Add warning to suppress png scaling warning

Close #120

CHANGELOG.md

@@ -7,6 +7,7 @@ Features:
 * Crop your PNGs and SVGs! This means you can work from spritesheets if you want. New options to `png` and `svg` are documented in the API docs and demonstrated in the `load_images.rb` sample. (#11)
 * Flip your PNGs and SVGs! Set `flip_horizontal: true` or `flip_vertical: true` (or both!) to flip the image about it's center. (#11)
 * Added a `grid` shape that fills the whole card with a grid of your choosing. (#68)
+* Added `warn_png_scale` configuration option to suppress the PNG scale warning. Also: warning only occurs on upscale, not on downscaling (#121)
 
 Chores:
 * Ripped out a lot of old constants used from the old way we handled arguments. Yay negative churn!

README.md

@@ -463,6 +463,8 @@ Squib supports various configuration properties that can be specified in an exte
 * `antialias` (`fast, good, best, none, gray, subpixel`, default: best). Set the algorithm that Cairo will use for antialiasing. Using our benchmarks on large decks, `best` is only ~10% slower anyway. For more info see the [Cairo docs](http://www.cairographics.org/manual/cairo-cairo-t.html#cairo-antialias-t).
 * `backend` (`svg` or `memory`, default: `memory`). Defines how Cairo will store the operations. Memory is recommended for higher quality rendering.
 * `prefix` (default: `card_`). When using an SVG backend, cards are auto-saved with this prefix and `"%02d"` numbering format.
+* `warn_ellipsize` (default: true). Warn when text is ellipsized
+* `warn_png_scale` (default: true). Warn when a PNG file is upscaled
 
 For debugging/sanity purposes, if you want to make sure your configuration options are parsed correclty, the above options are also available as methods within Squib::Deck, for example:
 

lib/squib/card.rb

@@ -42,7 +42,6 @@ module Squib
       end
     end
 
-
   # A save/restore wrapper for using Cairo
   # :nodoc:
   # @api private

lib/squib/conf.rb

@@ -26,6 +26,7 @@ module Squib
       'smart_quotes'  => true,
       'text_hint'     => 'off',
       'warn_ellipsize'=> true,
+      'warn_png_scale'=> true,
     }
 
     #Translate the hints to the methods.
@@ -108,6 +109,10 @@ module Squib
       @config_hash['warn_ellipsize']
     end
 
+    def warn_png_scale?
+      @config_hash['warn_png_scale']
+    end
+
     private
 
     def normalize_antialias

lib/squib/graphics/image.rb

@@ -20,12 +20,15 @@ module Squib
       png = Squib.cache_load_image(file)
       use_cairo do |cc|
         cc.translate(box.x, box.y)
-        Squib.logger.warn "PNG scaling results in aliasing." if box.width != :native || box.height != :native
+        box.width    = png.width.to_f  if box.width  == :native
-        box.width  = png.width.to_f  if box.width  == :native
+        box.height   = png.height.to_f if box.height == :native
-        box.height = png.height.to_f if box.height == :native
+        box.width    = png.width.to_f * box.height.to_f / png.height.to_f if box.width == :scale
-        box.width  = png.width.to_f * box.height.to_f / png.height.to_f if box.width == :scale
+        box.height   = png.height.to_f * box.width.to_f / png.width.to_f  if box.height == :scale
-        box.height = png.height.to_f * box.width.to_f / png.width.to_f  if box.height == :scale
+
-        cc.scale(box.width.to_f / png.width.to_f, box.height.to_f / png.height.to_f)
+        scale_width  = box.width.to_f / png.width.to_f
+        scale_height = box.height.to_f / png.height.to_f
+        warn_png_scale(file, scale_width, scale_height)
+        cc.scale(scale_width, scale_height)
 
         cc.rotate(trans.angle)
         cc.flip(trans.flip_vertical, trans.flip_horizontal, box.width / 2, box.height / 2)
@@ -49,6 +52,14 @@ module Squib
       end
     end
 
+    # :nodoc:
+    # @api private
+    def warn_png_scale(file, scale_width, scale_height)
+      if @deck.conf.warn_png_scale? && (scale_width > 1.0 || scale_height > 1.0)
+        Squib.logger.warn "PNG is being upscaled - antialiasing could result: #{file}"
+      end
+    end
+
     # :nodoc:
     # @api private
     def svg(file, svg_args, box, paint, trans)

lib/squib/project_template/config.yml

@@ -42,4 +42,8 @@
 # By default, Squib warns when a text box is ellipsized. This can get verbose
 # and can be turned off here
 # warn_ellipsize: true # default
-# warn_ellipsize: false # default
+# warn_ellipsize: false # turn off entirely
+
+# By default, Squib will warn if a PNG is being up-scaled.
+# warn_png_scale: true # default
+# warn_png_scale: false # turn off entirely

samples/load_images.rb

@@ -1,6 +1,6 @@
 require 'squib'
 
-Squib::Deck.new(width: 825, height: 1125, cards: 1) do
+Squib::Deck.new(width: 825, height: 1125, cards: 1, config: 'load_images_config.yml') do
   background color: '#0b7c8e'
   rect x: 38, y: 38, width: 750, height: 1050, x_radius: 38, y_radius: 38
 
@@ -10,7 +10,7 @@ Squib::Deck.new(width: 825, height: 1125, cards: 1) do
   # Can be scaled if width and height are set
   svg file: 'spanner.svg', x: 50, y: 50, width: 250, height: 250
   png file: 'shiny-purse.png', x: 305, y: 50, width: 250, height: 250
-  #...but PNGs will warn if it's an upscale
+  #...but PNGs will warn if it's an upscale, unless you disable them in config.yml
 
   # Can be scaled using just width or height, if one of them is set to :scale
   svg file: 'spanner.svg', x: 200, y: 350, width: 35,     height: :scale

samples/load_images_config.yml

@@ -0,0 +1 @@
+warn_png_scale: false