Header.lua

-- The pocket header: a name between two arrows.
--
-- The arrows are hand drawn rather than font glyphs.  The charmap has a
-- filled right arrow at $ED but no left companion, and Bill's PC+ hit the
-- same wall on its box pager, where the font has a down marker and no up
-- one.  It drew both halves by hand on the reasoning that two shapes from
-- the same hand read cleaner than one glyph beside one hand drawn cousin.
-- Its pair is 5 wide by 3 tall; this is the same triangle turned a quarter
-- turn, 3 wide by 5 tall.
--
-- Font is passed in rather than required so this file keeps no engine
-- dependency and tests with dofile alone.

local Header = {}

-- A bordered window across the top, the same primitive the engine frames its
-- money box and text boxes with, so the header reads as a window rather than
-- as text floating on the list's white fill.  Three tiles tall: two borders
-- and one interior row.  It occupies only the space ListMenu's own title
-- already used, so no list row is lost -- the first row still starts at y=24,
-- immediately under the bottom border.
--
-- Sized and placed against the engine's own bag window, so the two read as
-- one stacked unit rather than two boxes that happen to be near each other.
-- src/ui/ListMenu.lua draws the bag through drawItemBox with
--   ITEM_BOX = { tx = 4, ty = 2, tw = 16, th = 11 }
-- which is pokered's LIST_MENU_BOX 4,2-19,12 (data/text_boxes.asm).  The
-- header takes that box's tx and tw exactly, so the left and right borders
-- line up, and sits at ty=0 so its bottom border row falls on the item box's
-- top border row -- one shared divider, not two edges 8px apart.
--
-- Do not "fix" the apparent overlap: the strip above ITEM_BOX is only two
-- tiles, and a bordered box needs three (two borders and an interior), so
-- sharing the divider row is what makes a framed header fit at all.  The
-- engine stacks its own money box the same way in shop mode.
Header.BOX = { 4, 0, 16, 3 }   -- tile coords for Font.drawBox: x 32..160

-- Interior runs x=40..152, so the name centres on 96.  The arrows are fixed
-- and the name moves: anchoring an arrow to the name's own width would swing
-- it 32px between TM/HM and KEY ITEMS, which reads as the interface twitching
-- rather than as a page turning.
Header.LEFT_X  = 40   -- interior's left edge, and ITEM_CURSOR_X: the arrow
                      -- sits directly over the list's cursor column
Header.RIGHT_X = 149  -- 3 wide, so its right edge is the interior's, 152
Header.MID_X   = 96   -- interior centre; names centre here
Header.TEXT_Y  = 8    -- the box's interior row
Header.ARROW_Y = 10   -- the 5px arrow centred in that 8px row

function Header.nameX(width)
  return math.floor(Header.MID_X - width / 2)
end

function Header.leftArrow(x, y)
  love.graphics.rectangle("fill", x + 2, y,     1, 5)
  love.graphics.rectangle("fill", x + 1, y + 1, 1, 3)
  love.graphics.rectangle("fill", x,     y + 2, 1, 1)
end

function Header.rightArrow(x, y)
  love.graphics.rectangle("fill", x,     y,     1, 5)
  love.graphics.rectangle("fill", x + 1, y + 1, 1, 3)
  love.graphics.rectangle("fill", x + 2, y + 2, 1, 1)
end

-- ListMenu:draw sets the colour back to white as its last statement, so the
-- caller wrapping it has to set black again or everything here renders
-- invisible against the white fill.  Font.drawBox fills its own interior
-- white and restores whatever colour it found, so black survives it.
function Header.draw(Font, label)
  love.graphics.setColor(0, 0, 0, 1)
  Font.drawBox(Header.BOX[1], Header.BOX[2], Header.BOX[3], Header.BOX[4])
  Header.leftArrow(Header.LEFT_X, Header.ARROW_Y)
  Header.rightArrow(Header.RIGHT_X, Header.ARROW_Y)
  Font.draw(label, Header.nameX(Font.width(label)), Header.TEXT_Y)
  love.graphics.setColor(1, 1, 1, 1)
end

return Header