Fix webp export to export one tag correctly instead of all frames (fix #3622)

src/app/file/webp_format.cpp

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2018-2022  Igara Studio S.A.
+// Copyright (C) 2018-2023  Igara Studio S.A.
 // Copyright (C) 2015-2018  David Capello
 // Copyright (C) 2015  Gabriel Rauter
 //
@@ -257,7 +257,6 @@ bool WebPFormat::onSave(FileOp* fop)
   FILE* fp = handle.get();
 
   const FileAbstractImage* sprite = fop->abstractImage();
-  const doc::frame_t totalFrames = sprite->frames();
   const int w = sprite->width();
   const int h = sprite->height();
 
@@ -302,6 +301,7 @@ bool WebPFormat::onSave(FileOp* fop)
 
   ImageRef image(Image::create(IMAGE_RGB, w, h));
 
+  const doc::frame_t totalFrames = fop->roi().frames();
   WriterData wd(fp, fop, 0, totalFrames, 0.0);
   WebPPicture pic;
   WebPPictureInit(&pic);
@@ -315,10 +315,18 @@ bool WebPFormat::onSave(FileOp* fop)
 
   WebPAnimEncoder* enc = WebPAnimEncoderNew(w, h, &enc_options);
   int timestamp_ms = 0;
+    auto frame_beg = fop->roi().selectedFrames().begin();
+#if _DEBUG
+    auto frame_end = fop->roi().selectedFrames().end();
+#endif
+    auto frame_it = frame_beg;
   for (frame_t f=0; f<totalFrames; ++f) {
+    ASSERT(frame_it != frame_end);
+    frame_t frame = *frame_it;
+    ++frame_it;
     // Render the frame in the bitmap
     clear_image(image.get(), image->maskColor());
-    sprite->renderFrame(f, image.get());
+    sprite->renderFrame(frame, image.get());
 
     // Switch R <-> B channels because WebPAnimEncoderAssemble()
     // expects MODE_BGRA pictures.
@@ -342,7 +350,7 @@ bool WebPFormat::onSave(FileOp* fop)
       else
         return true;
     }
-    timestamp_ms += sprite->frameDuration(f);
+    timestamp_ms += sprite->frameDuration(frame);
 
     wd.f = f;
   }

tests/cli/save-as.sh

@@ -322,3 +322,38 @@ d=$t/save-as-with-slice
 $ASEPRITE -b sprites/slices.aseprite -save-as $d/{slice}.png
 expect "line.png
 square.png" "list_files $d"
+
+# Test https://github.com/aseprite/aseprite/issues/3622
+# Test that -save-as -tag will save the right tag frames in webp file format
+
+d=$t/save-as-tag-webp
+mkdir $d  # TODO why do we need this?
+$ASEPRITE -b -frame-tag "a" sprites/1empty3.aseprite -save-as $d/save-as-tag.webp || exit 1
+expect "save-as-tag.webp" "list_files $d"
+cat >$d/compare.lua <<EOF
+local a = app.open("sprites/1empty3.aseprite")
+app.command.FlattenLayers()
+local b = app.open("$d/save-as-tag.webp")
+-- Shrink frames:
+for f = 1,#b.frames do
+  local oldColor = b.layers[1]:cel(f).image:getPixel(0,0)
+  app.useTool{tool="pencil", points={Point(0,0)}, color=Color(255,0,0)}
+  app.useTool{tool='pencil', points={Point(0,0)}, color=oldColor}
+end
+local tagA = a.tags[1]
+assert(tagA.name == "a")
+assert(tagA.frames == #b.frames)
+local cleanImage = Image(b.spec)
+cleanImage:clear()
+for f = 1,#b.frames do
+  local celA = a.layers[1]:cel(f + tagA.fromFrame.frameNumber - 1)
+  local celB = b.layers[1]:cel(f)
+  if celA and celB then
+    assert(celA.image:isEqual(celB.image))
+  else
+    assert(not celA)
+    assert(not celB or celB.image:isEqual(cleanImage))
+  end
+end
+EOF
+$ASEPRITE -b -script "$d/compare.lua" || exit 1