Add support for custom anchors for PNGs and SVGs

Author: Ninjananas

docs/args/anchor.rst

@@ -0,0 +1,6 @@
+.. :orphan:
+
+anchor
+  default: ``:top_left``
+
+  the anchor of the image. Available values are ``:top_left``, ``:top_right``, ``:bottom_left``, ``:bottom_right``, and ``:middle`` or ``:center``. The first 4 options anchor the image relative to the corresponding corner, and ``:middle`` and ``:center`` set the anchor to the middle of the image

docs/dsl/png.rst

@@ -12,6 +12,8 @@ file
 
   file(s) to read in. As in :doc:`/arrays`, if this a single file, then it's use for every card in range. If the parameter is an Array of files, then each file is looked up for each card. If any of them are nil or '', nothing is done for that card.
 
+.. include:: /args/anchor.rst
+
 .. include:: /args/xy.rst
 
 width

docs/dsl/svg.rst

@@ -19,6 +19,8 @@ file
 
   By default, if ``file`` is not found, a warning is logged. This behavior can be configured in :doc:`/config`
 
+.. include:: /args/anchor.rst
+
 .. include:: /args/xy.rst
 
 data

lib/squib/args/scale_box.rb

@@ -13,7 +13,8 @@ class ScaleBox
     def self.parameters
       {
         x: 0, y: 0,
-        width: :native, height: :native
+        width: :native, height: :native,
+        anchor: :top_left
       }
     end
 
@@ -52,6 +53,11 @@ def validate_height(arg, i)
       raise 'height must be a number, :scale, :native, or :deck'
     end
 
+    def validate_anchor(arg, i)
+      raise 'anchor must be one of :top_left, :top_right, :bottom_left, :bottom_right, or :center/:middle' unless [:top_left, :top_right, :bottom_left, :bottom_right, :center, :middle].include? arg
+      arg
+    end
+
   end
 
 end

lib/squib/dsl/png.rb

@@ -25,7 +25,7 @@ def initialize(deck, dsl_method)
       def self.accepted_params
         %i(
           file
-          x y width height
+          x y width height anchor
           alpha blend mask angle
           crop_x crop_y crop_width crop_height
           crop_corner_radius crop_corner_x_radius crop_corner_y_radius

lib/squib/dsl/svg.rb

@@ -26,7 +26,7 @@ def initialize(deck, dsl_method)
       def self.accepted_params
         %i(
           file
-          x y width height
+          x y width height anchor
           blend mask
           crop_x crop_y crop_width crop_height
           crop_corner_radius crop_corner_x_radius crop_corner_y_radius

lib/squib/graphics/image.rb

@@ -33,19 +33,42 @@ def png(file, box, paint, trans)
       Squib.logger.debug {"RENDERING PNG: \n  file: #{file}\n  box: #{box}\n  paint: #{paint}\n  trans: #{trans}"}
       return if file.nil? or file.eql? ''
       png = Squib.cache_load_image(file)
+      box.width    = png.width.to_f  if box.width  == :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.height   = png.height.to_f * box.width.to_f / png.width.to_f  if box.height == :scale
+
+      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)
+
+      rotate_offset_x = 0
+      rotate_offset_y = 0
+      if [:top_right, :bottom_right].include? box.anchor
+        box.x = box.x - box.width
+        rotate_offset_x = box.width
+      end
+      if [:bottom_left, :bottom_right].include? box.anchor
+        box.y = box.y - box.height
+        rotate_offset_y = box.height
+      end
+      if [:center, :middle].include? box.anchor
+        rotate_offset_x = (box.width / 2.0)
+        box.x = box.x - rotate_offset_x
+        rotate_offset_y = (box.height / 2.0)
+        box.y = box.y - rotate_offset_y
+      end
+
       use_cairo do |cc|
         cc.translate(box.x, box.y)
-        box.width    = png.width.to_f  if box.width  == :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.height   = png.height.to_f * box.width.to_f / png.width.to_f  if box.height == :scale
-
-        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)
+        if box.anchor == :top_left
+          # Avoid doing useless translate([0, 0]) in Cairo and break regression tests
+          cc.rotate(trans.angle)
+        else
+          cc.rotate_about(rotate_offset_x, rotate_offset_y, trans.angle)
+        end
         cc.flip(trans.flip_vertical, trans.flip_horizontal, box.width / 2, box.height / 2)
         cc.translate(-box.x, -box.y)
 
