Added several convenience features.

Including allowing specifying number of tiles for each dimension, if for
example it is known that the image will contain 16x16 sprites, but the
size of the individual sprite is unknown.

spritesheet.lua

@@ -1,5 +1,14 @@
 
-local error = require 'errors' 'SpriteSheet2'
+local error_orig = error
+local error, error_internal do
+    error, error_internal  =  error_orig, error_orig
+    error_orig = nil
+    local success, errorlib = pcall(require,'errors')
+    if success then
+        error = errorlib 'spritesheet'
+        error_internal  =  error.internal
+    end
+end
 
 --------------------------------------------------------------------------------
 -- Util
@@ -102,7 +111,7 @@ function Animation:generateImage ()
 
         if self.wrap then  t = t % self.duration  end
         local quad = get_quad_based_on_time(self, t)
-        if not quad then  error.internal('Could not determine quad when drawing animation. Time was %f.', t)  end
+        if not quad then  error_internal('Could not determine quad when drawing animation. Time was %f.', t)  end
         love.graphics.draw(self.imagesheet.image, quad, x, y, 0, 1, 1, self.imagesheet.origin_x, self.imagesheet.origin_y)
     end
 end
@@ -165,8 +174,8 @@ local function load_quads (image, quad_data, imagesheet)
 
     local image_width, image_height  = image:getDimensions()
     local  tile_width,  tile_height  = quad_data.tile_width, quad_data.tile_height
-    local tiles_pr_row  =  image_width/tile_width
+    local tiles_per_row  =  image_width/tile_width
-    local max_quad_id   =  tiles_pr_row * (image_height/tile_height) - 1
+    local max_quad_id   =  tiles_per_row * (image_height/tile_height) - 1
     local quad_cache = {}
 
     local function quad_from_id (id)
@@ -177,7 +186,7 @@ local function load_quads (image, quad_data, imagesheet)
 
         -- Calculate
         if not quad_cache[id] then
-            quad_cache[id] = love.graphics.newQuad((id%tiles_pr_row)*tile_width, math.floor(id/tiles_pr_row)*tile_height, tile_width, tile_height, image_width, image_height)
+            quad_cache[id] = love.graphics.newQuad((id%tiles_per_row)*tile_width, math.floor(id/tiles_per_row)*tile_height, tile_width, tile_height, image_width, image_height)
         end
         return quad_cache[id]
     end
@@ -226,15 +235,40 @@ local function load_quad_data (filename)
         local chunk, error_msg = love.filesystem.load(filename..'.lua')
         if chunk then
             local data  =  setfenv(chunk, SPRITESHEET_ENV)()
+
             -- Error check
-            if type(data) ~= 'table' then  error('Bad spritesheet "%s". Must return a table, but returned %s (%s)', filename, data, type(data))  end
+            if type(data) ~= 'table' then
-            if type(data.tile_width)  ~= 'number' then  error('Bad spritesheet "%s". The root table must contain key "tile_width", with integer value, but it was %s (%s)', filename, data.tile_width, type(data.tile_width))  end
+                error('Bad spritesheet "%s". Must return a table, but returned %s (%s)', filename, data, type(data))
-            if data.tile_width ~= math.floor(data.tile_width)  then  error('Bad spritesheet "%s". The root table must contain key "tile_width", with integer value, but it was %f (float)', filename, data.tile_width)  end
+            end
-            if type(data.tile_height) ~= 'number' then  error('Bad spritesheet "%s". The root table must contain key "tile_height", with integer value, but it was %s (%s)', filename, data.tile_height, type(data.tile_height))  end
+            local l = {'Bad spritesheet "'.. filename.. '"'}
-            if data.tile_height ~= math.floor(data.tile_height) then  error('Bad spritesheet "%s". The root table must contain key "tile_height", with integer value, but it was %f (float)', filename, data.tile_height)  end
+            if data.tiles_per_row ~= nil and data.tile_width ~= nil then
-            if not (type(data.tile_names) == 'table' or type(data.tile_names) == 'number') then  error('Bad spritesheet "%s". The root table must contain key "tile_names", with either a table or a number value, but it was %s (%s)', filename, data.tile_names, type(data.tile_names))  end
+                l[#l+1] = 'Root table must not contain both keys "tiles_per_row" and "tile_width"'
-            if data.tile_origin and type(data.tile_origin) ~= 'table' then  error('Bad spritesheet "%s". If the root table contains key "tile_origin", it must be a table value, but it was %s (%s)', filename, data.tile_origin, type(data.tile_origin))  end
+            elseif data.tiles_per_row == nil and data.tile_width == nil then
-            --
+                l[#l+1] = 'Root table must contain either keys "tiles_per_row" or "tile_width"'
+            end
+            if data.tiles_per_column ~= nil and data.tile_height ~= nil then
+                l[#l+1] = 'Root table must not contain both keys "tiles_per_column" and "tile_height"'
+            elseif data.tiles_per_column == nil and data.tile_height == nil then
+                l[#l+1] = 'Root table must contain either keys "tiles_per_column" or "tile_height"'
+            end
+            local INTEGER_TILESET_KEYS = {'tile_width', 'tile_height', 'tiles_per_row', 'tiles_per_column'}
+            for _, integer_key in ipairs(INTEGER_TILESET_KEYS) do
+                local v = data[integer_key]
+                if v and (type(v)  ~= 'number' or v % 1 ~= 0) then
+                    l[#l+1] = string.format('Key "%s" in root table must map to integer value, but it was %s (%s)', integer_key, v, type(v))
+                end
+            end
+            if not (type(data.tile_names) == 'table' or type(data.tile_names) == 'number') then
+                l[#l+1] = string.format('Root table must contain key "tile_names", with either a table or a number value, but it was %s (%s)', data.tile_names, type(data.tile_names))
+            end
+            if data.tile_origin and type(data.tile_origin) ~= 'table' then
+                l[#l+1] = string.format('Key "%s" in root table must map to a table value, but it was %s (%s)', 'tile_origin', data.tile_origin, type(data.tile_origin))
+            end
+
+            -- Throw error or return
+            if #l > 1 then
+                error(table.concat(l, '\n    '))
+            end
             return data
         end
         print(error_msg)
@@ -253,18 +287,38 @@ local SpriteSheet = {}
 function SpriteSheet.new (filename)
     local quad_data = load_quad_data(filename)
 
