drawing.lua

   1 -- primitives for editing drawings
   2 Drawing = {}
   3 require 'drawing_tests'
   4
   5 -- All drawings span 100% of some conceptual 'page width' and divide it up
   6 -- into 256 parts.
   7 function Drawing.draw(State, line_index, y)
   8   local line = State.lines[line_index]
   9   local line_cache = State.line_cache[line_index]
  10   line_cache.starty = y
  11   local pmx,pmy = App.mouse_x(), App.mouse_y()
  12   if pmx < State.right and pmy > line_cache.starty and pmy < line_cache.starty+Drawing.pixels(line.h, State.width) then
  13     App.color(Icon_color)
  14     love.graphics.rectangle('line', State.left,line_cache.starty, State.width,Drawing.pixels(line.h, State.width))
  15     if icon[State.current_drawing_mode] then
  16       icon[State.current_drawing_mode](State.right-22, line_cache.starty+4)
  17     else
  18       icon[State.previous_drawing_mode](State.right-22, line_cache.starty+4)
  19     end
  20
  21     if App.mouse_down(1) and love.keyboard.isDown('h') then
  22       draw_help_with_mouse_pressed(State, line_index)
  23       return
  24     end
  25   end
  26
  27   if line.show_help then
  28     draw_help_without_mouse_pressed(State, line_index)
  29     return
  30   end
  31
  32   local mx = Drawing.coord(pmx-State.left, State.width)
  33   local my = Drawing.coord(pmy-line_cache.starty, State.width)
  34
  35   for _,shape in ipairs(line.shapes) do
  36     assert(shape)
  37     if geom.on_shape(mx,my, line, shape) then
  38       App.color(Focus_stroke_color)
  39     else
  40       App.color(Stroke_color)
  41     end
  42     Drawing.draw_shape(line, shape, line_cache.starty, State.left,State.right)
  43   end
  44
  45   local function px(x) return Drawing.pixels(x, State.width)+State.left end
  46   local function py(y) return Drawing.pixels(y, State.width)+line_cache.starty end
  47   for i,p in ipairs(line.points) do
  48     if p.deleted == nil then
  49       if Drawing.near(p, mx,my, State.width) then
  50         App.color(Focus_stroke_color)
  51         love.graphics.circle('line', px(p.x),py(p.y), Same_point_distance)
  52       else
  53         App.color(Stroke_color)
  54         love.graphics.circle('fill', px(p.x),py(p.y), 2)
  55       end
  56       if p.name then
  57         -- TODO: clip
  58         local x,y = px(p.x)+5, py(p.y)+5
  59         love.graphics.print(p.name, x,y)
  60         if State.current_drawing_mode == 'name' and i == line.pending.target_point then
  61           -- create a faint red box for the name
  62           App.color(Current_name_background_color)
  63           local name_width
  64           if p.name == '' then
  65             name_width = App.width('m')
  66           else
  67             name_width = App.width(p.name)
  68           end
  69           love.graphics.rectangle('fill', x,y, name_width, State.line_height)
  70         end
  71       end
  72     end
  73   end
  74   App.color(Current_stroke_color)
  75   Drawing.draw_pending_shape(line, line_cache.starty, State.left,State.right)
  76 end
  77
  78 function Drawing.draw_shape(drawing, shape, top, left,right)
  79   local width = right-left
  80   local function px(x) return Drawing.pixels(x, width)+left end
  81   local function py(y) return Drawing.pixels(y, width)+top end
  82   if shape.mode == 'freehand' then
  83     local prev = nil
  84     for _,point in ipairs(shape.points) do
  85       if prev then
  86         love.graphics.line(px(prev.x),py(prev.y), px(point.x),py(point.y))
  87       end
  88       prev = point
  89     end
  90   elseif shape.mode == 'line' or shape.mode == 'manhattan' then
  91     local p1 = drawing.points[shape.p1]
  92     local p2 = drawing.points[shape.p2]
  93     love.graphics.line(px(p1.x),py(p1.y), px(p2.x),py(p2.y))
  94   elseif shape.mode == 'polygon' or shape.mode == 'rectangle' or shape.mode == 'square' then
  95     local prev = nil
  96     for _,point in ipairs(shape.vertices) do
  97       local curr = drawing.points[point]
  98       if prev then
  99         love.graphics.line(px(prev.x),py(prev.y), px(curr.x),py(curr.y))
 100       end
 101       prev = curr
 102     end
 103     -- close the loop
 104     local curr = drawing.points[shape.vertices[1]]
