-- primitives for editing drawings
Drawing = {}
require 'drawing_tests'

-- All drawings span 100% of some conceptual 'page width' and divide it up
-- into 256 parts.
function Drawing.draw(State, line_index, y)
  local line = State.lines[line_index]
  local line_cache = State.line_cache[line_index]
  line_cache.starty = y
  local pmx,pmy = App.mouse_x(), App.mouse_y()
  if pmx < State.right and pmy > line_cache.starty and pmy < line_cache.starty+Drawing.pixels(line.h, State.width) then
    App.color(Icon_color)
    love.graphics.rectangle('line', State.left,line_cache.starty, State.width,Drawing.pixels(line.h, State.width))
    if icon[State.current_drawing_mode] then
      icon[State.current_drawing_mode](State.right-22, line_cache.starty+4)
    else
      icon[State.previous_drawing_mode](State.right-22, line_cache.starty+4)
    end

    if App.mouse_down(1) and love.keyboard.isDown('h') then
      draw_help_with_mouse_pressed(State, line_index)
      return
    end
  end

  if line.show_help then
    draw_help_without_mouse_pressed(State, line_index)
    return
  end

  local mx = Drawing.coord(pmx-State.left, State.width)
  local my = Drawing.coord(pmy-line_cache.starty, State.width)

  for _,shape in ipairs(line.shapes) do
    assert(shape)
    if geom.on_shape(mx,my, line, shape) then
      App.color(Focus_stroke_color)
    else
      App.color(Stroke_color)
    end
    Drawing.draw_shape(line, shape, line_cache.starty, State.left,State.right)
  end

  local function px(x) return Drawing.pixels(x, State.width)+State.left end
  local function py(y) return Drawing.pixels(y, State.width)+line_cache.starty end
  for i,p in ipairs(line.points) do
    if p.deleted == nil then
      if Drawing.near(p, mx,my, State.width) then
        App.color(Focus_stroke_color)
        love.graphics.circle('line', px(p.x),py(p.y), Same_point_distance)
      else
        App.color(Stroke_color)
        love.graphics.circle('fill', px(p.x),py(p.y), 2)
      end
      if p.name then
        -- TODO: clip
        local x,y = px(p.x)+5, py(p.y)+5
        love.graphics.print(p.name, x,y)
        if State.current_drawing_mode == 'name' and i == line.pending.target_point then
          -- create a faint red box for the name
          App.color(Current_name_background_color)
          local name_text
          -- TODO: avoid computing name width on every repaint
          if p.name == '' then
            name_text = State.em
          else
            name_text = App.newText(love.graphics.getFont(), p.name)
          end
          love.graphics.rectangle('fill', x,y, App.width(name_text), State.line_height)
        end
      end
    end
  end
  App.color(Current_stroke_color)
  Drawing.draw_pending_shape(line, line_cache.starty, State.left,State.right)
end