+    -- NOTE: `force_uneven_tile_size` in quad_data can be used to
+    -- ignore the image size-tile size divisibility check. Edit the
+    -- spriteimage itself if you can, as it will silently ignore
+    -- several errors.
+
     -- Set info
     local  self = setmetatable({}, SpriteSheet)
            self.filename     = filename
            self.image        = love.graphics.newImage(filename..'.png')
            self.origin_x     = 0
            self.origin_y     = 0
-           self.tile_width   = quad_data.tile_width
+
-           self.tile_height  = quad_data.tile_height
+    -- TODO: Give warning/error due to rounding down.
+    quad_data.tile_width    =  quad_data.tile_width  or math.floor(self.image:getWidth()  / quad_data.tiles_per_row)
+    quad_data.tile_height   =  quad_data.tile_height or math.floor(self.image:getHeight() / quad_data.tiles_per_column)
+    print(self.tile_width, self.tile_height)
+
+    self.tile_width    =  quad_data.tile_width
+    self.tile_height   =  quad_data.tile_height
 
     -- Error checking
-    if self.image:getWidth()  % self.tile_width  ~= 0 then  error('Bad spritesheet "%s". Image size (%i, %i) must be dividable by tile size (%i, %i), but width leaves a remainder of %i.',  filename, self.image:getWidth(), self.image:getHeight(), self.tile_width, self.tile_height, self.image:getWidth() % self.tile_width)  end
+    do
-    if self.image:getHeight() % self.tile_height ~= 0 then  error('Bad spritesheet "%s". Image size (%i, %i) must be dividable by tile size (%i, %i), but height leaves a remainder of %i.', filename, self.image:getWidth(), self.image:getHeight(), self.tile_width, self.tile_height, self.image:getHeight() % self.tile_height)  end
+        local rem_width  = self.image:getWidth()  % self.tile_width
+        local rem_height = self.image:getHeight() % self.tile_height
+        if not quad_data.force_uneven_tile_size and (rem_width ~= 0 or rem_height ~= 0) then
+            local s = ('Bad spritesheet "%s". Image size (%i, %i) must be dividable by tile size (%i, %i)')
+                       :format(filename, self.image:getWidth(), self.image:getHeight(), self.tile_width, self.tile_height)
+            if rem_width  ~= 0 then  s = s..('\n    Width  leaves a remainder of %i.'):format(rem_width)   end
+            if rem_height ~= 0 then  s = s..('\n    Height leaves a remainder of %i.'):format(rem_height)  end
+            error(s)
+        end
+    end
 
     -- Set origin
     if quad_data.tile_origin then