 105     love.graphics.line(px(prev.x),py(prev.y), px(curr.x),py(curr.y))
 106   elseif shape.mode == 'circle' then
 107     -- TODO: clip
 108     local center = drawing.points[shape.center]
 109     love.graphics.circle('line', px(center.x),py(center.y), Drawing.pixels(shape.radius, width))
 110   elseif shape.mode == 'arc' then
 111     local center = drawing.points[shape.center]
 112     love.graphics.arc('line', 'open', px(center.x),py(center.y), Drawing.pixels(shape.radius, width), shape.start_angle, shape.end_angle, 360)
 113   elseif shape.mode == 'deleted' then
 114     -- ignore
 115   else
 116     print(shape.mode)
 117     assert(false)
 118   end
 119 end
 120
 121 function Drawing.draw_pending_shape(drawing, top, left,right)
 122   local width = right-left
 123   local pmx,pmy = App.mouse_x(), App.mouse_y()
 124   local function px(x) return Drawing.pixels(x, width)+left end
 125   local function py(y) return Drawing.pixels(y, width)+top end
 126   local mx = Drawing.coord(pmx-left, width)
 127   local my = Drawing.coord(pmy-top, width)
 128   -- recreate pixels from coords to precisely mimic how the drawing will look
 129   -- after mouse_release
 130   pmx,pmy = px(mx), py(my)
 131   local shape = drawing.pending
 132   if shape.mode == nil then
 133     -- nothing pending
 134   elseif shape.mode == 'freehand' then
 135     local shape_copy = deepcopy(shape)
 136     Drawing.smoothen(shape_copy)
 137     Drawing.draw_shape(drawing, shape_copy, top, left,right)
 138   elseif shape.mode == 'line' then
 139     if mx < 0 or mx >= 256 or my < 0 or my >= drawing.h then
 140       return
 141     end
 142     local p1 = drawing.points[shape.p1]
 143     love.graphics.line(px(p1.x),py(p1.y), pmx,pmy)
 144   elseif shape.mode == 'manhattan' then
 145     if mx < 0 or mx >= 256 or my < 0 or my >= drawing.h then
 146       return
 147     end
 148     local p1 = drawing.points[shape.p1]
 149     if math.abs(mx-p1.x) > math.abs(my-p1.y) then
 150       love.graphics.line(px(p1.x),py(p1.y), pmx,     py(p1.y))
 151     else
 152       love.graphics.line(px(p1.x),py(p1.y), px(p1.x),pmy)
 153     end
 154   elseif shape.mode == 'polygon' then
 155     -- don't close the loop on a pending polygon
 156     local prev = nil
 157     for _,point in ipairs(shape.vertices) do
 158       local curr = drawing.points[point]
 159       if prev then
 160         love.graphics.line(px(prev.x),py(prev.y), px(curr.x),py(curr.y))
 161       end
 162       prev = curr
 163     end
 164     love.graphics.line(px(prev.x),py(prev.y), pmx,pmy)
 165   elseif shape.mode == 'rectangle' then
 166     local first = drawing.points[shape.vertices[1]]
 167     if #shape.vertices == 1 then
 168       love.graphics.line(px(first.x),py(first.y), pmx,pmy)
 169       return
 170     end
 171     local second = drawing.points[shape.vertices[2]]
 172     local thirdx,thirdy, fourthx,fourthy = Drawing.complete_rectangle(first.x,first.y, second.x,second.y, mx,my)
 173     love.graphics.line(px(first.x),py(first.y), px(second.x),py(second.y))
 174     love.graphics.line(px(second.x),py(second.y), px(thirdx),py(thirdy))
 175     love.graphics.line(px(thirdx),py(thirdy), px(fourthx),py(fourthy))
 176     love.graphics.line(px(fourthx),py(fourthy), px(first.x),py(first.y))
 177   elseif shape.mode == 'square' then
 178     local first = drawing.points[shape.vertices[1]]
 179     if #shape.vertices == 1 then
 180       love.graphics.line(px(first.x),py(first.y), pmx,pmy)
 181       return
 182     end
 183     local second = drawing.points[shape.vertices[2]]
 184     local thirdx,thirdy, fourthx,fourthy = Drawing.complete_square(first.x,first.y, second.x,second.y, mx,my)
 185     love.graphics.line(px(first.x),py(first.y), px(second.x),py(second.y))
 186     love.graphics.line(px(second.x),py(second.y), px(thirdx),py(thirdy))
 187     love.graphics.line(px(thirdx),py(thirdy), px(fourthx),py(fourthy))
 188     love.graphics.line(px(fourthx),py(fourthy), px(first.x),py(first.y))
 189   elseif shape.mode == 'circle' then
 190     local center = drawing.points[shape.center]
 191     if mx < 0 or mx >= 256 or my < 0 or my >= drawing.h then
 192       return
 193     end
 194     local r = round(geom.dist(center.x, center.y, mx, my))
 195     local cx,cy = px(center.x), py(center.y)
