Beginning GIF export
Beginning addition of an option to export animated GIFs from the Open -> Slideshow dialog, after choosing the images. Non-operable at this time, but a button has been added (and will provide a hint to select 2 or more images, when clicked).
This commit is contained in:
Bill Kendrick
parent
3ede0b96bf
commit
8c3a07294b
7 changed files with 408 additions and 16 deletions
287
src/gifenc.c
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287
src/gifenc.c
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#include "gifenc.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#ifdef _WIN32
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#include <io.h>
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#else
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#include <unistd.h>
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#endif
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/* helper to write a little-endian 16-bit number portably */
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#define write_num(fd, n) write((fd), (uint8_t []) {(n) & 0xFF, (n) >> 8}, 2)
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static uint8_t vga[0x30] = {
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0x00, 0x00, 0x00,
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0xAA, 0x00, 0x00,
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0x00, 0xAA, 0x00,
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0xAA, 0x55, 0x00,
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0x00, 0x00, 0xAA,
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0xAA, 0x00, 0xAA,
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0x00, 0xAA, 0xAA,
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0xAA, 0xAA, 0xAA,
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0x55, 0x55, 0x55,
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0xFF, 0x55, 0x55,
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0x55, 0xFF, 0x55,
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0xFF, 0xFF, 0x55,
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0x55, 0x55, 0xFF,
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0xFF, 0x55, 0xFF,
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0x55, 0xFF, 0xFF,
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0xFF, 0xFF, 0xFF,
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};
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struct Node {
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uint16_t key;
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struct Node *children[];
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};
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typedef struct Node Node;
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static Node *
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new_node(uint16_t key, int degree)
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{
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Node *node = calloc(1, sizeof(*node) + degree * sizeof(Node *));
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if (node)
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node->key = key;
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return node;
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}
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static Node *
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new_trie(int degree, int *nkeys)
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{
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Node *root = new_node(0, degree);
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/* Create nodes for single pixels. */
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for (*nkeys = 0; *nkeys < degree; (*nkeys)++)
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root->children[*nkeys] = new_node(*nkeys, degree);
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*nkeys += 2; /* skip clear code and stop code */
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return root;
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}
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static void
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del_trie(Node *root, int degree)
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{
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if (!root)
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return;
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for (int i = 0; i < degree; i++)
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del_trie(root->children[i], degree);
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free(root);
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}
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static void put_loop(ge_GIF *gif, uint16_t loop);
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ge_GIF *
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ge_new_gif(
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const char *fname, uint16_t width, uint16_t height,
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uint8_t *palette, int depth, int loop
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)
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{
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int i, r, g, b, v;
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ge_GIF *gif = calloc(1, sizeof(*gif) + 2*width*height);
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if (!gif)
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goto no_gif;
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gif->w = width; gif->h = height;
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gif->depth = depth > 1 ? depth : 2;
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gif->frame = (uint8_t *) &gif[1];
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gif->back = &gif->frame[width*height];
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gif->fd = creat(fname, 0666);
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if (gif->fd == -1)
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goto no_fd;
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#ifdef _WIN32
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setmode(gif->fd, O_BINARY);
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#endif
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write(gif->fd, "GIF89a", 6);
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write_num(gif->fd, width);
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write_num(gif->fd, height);
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write(gif->fd, (uint8_t []) {0xF0 | (depth-1), 0x00, 0x00}, 3);
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if (palette) {
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write(gif->fd, palette, 3 << depth);
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} else if (depth <= 4) {
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write(gif->fd, vga, 3 << depth);
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} else {
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write(gif->fd, vga, sizeof(vga));
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i = 0x10;
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for (r = 0; r < 6; r++) {
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for (g = 0; g < 6; g++) {
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for (b = 0; b < 6; b++) {
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write(gif->fd, (uint8_t []) {r*51, g*51, b*51}, 3);
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if (++i == 1 << depth)
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goto done_gct;
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}
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}
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}
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for (i = 1; i <= 24; i++) {
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v = i * 0xFF / 25;
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write(gif->fd, (uint8_t []) {v, v, v}, 3);
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}
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}
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done_gct:
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if (loop >= 0 && loop <= 0xFFFF)
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put_loop(gif, (uint16_t) loop);
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return gif;
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no_fd:
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free(gif);
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no_gif:
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return NULL;
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}
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static void
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put_loop(ge_GIF *gif, uint16_t loop)
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{
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write(gif->fd, (uint8_t []) {'!', 0xFF, 0x0B}, 3);
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write(gif->fd, "NETSCAPE2.0", 11);
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write(gif->fd, (uint8_t []) {0x03, 0x01}, 2);
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write_num(gif->fd, loop);
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write(gif->fd, "\0", 1);
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}
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/* Add packed key to buffer, updating offset and partial.
