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).

Makefile

@@ -4,7 +4,7 @@
 # Various contributors (see AUTHORS.txt)
 # http://www.tuxpaint.org/
 
-# June 14, 2002 - June 22, 2020
+# June 14, 2002 - July 24, 2020
 
 
 # The version number, for release:
@@ -115,10 +115,10 @@ PNG:=$(if $(PNG),$(PNG),$(call linktest,-lpng12,))
 FRIBIDI_LIB:=$(shell $(PKG_CONFIG) --libs fribidi)
 FRIBIDI_CFLAGS:=$(shell $(PKG_CONFIG) --cflags fribidi)
 
-windows_ARCH_LINKS:=-lintl $(PNG) -lzdll -lwinspool -lshlwapi $(FRIBIDI_LIB) -liconv
+windows_ARCH_LINKS:=-lintl $(PNG) -lzdll -lwinspool -lshlwapi $(FRIBIDI_LIB) -liconv -limagequant
-osx_ARCH_LINKS:=$(FRIBIDI_LIB)
+osx_ARCH_LINKS:=$(FRIBIDI_LIB) -limagequant
-beos_ARCH_LINKS:=-lintl $(PNG) -lz -lbe -lnetwork -liconv $(FRIBIDI_LIB) $(PAPER_LIB) $(STDC_LIB)
+beos_ARCH_LINKS:=-lintl $(PNG) -lz -lbe -lnetwork -liconv $(FRIBIDI_LIB) $(PAPER_LIB) $(STDC_LIB) -limagequant
-linux_ARCH_LINKS:=$(PAPER_LIB) $(FRIBIDI_LIB)
+linux_ARCH_LINKS:=$(PAPER_LIB) $(FRIBIDI_LIB) -limagequant
 ARCH_LINKS:=$($(OS)_ARCH_LINKS)
 
 windows_ARCH_HEADERS:=src/win32_print.h
@@ -1035,6 +1035,7 @@ TuxPaint.dmg:
 tuxpaint:	obj/tuxpaint.o obj/i18n.o obj/im.o obj/cursor.o obj/pixels.o \
 		obj/rgblinear.o obj/playsound.o obj/fonts.o obj/parse.o obj/fill.o \
 		obj/progressbar.o obj/dirwalk.o obj/get_fname.o obj/onscreen_keyboard.o \
+		obj/gifenc.o \
 		$(ARCH_LIBS)
 	@echo
 	@echo "...Linking Tux Paint..."
@@ -1055,6 +1056,7 @@ obj/tuxpaint.o:	src/tuxpaint.c \
 		src/tools.h src/titles.h src/colors.h src/shapes.h \
 		src/sounds.h src/tip_tux.h src/great.h \
 		src/tp_magic_api.h src/parse.h src/onscreen_keyboard.h \
+		src/gifenc.h \
 		src/$(MOUSEDIR)/arrow.xbm src/$(MOUSEDIR)/arrow-mask.xbm \
 		src/$(MOUSEDIR)/hand.xbm src/$(MOUSEDIR)/hand-mask.xbm \
 		src/$(MOUSEDIR)/insertion.xbm \
@@ -1140,6 +1142,12 @@ obj/pixels.o:	src/pixels.c src/pixels.h src/compiler.h src/debug.h
 	@$(CC) $(CFLAGS) $(DEBUG_FLAGS) $(SDL_CFLAGS) $(DEFS) \
 		-c src/pixels.c -o obj/pixels.o
 
+obj/gifenc.o:	src/gifenc.c src/gifenc.h
+	@echo
+	@echo "...Compiling animated GIF export libary..."
+	@$(CC) $(CFLAGS) $(DEBUG_FLAGS) $(DEFS) \
+		-c src/gifenc.c -o obj/gifenc.o
+
 obj/playsound.o:	src/playsound.c src/playsound.h \
 			src/compiler.h src/debug.h
 	@echo

docs/AUTHORS.txt

@@ -103,6 +103,10 @@ $Id$
   which was from "Gimp-gluas" plug-in for The GIMP:
   http://pippin.gimp.org/plug-ins/gluas/
 