 196     love.graphics.circle('line', cx,cy, Drawing.pixels(r, width))
 197   elseif shape.mode == 'arc' then
 198     local center = drawing.points[shape.center]
 199     if mx < 0 or mx >= 256 or my < 0 or my >= drawing.h then
 200       return
 201     end
 202     shape.end_angle = geom.angle_with_hint(center.x,center.y, mx,my, shape.end_angle)
 203     local cx,cy = px(center.x), py(center.y)
 204     love.graphics.arc('line', 'open', cx,cy, Drawing.pixels(shape.radius, width), shape.start_angle, shape.end_angle, 360)
 205   elseif shape.mode == 'move' then
 206     -- nothing pending; changes are immediately committed
 207   elseif shape.mode == 'name' then
 208     -- nothing pending; changes are immediately committed
 209   else
 210     print(shape.mode)
 211     assert(false)
 212   end
 213 end
 214
 215 function Drawing.in_drawing(drawing, line_cache, x,y, left,right)
 216   if line_cache.starty == nil then return false end  -- outside current page
 217   local width = right-left
 218   return y >= line_cache.starty and y < line_cache.starty + Drawing.pixels(drawing.h, width) and x >= left and x < right
 219 end
 220
 221 function Drawing.mouse_press(State, drawing_index, x,y, mouse_button)
 222   local drawing = State.lines[drawing_index]
 223   local line_cache = State.line_cache[drawing_index]
 224   local cx = Drawing.coord(x-State.left, State.width)
 225   local cy = Drawing.coord(y-line_cache.starty, State.width)
 226   if State.current_drawing_mode == 'freehand' then
 227     drawing.pending = {mode=State.current_drawing_mode, points={{x=cx, y=cy}}}
 228   elseif State.current_drawing_mode == 'line' or State.current_drawing_mode == 'manhattan' then
 229     local j = Drawing.find_or_insert_point(drawing.points, cx, cy, State.width)
 230     drawing.pending = {mode=State.current_drawing_mode, p1=j}
 231   elseif State.current_drawing_mode == 'polygon' or State.current_drawing_mode == 'rectangle' or State.current_drawing_mode == 'square' then
 232     local j = Drawing.find_or_insert_point(drawing.points, cx, cy, State.width)
 233     drawing.pending = {mode=State.current_drawing_mode, vertices={j}}
 234   elseif State.current_drawing_mode == 'circle' then
 235     local j = Drawing.find_or_insert_point(drawing.points, cx, cy, State.width)
 236     drawing.pending = {mode=State.current_drawing_mode, center=j}
 237   elseif State.current_drawing_mode == 'move' then
 238     -- all the action is in mouse_release
 239   elseif State.current_drawing_mode == 'name' then
 240     -- nothing
 241   else
 242     print(State.current_drawing_mode)
 243     assert(false)
 244   end
 245 end
 246
 247 -- a couple of operations on drawings need to constantly check the state of the mouse
 248 function Drawing.update(State)
 249   if State.lines.current_drawing == nil then return end
 250   local drawing = State.lines.current_drawing
 251   local line_cache = State.line_cache[State.lines.current_drawing_index]
 252   if line_cache.starty == nil then
 253     -- some event cleared starty just this frame
 254     -- draw in this frame will soon set starty
 255     -- just skip this frame
 256     return
 257   end
 258   assert(drawing.mode == 'drawing')
 259   local pmx, pmy = App.mouse_x(), App.mouse_y()
 260   local mx = Drawing.coord(pmx-State.left, State.width)
 261   local my = Drawing.coord(pmy-line_cache.starty, State.width)
 262   if App.mouse_down(1) then
 263     if Drawing.in_drawing(drawing, line_cache, pmx,pmy, State.left,State.right) then
 264       if drawing.pending.mode == 'freehand' then
 265         table.insert(drawing.pending.points, {x=mx, y=my})
 266       elseif drawing.pending.mode == 'move' then
 267         drawing.pending.target_point.x = mx
 268         drawing.pending.target_point.y = my
 269         Drawing.relax_constraints(drawing, drawing.pending.target_point_index)
 270       end
 271     end
 272   elseif State.current_drawing_mode == 'move' then
 273     if Drawing.in_drawing(drawing, line_cache, pmx, pmy, State.left,State.right) then
 274       drawing.pending.target_point.x = mx
 275       drawing.pending.target_point.y = my
 276       Drawing.relax_constraints(drawing, drawing.pending.target_point_index)
 277     end
 278   else
 279     -- do nothing
 280   end
 281 end
 282
 283 function Drawing.relax_constraints(drawing, p)