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* gif->offset holds position to put next *bit*
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* gif->partial holds bits to include in next byte */
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static void
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put_key(ge_GIF *gif, uint16_t key, int key_size)
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{
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int byte_offset, bit_offset, bits_to_write;
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byte_offset = gif->offset / 8;
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bit_offset = gif->offset % 8;
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gif->partial |= ((uint32_t) key) << bit_offset;
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bits_to_write = bit_offset + key_size;
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while (bits_to_write >= 8) {
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gif->buffer[byte_offset++] = gif->partial & 0xFF;
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if (byte_offset == 0xFF) {
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write(gif->fd, "\xFF", 1);
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write(gif->fd, gif->buffer, 0xFF);
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byte_offset = 0;
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}
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gif->partial >>= 8;
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bits_to_write -= 8;
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}
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gif->offset = (gif->offset + key_size) % (0xFF * 8);
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}
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static void
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end_key(ge_GIF *gif)
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{
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int byte_offset;
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byte_offset = gif->offset / 8;
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if (gif->offset % 8)
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gif->buffer[byte_offset++] = gif->partial & 0xFF;
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write(gif->fd, (uint8_t []) {byte_offset}, 1);
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write(gif->fd, gif->buffer, byte_offset);
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write(gif->fd, "\0", 1);
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gif->offset = gif->partial = 0;
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}
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static void
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put_image(ge_GIF *gif, uint16_t w, uint16_t h, uint16_t x, uint16_t y)
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{
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int nkeys, key_size, i, j;
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Node *node, *child, *root;
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int degree = 1 << gif->depth;
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write(gif->fd, ",", 1);
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write_num(gif->fd, x);
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write_num(gif->fd, y);
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write_num(gif->fd, w);
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write_num(gif->fd, h);
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write(gif->fd, (uint8_t []) {0x00, gif->depth}, 2);
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root = node = new_trie(degree, &nkeys);
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key_size = gif->depth + 1;
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put_key(gif, degree, key_size); /* clear code */
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for (i = y; i < y+h; i++) {
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for (j = x; j < x+w; j++) {
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uint8_t pixel = gif->frame[i*gif->w+j] & (degree - 1);
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child = node->children[pixel];
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if (child) {
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node = child;
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} else {
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put_key(gif, node->key, key_size);
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if (nkeys < 0x1000) {
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if (nkeys == (1 << key_size))
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key_size++;
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node->children[pixel] = new_node(nkeys++, degree);
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} else {
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put_key(gif, degree, key_size); /* clear code */
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del_trie(root, degree);
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root = node = new_trie(degree, &nkeys);
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key_size = gif->depth + 1;
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}
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node = root->children[pixel];
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}
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}
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}
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put_key(gif, node->key, key_size);
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put_key(gif, degree + 1, key_size); /* stop code */
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end_key(gif);
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del_trie(root, degree);
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}
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static int
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get_bbox(ge_GIF *gif, uint16_t *w, uint16_t *h, uint16_t *x, uint16_t *y)
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{
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int i, j, k;
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int left, right, top, bottom;
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left = gif->w; right = 0;
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top = gif->h; bottom = 0;
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k = 0;
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for (i = 0; i < gif->h; i++) {
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for (j = 0; j < gif->w; j++, k++) {
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if (gif->frame[k] != gif->back[k]) {
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if (j < left) left = j;
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if (j > right) right = j;
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if (i < top) top = i;
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if (i > bottom) bottom = i;
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}
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}
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}
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if (left != gif->w && top != gif->h) {
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*x = left; *y = top;
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*w = right - left + 1;
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*h = bottom - top + 1;
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return 1;
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} else {
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return 0;
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}
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}
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static void
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set_delay(ge_GIF *gif, uint16_t d)
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{
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write(gif->fd, (uint8_t []) {'!', 0xF9, 0x04, 0x04}, 4);
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write_num(gif->fd, d);
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write(gif->fd, "\0\0", 2);
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}
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void
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ge_add_frame(ge_GIF *gif, uint16_t delay)
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{
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uint16_t w, h, x, y;
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uint8_t *tmp;
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if (delay)
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set_delay(gif, delay);
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if (gif->nframes == 0) {
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w = gif->w;
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h = gif->h;
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x = y = 0;
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} else if (!get_bbox(gif, &w, &h, &x, &y)) {
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/* image's not changed; save one pixel just to add delay */
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w = h = 1;
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x = y = 0;
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}
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put_image(gif, w, h, x, y);
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gif->nframes++;
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tmp = gif->back;
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gif->back = gif->frame;
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gif->frame = tmp;
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}
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void
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ge_close_gif(ge_GIF* gif)
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{
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write(gif->fd, ";", 1);
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close(gif->fd);
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free(gif);
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}
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