Add gif support

builtin-programs/draw/image.folk

@@ -1,6 +1,7 @@
 When the image library is /imageLib/ &\
      the jpeg library is /jpegLib/ &\
-     the png library is /pngLib/ {
+     the png library is /pngLib/ &\
+     the gif library is /gifLib/ {
     set cc [C]
     $cc extend $imageLib
 
@@ -65,17 +66,26 @@ When the image library is /imageLib/ &\
         set impath $im
         if {[string match "http*://*" $impath]} {
             set im /tmp/[regsub -all {\W+} $impath "_"]
-            exec curl -o$im $impath
+            if {![file exists $im]} {
+                exec curl -s -L -o$im $impath
+            }
         }
         if {[string match "*jpg" $im] ||
             [string match "*jpeg" $im] ||
-            [string match "*png" $im]} {
+            [string match "*png" $im] ||
+            [string match "*gif" $im]} {
             set path [expr {[string index $im 0] eq "/" ?
                             $im : "$::env(HOME)/folk-images/$im"}]
+            if {![file exists $path]} {
+                set path [file join [pwd] $im]
+            }
             if {[string match "*jpg" $im] || [string match "*jpeg" $im]} {
                 set im [$jpegLib loadJpeg $path]
-            } else {
+            } elseif {[string match "*png" $im]} {
                 set im [$pngLib loadPng $path]
+            } else {
+                set gif [$gifLib loadGif $path]
+                set im [lindex [dict get $gif frames] 0]
             }
             $cacheLib cachePut $impath $im
         }

builtin-programs/image/animated-gif.folk

@@ -0,0 +1,84 @@
+When the gif library is /gifLib/ {
+  set gifCache [dict create]
+
+  When /someone/ wishes /p/ displays gif /path/ with /...options/ &\
+       /p/ has resolved geometry /geom/ {
+
+      if {![dict exists $gifCache $path]} {
+          set path_resolved $path
+
+          # Support remote images via HTTP
+          if {[string match "http*://*" $path]} {
+              set path_resolved /tmp/[regsub -all {\W+} $path "_"].gif
+              if {![file exists $path_resolved]} {
+                  puts stderr "gif: downloading $path to $path_resolved"
+                  if {[catch {exec curl -s -L -o $path_resolved $path} err]} {
+                      puts stderr "gif: download failed: $err"
+                      return
+                  }
+              }
+          }
+
+          if {![file exists $path_resolved]} {
+              set path_resolved_local "$::env(HOME)/folk-images/$path_resolved"
+              if {[file exists $path_resolved_local]} {
+                  set path_resolved $path_resolved_local
+              }
+          }
+          if {![file exists $path_resolved]} {
+              # Fallback to current directory
+              set path_resolved_local [file join [pwd] $path_resolved]
+              if {[file exists $path_resolved_local]} {
+                  set path_resolved $path_resolved_local
+              }
+          }
+
+          if {![file exists $path_resolved]} {
+              return
+          }
+
+          try {
+              dict set gifCache $path [$gifLib loadGif $path_resolved]
+          } on error {err} {
+              puts stderr "gif: error loading $path: $err"
+              return
+          }
+      }
+
+      set gif [dict get $gifCache $path]
+      set frames [dict get $gif frames]
+      set delays [dict get $gif delays]
+
+      set totalDuration 0
+      set cumulativeDelays [list]
+      foreach d $delays {
+          if {$d <= 10} { set d 100 }
+          incr totalDuration $d
+          lappend cumulativeDelays $totalDuration
+      }
+
+      if {[llength $frames] == 0} { return }
+
+      if {[llength $frames] == 1} {
+          Wish $p displays image [lindex $frames 0] with {*}$options
+          return
+      }
+
+      When the clock time is /t/ {
+          set ms [expr {int($t * 1000) % $totalDuration}]
+          set frameIdx 0
+          foreach cd $cumulativeDelays {
+              if {$ms < $cd} { break }
+              incr frameIdx
+          }
+          if {$frameIdx >= [llength $frames]} { set frameIdx 0 }
+          set im [lindex $frames $frameIdx]
+
+          Wish $p displays image $im with {*}$options
+      }
+  }
+
+  When /someone/ wishes /p/ displays gif /path/ {
+      Wish $p displays gif $path with scale 1.0
+  }
+}

builtin-programs/image/gif-lib.folk

@@ -0,0 +1,52 @@
+When the image library is /imageLib/ {
+    set cc [C]
+    $cc extend $imageLib
+    $cc cflags -I[pwd]/vendor/gifdec
+    $cc endcflags [pwd]/vendor/gifdec/gifdec.c
+    $cc include "gifdec.h"
+    $cc include <stdlib.h>
+
+    $cc proc loadGif {char* filename} Jim_Obj* {
+        gd_GIF *gif = gd_open_gif(filename);
+        if (!gif) {
+            FOLK_ERROR("loadGif: Failed to open %s", filename);
+        }
+
+        Jim_Obj *framesList = Jim_NewListObj(interp, NULL, 0);
+        Jim_Obj *delaysList = Jim_NewListObj(interp, NULL, 0);
+
+        while (gd_get_frame(gif)) {
+            Image im;
+            im.width = gif->width;
+            im.height = gif->height;
+            im.components = 3;
+            im.bytesPerRow = im.width * 3;
+            im.data = malloc(im.bytesPerRow * im.height);
+            im.uniq = 0;
+
+            gd_render_frame(gif, im.data);
+
+            // Box the Image struct into a Tcl object
+            Jim_Obj *imObj;
+            $[$cc ret Image imObj im]
+            Jim_ListAppendElement(interp, framesList, imObj);
+
+            // gifdec delay is in 1/100s of a second. Convert to milliseconds.
+            Jim_ListAppendElement(interp, delaysList, Jim_NewIntObj(interp, gif->gce.delay * 10));
+        }
+
+        uint16_t w = gif->width;
+        uint16_t h = gif->height;
+        gd_close_gif(gif);
+
+        Jim_Obj *result = Jim_NewDictObj(interp, NULL, 0);
+        Jim_DictAddElement(interp, result, Jim_NewStringObj(interp, "frames", -1), framesList);
+        Jim_DictAddElement(interp, result, Jim_NewStringObj(interp, "delays", -1), delaysList);
+        Jim_DictAddElement(interp, result, Jim_NewStringObj(interp, "width", -1), Jim_NewIntObj(interp, w));
+        Jim_DictAddElement(interp, result, Jim_NewStringObj(interp, "height", -1), Jim_NewIntObj(interp, h));
+        return result;
+    }
+
+    set gifLib [$cc compile]
+    Claim the gif library is $gifLib
+}