Fix regression with timeline thumbnails (fix #5083)

This fix adds an option to scale timeline thumbnails to fill
the entire cell, or simply leave the timeline thumbnails at 1:1 scale
as before issue #4974.

data/pref.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <!-- Aseprite -->
-<!-- Copyright (C) 2018-2024  Igara Studio S.A. -->
+<!-- Copyright (C) 2018-2025  Igara Studio S.A. -->
 <!-- Copyright (C) 2014-2018  David Capello -->
 <preferences>
 
@@ -550,6 +550,7 @@
       <option id="enabled" type="bool" default="false" />
       <option id="overlay_enabled" type="bool" default="false" />
       <option id="overlay_size" type="int" default="5" />
+      <option id="scale_up_to_fit" type="bool" default="false" />
     </section>
     <section id="onionskin">
       <option id="active" type="bool" default="false" />

data/strings/en.ini

@@ -1843,6 +1843,7 @@ first_frame = First Frame:
 thumbnails = Thumbnails
 thumbnail_size = Thumbnail Size:
 overlay_size = Overlay Size:
+scale_up_to_fit = Scale up to fit
 onion_skin = Onion Skin:
 merge_frames = Merge Frames
 red_blue_tint = Red/Blue Tint

data/widgets/timeline_conf.xml

@@ -1,4 +1,5 @@
 <!-- Aseprite -->
+<!-- Copyright (C) 2025 Igara Studio S.A. -->
 <!-- Copyright (C) 2014-2018 by David Capello -->
 <gui>
 <vbox id="timeline_conf">
@@ -30,6 +31,7 @@
 
         <check id="thumb_overlay_enabled" text="@.overlay_size"/>
         <slider min="2" max="10" id="thumb_overlay_size" cell_align="horizontal" width="128" />
+        <check id="thumb_scale_up_to_fit" text="@.scale_up_to_fit" cell_hspan="2" />
       </grid>
     </vbox>
   </hbox>

src/app/thumbnails.cpp

@@ -21,9 +21,17 @@
 
 namespace app { namespace thumb {
 
-os::SurfaceRef get_cel_thumbnail(const doc::Cel* cel, const gfx::Size& fitInSize)
+os::SurfaceRef get_cel_thumbnail(const doc::Cel* cel,
+                                 const bool scaleUpToFit,
+                                 const gfx::Size& fitInSize)
 {
-  gfx::Size newSize(gfx::Rect(cel->bounds()).fitIn(gfx::Rect(fitInSize)).size());
+  gfx::Size newSize;
+
+  if (scaleUpToFit || cel->bounds().w > fitInSize.w || cel->bounds().h > fitInSize.h)
+    newSize = gfx::Rect(cel->bounds()).fitIn(gfx::Rect(fitInSize)).size();
+  else
+    newSize = cel->bounds().size();
+
   if (newSize.w < 1 || newSize.h < 1)
     return nullptr;
 

src/app/thumbnails.h

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2019-2020  Igara Studio S.A.
+// Copyright (C) 2019-2025  Igara Studio S.A.
 // Copyright (C) 2016  Carlo Caputo
 //
 // This program is distributed under the terms of
@@ -22,7 +22,9 @@ class Surface;
 
 namespace app { namespace thumb {
 
-os::SurfaceRef get_cel_thumbnail(const doc::Cel* cel, const gfx::Size& fitInSize);
+os::SurfaceRef get_cel_thumbnail(const doc::Cel* cel,
+                                 const bool scaleUpToFit,
+                                 const gfx::Size& fitInSize);
 
 }} // namespace app::thumb
 

src/app/ui/configure_timeline_popup.cpp

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2020-2021  Igara Studio S.A.
+// Copyright (C) 2020-2025  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -69,6 +69,7 @@ ConfigureTimelinePopup::ConfigureTimelinePopup()
   m_box->thumbEnabled()->Click.connect([this] { onThumbEnabledChange(); });
   m_box->thumbOverlayEnabled()->Click.connect([this] { onThumbOverlayEnabledChange(); });
   m_box->thumbOverlaySize()->Change.connect([this] { onThumbOverlaySizeChange(); });
+  m_box->thumbScaleUpToFit()->Click.connect([this] { onScaleUpToFitChange(); });
 
   const bool visibleThumb = docPref().thumbnails.enabled();
   m_box->thumbHSeparator()->setVisible(visibleThumb);
@@ -128,6 +129,7 @@ void ConfigureTimelinePopup::updateWidgetsFromCurrentSettings()
   m_box->thumbBox()->setVisible(visibleThumb);
   m_box->thumbOverlayEnabled()->setSelected(docPref.thumbnails.overlayEnabled());
   m_box->thumbOverlaySize()->setValue(docPref.thumbnails.overlaySize());
+  m_box->thumbScaleUpToFit()->setSelected(docPref.thumbnails.scaleUpToFit());
 
   expandWindow(sizeHint());
 }
@@ -237,4 +239,9 @@ void ConfigureTimelinePopup::onThumbOverlaySizeChange()
   docPref().thumbnails.overlaySize(m_box->thumbOverlaySize()->getValue());
 }
 