function Drawing.draw_shape(drawing, shape, top, left,right)
  local width = right-left
  local function px(x) return Drawing.pixels(x, width)+left end
  local function py(y) return Drawing.pixels(y, width)+top end
  if shape.mode == 'freehand' then
    local prev = nil
    for _,point in ipairs(shape.points) do
      if prev then
        love.graphics.line(px(prev.x),py(prev.y), px(point.x),py(point.y))
      end
      prev = point
    end
  elseif shape.mode == 'line' or shape.mode == 'manhattan' then
    local p1 = drawing.points[shape.p1]
    local p2 = drawing.points[shape.p2]
    love.graphics.line(px(p1.x),py(p1.y), px(p2.x),py(p2.y))
  elseif shape.mode == 'polygon' or shape.mode == 'rectangle' or shape.mode == 'square' then
    local prev = nil
    for _,point in ipairs(shape.vertices) do
      local curr = drawing.points[point]
      if prev then
        love.graphics.line(px(prev.x),py(prev.y), px(curr.x),py(curr.y))
      end
      prev = curr
    end
    -- close the loop
    local curr = drawing.points[shape.vertices[1]]
    love.graphics.line(px(prev.x),py(prev.y), px(curr.x),py(curr.y))
  elseif shape.mode <style>pre { line-height: 125%; }
td.linenos .normal { color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; }
span.linenos { color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; }
td.linenos .special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; }
span.linenos.special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; }
.highlight .hll { background-color: #ffffcc }
.highlight .c { color: #888888 } /* Comment */
.highlight .err { color: #a61717; background-color: #e3d2d2 } /* Error */
.highlight .k { color: #008800; font-weight: bold } /* Keyword */
.highlight .ch { color: #888888 } /* Comment.Hashbang */
.highlight .cm { color: #888888 } /* Comment.Multiline */
.highlight .cp { color: #cc0000; font-weight: bold } /* Comment.Preproc */
.highlight .cpf { color: #888888 } /* Comment.PreprocFile */
.highlight .c1 { color: #888888 } /* Comment.Single */
.highlight .cs { color: #cc0000; font-weight: bold; background-color: #fff0f0 } /* Comment.Special */
.highlight .gd { color: #000000; background-color: #ffdddd } /* Generic.Deleted */
.highlight .ge { font-style: italic } /* Generic.Emph */
.highlight .ges { font-weight: bold; font-style: italic } /* Generic.EmphStrong */
.highlight .gr { color: #aa0000 } /* Generic.Error */
.highlight .gh { color: #333333 } /* Generic.Heading */
.highlight .gi { color: #000000; background-color: #ddffdd } /* Generic.Inserted */
.highlight .go { color: #888888 } /* Generic.Output */
.highlight .gp { color: #555555 } /* Generic.Prompt */
.highlight .gs { font-weight: bold } /* Generic.Strong */
.highlight .gu { color: #666666 } /* Generic.Subheading */
.highlight .gt { color: #aa0000 } /* Generic.Traceback */
.highlight .kc { color: #008800; font-weight: bold } /* Keyword.Constant */
.highlight .kd { color: #008800; font-weight: bold } /* Keyword.Declaration */
.highlight .kn { color: #008800; font-weight: bold } /* Keyword.Namespace */
.highlight .kp { color: #008800 } /* Keyword.Pseudo */
.highlight .kr { color: #008800; font-weight: bold } /* Keyword.Reserved */
.highlight .kt { color: #888888; font-weight: bold } /* Keyword.Type */
.highlight .m { color: #0000DD; font-weight: bold } /* Literal.Number */
.highlight .s { color: #dd2200; background-color: #fff0f0 } /* Literal.String */
.highlight .na { color: #336699 } /* Name.Attribute */
.highlight .nb { color: #003388 } /* Name.Builtin */
.highlight .nc { color: #bb0066; font-weight: bold } /* Name.Class */
.highlight .no { color: #003366; font-weight: bold } /* Name.Constant */
.highlight .nd { color: #555555 } /* Name.Decorator */
.highlight .ne { color: #bb0066; font-weight: bold } /* Name.Exception */
.highlight .nf { color: #0066bb; font-weight: bold } /* Name.Function */
.highlight .nl { color: #336699; font-style: italic } /* Name.Label */
.highlight .nn { color: #bb0066; font-weight: bold } /* Name.Namespace */
.highlight .py { color: #336699; font-weight: bold } /* Name.Property */
.highlight .nt { color: #bb0066; font-weight: bold } /* Name.Tag */
.highlight .nv { color: #336699 } /* Name.Variable */
.highlight .ow { color: #008800 } /* Operator.Word */
.highlight .w { color: #bbbbbb } /* Text.Whitespace */
.highlight .mb { color: #0000DD; font-weight: bold } /* Literal.Number.Bin */
.highlight .mf { color: #0000DD; font-weight: bold } /* Literal.Number.Float */
.highlight .mh { color: #0000DD; font-weight: bold } /* Literal.Number.Hex */
.highlight .mi { color: #0000DD; font-weight: bold } /* Literal.Number.Integer */
.highlight .mo { color: #0000DD; font-weight: bold } /* Literal.Number.Oct */
.highlight .sa { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Affix */
.highlight .sb { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Backtick */
.highlight .sc { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Char */
.highlight .dl { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Delimiter */
.highlight .sd { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Doc */
.highlight .s2 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Double */
.highlight .se { color: #0044dd; background-color: #fff0f0 } /* Literal.String.Escape */
.highlight .sh { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Heredoc */
.highlight .si { color: #3333bb; background-color: #fff0f0 } /* Literal.String.Interpol */
.highlight .sx { color: #22bb22; background-color: #f0fff0 } /* Literal.String.Other */
.highlight .sr { color: #008800; background-color: #fff0ff } /* Literal.String.Regex */
.highlight .s1 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Single */
.highlight .ss { color: #aa6600; background-color: #fff0f0 } /* Literal.String.Symbol */
.highlight .bp { color: #003388 } /* Name.Builtin.Pseudo */
.highlight .fm { color: #0066bb; font-weight: bold } /* Name.Function.Magic */
.highlight .vc { color: #336699 } /* Name.Variable.Class */
.highlight .vg { color: #dd7700 } /* Name.Variable.Global */
.highlight .vi { color: #3333bb } /* Name.Variable.Instance */
.highlight .vm { color: #336699 } /* Name.Variable.Magic */
.highlight .il { color: #0000DD; font-weight: bold } /* Literal.Number.Integer.Long */</style><div class="highlight"><pre><span></span><span class="c"># dwm version</span>
<span class="nv">VERSION</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="m">4</span>.2