+  Animated GIF export from "gifenc",
+  https://github.com/lecram/gifenc,
+  by Marcel Rodrigues <http://lecram.github.io/>
+
   Mouse accessibility code and keyboard access
   Ankit Choudary <ankit.goaldecided@gmail.com>, as part of GSOC 2010,
   with integration and fixes by Pere Pujal i Carabantes <pere@fornol.no-ip.org>

docs/CHANGES.txt

@@ -8,7 +8,16 @@ http://www.tuxpaint.org/
 
 $Id$
 
-2020.June.22 (0.9.25)
+2020.July.24 (0.9.25)
+  * New Features
+    ------------
+    * [WIP] GIF export option from Open -> Slideshow dialog.
+      * Utilizes "gifenc", public domain by Marcel Rodrigues:
+        https://github.com/lecram/gifenc
+      * Depends on "libimagequant", from the "pngquant2" project:
+        https://github.com/ImageOptim/libimagequant
+        (GPL v3 or later, for Free/Libre Open Source Software)
+
   * Ports & Building
     ----------------
     * Corrections for Haiku not opening saved files.

src/gifenc.c

@@ -0,0 +1,287 @@
+#include "gifenc.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#ifdef _WIN32
+#include <io.h>
+#else
+#include <unistd.h>
+#endif
+
+/* helper to write a little-endian 16-bit number portably */
+#define write_num(fd, n) write((fd), (uint8_t []) {(n) & 0xFF, (n) >> 8}, 2)
+
+static uint8_t vga[0x30] = {
+    0x00, 0x00, 0x00,
+    0xAA, 0x00, 0x00,
+    0x00, 0xAA, 0x00,
+    0xAA, 0x55, 0x00,
+    0x00, 0x00, 0xAA,
+    0xAA, 0x00, 0xAA,
+    0x00, 0xAA, 0xAA,
+    0xAA, 0xAA, 0xAA,
+    0x55, 0x55, 0x55,
+    0xFF, 0x55, 0x55,
+    0x55, 0xFF, 0x55,
+    0xFF, 0xFF, 0x55,
+    0x55, 0x55, 0xFF,
+    0xFF, 0x55, 0xFF,
+    0x55, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF,
+};
+
+struct Node {
+    uint16_t key;
+    struct Node *children[];
+};
+typedef struct Node Node;
+
+static Node *
+new_node(uint16_t key, int degree)
+{
+    Node *node = calloc(1, sizeof(*node) + degree * sizeof(Node *));
+    if (node)
+        node->key = key;
+    return node;
+}
+
+static Node *
+new_trie(int degree, int *nkeys)
+{
+    Node *root = new_node(0, degree);
+    /* Create nodes for single pixels. */
+    for (*nkeys = 0; *nkeys < degree; (*nkeys)++)
+        root->children[*nkeys] = new_node(*nkeys, degree);
+    *nkeys += 2; /* skip clear code and stop code */
+    return root;
+}
+
+static void
+del_trie(Node *root, int degree)
+{
+    if (!root)
+        return;
+    for (int i = 0; i < degree; i++)
+        del_trie(root->children[i], degree);
+    free(root);
+}
+
+static void put_loop(ge_GIF *gif, uint16_t loop);
+
+ge_GIF *
+ge_new_gif(
+    const char *fname, uint16_t width, uint16_t height,
+    uint8_t *palette, int depth, int loop
+)
+{
+    int i, r, g, b, v;
+    ge_GIF *gif = calloc(1, sizeof(*gif) + 2*width*height);
+    if (!gif)
+        goto no_gif;
+    gif->w = width; gif->h = height;
+    gif->depth = depth > 1 ? depth : 2;
+    gif->frame = (uint8_t *) &gif[1];
+    gif->back = &gif->frame[width*height];
+    gif->fd = creat(fname, 0666);
+    if (gif->fd == -1)
+        goto no_fd;
+#ifdef _WIN32
+    setmode(gif->fd, O_BINARY);
+#endif
+    write(gif->fd, "GIF89a", 6);
+    write_num(gif->fd, width);
+    write_num(gif->fd, height);
+    write(gif->fd, (uint8_t []) {0xF0 | (depth-1), 0x00, 0x00}, 3);
+    if (palette) {
+        write(gif->fd, palette, 3 << depth);
+    } else if (depth <= 4) {
+        write(gif->fd, vga, 3 << depth);
+    } else {
+        write(gif->fd, vga, sizeof(vga));
+        i = 0x10;
+        for (r = 0; r < 6; r++) {
+            for (g = 0; g < 6; g++) {
+                for (b = 0; b < 6; b++) {
+                    write(gif->fd, (uint8_t []) {r*51, g*51, b*51}, 3);
+                    if (++i == 1 << depth)
+                        goto done_gct;
+                }
+            }
+        }
+        for (i = 1; i <= 24; i++) {
+            v = i * 0xFF / 25;
+            write(gif->fd, (uint8_t []) {v, v, v}, 3);
+        }
+    }
+done_gct:
+    if (loop >= 0 && loop <= 0xFFFF)
+        put_loop(gif, (uint16_t) loop);
+    return gif;
+no_fd:
+    free(gif);
+no_gif:
+    return NULL;
+}
+
+static void
+put_loop(ge_GIF *gif, uint16_t loop)
+{
+    write(gif->fd, (uint8_t []) {'!', 0xFF, 0x0B}, 3);
+    write(gif->fd, "NETSCAPE2.0", 11);
+    write(gif->fd, (uint8_t []) {0x03, 0x01}, 2);
+    write_num(gif->fd, loop);
+    write(gif->fd, "\0", 1);