 284   for _,shape in ipairs(drawing.shapes) do
 285     if shape.mode == 'manhattan' then
 286       if shape.p1 == p then
 287         shape.mode = 'line'
 288       elseif shape.p2 == p then
 289         shape.mode = 'line'
 290       end
 291     elseif shape.mode == 'rectangle' or shape.mode == 'square' then
 292       for _,v in ipairs(shape.vertices) do
 293         if v == p then
 294           shape.mode = 'polygon'
 295         end
 296       end
 297     end
 298   end
 299 end
 300
 301 function Drawing.mouse_release(State, x,y, mouse_button)
 302   if State.current_drawing_mode == 'move' then
 303     State.current_drawing_mode = State.previous_drawing_mode
 304     State.previous_drawing_mode = nil
 305     if State.lines.current_drawing then
 306       State.lines.current_drawing.pending = {}
 307       State.lines.current_drawing = nil
 308     end
 309   elseif State.lines.current_drawing then
 310     local drawing = State.lines.current_drawing
 311     local line_cache = State.line_cache[State.lines.current_drawing_index]
 312     if drawing.pending then
 313       if drawing.pending.mode == nil then
 314         -- nothing pending
 315       elseif drawing.pending.mode == 'freehand' then
 316         -- the last point added during update is good enough
 317         Drawing.smoothen(drawing.pending)
 318         table.insert(drawing.shapes, drawing.pending)
 319       elseif drawing.pending.mode == 'line' then
 320         local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 321         if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
 322           drawing.pending.p2 = Drawing.find_or_insert_point(drawing.points, mx,my, State.width)
 323           table.insert(drawing.shapes, drawing.pending)
 324         end
 325       elseif drawing.pending.mode == 'manhattan' then
 326         local p1 = drawing.points[drawing.pending.p1]
 327         local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 328         if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
 329           if math.abs(mx-p1.x) > math.abs(my-p1.y) then
 330             drawing.pending.p2 = Drawing.find_or_insert_point(drawing.points, mx, p1.y, State.width)
 331           else
 332             drawing.pending.p2 = Drawing.find_or_insert_point(drawing.points, p1.x, my, State.width)
 333           end
 334           local p2 = drawing.points[drawing.pending.p2]
 335           App.mouse_move(State.left+Drawing.pixels(p2.x, State.width), line_cache.starty+Drawing.pixels(p2.y, State.width))
 336           table.insert(drawing.shapes, drawing.pending)
 337         end
 338       elseif drawing.pending.mode == 'polygon' then
 339         local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 340         if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
 341           table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, mx,my, State.width))
 342           table.insert(drawing.shapes, drawing.pending)
 343         end
 344       elseif drawing.pending.mode == 'rectangle' then
 345         assert(#drawing.pending.vertices <= 2)
 346         if #drawing.pending.vertices == 2 then
 347           local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 348           if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
 349             local first = drawing.points[drawing.pending.vertices[1]]
 350             local second = drawing.points[drawing.pending.vertices[2]]
 351             local thirdx,thirdy, fourthx,fourthy = Drawing.complete_rectangle(first.x,first.y, second.x,second.y, mx,my)
 352             table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, thirdx,thirdy, State.width))
 353             table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, fourthx,fourthy, State.width))
 354             table.insert(drawing.shapes, drawing.pending)
 355           end
 356         else
 357           -- too few points; draw nothing
 358         end
 359       elseif drawing.pending.mode == 'square' then
 360         assert(#drawing.pending.vertices <= 2)
 361         if #drawing.pending.vertices == 2 then
 362           local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 363           if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
 364             local first = drawing.points[drawing.pending.vertices[1]]