<span class="c"># Customize below to fit your system</span>

<span class="c"># paths</span>
<span class="nv">PREFIX</span><span class="w"> </span><span class="o">=</span><span class="w"> </span>/usr/local
<span class="nv">MANPREFIX</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="si">${</span><span class="nv">PREFIX</span><span class="si">}</span>/share/man

<span class="nv">X11INC</span><span class="w"> </span><span class="o">=</span><span class="w"> </span>/usr/X11R6/include
<span class="nv">X11LIB</span><span class="w"> </span><span class="o">=</span><span class="w"> </span>/usr/X11R6/lib

<span class="c"># includes and libs</span>
<span class="nv">INCS</span><span class="w"> </span><span class="o">=</span><span class="w"> </span>-I.<span class="w"> </span>-I/usr/include<span class="w"> </span>-I<span class="si">${</span><span class="nv">X11INC</span><span class="si">}</span>
<span class="nv">LIBS</span><span class="w"> </span><span class="o">=</span><span class="w"> </span>-L/usr/lib<span class="w"> </span>-lc<span class="w"> </span>-L<span class="si">${</span><span class="nv">X11LIB</span><span class="si">}</span><span class="w"> </span>-lX11

<span class="c"># flags</span>
<span class="nv">CFLAGS</span><span class="w"> </span><span class="o">=</span><span class="w"> </span>-Os<span class="w"> </span><span class="si">${</span><span class="nv">INCS</span><span class="si">}</span><span class="w"> </span>-DVERSION<span class="o">=</span><span class="se">\&quot;</span><span class="si">${</span><span class="nv">VERSION</span><span class="si">}</span><span class="se">\&quot;</span>
<span class="nv">LDFLAGS</span><span class="w"> </span><span class="o">=</span><span class="w"> </span>-s<span class="w"> </span><span class="si">${</span><span class="nv">LIBS</span><span class="si">}</span>
<span class="c">#CFLAGS = -g -Wall -O2 ${INCS} -DVERSION=\&quot;${VERSION}\&quot;</span>
<span class="c">#LDFLAGS = -g ${LIBS}</span>

<span class="c"># Solaris</span>
<span class="c">#CFLAGS = -fast ${INCS} -DVERSION=\&quot;${VERSION}\&quot;</span>
<span class="c">#LDFLAGS = ${LIBS}</span>
<span class="c">#CFLAGS += -xtarget=ultra</span>

