), box.y1); + + // Go one unit past the boundary to find an adjacent box. + int x_ext = floor(x) + (dx == 0 ? 0 : dx > 0 ? 1 : -1); + int y_ext = floor(y) + (dy == 0 ? 0 : dy > 0 ? 1 : -1); + + if (pixman_region32_contains_point(region, x_ext, y_ext, &box)) { + return region_confine(region, x1, y1, x2, y2, x2_out, y2_out, box); + } else if (dx == 0 || dy == 0) { + *x2_out = x; + *y2_out = y; + } else { + bool bordering_x = x == box.x1 || x == box.x2 - 1; + bool bordering_y = y == box.y1 || y == box.y2 - 1; + + if ((bordering_x && bordering_y) || (!bordering_x && !bordering_y)) { + double x2_potential, y2_potential; + double tmp1, tmp2; + region_confine(region, x, y, x, y2, &tmp1, &y2_potential, box); + region_confine(region, x, y, x2, y, &x2_potential, &tmp2, box); + if (fabs(x2_potential - x) > fabs(y2_potential - y)) { + *x2_out = x2_potential; + *y2_out = y; + } else { + *x2_out = x; + *y2_out = y2_potential; + } + } else if (bordering_x) { + return region_confine(region, x, y, x, y2, x2_out, y2_out, box); + } else if (bordering_y) { + return region_confine(region, x, y, x2, y, x2_out, y2_out, box); + } + } +} + +bool wlr_region_confine(pixman_region32_t *region, double x1, double y1, double x2, + double y2, double *x2_out, double *y2_out) { + pixman_box32_t box; + if (pixman_region32_contains_point(region, x1, y1, &box)) { + region_confine(region, x1, y1, x2, y2, x2_out, y2_out, box); + return true; + } else { + return false; + } +} |