 365             local second = drawing.points[drawing.pending.vertices[2]]
 366             local thirdx,thirdy, fourthx,fourthy = Drawing.complete_square(first.x,first.y, second.x,second.y, mx,my)
 367             table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, thirdx,thirdy, State.width))
 368             table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, fourthx,fourthy, State.width))
 369             table.insert(drawing.shapes, drawing.pending)
 370           end
 371         end
 372       elseif drawing.pending.mode == 'circle' then
 373         local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 374         if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
 375           local center = drawing.points[drawing.pending.center]
 376           drawing.pending.radius = round(geom.dist(center.x,center.y, mx,my))
 377           table.insert(drawing.shapes, drawing.pending)
 378         end
 379       elseif drawing.pending.mode == 'arc' then
 380         local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 381         if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
 382           local center = drawing.points[drawing.pending.center]
 383           drawing.pending.end_angle = geom.angle_with_hint(center.x,center.y, mx,my, drawing.pending.end_angle)
 384           table.insert(drawing.shapes, drawing.pending)
 385         end
 386       elseif drawing.pending.mode == 'name' then
 387         -- drop it
 388       else
 389         print(drawing.pending.mode)
 390         assert(false)
 391       end
 392       State.lines.current_drawing.pending = {}
 393       State.lines.current_drawing = nil
 394     end
 395   end
 396 end
 397
 398 function Drawing.keychord_press(State, chord)
 399   if chord == 'C-p' and not App.mouse_down(1) then
 400     State.current_drawing_mode = 'freehand'
 401   elseif App.mouse_down(1) and chord == 'l' then
 402     State.current_drawing_mode = 'line'
 403     local _,drawing = Drawing.current_drawing(State)
 404     if drawing.pending.mode == 'freehand' then
 405       drawing.pending.p1 = Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)
 406     elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
 407       drawing.pending.p1 = drawing.pending.vertices[1]
 408     elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
 409       drawing.pending.p1 = drawing.pending.center
 410     end
 411     drawing.pending.mode = 'line'
 412   elseif chord == 'C-l' and not App.mouse_down(1) then
 413     State.current_drawing_mode = 'line'
 414   elseif App.mouse_down(1) and chord == 'm' then
 415     State.current_drawing_mode = 'manhattan'
 416     local drawing = Drawing.select_drawing_at_mouse(State)
 417     if drawing.pending.mode == 'freehand' then
 418       drawing.pending.p1 = Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)
 419     elseif drawing.pending.mode == 'line' then
 420       -- do nothing
 421     elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
 422       drawing.pending.p1 = drawing.pending.vertices[1]
 423     elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
 424       drawing.pending.p1 = drawing.pending.center
 425     end
 426     drawing.pending.mode = 'manhattan'
 427   elseif chord == 'C-m' and not App.mouse_down(1) then
 428     State.current_drawing_mode = 'manhattan'
 429   elseif chord == 'C-g' and not App.mouse_down(1) then
 430     State.current_drawing_mode = 'polygon'
 431   elseif App.mouse_down(1) and chord == 'g' then
 432     State.current_drawing_mode = 'polygon'
 433     local _,drawing = Drawing.current_drawing(State)
 434     if drawing.pending.mode == 'freehand' then
 435       drawing.pending.vertices = {Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)}
 436     elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
 437       if drawing.pending.vertices == nil then
 438         drawing.pending.vertices = {drawing.pending.p1}
 439       end
 440     elseif drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
 441       -- reuse existing vertices
 442     elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
 443       drawing.pending.vertices = {drawing.pending.center}
 444     end
 445     drawing.pending.mode = 'polygon'