<span class="c"># compiler and linker</span>
<span class="nv">CC</span><span class="w"> </span><span class="o">=</span><span class="w"> </span>cc
</pre></div>
</code></pre></td></tr></table>
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rawing = nil
    end
  elseif State.lines.current_drawing then
    local drawing = State.lines.current_drawing
    local line_cache = State.line_cache[State.lines.current_drawing_index]
    if drawing.pending then
      if drawing.pending.mode == nil then
        -- nothing pending
      elseif drawing.pending.mode == 'freehand' then
        -- the last point added during update is good enough
        Drawing.smoothen(drawing.pending)
        table.insert(drawing.shapes, drawing.pending)
      elseif drawing.pending.mode == 'line' then
        local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
        if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
          drawing.pending.p2 = Drawing.find_or_insert_point(drawing.points, mx,my, State.width)
          table.insert(drawing.shapes, drawing.pending)
        end
      elseif drawing.pending.mode == 'manhattan' then
        local p1 = drawing.points[drawing.pending.p1]
        local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
        if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
          if math.abs(mx-p1.x) > math.abs(my-p1.y) then
            drawing.pending.p2 = Drawing.find_or_insert_point(drawing.points, mx, p1.y, State.width)
          else
            drawing.pending.p2 = Drawing.find_or_insert_point(drawing.points, p1.x, my, State.width)
          end
          local p2 = drawing.points[drawing.pending.p2]
          App.mouse_move(State.left+Drawing.pixels(p2.x, State.width), line_cache.starty+Drawing.pixels(p2.y, State.width))
          table.insert(drawing.shapes, drawing.pending)
        end
      elseif drawing.pending.mode == 'polygon' then
        local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
        if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
          table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, mx,my, State.width))
          table.insert(drawing.shapes, drawing.pending)
        end
      elseif drawing.pending.mode == 'rectangle' then
        assert(#drawing.pending.vertices <= 2)
        if #drawing.pending.vertices == 2 then
          local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
          if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
            local first = drawing.points[drawing.pending.vertices[1]]
            local second = drawing.points[drawing.pending.vertices[2]]
            local thirdx,thirdy, fourthx,fourthy = Drawing.complete_rectangle(first.x,first.y, second.x,second.y, mx,my)
            table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, thirdx,thirdy, State.width))
            table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, fourthx,fourthy, State.width))
            table.insert(drawing.shapes, drawing.pending)
          end
        else
          -- too few points; draw nothing
        end
      elseif drawing.pending.mode == 'square' then
        assert(#drawing.pending.vertices <= 2)
        if #drawing.pending.vertices == 2 then
          local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
          if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
            local first = drawing.points[drawing.pending.vertices[1]]
            local second = drawing.points[drawing.pending.vertices[2]]
            local thirdx,thirdy, fourthx,fourthy = Drawing.complete_square(first.x,first.y, second.x,second.y, mx,my)
            table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, thirdx,thirdy, State.width))
            table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, fourthx,fourthy, State.width))
            table.insert(drawing.shapes, drawing.pending)
          end
        end
      elseif drawing.pending.mode == 'circle' then
        local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
        if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
          local center = drawing.points[drawing.pending.center]
          drawing.pending.radius = round(geom.dist(center.x,center.y, mx,my))
          table.insert(drawing.shapes, drawing.pending)
        end
      elseif drawing.pending.mode == 'arc' then
        local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
        if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
          local center = drawing.points[drawing.pending.center]
          drawing.pending.end_angle = geom.angle_with_hint(center.x,center.y, mx,my, drawing.pending.end_angle)
          table.insert(drawing.shapes, drawing.pending)
        end
      elseif drawing.pending.mode == 'name' then
        -- drop it
      else
        print(drawing.pending.mode)
        assert(false)
      end
      State.lines.current_drawing.pending = {}
      State.lines.current_drawing = nil
    end
  end
end

