Round 5: preview layout config, single/all mode, offset indicator

- Frame offset indicator: cyan dot on thumbnails when offX/offY != 0
- GB canvases taller (220px each) to match Animations tab height
- Preview layout config: auto/fixedCols/fixedRows with value setting
- Preview Show All/Single toggle with <- -> navigation in single mode
- Preview canvas resizes responsively on zoom and mode change
- calcPreviewSize() and getPreviewGrid() helpers for layout math
- Preview zoom and mode saved/loaded in preferences
- previewSingleIdx clamped on load and mode switch

aniphallow.lua

@@ -103,6 +103,11 @@ local S = {
     srcClickX      = 0,
     srcClickY      = 0,
     srcIsDrag      = false,
+    -- Preview layout configuration
+    previewLayout      = "auto",      -- "auto", "fixedCols", "fixedRows"
+    previewLayoutValue = 2,           -- number for fixed cols/rows
+    previewMode        = "all",       -- "all" or "single"
+    previewSingleIdx   = 1,           -- which animation to show in single mode
 }
 
 ----------------------------------------------------------------------
@@ -128,8 +133,8 @@ local GB_IDS = {
 }
 
 -- GB canvas heights (taller to match Animations tab and prevent resize on tab switch)
-local GB_SRC_H = 200
+local GB_SRC_H = 220
-local GB_OPT_H = 200
+local GB_OPT_H = 220
 
 ----------------------------------------------------------------------
 -- Module-level window/timer variables
@@ -235,6 +240,11 @@ local function loadPrefs()
         end
         -- Load previewWindowOpen
         if k == "previewWindowOpen" then S.previewWindowOpen = (v == "true") end
+        -- Preview layout prefs
+        if k == "previewLayout" then S.previewLayout = v end
+        if k == "previewLayoutValue" then S.previewLayoutValue = tonumber(v) or 2 end
+        if k == "previewMode" then S.previewMode = v end
+        if k == "previewSingleIdx" then S.previewSingleIdx = tonumber(v) or 1 end
         -- Dynamic anim frames: anim_0, anim_1, ...
         local animIdx = k and string.match(k, "^anim_(%d+)$")
         if animIdx then
@@ -261,6 +271,11 @@ local function loadPrefs()
     -- Clamp currentAnim to valid range
     if S.currentAnim < 1 then S.currentAnim = 1 end
     if S.currentAnim > #S.animNames then S.currentAnim = math.max(1, #S.animNames) end
+    -- Clamp previewSingleIdx
+    if S.previewSingleIdx < 1 then S.previewSingleIdx = 1 end
+    if #S.animNames > 0 and S.previewSingleIdx > #S.animNames then
+        S.previewSingleIdx = #S.animNames
+    end
 end
 
 local function savePrefs()
@@ -302,6 +317,11 @@ local function savePrefs()
     f:write("gbTileH=" .. S.gbTileH .. "\n")
     -- Save previewWindowOpen
     f:write("previewWindowOpen=" .. tostring(S.previewWindowOpen) .. "\n")
+    -- Save preview layout prefs
+    f:write("previewLayout=" .. S.previewLayout .. "\n")
+    f:write("previewLayoutValue=" .. S.previewLayoutValue .. "\n")
+    f:write("previewMode=" .. S.previewMode .. "\n")
+    f:write("previewSingleIdx=" .. S.previewSingleIdx .. "\n")
     for i, name in ipairs(S.animNames) do
         f:write("anim_" .. (i - 1) .. "=" .. serializeFrames(S.anims[name] or {}) .. "\n")
     end
@@ -405,6 +425,26 @@ local function getDarkestPaletteColor()
     return Color(0, 0, 0)
 end
 
+----------------------------------------------------------------------
+-- Preview grid helper (module-level)
+----------------------------------------------------------------------
+local function getPreviewGrid(numAnims)
+    if numAnims <= 0 then return 1, 1 end
+    if S.previewLayout == "fixedCols" then
+        local cols = math.max(1, S.previewLayoutValue)
+        local rows = math.max(1, math.ceil(numAnims / cols))
+        return cols, rows
+    elseif S.previewLayout == "fixedRows" then
+        local rows = math.max(1, S.previewLayoutValue)
+        local cols = math.max(1, math.ceil(numAnims / rows))
+        return cols, rows
+    else -- auto: tend to square
+        local cols = math.max(1, math.ceil(math.sqrt(numAnims)))
+        local rows = math.max(1, math.ceil(numAnims / cols))
+        return cols, rows
+    end
+end
+
 ----------------------------------------------------------------------
 -- Module-level refreshSource
 ----------------------------------------------------------------------
@@ -930,18 +970,35 @@ openPreviewWindow = function()
     end
 
     local pvAnimFrame = { value = 0 }
-    local PV_RENDER_MARGIN = 2
+    local PV_MARGIN = 2
 