+}
+
+/* Add packed key to buffer, updating offset and partial.
+ *   gif->offset holds position to put next *bit*
+ *   gif->partial holds bits to include in next byte */
+static void
+put_key(ge_GIF *gif, uint16_t key, int key_size)
+{
+    int byte_offset, bit_offset, bits_to_write;
+    byte_offset = gif->offset / 8;
+    bit_offset = gif->offset % 8;
+    gif->partial |= ((uint32_t) key) << bit_offset;
+    bits_to_write = bit_offset + key_size;
+    while (bits_to_write >= 8) {
+        gif->buffer[byte_offset++] = gif->partial & 0xFF;
+        if (byte_offset == 0xFF) {
+            write(gif->fd, "\xFF", 1);
+            write(gif->fd, gif->buffer, 0xFF);
+            byte_offset = 0;
+        }
+        gif->partial >>= 8;
+        bits_to_write -= 8;
+    }
+    gif->offset = (gif->offset + key_size) % (0xFF * 8);
+}
+
+static void
+end_key(ge_GIF *gif)
+{
+    int byte_offset;
+    byte_offset = gif->offset / 8;
+    if (gif->offset % 8)
+        gif->buffer[byte_offset++] = gif->partial & 0xFF;
+    write(gif->fd, (uint8_t []) {byte_offset}, 1);
+    write(gif->fd, gif->buffer, byte_offset);
+    write(gif->fd, "\0", 1);
+    gif->offset = gif->partial = 0;
+}
+
+static void
+put_image(ge_GIF *gif, uint16_t w, uint16_t h, uint16_t x, uint16_t y)
+{
+    int nkeys, key_size, i, j;
+    Node *node, *child, *root;
+    int degree = 1 << gif->depth;
+
+    write(gif->fd, ",", 1);
+    write_num(gif->fd, x);
+    write_num(gif->fd, y);
+    write_num(gif->fd, w);
+    write_num(gif->fd, h);
+    write(gif->fd, (uint8_t []) {0x00, gif->depth}, 2);
+    root = node = new_trie(degree, &nkeys);
+    key_size = gif->depth + 1;
+    put_key(gif, degree, key_size); /* clear code */
+    for (i = y; i < y+h; i++) {
+        for (j = x; j < x+w; j++) {
+            uint8_t pixel = gif->frame[i*gif->w+j] & (degree - 1);
+            child = node->children[pixel];
+            if (child) {
+                node = child;
+            } else {
+                put_key(gif, node->key, key_size);
+                if (nkeys < 0x1000) {
+                    if (nkeys == (1 << key_size))
+                        key_size++;
+                    node->children[pixel] = new_node(nkeys++, degree);
+                } else {
+                    put_key(gif, degree, key_size); /* clear code */
+                    del_trie(root, degree);
+                    root = node = new_trie(degree, &nkeys);
+                    key_size = gif->depth + 1;
+                }
+                node = root->children[pixel];
+            }
+        }
+    }
+    put_key(gif, node->key, key_size);
+    put_key(gif, degree + 1, key_size); /* stop code */
+    end_key(gif);
+    del_trie(root, degree);
+}
+
+static int
+get_bbox(ge_GIF *gif, uint16_t *w, uint16_t *h, uint16_t *x, uint16_t *y)
+{
+    int i, j, k;
+    int left, right, top, bottom;
+    left = gif->w; right = 0;
+    top = gif->h; bottom = 0;
+    k = 0;
+    for (i = 0; i < gif->h; i++) {
+        for (j = 0; j < gif->w; j++, k++) {
+            if (gif->frame[k] != gif->back[k]) {
+                if (j < left)   left    = j;
+                if (j > right)  right   = j;
+                if (i < top)    top     = i;
+                if (i > bottom) bottom  = i;
+            }
+        }
+    }
+    if (left != gif->w && top != gif->h) {
+        *x = left; *y = top;
+        *w = right - left + 1;
+        *h = bottom - top + 1;
+        return 1;
+    } else {
+        return 0;
+    }
+}
+
+static void
+set_delay(ge_GIF *gif, uint16_t d)
+{
+    write(gif->fd, (uint8_t []) {'!', 0xF9, 0x04, 0x04}, 4);
+    write_num(gif->fd, d);
+    write(gif->fd, "\0\0", 2);
+}
+
+void
+ge_add_frame(ge_GIF *gif, uint16_t delay)
+{
+    uint16_t w, h, x, y;
+    uint8_t *tmp;
+
+    if (delay)
+        set_delay(gif, delay);
+    if (gif->nframes == 0) {
+        w = gif->w;
+        h = gif->h;
+        x = y = 0;
+    } else if (!get_bbox(gif, &w, &h, &x, &y)) {
+        /* image's not changed; save one pixel just to add delay */
+        w = h = 1;
+        x = y = 0;
+    }
+    put_image(gif, w, h, x, y);
+    gif->nframes++;
+    tmp = gif->back;
+    gif->back = gif->frame;
+    gif->frame = tmp;
+}
+
+void
+ge_close_gif(ge_GIF* gif)
+{
+    write(gif->fd, ";", 1);
+    close(gif->fd);
+    free(gif);
+}