function Drawing.keychord_press(State, chord)
  if chord == 'C-p' and not App.mouse_down(1) then
    State.current_drawing_mode = 'freehand'
  elseif App.mouse_down(1) and chord == 'l' then
    State.current_drawing_mode = 'line'
    local _,drawing = Drawing.current_drawing(State)
    if drawing.pending.mode == 'freehand' then
      drawing.pending.p1 = Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)
    elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
      drawing.pending.p1 = drawing.pending.vertices[1]
    elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
      drawing.pending.p1 = drawing.pending.center
    end
    drawing.pending.mode = 'line'
  elseif chord == 'C-l' and not App.mouse_down(1) then
    State.current_drawing_mode = 'line'
  elseif App.mouse_down(1) and chord == 'm' then
    State.current_drawing_mode = 'manhattan'
    local drawing = Drawing.select_drawing_at_mouse(State)
    if drawing.pending.mode == 'freehand' then
      drawing.pending.p1 = Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)
    elseif drawing.pending.mode == 'line' then
      -- do nothing
    elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
      drawing.pending.p1 = drawing.pending.vertices[1]
    elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
      drawing.pending.p1 = drawing.pending.center
    end
    drawing.pending.mode = 'manhattan'
  elseif chord == 'C-m' and not App.mouse_down(1) then
    State.current_drawing_mode = 'manhattan'
  elseif chord == 'C-g' and not App.mouse_down(1) then
    State.current_drawing_mode = 'polygon'
  elseif App.mouse_down(1) and chord == 'g' then
    State.current_drawing_mode = 'polygon'
    local _,drawing = Drawing.current_drawing(State)
    if drawing.pending.mode == 'freehand' then
      drawing.pending.vertices = {Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)}
    elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
      if drawing.pending.vertices == nil then
        drawing.pending.vertices = {drawing.pending.p1}
      end
    elseif drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
      -- reuse existing vertices
    elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
      drawing.pending.vertices = {drawing.pending.center}
    end
    drawing.pending.mode = 'polygon'
  elseif chord == 'C-r' and not App.mouse_down(1) then
    State.current_drawing_mode = 'rectangle'
  elseif App.mouse_down(1) and chord == 'r' then
    State.current_drawing_mode = 'rectangle'
    local _,drawing = Drawing.current_drawing(State)
    if drawing.pending.mode == 'freehand' then
      drawing.pending.vertices = {Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)}
    elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
      if drawing.pending.vertices == nil then
        drawing.pending.vertices = {drawing.pending.p1}
      end
    elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'square' then
      -- reuse existing (1-2) vertices
    elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
      drawing.pending.vertices = {drawing.pending.center}
    end
    drawing.pending.mode = 'rectangle'
  elseif chord == 'C-s' and not App.mouse_down(1) then
    State.current_drawing_mode = 'square'
  elseif App.mouse_down(1) and chord == 's' then
    State.current_drawing_mode = 'square'
    local _,drawing = Drawing.current_drawing(State)
    if drawing.pending.mode == 'freehand' then
      drawing.pending.vertices = {Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)}
    elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
      if drawing.pending.vertices == nil then
        drawing.pending.vertices = {drawing.pending.p1}
      end
    elseif drawing.pending.mode == 'polygon' then
      while #drawing.pending.vertices > 2 do
        table.remove(drawing.pending.vertices)
      end
    elseif drawing.pending.mode == 'rectangle' then
      -- reuse existing (1-2) vertices
    elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
      drawing.pending.vertices = {drawing.pending.center}
    end
    drawing.pending.mode = 'square'
  elseif App.mouse_down(1) and chord == 'p' and State.current_drawing_mode == 'polygon' then
    local _,drawing,line_cache = Drawing.current_drawing(State)
    local mx,my = Drawing.coord(App.mouse_x()-State.left, State.width), Drawing.coord(App.mouse_y()-line_cache.starty, State.width)
    local j = Drawing.find_or_insert_point(drawing.points, mx,my, State.width)
    table.insert(drawing.pending.vertices, j)
  elseif App.mouse_down(1) and chord == 'p' and (State.current_drawing_mode == 'rectangle' or State.current_drawing_mode == 'square') then
    local _,drawing,line_cache = Drawing.current_drawing(State)
    local mx,my = Drawing.coord(App.mouse_x()-State.left, State.width), Drawing.coord(App.mouse_y()-line_cache.starty, State.width)
    local j = Drawing.find_or_insert_point(drawing.points, mx,my, State.width)
    while #drawing.pending.vertices >= 2 do
      table.remove(drawing.pending.vertices)
    end
    table.insert(drawing.pending.vertices, j)
  elseif chord == 'C-o' and not App.mouse_down(1) then
    State.current_drawing_mode = 'circle'
  elseif App.mouse_down(1) and chord == 'a' and State.current_drawing_mode == 'circle' then
    local _,drawing,line_cache = Drawing.current_drawing(State)
    drawing.pending.mode = 'arc'
    local mx,my = Drawing.coord(App.mouse_x()-State.left, State.width), Drawing.coord(App.mouse_y()-line_cache.starty, State.width)
    local center = drawing.points[drawing.pending.center]
    drawing.pending.radius = round(geom.dist(center.x,center.y, mx,my))
    drawing.pending.start_angle = geom.angle(center.x,center.y, mx,my)
  elseif App.mouse_down(1) and chord == 'o' then
    State.current_drawing_mode = 'circle'
    local _,drawing = Drawing.current_drawing(State)
    if drawing.pending.mode == 'freehand' then
      drawing.pending.center = Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)
    elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
      drawing.pending.center = drawing.pending.p1
    elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
      drawing.pending.center = drawing.pending.vertices[1]
    end
    drawing.pending.mode = 'circle'
  elseif chord == 'C-u' and not App.mouse_down(1) then
    local drawing_index,drawing,line_cache,i,p = Drawing.select_point_at_mouse(State)
    if drawing then
      if State.previous_drawing_mode == nil then
        State.previous_drawing_mode = State.current_drawing_mode
      end
      State.current_drawing_mode = 'move'
      drawing.pending = {mode=State.current_drawing_mode, target_point=p, target_point_index=i}
      State.lines.current_drawing_index = drawing_index
      State.lines.current_drawing = drawing
    end
  elseif chord == 'C-n' and not App.mouse_down(1) then
    local drawing_index,drawing,line_cache,point_index,p = Drawing.select_point_at_mouse(State)
    if drawing then
      if State.previous_drawing_mode == nil then
        -- don't clobber
        State.previous_drawing_mode = State.current_drawing_mode
      end
      State.current_drawing_mode = 'name'
      p.name = ''
      drawing.pending = {mode=State.current_drawing_mode, target_point=point_index}
      State.lines.current_drawing_index = drawing_index
      State.lines.current_drawing = drawing
    end
  elseif chord == 'C-d' and not App.mouse_down(1) then
    local _,drawing,_,i,p = Drawing.select_point_at_mouse(State)
    if drawing then
      for _,shape in ipairs(drawing.shapes) do
        if Drawing.contains_point(shape, i) then
          if shape.mode == 'polygon' then
            local idx = table.find(shape.vertices, i)
            assert(idx)
            table.remove(shape.vertices, idx)
            if #shape.vertices < 3 then
              shape.mode = 'deleted'
            end
          else
            shape.mode = 'deleted'
          end
        end
      end
      drawing.points[i].deleted = true
    end
    local drawing,_,_,shape = Drawing.select_shape_at_mouse(State)
    if drawing then
      shape.mode = 'deleted'
    end
  elseif chord == 'C-h' and not App.mouse_down(1) then
    local drawing = Drawing.select_drawing_at_mouse(State)
    if drawing then
      drawing.show_help = true
    end
  elseif chord == 'escape' and App.mouse_down(1) then
    local _,drawing = Drawing.current_drawing(State)
    drawing.pending = {}
  end
end

