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| #include <stdbool.h> |
| |
| #define NULL 0 |
| #include "palette.h" |
| #include "libnsfb.h" |
| #include "libnsfb_plot.h" |
| #include "libnsfb_plot_util.h" |
| |
| #include "nsfb.h" |
| |
| enum { |
| POINT_LEFTOF_REGION = 1, |
| POINT_RIGHTOF_REGION = 2, |
| POINT_ABOVE_REGION = 4, |
| POINT_BELOW_REGION = 8, |
| }; |
| |
| #define REGION(x,y,cx1,cx2,cy1,cy2) \ |
| ( ( (y) > (cy2) ? POINT_BELOW_REGION : 0) | \ |
| ( (y) < (cy1) ? POINT_ABOVE_REGION : 0) | \ |
| ( (x) > (cx2) ? POINT_RIGHTOF_REGION : 0) | \ |
| ( (x) < (cx1) ? POINT_LEFTOF_REGION : 0) ) |
| |
| #define SWAP(a, b) do { int t; t=(a); (a)=(b); (b)=t; } while(0) |
| |
| /* clip a rectangle with another clipping rectangle. |
| * |
| * @param clip The rectangle to clip to. |
| * @param rect The rectangle to clip. |
| * @return false if the \a rect lies completely outside the \a clip rectangle, |
| * true if some of the \a rect is still visible. |
| */ |
| bool |
| nsfb_plot_clip(const nsfb_bbox_t * clip, nsfb_bbox_t * rect) |
| { |
| char region1; |
| char region2; |
| |
| if (rect->x1 < rect->x0) SWAP(rect->x0, rect->x1); |
| |
| if (rect->y1 < rect->y0) SWAP(rect->y0, rect->y1); |
| |
| region1 = REGION(rect->x0, rect->y0, clip->x0, clip->x1 - 1, clip->y0, clip->y1 - 1); |
| region2 = REGION(rect->x1, rect->y1, clip->x0, clip->x1 - 1, clip->y0, clip->y1 - 1); |
| |
| /* area lies entirely outside the clipping rectangle */ |
| if ((region1 | region2) && (region1 & region2)) |
| return false; |
| |
| if (rect->x0 < clip->x0) |
| rect->x0 = clip->x0; |
| if (rect->x0 > clip->x1) |
| rect->x0 = clip->x1; |
| |
| if (rect->x1 < clip->x0) |
| rect->x1 = clip->x0; |
| if (rect->x1 > clip->x1) |
| rect->x1 = clip->x1; |
| |
| if (rect->y0 < clip->y0) |
| rect->y0 = clip->y0; |
| if (rect->y0 > clip->y1) |
| rect->y0 = clip->y1; |
| |
| if (rect->y1 < clip->y0) |
| rect->y1 = clip->y0; |
| if (rect->y1 > clip->y1) |
| rect->y1 = clip->y1; |
| |
| return true; |
| } |
| |
| bool |
| nsfb_plot_clip_ctx(nsfb_t *nsfb, nsfb_bbox_t * rect) |
| { |
| return nsfb_plot_clip(&nsfb->clip, rect); |
| } |
| |
| /** Clip a line to a bounding box. |
| */ |
| bool nsfb_plot_clip_line(const nsfb_bbox_t *clip, nsfb_bbox_t * line) |
| { |
| char region1; |
| char region2; |
| region1 = REGION(line->x0, line->y0, clip->x0, clip->x1 - 1, clip->y0, clip->y1 - 1); |
| region2 = REGION(line->x1, line->y1, clip->x0, clip->x1 - 1, clip->y0, clip->y1 - 1); |
| |
| while (region1 | region2) { |
| if (region1 & region2) { |
| /* line lies entirely outside the clipping rectangle */ |
| return false; |
| } |
| |
| if (region1) { |
| /* first point */ |
| if (region1 & POINT_BELOW_REGION) { |
| /* divide line at bottom */ |
| line->x0 = (line->x0 + (line->x1 - line->x0) * |
| (clip->y1 - 1 - line->y0) / (line->y1 - line->y0)); |
| line->y0 = clip->y1 - 1; |