+void ConfigureTimelinePopup::onScaleUpToFitChange()
+{
+  docPref().thumbnails.scaleUpToFit(m_box->thumbScaleUpToFit()->isSelected());
+}
+
 } // namespace app

src/app/ui/configure_timeline_popup.h

@@ -1,4 +1,5 @@
 // Aseprite
+// Copyright (C) 2025  Igara Studio S.A.
 // Copyright (C) 2001-2017  David Capello
 //
 // This program is distributed under the terms of
@@ -46,6 +47,7 @@ protected:
   void onThumbEnabledChange();
   void onThumbOverlayEnabledChange();
   void onThumbOverlaySizeChange();
+  void onScaleUpToFitChange();
 
 private:
   void updateWidgetsFromCurrentSettings();

src/app/ui/timeline/timeline.cpp

@@ -234,6 +234,7 @@ Timeline::Timeline(TooltipManager* tooltipManager)
   , m_hbar(HORIZONTAL, this)
   , m_vbar(VERTICAL, this)
   , m_zoom(1.0)
+  , m_scaleUpToFit(false)
   , m_context(UIContext::instance())
   , m_editor(NULL)
   , m_document(NULL)
@@ -308,6 +309,10 @@ void Timeline::setZoomAndUpdate(const double zoom, const bool updatePref)
 
 void Timeline::onThumbnailsPrefChange()
 {
+  if (m_scaleUpToFit != docPref().thumbnails.scaleUpToFit()) {
+    m_scaleUpToFit = docPref().thumbnails.scaleUpToFit();
+    invalidate();
+  }
   setZoomAndUpdate(docPref().thumbnails.enabled() ? docPref().thumbnails.zoom() : 1.0, false);
 }
 
@@ -357,6 +362,7 @@ void Timeline::updateUsingEditor(Editor* editor)
   m_thumbnailsPrefConn = docPref.thumbnails.AfterChange.connect(
     [this] { onThumbnailsPrefChange(); });
   setZoom(docPref.thumbnails.enabled() ? docPref.thumbnails.zoom() : 1.0);
+  m_scaleUpToFit = docPref.thumbnails.scaleUpToFit();
 
   m_state = STATE_STANDBY;
   m_hot.part = PART_NOTHING;
@@ -2516,7 +2522,8 @@ void Timeline::drawCel(ui::Graphics* g,
     gfx::Rect thumb_bounds = gfx::Rect(bounds).shrink(skinTheme()->calcBorder(this, style));
 
     if (!thumb_bounds.isEmpty()) {
-      if (os::SurfaceRef surface = thumb::get_cel_thumbnail(cel, thumb_bounds.size())) {
+      if (os::SurfaceRef surface =
+            thumb::get_cel_thumbnail(cel, m_scaleUpToFit, thumb_bounds.size())) {
         const int t = std::clamp(thumb_bounds.w / 8, 4, 16);
         draw_checkered_grid(g, thumb_bounds, gfx::Size(t, t), docPref());
 
@@ -2608,7 +2615,7 @@ void Timeline::drawCelOverlay(ui::Graphics* g)
     return;
 
   gfx::Rect rc = m_sprite->bounds().fitIn(gfx::Rect(m_thumbnailsOverlayBounds).shrink(1));
-  if (os::SurfaceRef surface = thumb::get_cel_thumbnail(cel, rc.size())) {
+  if (os::SurfaceRef surface = thumb::get_cel_thumbnail(cel, m_scaleUpToFit, rc.size())) {
     draw_checkered_grid(g, rc, gfx::Size(8, 8) * ui::guiscale(), docPref());
 
     g->drawRgbaSurface(surface.get(),

src/app/ui/timeline/timeline.h

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2018-2024  Igara Studio S.A.
+// Copyright (C) 2018-2025  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -410,6 +410,7 @@ private:
   ui::ScrollBar m_vbar;
   gfx::Rect m_viewportArea;
   double m_zoom;
+  bool m_scaleUpToFit;
   Context* m_context;
   Editor* m_editor;
   Doc* m_document;