 446   elseif chord == 'C-r' and not App.mouse_down(1) then
 447     State.current_drawing_mode = 'rectangle'
 448   elseif App.mouse_down(1) and chord == 'r' then
 449     State.current_drawing_mode = 'rectangle'
 450     local _,drawing = Drawing.current_drawing(State)
 451     if drawing.pending.mode == 'freehand' then
 452       drawing.pending.vertices = {Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)}
 453     elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
 454       if drawing.pending.vertices == nil then
 455         drawing.pending.vertices = {drawing.pending.p1}
 456       end
 457     elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'square' then
 458       -- reuse existing (1-2) vertices
 459     elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
 460       drawing.pending.vertices = {drawing.pending.center}
 461     end
 462     drawing.pending.mode = 'rectangle'
 463   elseif chord == 'C-s' and not App.mouse_down(1) then
 464     State.current_drawing_mode = 'square'
 465   elseif App.mouse_down(1) and chord == 's' then
 466     State.current_drawing_mode = 'square'
 467     local _,drawing = Drawing.current_drawing(State)
 468     if drawing.pending.mode == 'freehand' then
 469       drawing.pending.vertices = {Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)}
 470     elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
 471       if drawing.pending.vertices == nil then
 472         drawing.pending.vertices = {drawing.pending.p1}
 473       end
 474     elseif drawing.pending.mode == 'polygon' then
 475       while #drawing.pending.vertices > 2 do
 476         table.remove(drawing.pending.vertices)
 477       end
 478     elseif drawing.pending.mode == 'rectangle' then
 479       -- reuse existing (1-2) vertices
 480     elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
 481       drawing.pending.vertices = {drawing.pending.center}
 482     end
 483     drawing.pending.mode = 'square'
 484   elseif App.mouse_down(1) and chord == 'p' and State.current_drawing_mode == 'polygon' then
 485     local _,drawing,line_cache = Drawing.current_drawing(State)
 486     local mx,my = Drawing.coord(App.mouse_x()-State.left, State.width), Drawing.coord(App.mouse_y()-line_cache.starty, State.width)
 487     local j = Drawing.find_or_insert_point(drawing.points, mx,my, State.width)
 488     table.insert(drawing.pending.vertices, j)
 489   elseif App.mouse_down(1) and chord == 'p' and (State.current_drawing_mode == 'rectangle' or State.current_drawing_mode == 'square') then
 490     local _,drawing,line_cache = Drawing.current_drawing(State)
 491     local mx,my = Drawing.coord(App.mouse_x()-State.left, State.width), Drawing.coord(App.mouse_y()-line_cache.starty, State.width)
 492     local j = Drawing.find_or_insert_point(drawing.points, mx,my, State.width)
 493     while #drawing.pending.vertices >= 2 do
 494       table.remove(drawing.pending.vertices)
 495     end
 496     table.insert(drawing.pending.vertices, j)
 497   elseif chord == 'C-o' and not App.mouse_down(1) then
 498     State.current_drawing_mode = 'circle'
 499   elseif App.mouse_down(1) and chord == 'a' and State.current_drawing_mode == 'circle' then
 500     local _,drawing,line_cache = Drawing.current_drawing(State)
 501     drawing.pending.mode = 'arc'
 502     local mx,my = Drawing.coord(App.mouse_x()-State.left, State.width), Drawing.coord(App.mouse_y()-line_cache.starty, State.width)
 503     local center = drawing.points[drawing.pending.center]
 504     drawing.pending.radius = round(geom.dist(center.x,center.y, mx,my))
 505     drawing.pending.start_angle = geom.angle(center.x,center.y, mx,my)
 506   elseif App.mouse_down(1) and chord == 'o' then
 507     State.current_drawing_mode = 'circle'
 508     local _,drawing = Drawing.current_drawing(State)
 509     if drawing.pending.mode == 'freehand' then
 510       drawing.pending.center = Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)
 511     elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
 512       drawing.pending.center = drawing.pending.p1
 513     elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
 514       drawing.pending.center = drawing.pending.vertices[1]
 515     end
 516     drawing.pending.mode = 'circle'
 517   elseif chord == 'C-u' and not App.mouse_down(1) then