-    -- Calculate content-based size
+    -- Clamp previewSingleIdx
-    local numAnims = #S.animNames
+    if #S.animNames > 0 then
+        if S.previewSingleIdx < 1 then S.previewSingleIdx = 1 end
+        if S.previewSingleIdx > #S.animNames then S.previewSingleIdx = #S.animNames end
+    else
+        S.previewSingleIdx = 1
+    end
+
+    -- calcPreviewSize helper
+    local function calcPreviewSize()
         local ptw = S.tileW * S.previewZoom
         local pth = S.tileH * S.previewZoom
-    local cellW = ptw + PV_RENDER_MARGIN * 2
+        local cellW = ptw + PV_MARGIN * 2
-    local cellH = pth + PV_RENDER_MARGIN * 2
+        local cellH = pth + PV_MARGIN * 2
-    local pvCols = 2
+        if S.previewMode == "single" then
-    local pvRows = math.max(1, math.ceil(numAnims / pvCols))
+            return cellW, cellH
-    local pvWidth = math.max(pvCols * cellW, 120)
+        else
-    local pvHeight = math.max(pvRows * cellH, 40)
+            local numAnims = #S.animNames
+            local cols, rows = getPreviewGrid(numAnims)
+            return cols * cellW, rows * cellH
+        end
+    end
+
+    -- Calculate initial size
+    local pvWidth, pvHeight = calcPreviewSize()
+    pvWidth = math.max(pvWidth, 120)
+    pvHeight = math.max(pvHeight, 40)
 
     previewDlg = Dialog{
         title = "AniPhallow Preview",
@@ -968,6 +1025,57 @@ openPreviewWindow = function()
         end
     }
 
+    previewDlg:button{
+        id = "pvToggleMode",
+        text = S.previewMode == "all" and "Single" or "Show All",
+        onclick = function()
+            if S.previewMode == "all" then
+                S.previewMode = "single"
+                -- Clamp
+                if #S.animNames > 0 then
+                    if S.previewSingleIdx < 1 then S.previewSingleIdx = 1 end
+                    if S.previewSingleIdx > #S.animNames then S.previewSingleIdx = #S.animNames end
+                end
+                previewDlg:modify{ id = "pvToggleMode", text = "Show All" }
+                previewDlg:modify{ id = "pvPrev", visible = true }
+                previewDlg:modify{ id = "pvNext", visible = true }
+            else
+                S.previewMode = "all"
+                previewDlg:modify{ id = "pvToggleMode", text = "Single" }
+                previewDlg:modify{ id = "pvPrev", visible = false }
+                previewDlg:modify{ id = "pvNext", visible = false }
+            end
+            -- Resize canvas to fit new content
+            local pw, ph = calcPreviewSize()
+            previewDlg:modify{ id = "pvCanvas", width = math.max(pw, 120), height = math.max(ph, 40) }
+            previewDlg:repaint()
+        end
+    }
+    previewDlg:button{
+        id = "pvPrev",
+        text = "<-",
+        visible = (S.previewMode == "single"),
+        onclick = function()
+            if #S.animNames > 0 then
+                S.previewSingleIdx = S.previewSingleIdx - 1
+                if S.previewSingleIdx < 1 then S.previewSingleIdx = #S.animNames end
+                previewDlg:repaint()
+            end
+        end
+    }
+    previewDlg:button{
+        id = "pvNext",
+        text = "->",
+        visible = (S.previewMode == "single"),
+        onclick = function()
+            if #S.animNames > 0 then
+                S.previewSingleIdx = S.previewSingleIdx + 1
+                if S.previewSingleIdx > #S.animNames then S.previewSingleIdx = 1 end
+                previewDlg:repaint()
+            end
+        end
+    }
+
     previewDlg:canvas{
         id = "pvCanvas",
         width = pvWidth,
@@ -980,11 +1088,39 @@ openPreviewWindow = function()
 
             local pw = S.tileW * S.previewZoom
             local ph = S.tileH * S.previewZoom
-            local cW = pw + PV_RENDER_MARGIN * 2
+            local cW = pw + PV_MARGIN * 2
-            local cH = ph + PV_RENDER_MARGIN * 2
+            local cH = ph + PV_MARGIN * 2
-            local cols = 2
             local af = pvAnimFrame.value
 