| } else if (region1 & POINT_ABOVE_REGION) { |
| /* divide line at top */ |
| line->x0 = (line->x0 + (line->x1 - line->x0) * |
| (clip->y0 - line->y0) / (line->y1 - line->y0)); |
| line->y0 = clip->y0; |
| } else if (region1 & POINT_RIGHTOF_REGION) { |
| /* divide line at right */ |
| line->y0 = (line->y0 + (line->y1 - line->y0) * |
| (clip->x1 - 1 - line->x0) / (line->x1 - line->x0)); |
| line->x0 = clip->x1 - 1; |
| } else if (region1 & POINT_LEFTOF_REGION) { |
| /* divide line at right */ |
| line->y0 = (line->y0 + (line->y1 - line->y0) * |
| (clip->x0 - line->x0) / (line->x1 - line->x0)); |
| line->x0 = clip->x0; |
| } |
| |
| region1 = REGION(line->x0, line->y0, clip->x0, clip->x1 - 1, clip->y0, clip->y1 - 1); |
| } else { |
| /* second point */ |
| if (region2 & POINT_BELOW_REGION) { |
| /* divide line at bottom*/ |
| line->x1 = (line->x0 + (line->x1 - line->x0) * |
| (clip->y1 - 1 - line->y0) / (line->y1 - line->y0)); |
| line->y1 = clip->y1 - 1; |
| } else if (region2 & POINT_ABOVE_REGION) { |
| /* divide line at top*/ |
| line->x1 = (line->x0 + (line->x1 - line->x0) * |
| (clip->y0 - line->y0) / (line->y1 - line->y0)); |
| line->y1 = clip->y0; |
| } else if (region2 & POINT_RIGHTOF_REGION) { |
| /* divide line at right*/ |
| line->y1 = (line->y0 + (line->y1 - line->y0) * |
| (clip->x1 - 1 - line->x0) / (line->x1 - line->x0)); |
| line->x1 = clip->x1 - 1; |
| } else if (region2 & POINT_LEFTOF_REGION) { |
| /* divide line at right*/ |
| line->y1 = (line->y0 + (line->y1 - line->y0) * |
| (clip->x0 - line->x0) / (line->x1 - line->x0)); |
| line->x1 = clip->x0; |
| } |
| |
| region2 = REGION(line->x1, line->y1, clip->x0, clip->x1 - 1, clip->y0, clip->y1 - 1); |
| } |
| } |
| |
| return true; |
| } |
| |
| bool nsfb_plot_clip_line_ctx(nsfb_t *nsfb, nsfb_bbox_t * line) |
| { |
| return nsfb_plot_clip_line(&nsfb->clip, line); |
| } |
| |
| /* documented in libnsfb_plot_util.h */ |
| bool |
| nsfb_plot_add_rect(const nsfb_bbox_t *box1, const nsfb_bbox_t *box2, nsfb_bbox_t *result) |
| { |
| /* lower x coordinate */ |
| if (box1->x0 < box2->x0) |
| result->x0 = box1->x0; |
| else |
| result->x0 = box2->x0; |
| |
| /* lower y coordinate */ |
| if (box1->y0 < box2->y0) |
| result->y0 = box1->y0; |
| else |
| result->y0 = box2->y0; |
| |
| /* upper x coordinate */ |
| if (box1->x1 > box2->x1) |
| result->x1 = box1->x1; |
| else |
| result->x1 = box2->x1; |
| |
| /* upper y coordinate */ |
| if (box1->y1 > box2->y1) |
| result->y1 = box1->y1; |
| else |
| result->y1 = box2->y1; |
| |
| return true; |
| } |
| |
| bool nsfb_plot_bbox_intersect(const nsfb_bbox_t *box1, const nsfb_bbox_t *box2) |
| { |
| if (box2->x1 < box1->x0) |
| return false; |
| |
| if (box2->y1 < box1->y0) |
| return false; |
| |
| if (box2->x0 > box1->x1) |
| return false; |
| |
| if (box2->y0 > box1->y1) |
| return false; |
| |
| return true; |
| } |