mirror of
https://github.com/mpv-player/mpv
synced 2024-12-25 16:33:02 +00:00
200 lines
6.9 KiB
C
200 lines
6.9 KiB
C
/*
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* Calculate how to pack bitmap rectangles into a larger surface
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*
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* Copyright 2009, 2012 Uoti Urpala
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*
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* This file is part of mpv.
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*
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* mpv is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* mpv is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with mpv. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdlib.h>
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#include <assert.h>
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#include <stdio.h>
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#include <limits.h>
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#include <libavutil/common.h>
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#include "mpv_talloc.h"
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#include "bitmap_packer.h"
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#include "common/common.h"
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#define IS_POWER_OF_2(x) (((x) > 0) && !(((x) - 1) & (x)))
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void packer_reset(struct bitmap_packer *packer)
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{
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struct bitmap_packer old = *packer;
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*packer = (struct bitmap_packer) {
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.w_max = old.w_max,
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.h_max = old.h_max,
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};
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talloc_free_children(packer);
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}
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void packer_get_bb(struct bitmap_packer *packer, struct pos out_bb[2])
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{
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out_bb[0] = (struct pos) {0};
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out_bb[1] = (struct pos) {packer->used_width, packer->used_height};
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}
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#define HEIGHT_SORT_BITS 4
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static int size_index(int s)
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{
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int n = av_log2_16bit(s);
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return (n << HEIGHT_SORT_BITS)
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+ ((- 1 - (s << HEIGHT_SORT_BITS >> n)) & ((1 << HEIGHT_SORT_BITS) - 1));
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}
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/* Pack the given rectangles into an area of size w * h.
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* The size of each rectangle is read from in[i].x / in[i].y.
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* The height of each rectangle must be less than 65536.
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* 'scratch' must point to work memory for num_rects+16 ints.
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* The packed position for rectangle number i is set in out[i].
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* Return 0 on success, -1 if the rectangles did not fit in w*h.
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*
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* The rectangles are placed in rows in order approximately sorted by
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* height (the approximate sorting is simpler than a full one would be,
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* and allows the algorithm to work in linear time). Additionally, to
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* reduce wasted space when there are a few tall rectangles, empty
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* lower-right parts of rows are filled recursively when the size of
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* rectangles in the row drops past a power-of-two threshold. So if a
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* row starts with rectangles of size 3x50, 10x40 and 5x20 then the
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* free rectangle with corners (13, 20)-(w, 50) is filled recursively.
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*/
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static int pack_rectangles(struct pos *in, struct pos *out, int num_rects,
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int w, int h, int *scratch, int *used_width)
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{
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int bins[16 << HEIGHT_SORT_BITS];
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int sizes[16 << HEIGHT_SORT_BITS] = { 0 };
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for (int i = 0; i < num_rects; i++)
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sizes[size_index(in[i].y)]++;
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int idx = 0;
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for (int i = 0; i < 16 << HEIGHT_SORT_BITS; i += 1 << HEIGHT_SORT_BITS) {
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for (int j = 0; j < 1 << HEIGHT_SORT_BITS; j++) {
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bins[i + j] = idx;
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idx += sizes[i + j];
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}
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scratch[idx++] = -1;
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}
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for (int i = 0; i < num_rects; i++)
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scratch[bins[size_index(in[i].y)]++] = i;
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for (int i = 0; i < 16; i++)
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bins[i] = bins[i << HEIGHT_SORT_BITS] - sizes[i << HEIGHT_SORT_BITS];
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struct {
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int size, x, bottom;
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} stack[16] = {{15, 0, h}}, s = {};
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int stackpos = 1;
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int y;
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while (stackpos) {
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y = s.bottom;
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s = stack[--stackpos];
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s.size++;
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while (s.size--) {
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int maxy = -1;
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int obj;
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while ((obj = scratch[bins[s.size]]) >= 0) {
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int bottom = y + in[obj].y;
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if (bottom > s.bottom)
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break;
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int right = s.x + in[obj].x;
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if (right > w)
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break;
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bins[s.size]++;
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out[obj] = (struct pos){s.x, y};
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num_rects--;
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if (maxy < 0)
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stack[stackpos++] = s;
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s.x = right;
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maxy = FFMAX(maxy, bottom);
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}
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*used_width = FFMAX(*used_width, s.x);
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if (maxy > 0)
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s.bottom = maxy;
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}
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}
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return num_rects ? -1 : y;
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}
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int packer_pack(struct bitmap_packer *packer)
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{
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if (packer->count == 0)
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return 0;
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int w_orig = packer->w, h_orig = packer->h;
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struct pos *in = packer->in;
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int xmax = 0, ymax = 0;
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for (int i = 0; i < packer->count; i++) {
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if (in[i].x <= 0 || in[i].y <= 0) {
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in[i] = (struct pos){0, 0};
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} else {
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in[i].x += packer->padding * 2;
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in[i].y += packer->padding * 2;
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}
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if (in[i].x < 0 || in [i].x > 65535 || in[i].y < 0 || in[i].y > 65535) {
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fprintf(stderr, "Invalid OSD / subtitle bitmap size\n");
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abort();
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}
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xmax = FFMAX(xmax, in[i].x);
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ymax = FFMAX(ymax, in[i].y);
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}
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if (xmax > packer->w)
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packer->w = 1 << (av_log2(xmax - 1) + 1);
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if (ymax > packer->h)
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packer->h = 1 << (av_log2(ymax - 1) + 1);
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while (1) {
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int used_width = 0;
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int y = pack_rectangles(in, packer->result, packer->count,
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packer->w, packer->h,
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packer->scratch, &used_width);
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if (y >= 0) {
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packer->used_width = FFMIN(used_width, packer->w);
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packer->used_height = FFMIN(y, packer->h);
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assert(packer->w == 0 || IS_POWER_OF_2(packer->w));
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assert(packer->h == 0 || IS_POWER_OF_2(packer->h));
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if (packer->padding) {
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for (int i = 0; i < packer->count; i++) {
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packer->result[i].x += packer->padding;
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packer->result[i].y += packer->padding;
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}
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}
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return packer->w != w_orig || packer->h != h_orig;
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}
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int w_max = packer->w_max > 0 ? packer->w_max : INT_MAX;
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int h_max = packer->h_max > 0 ? packer->h_max : INT_MAX;
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if (packer->w <= packer->h && packer->w != w_max)
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packer->w = FFMIN(packer->w * 2, w_max);
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else if (packer->h != h_max)
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packer->h = FFMIN(packer->h * 2, h_max);
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else {
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packer->w = w_orig;
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packer->h = h_orig;
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return -1;
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}
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}
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}
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void packer_set_size(struct bitmap_packer *packer, int size)
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{
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packer->count = size;
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if (size <= packer->asize)
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return;
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packer->asize = FFMAX(packer->asize * 2, size);
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talloc_free(packer->result);
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talloc_free(packer->scratch);
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packer->in = talloc_realloc(packer, packer->in, struct pos, packer->asize);
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packer->result = talloc_array_ptrtype(packer, packer->result,
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packer->asize);
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packer->scratch = talloc_array_ptrtype(packer, packer->scratch,
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packer->asize + 16);
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}
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