From ed962118698e6c070d84711a07b4f9396127748a Mon Sep 17 00:00:00 2001
From: Gavin Laking <gavinlaking@gmail.com>
Date: Sat, 21 May 2016 20:18:16 +0100
Subject: [PATCH] Calculate y and x for alignment methods, also;

Expose 'Vedeu.centre_x' and 'Vedeu.centre_y'.

This fixed a bug in the Geometries::DSL exhibited in some examples where
moving the interface caused it to 'jump' to the wrong location because either
x or y is not set.
---
 docs/dsl/by_method/centre_x.md  |  6 +++++
 docs/dsl/by_method/centre_y.md  |  6 +++++
 lib/vedeu/geometries/dsl/dsl.rb | 40 ++++++++++++++++++++++++++++-----
 lib/vedeu/terminal/terminal.rb  |  6 +++++
 test/lib/vedeu_test.rb          |  2 ++
 5 files changed, 54 insertions(+), 6 deletions(-)
 create mode 100644 docs/dsl/by_method/centre_x.md
 create mode 100644 docs/dsl/by_method/centre_y.md

diff --git a/docs/dsl/by_method/centre_x.md b/docs/dsl/by_method/centre_x.md
new file mode 100644
index 000000000..294932799
--- /dev/null
+++ b/docs/dsl/by_method/centre_x.md
@@ -0,0 +1,6 @@
+### Vedeu.centre_x
+
+Provides the horizontal centre coordinate for the terminal. For
+example, a terminal of width 40 characters:
+
+    Vedeu.centre_x # => 20
diff --git a/docs/dsl/by_method/centre_y.md b/docs/dsl/by_method/centre_y.md
new file mode 100644
index 000000000..21a6fcb58
--- /dev/null
+++ b/docs/dsl/by_method/centre_y.md
@@ -0,0 +1,6 @@
+### Vedeu.centre_y
+
+Provides the vertical centre coordinate for the terminal. For example,
+a terminal of height 40 lines:
+
+    Vedeu.centre_y # => 20
diff --git a/lib/vedeu/geometries/dsl/dsl.rb b/lib/vedeu/geometries/dsl/dsl.rb
index f73e4d83e..95a4cffa2 100644
--- a/lib/vedeu/geometries/dsl/dsl.rb
+++ b/lib/vedeu/geometries/dsl/dsl.rb
@@ -105,23 +105,27 @@ def align(vertical: :none, horizontal: :none, width: nil, height: nil)
       # @param value [Symbol] One of :center, :centre, :left, :none,
       #   :right.
       # @param width [Fixnum] The number of characters/columns.
+      # @param x [Fixnum] When given, sets the x coordinate.
       # @return [Vedeu::Geometries::Geometry]
-      def horizontal_alignment(value = :none, width = nil)
+      def horizontal_alignment(value = :none, width = nil, x = nil)
         alignment = Vedeu::Coercers::HorizontalAlignment.validate(value)
 
         model.width = width if width
         model.horizontal_alignment = alignment
+        model.x = x if x
         model
       end
 
       # @param value [Symbol] One of :bottom, :middle, :none, :top.
       # @param height [Fixnum] The number of lines/rows.
+      # @param y [Fixnum] When given, sets the y coordinate.
       # @return [Vedeu::Geometries::Geometry]
-      def vertical_alignment(value = :none, height = nil)
+      def vertical_alignment(value = :none, height = nil, y = nil)
         alignment = Vedeu::Coercers::VerticalAlignment.validate(value)
 
         model.height = height if height
         model.vertical_alignment = alignment
+        model.y = y if y
         model
       end
 
@@ -129,14 +133,26 @@ def vertical_alignment(value = :none, height = nil)
       # @param height [Fixnum] The number of lines/rows.
       # @return [Vedeu::Geometries::Geometry]
       def align_bottom(height = nil)
-        vertical_alignment(:bottom, height)
+        y = if height
+              Vedeu.height - height
+            elsif model.height
+              Vedeu.height - model.height
+            end
+
+        vertical_alignment(:bottom, height, y)
       end
 
       # {include:file:docs/dsl/by_method/geometry/align_centre.md}
       # @param width [Fixnum] The number of characters/columns.
       # @return [Vedeu::Geometries::Geometry]
       def align_centre(width = nil)
-        horizontal_alignment(:centre, width)
+        x = if width
+              Vedeu.centre_x - (width / 2)
+            elsif model.width
+              Vedeu.centre_x - (model.width / 2)
+            end
+
+        horizontal_alignment(:centre, width, x)
       end
       alias align_center align_centre
 
@@ -151,14 +167,26 @@ def align_left(width = nil)
       # @param height [Fixnum] The number of lines/rows.
       # @return [Vedeu::Geometries::Geometry]
       def align_middle(height = nil)
-        vertical_alignment(:middle, height)
+        y = if height
+              Vedeu.centre_y - (height / 2)
+            elsif model.height
+              Vedeu.centre_y - (model.height / 2)
+            end
+
+        vertical_alignment(:middle, height, y)
       end
 
       # {include:file:docs/dsl/by_method/geometry/align_right.md}
       # @param width [Fixnum] The number of characters/columns.
       # @return [Vedeu::Geometries::Geometry]
       def align_right(width = nil)
-        horizontal_alignment(:right, width)
+        x = if width
+              Vedeu.width - width
+            elsif model.width
+              Vedeu.width - model.width
+            end
+
+        horizontal_alignment(:right, width, x)
       end
 
       # {include:file:docs/dsl/by_method/geometry/align_top.md}
diff --git a/lib/vedeu/terminal/terminal.rb b/lib/vedeu/terminal/terminal.rb
index 7a65d5023..284305e8d 100644
--- a/lib/vedeu/terminal/terminal.rb
+++ b/lib/vedeu/terminal/terminal.rb
@@ -166,7 +166,13 @@ def console
   # @api public
   # @!method resize
   #   @see Vedeu::Terminal#resize
+  # @!method centre_x
+  #   @see Vedeu::Terminal#centre_x
+  # @!method centre_y
+  #   @see Vedeu::Terminal#centre_y
   def_delegators Vedeu::Terminal,
+                 :centre_x,
+                 :centre_y,
                  :resize
 
 end # Vedeu
diff --git a/test/lib/vedeu_test.rb b/test/lib/vedeu_test.rb
index 10ad32cbe..56ae61911 100644
--- a/test/lib/vedeu_test.rb
+++ b/test/lib/vedeu_test.rb
@@ -17,6 +17,8 @@
   it { Vedeu.must_respond_to(:buffers) }
   it { Vedeu.must_respond_to(:buffer_update) }
   it { Vedeu.must_respond_to(:buffer_write) }
+  it { Vedeu.must_respond_to(:centre_x) }
+  it { Vedeu.must_respond_to(:centre_y) }
   it { Vedeu.must_respond_to(:clear) }
   it { Vedeu.must_respond_to(:clear_by_group) }
   it { Vedeu.must_respond_to(:clear_by_name) }