function Drawing.complete_rectangle(firstx,firsty, secondx,secondy, x,y)
  if firstx == secondx then
    return x,secondy, x,firsty
  end
  if firsty == secondy then
    return secondx,y, firstx,y
  end
  local first_slope = (secondy-firsty)/(secondx-firstx)
  -- slope of second edge:
  --    -1/first_slope
  -- equation of line containing the second edge:
  --    y-secondy = -1/first_slope*(x-secondx)
  -- => 1/first_slope*x + y + (- secondy - secondx/first_slope) = 0
  -- now we want to find the point on this line that's closest to the mouse pointer.
  -- https://en.wikipedia.org/wiki/Distance_from_a_point_to_a_line#Line_defined_by_an_equation
  local a = 1/first_slope
  local c = -secondy - secondx/first_slope
  local thirdx = round(((x-a*y) - a*c) / (a*a + 1))
  local thirdy = round((a*(-x + a*y) - c) / (a*a + 1))
  -- slope of third edge = first_slope
  -- equation of line containing third edge:
  --     y - thirdy = first_slope*(x-thirdx)
  --  => -first_slope*x + y + (-thirdy + thirdx*first_slope) = 0
  -- now we want to find the point on this line that's closest to the first point
  local a = -first_slope
  local c = -thirdy + thirdx*first_slope
  local fourthx = round(((firstx-a*firsty) - a*c) / (a*a + 1))
  local fourthy = round((a*(-firstx + a*firsty) - c) / (a*a + 1))
  return thirdx,thirdy, fourthx,fourthy
end