src/gifenc.h

@@ -0,0 +1,24 @@
+#ifndef GIFENC_H
+#define GIFENC_H
+
+#include <stdint.h>
+
+typedef struct ge_GIF {
+    uint16_t w, h;
+    int depth;
+    int fd;
+    int offset;
+    int nframes;
+    uint8_t *frame, *back;
+    uint32_t partial;
+    uint8_t buffer[0xFF];
+} ge_GIF;
+
+ge_GIF *ge_new_gif(
+    const char *fname, uint16_t width, uint16_t height,
+    uint8_t *palette, int depth, int loop
+);
+void ge_add_frame(ge_GIF *gif, uint16_t delay);
+void ge_close_gif(ge_GIF* gif);
+
+#endif /* GIFENC_H */

src/tuxpaint.c

@@ -483,6 +483,8 @@ static void mtw(wchar_t * wtok, char *tok)
 #error "---------------------------------------------------"
 #endif
 
+#include "libimagequant.h"
+
 #include "SDL_getenv.h"
 
 #include "i18n.h"
@@ -495,6 +497,7 @@ static void mtw(wchar_t * wtok, char *tok)
 #include "dirwalk.h"
 #include "get_fname.h"
 #include "onscreen_keyboard.h"
+#include "gifenc.h"
 