 518     local drawing_index,drawing,line_cache,i,p = Drawing.select_point_at_mouse(State)
 519     if drawing then
 520       if State.previous_drawing_mode == nil then
 521         State.previous_drawing_mode = State.current_drawing_mode
 522       end
 523       State.current_drawing_mode = 'move'
 524       drawing.pending = {mode=State.current_drawing_mode, target_point=p, target_point_index=i}
 525       State.lines.current_drawing_index = drawing_index
 526       State.lines.current_drawing = drawing
 527     end
 528   elseif chord == 'C-n' and not App.mouse_down(1) then
 529     local drawing_index,drawing,line_cache,point_index,p = Drawing.select_point_at_mouse(State)
 530     if drawing then
 531       if State.previous_drawing_mode == nil then
 532         -- don't clobber
 533         State.previous_drawing_mode = State.current_drawing_mode
 534       end
 535       State.current_drawing_mode = 'name'
 536       p.name = ''
 537       drawing.pending = {mode=State.current_drawing_mode, target_point=point_index}
 538       State.lines.current_drawing_index = drawing_index
 539       State.lines.current_drawing = drawing
 540     end
 541   elseif chord == 'C-d' and not App.mouse_down(1) then
 542     local _,drawing,_,i,p = Drawing.select_point_at_mouse(State)
 543     if drawing then
 544       for _,shape in ipairs(drawing.shapes) do
 545         if Drawing.contains_point(shape, i) then
 546           if shape.mode == 'polygon' then
 547             local idx = table.find(shape.vertices, i)
 548             assert(idx)
 549             table.remove(shape.vertices, idx)
 550             if #shape.vertices < 3 then
 551               shape.mode = 'deleted'
 552             end
 553           else
 554             shape.mode = 'deleted'
 555           end
 556         end
 557       end
 558       drawing.points[i].deleted = true
 559     end
 560     local drawing,_,_,shape = Drawing.select_shape_at_mouse(State)
 561     if drawing then
 562       shape.mode = 'deleted'
 563     end
 564   elseif chord == 'C-h' and not App.mouse_down(1) then
 565     local drawing = Drawing.select_drawing_at_mouse(State)
 566     if drawing then
 567       drawing.show_help = true
 568     end
 569   elseif chord == 'escape' and App.mouse_down(1) then
 570     local _,drawing = Drawing.current_drawing(State)
 571     drawing.pending = {}
 572   end
 573 end
 574
 575 function Drawing.complete_rectangle(firstx,firsty, secondx,secondy, x,y)
 576   if firstx == secondx then
 577     return x,secondy, x,firsty
 578   end
 579   if firsty == secondy then
 580     return secondx,y, firstx,y
 581   end
 582   local first_slope = (secondy-firsty)/(secondx-firstx)
 583   -- slope of second edge:
 584   --    -1/first_slope
 585   -- equation of line containing the second edge:
 586   --    y-secondy = -1/first_slope*(x-secondx)
 587   -- => 1/first_slope*x + y + (- secondy - secondx/first_slope) = 0
 588   -- now we want to find the point on this line that's closest to the mouse pointer.
 589   -- https://en.wikipedia.org/wiki/Distance_from_a_point_to_a_line#Line_defined_by_an_equation
 590   local a = 1/first_slope
 591   local c = -secondy - secondx/first_slope
 592   local thirdx = round(((x-a*y) - a*c) / (a*a + 1))
 593   local thirdy = round((a*(-x + a*y) - c) / (a*a + 1))
 594   -- slope of third edge = first_slope
 595   -- equation of line containing third edge:
 596   --     y - thirdy = first_slope*(x-thirdx)
 597   --  => -first_slope*x + y + (-thirdy + thirdx*first_slope) = 0
 598   -- now we want to find the point on this line that's closest to the first point
 599   local a = -first_slope
 600   local c = -thirdy + thirdx*first_slope
 601   local fourthx = round(((firstx-a*firsty) - a*c) / (a*a + 1))
 602   local fourthy = round((a*(-firstx + a*firsty) - c) / (a*a + 1))
 603   return thirdx,thirdy, fourthx,fourthy
 604 end
 605
 606 function Drawing.complete_square(firstx,firsty, secondx,secondy, x,y)
 607   -- use x,y only to decide which side of the first edge to complete the square on
 608   local deltax = secondx-firstx
 609   local deltay = secondy-firsty
 610   local thirdx = secondx+deltay
 611   local thirdy = secondy-deltax
 612   if not geom.same_side(firstx,firsty, secondx,secondy, thirdx,thirdy, x,y) then