+            if S.previewMode == "single" and S.previewSingleIdx >= 1 and S.previewSingleIdx <= #S.animNames then
+                -- Single mode: draw only one animation centered
+                local name = S.animNames[S.previewSingleIdx]
+                local frames = S.anims[name] or {}
+                -- Draw background
+                if S.useBgColor then
+                    gc.color = S.bgColor
+                    gc:fillRect(Rectangle(PV_MARGIN, PV_MARGIN, pw, ph))
+                else
+                    drawCheckerboard(gc, pw, ph, S.previewZoom, PV_MARGIN, PV_MARGIN)
+                end
+                -- Draw frame with offset
+                local totalFrames = #frames
+                if totalFrames > 0 then
+                    local idx = (af % totalFrames) + 1
+                    local fimg = getFrameImageGlobal(name, idx)
+                    local f = frames[idx]
+                    local offX = (f.offX or 0) * S.previewZoom
+                    local offY = (f.offY or 0) * S.previewZoom
+                    if fimg then
+                        gc:drawImage(fimg,
+                            Rectangle(0, 0, S.tileW, S.tileH),
+                            Rectangle(PV_MARGIN + offX, PV_MARGIN + offY, pw, ph))
+                    end
+                end
+            else
+                -- All mode: draw all animations using grid
+                local cols, rows = getPreviewGrid(na)
+
                 for i, name in ipairs(S.animNames) do
                     local col = (i - 1) % cols
                     local row = math.floor((i - 1) / cols)
@@ -993,10 +1129,10 @@ openPreviewWindow = function()
 
                     if S.useBgColor then
                         gc.color = S.bgColor
-                    gc:fillRect(Rectangle(ox + PV_RENDER_MARGIN, oy + PV_RENDER_MARGIN, pw, ph))
+                        gc:fillRect(Rectangle(ox + PV_MARGIN, oy + PV_MARGIN, pw, ph))
                     else
                         drawCheckerboard(gc, pw, ph, S.previewZoom,
-                        ox + PV_RENDER_MARGIN, oy + PV_RENDER_MARGIN)
+                            ox + PV_MARGIN, oy + PV_MARGIN)
                     end
 
                     local frames = S.anims[name] or {}
@@ -1011,16 +1147,19 @@ openPreviewWindow = function()
                             gc:drawImage(
                                 fimg,
                                 Rectangle(0, 0, S.tileW, S.tileH),
-                            Rectangle(ox + PV_RENDER_MARGIN + fOffX, oy + PV_RENDER_MARGIN + fOffY, pw, ph)
+                                Rectangle(ox + PV_MARGIN + fOffX, oy + PV_MARGIN + fOffY, pw, ph)
                             )
                         end
                     end
                 end
+            end
         end,
         onwheel = function(ev)
             local dz = ev.deltaY < 0 and 1 or -1
             S.previewZoom = math.max(1, math.min(MAX_PREVIEW_ZOOM, S.previewZoom + dz))
-            pcall(function() previewDlg:repaint() end)
+            local pw, ph = calcPreviewSize()
+            previewDlg:modify{ id = "pvCanvas", width = math.max(pw, 120), height = math.max(ph, 40) }
+            previewDlg:repaint()
         end
     }
 
@@ -1188,6 +1327,9 @@ openMainDialog = function()
             d:color{ id = "silhouetteColor", label = "Silhouette:", color = silColor }
             d:entry{ id = "layerName", label = "Layer name:", text = S.gbLayerName }
             d:check{ id = "alwaysOverwrite", text = "Always overwrite layer", selected = S.gbAlwaysOverwrite }
+            d:separator{ text = "Preview" }
+            d:combobox{ id = "previewLayout", label = "Layout:", option = S.previewLayout, options = {"auto", "fixedCols", "fixedRows"} }
+            d:number{ id = "previewLayoutValue", label = "Value:", text = tostring(S.previewLayoutValue), decimals = 0 }
             d:button{ id = "ok", text = "OK" }
             d:button{ text = "Cancel" }
             d:show()
@@ -1213,6 +1355,11 @@ openMainDialog = function()
                 S.gbSilhouetteColorSet = true
                 S.gbLayerName = d.data.layerName
                 S.gbAlwaysOverwrite = d.data.alwaysOverwrite
+                -- Preview layout settings
+                S.previewLayout = d.data.previewLayout
+                local plv = d.data.previewLayoutValue
+                if plv < 1 then plv = 1 elseif plv > 20 then plv = 20 end
+                S.previewLayoutValue = plv
                 dlg:repaint()
             end
         end
@@ -1544,6 +1691,12 @@ openMainDialog = function()
                     gc:fillRect(Rectangle(tx, ty, 4, 4))
                 end
 
+                -- Offset indicator (cyan dot, bottom-left)
+                if (frames[i].offX or 0) ~= 0 or (frames[i].offY or 0) ~= 0 then
+                    gc.color = Color(0, 200, 255, 220)
+                    gc:fillRect(Rectangle(tx, ty + THUMB_SIZE - 4, 4, 4))
+                end
+
                 -- Current playback frame indicator
                 if cnt > 0 and ((S.animFrame % cnt)) == (i - 1) then
                     gc.color = Color(100, 200, 255, 200)