 #include "tools.h"
 #include "titles.h"
@@ -1432,7 +1435,7 @@ static SDL_Surface *img_black, *img_grey;
 static SDL_Surface *img_yes, *img_no;
 static SDL_Surface *img_sfx, *img_speak;
 static SDL_Surface *img_open, *img_erase, *img_back, *img_trash;
-static SDL_Surface *img_slideshow, *img_play, *img_select_digits;
+static SDL_Surface *img_slideshow, *img_play, *img_gif_export, *img_select_digits;
 static SDL_Surface *img_printer, *img_printer_wait;
 static SDL_Surface *img_save_over, *img_popup_arrow;
 static SDL_Surface *img_cursor_up, *img_cursor_down;
@@ -1755,7 +1758,8 @@ static short *brushes_directional = NULL;
 
 static SDL_Surface *img_shapes[NUM_SHAPES], *img_shape_names[NUM_SHAPES];
 static SDL_Surface *img_openlabels_open, *img_openlabels_erase,
-  *img_openlabels_slideshow, *img_openlabels_back, *img_openlabels_play, *img_openlabels_next;
+  *img_openlabels_slideshow, *img_openlabels_back, *img_openlabels_play,
+  *img_openlabels_gif_export, *img_openlabels_next;
 
 static SDL_Surface *img_tux[NUM_TIP_TUX];
 
@@ -7861,11 +7865,14 @@ static void create_button_labels(void)
   /* Open dialog: 'Back' button, to dismiss Open dialog without opening a picture */
   img_openlabels_back = do_render_button_label(gettext_noop("Back"));
 
-  /* Slideshow: 'Next' button, to load next slide (image) */
-  img_openlabels_next = do_render_button_label(gettext_noop("Next"));
-
   /* Slideshow: 'Play' button, to begin a slideshow sequence */
   img_openlabels_play = do_render_button_label(gettext_noop("Play"));
+
+  /* Slideshow: 'GIF Export' button, to create an animated GIF */
+  img_openlabels_gif_export = do_render_button_label(gettext_noop("GIF Export"));
+
+  /* Slideshow: 'Next' button, to load next slide (image) */
+  img_openlabels_next = do_render_button_label(gettext_noop("Next"));
 }
 
 
@@ -15029,7 +15036,7 @@ static int do_slideshow(void)
   SDL_Rect dest;
   SDL_Event event;
   SDLKey key;
-  char *freeme;
+  char *freeme, *instructions;
   int speeds;
   float x_per, y_per;
   int xx, yy;
@@ -15278,9 +15285,8 @@ static int do_slideshow(void)
   /* Let user choose images: */
 
   /* Instructions for Slideshow file dialog (FIXME: Make a #define) */
-  freeme = textdir(gettext_noop("Choose the pictures you want, " "then click “Play”."));
+  instructions = textdir(gettext_noop("Choose the pictures you want, " "then click “Play”."));
-  draw_tux_text(TUX_BORED, freeme, 1);
+  draw_tux_text(TUX_BORED, instructions, 1);
-  free(freeme);
 
   /* NOTE: cur is now set above; if file_id'th file is found, it's
      set to that file's index; otherwise, we default to '0' */
@@ -15386,6 +15392,21 @@ static int do_slideshow(void)
           SDL_BlitSurface(img_openlabels_play, NULL, screen, &dest);
 