function Drawing.complete_square(firstx,firsty, secondx,secondy, x,y)
  -- use x,y only to decide which side of the first edge to complete the square on
  local deltax = secondx-firstx
  local deltay = secondy-firsty
  local thirdx = secondx+deltay
  local thirdy = secondy-deltax
  if not geom.same_side(firstx,firsty, secondx,secondy, thirdx,thirdy, x,y) then
    deltax = -deltax
    deltay = -deltay
    thirdx = secondx+deltay
    thirdy = secondy-deltax
  end
  local fourthx = firstx+deltay
  local fourthy = firsty-deltax
  return thirdx,thirdy, fourthx,fourthy
end

function Drawing.current_drawing(State)
  local x, y = App.mouse_x(), App.mouse_y()
  for drawing_index,drawing in ipairs(State.lines) do
    if drawing.mode == 'drawing' then
      local line_cache = State.line_cache[drawing_index]
      if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
        return drawing_index,drawing,line_cache
      end
    end
  end
  return nil
end

function Drawing.select_shape_at_mouse(State)
  for drawing_index,drawing in ipairs(State.lines) do
    if drawing.mode == 'drawing' then
      local x, y = App.mouse_x(), App.mouse_y()
      local line_cache = State.line_cache[drawing_index]
      if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
        local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
        for i,shape in ipairs(drawing.shapes) do
          assert(shape)
          if geom.on_shape(mx,my, drawing, shape) then
            return drawing,line_cache,i,shape
          end
        end
      end
    end
  end
end

function Drawing.select_point_at_mouse(State)
  for drawing_index,drawing in ipairs(State.lines) do
    if drawing.mode == 'drawing' then
      local x, y = App.mouse_x(), App.mouse_y()
      local line_cache = State.line_cache[drawing_index]
      if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
        local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
        for i,point in ipairs(drawing.points) do
          assert(point)
          if Drawing.near(point, mx,my, State.width) then
            return drawing_index,drawing,line_cache,i,point
          end
        end
      end
    end
  end
end

function Drawing.select_drawing_at_mouse(State)
  for drawing_index,drawing in ipairs(State.lines) do
    if drawing.mode == 'drawing' then
      local x, y = App.mouse_x(), App.mouse_y()
      local line_cache = State.line_cache[drawing_index]
      if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
        return drawing
      end
    end
  end
end

function Drawing.contains_point(shape, p)
  if shape.mode == 'freehand' then
    -- not supported
  elseif shape.mode == 'line' or shape.mode == 'manhattan' then
    return shape.p1 == p or shape.p2 == p
  elseif shape.mode == 'polygon' or shape.mode == 'rectangle' or shape.mode == 'square' then
    return table.find(shape.vertices, p)
  elseif shape.mode == 'circle' then
    return shape.center == p
  elseif shape.mode == 'arc' then
    return shape.center == p
    -- ugh, how to support angles
  elseif shape.mode == 'deleted' then
    -- already done
  else
    print(shape.mode)
    assert(false)
  end
end

function Drawing.smoothen(shape)
  assert(shape.mode == 'freehand')
  for _=1,7 do
    for i=2,#shape.points-1 do
      local a = shape.points[i-1]
      local b = shape.points[i]
      local c = shape.points[i+1]
      b.x = round((a.x + b.x + c.x)/3)
      b.y = round((a.y + b.y + c.y)/3)
    end
  end
end

function round(num)
  return math.floor(num+.5)
end

function Drawing.find_or_insert_point(points, x,y, width)
  -- check if UI would snap the two points together
  for i,point in ipairs(points) do
    if Drawing.near(point, x,y, width) then
      return i
    end
  end
  table.insert(points, {x=x, y=y})
  return #points
end

function Drawing.near(point, x,y, width)
  local px,py = Drawing.pixels(x, width),Drawing.pixels(y, width)
  local cx,cy = Drawing.pixels(point.x, width), Drawing.pixels(point.y, width)
  return (cx-px)*(cx-px) + (cy-py)*(cy-py) < Same_point_distance*Same_point_distance
end

function Drawing.pixels(n, width)  -- parts to pixels
  return math.floor(n*width/256)
end
function Drawing.coord(n, width)  -- pixels to parts
  return math.floor(n*256/width)
end

function table.find(h, x)
  for k,v in pairs(h) do
    if v == x then
      return k
    end
  end
end