@@ -94,10 +117,31 @@ def svg(file, svg_args, box, paint, trans)
       box.height = svg.height.to_f * box.width.to_f / svg.width.to_f  if box.height == :scale
       scale_width  = box.width.to_f / svg.width.to_f
       scale_height = box.height.to_f / svg.height.to_f
+      rotate_offset_x = 0
+      rotate_offset_y = 0
+      if [:top_right, :bottom_right].include? box.anchor
+        box.x = box.x - box.width
+        rotate_offset_x = box.width
+      end
+      if [:bottom_left, :bottom_right].include? box.anchor
+        box.y = box.y - box.height
+        rotate_offset_y = box.height
+      end
+      if [:center, :middle].include? box.anchor
+        rotate_offset_x = (box.width / 2.0)
+        box.x = box.x - rotate_offset_x
+        rotate_offset_y = (box.height / 2.0)
+        box.y = box.y - rotate_offset_y
+      end
       use_cairo do |cc|
         cc.translate(box.x, box.y)
         cc.flip(trans.flip_vertical, trans.flip_horizontal, box.width / 2, box.height / 2)
-        cc.rotate(trans.angle)
+        if box.anchor == :top_left
+          # Avoid doing useless translate([0, 0]) in Cairo and break regression tests
+          cc.rotate(trans.angle)
+        else
+          cc.rotate_about(rotate_offset_x, rotate_offset_y, trans.angle)
+        end
         cc.scale(scale_width, scale_height)
 
         trans.crop_width  = box.width  if trans.crop_width  == :native

samples/images/_images.rb

@@ -1,7 +1,7 @@
 require 'squib'
 require 'squib/sample_helpers'
 
-Squib::Deck.new(width: 1000, height: 3000) do
+Squib::Deck.new(width: 1000, height: 3200) do
   draw_graph_paper width, height
 
   sample "This a PNG.\nNo scaling is done by default." do |x, y|
@@ -99,6 +99,16 @@
     png file: 'with-alpha.png', mask: mask, x: x + 150, y: y, width: 150, height: :scale
   end
 
+  sample 'PNGs and SVGs are top-left-anchored by default but this can be changed.' do |x,y|
+    rect x: x, y: y, width: 100, height: 100,    # draw the crop line
+         dash: '3 3', stroke_color: 'red', stroke_width: 3
+    png  x: x + 50, y: y + 50, width: 100, height: 100, file: 'angler-fish.png',
+         anchor: :center, angle: - Math::PI / 4 - 0.2
+    rect x: x + 150, y: y, width: 100, height: 100,    # draw the crop line
+         dash: '3 3', stroke_color: 'red', stroke_width: 3
+    svg  x: x + 250, y: y + 100, width: 100, height: 100, file: 'robot-golem.svg',
+         anchor: :bottom_right, angle: Math::PI / 5
+  end
 
   save_png prefix: '_images_'
 end

spec/args/scale_box_spec.rb

@@ -64,6 +64,17 @@
       expect { Squib::Args.extract_scale_box args, deck }.to raise_error('height must be a number, :scale, :native, or :deck')
     end
 
+    it 'allows setting anchors' do
+      args = { anchor: :middle }
+      box = Squib::Args.extract_scale_box args, deck
+      expect(box).to have_attributes(anchor: [:middle])
+    end
+
+    it 'disallows setting incorrect anchors' do
+      args = { anchor: :midle }
+      expect { Squib::Args.extract_scale_box args, deck }.to raise_error('anchor must be one of :top_left, :top_right, :bottom_left, :bottom_right, or :center/:middle')
+    end
+
   end