 
+          /* "GIF Export" button: */
+
+          dest.x = WINDOW_WIDTH - 96 - 48 * 2;
+          dest.y = (48 * 7 + 40 + HEIGHTOFFSET) - 48;
+          SDL_BlitSurface(img_btn_up, NULL, screen, &dest);
+
+          dest.x = WINDOW_WIDTH - 96 - 48 * 2 + (48 - img_gif_export->w) / 2;
+          dest.y = (48 * 7 + 40 + HEIGHTOFFSET) - 48;
+          SDL_BlitSurface(img_gif_export, NULL, screen, &dest);
+
+          dest.x = WINDOW_WIDTH - 96 - 48 * 2 + (48 - img_openlabels_gif_export->w) / 2;
+          dest.y = (48 * 7 + 40 + HEIGHTOFFSET) - img_openlabels_gif_export->h;
+          SDL_BlitSurface(img_openlabels_gif_export, NULL, screen, &dest);
+
+
           /* "Back" button: */
 
           dest.x = WINDOW_WIDTH - 96 - 48;
@@ -15633,6 +15654,31 @@ static int do_slideshow(void)
                       update_list = 1;
                     }
                 }
+              else if (event.button.x >= (WINDOW_WIDTH - 96 - 48 - 48) &&
+                       event.button.x < (WINDOW_WIDTH - 96 - 48) &&
+                       event.button.y >= (48 * 7 + 40 + HEIGHTOFFSET) - 48 &&
+                       event.button.y < (48 * 7 + 40 + HEIGHTOFFSET))
+                {
+                  /* GIF Export */
+
+                  playsound(screen, 1, SND_CLICK, 1, SNDPOS_RIGHT, SNDDIST_NEAR);
+
+                  if (num_selected < 2)
+		    {
+	              /* None selected? Too dangerous to select all.
+		         Only 1 selected?  No point in saving as GIF.
+                      */
+                      freeme = textdir(gettext_noop("Select 2 or more drawings to turn into an animated GIF."));
+                      draw_tux_text(TUX_BORED, freeme, 1);
+                      free(freeme);
+
+                      control_drawtext_timer(2000, instructions, 0); /* N.B. It will draw instructions, regardless */
+		    }
+		  else
+		    {
+		      /* FIXME: Do it */
+		    }
+                }
               else if (event.button.x >= (WINDOW_WIDTH - 96 - 48) &&
                        event.button.x < (WINDOW_WIDTH - 96) &&
                        event.button.y >= (48 * 7 + 40 + HEIGHTOFFSET) - 48 &&
@@ -15696,7 +15742,7 @@ static int do_slideshow(void)
                   do_setcursor(cursor_down);
                 }
               else if (((event.button.x >= 96 && event.button.x < 96 + 48 + 96) ||
-                        (event.button.x >= (WINDOW_WIDTH - 96 - 48) &&
+                        (event.button.x >= (WINDOW_WIDTH - 96 - 48 * 2) &&
                          event.button.x < (WINDOW_WIDTH - 96))) &&
                        event.button.y >= (48 * 7 + 40 + HEIGHTOFFSET) - 48 &&
                        event.button.y < (48 * 7 + 40 + HEIGHTOFFSET))
@@ -15736,6 +15782,17 @@ static int do_slideshow(void)
 
           else if (event.type == SDL_JOYBUTTONDOWN || event.type == SDL_JOYBUTTONUP)
             handle_joybuttonupdown(event, oldpos_x, oldpos_y);
+
+          else if (event.type == SDL_USEREVENT)
+            {
+              if (event.user.code == USEREVENT_TEXT_UPDATE)
+                {
+                  if (event.user.data1 != NULL)
+                    {
+                      draw_tux_text(TUX_BORED, instructions, 1);
+                    }
+		}
+	    }
         }
 
       if (motioner | hatmotioner)
@@ -15764,6 +15821,8 @@ static int do_slideshow(void)
   free(d_exts);
   free(selected);
 
+  control_drawtext_timer(0, "", 0);
+  free(instructions);
 
   return go_back;
 }
@@ -23990,6 +24049,7 @@ static void setup(void)
 
   img_slideshow = loadimage(DATA_PREFIX "images/ui/slideshow.png");
   img_play = loadimage(DATA_PREFIX "images/ui/play.png");
+  img_gif_export = loadimage(DATA_PREFIX "images/ui/gif_export.png");
   img_select_digits = loadimage(DATA_PREFIX "images/ui/select_digits.png");
 
   img_popup_arrow = loadimage(DATA_PREFIX "images/ui/popup_arrow.png");