 613     deltax = -deltax
 614     deltay = -deltay
 615     thirdx = secondx+deltay
 616     thirdy = secondy-deltax
 617   end
 618   local fourthx = firstx+deltay
 619   local fourthy = firsty-deltax
 620   return thirdx,thirdy, fourthx,fourthy
 621 end
 622
 623 function Drawing.current_drawing(State)
 624   local x, y = App.mouse_x(), App.mouse_y()
 625   for drawing_index,drawing in ipairs(State.lines) do
 626     if drawing.mode == 'drawing' then
 627       local line_cache = State.line_cache[drawing_index]
 628       if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
 629         return drawing_index,drawing,line_cache
 630       end
 631     end
 632   end
 633   return nil
 634 end
 635
 636 function Drawing.select_shape_at_mouse(State)
 637   for drawing_index,drawing in ipairs(State.lines) do
 638     if drawing.mode == 'drawing' then
 639       local x, y = App.mouse_x(), App.mouse_y()
 640       local line_cache = State.line_cache[drawing_index]
 641       if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
 642         local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 643         for i,shape in ipairs(drawing.shapes) do
 644           assert(shape)
 645           if geom.on_shape(mx,my, drawing, shape) then
 646             return drawing,line_cache,i,shape
 647           end
 648         end
 649       end
 650     end
 651   end
 652 end
 653
 654 function Drawing.select_point_at_mouse(State)
 655   for drawing_index,drawing in ipairs(State.lines) do
 656     if drawing.mode == 'drawing' then
 657       local x, y = App.mouse_x(), App.mouse_y()
 658       local line_cache = State.line_cache[drawing_index]
 659       if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
 660         local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 661         for i,point in ipairs(drawing.points) do
 662           assert(point)
 663           if Drawing.near(point, mx,my, State.width) then
 664             return drawing_index,drawing,line_cache,i,point
 665           end
 666         end
 667       end
 668     end
 669   end
 670 end
 671
 672 function Drawing.select_drawing_at_mouse(State)
 673   for drawing_index,drawing in ipairs(State.lines) do
 674     if drawing.mode == 'drawing' then
 675       local x, y = App.mouse_x(), App.mouse_y()
 676       local line_cache = State.line_cache[drawing_index]
 677       if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
 678         return drawing
 679       end
 680     end
 681   end
 682 end
 683
 684 function Drawing.contains_point(shape, p)
 685   if shape.mode == 'freehand' then
 686     -- not supported
 687   elseif shape.mode == 'line' or shape.mode == 'manhattan' then
 688     return shape.p1 == p or shape.p2 == p
 689   elseif shape.mode == 'polygon' or shape.mode == 'rectangle' or shape.mode == 'square' then
 690     return table.find(shape.vertices, p)
 691   elseif shape.mode == 'circle' then
 692     return shape.center == p
 693   elseif shape.mode == 'arc' then
 694     return shape.center == p
 695     -- ugh, how to support angles
 696   elseif shape.mode == 'deleted' then
 697     -- already done
 698   else
 699     print(shape.mode)
 700     assert(false)
 701   end
 702 end
 703
 704 function Drawing.smoothen(shape)
 705   assert(shape.mode == 'freehand')
 706   for _=1,7 do
 707     for i=2,#shape.points-1 do
 708       local a = shape.points[i-1]
 709       local b = shape.points[i]
 710       local c = shape.points[i+1]
 711       b.x = round((a.x + b.x + c.x)/3)
 712       b.y = round((a.y + b.y + c.y)/3)
 713     end
 714   end
 715 end
 716
 717 function round(num)
 718   return math.floor(num+.5)
 719 end
 720
 721 function Drawing.find_or_insert_point(points, x,y, width)
 722   -- check if UI would snap the two points together
 723   for i,point in ipairs(points) do
 724     if Drawing.near(point, x,y, width) then
 725       return i
 726     end
 727   end
 728   table.insert(points, {x=x, y=y})
 729   return #points
 730 end
 731
 732 function Drawing.near(point, x,y, width)
 733   local px,py = Drawing.pixels(x, width),Drawing.pixels(y, width)
 734   local cx,cy = Drawing.pixels(point.x, width), Drawing.pixels(point.y, width)
 735   return (cx-px)*(cx-px) + (cy-py)*(cy-py) < Same_point_distance*Same_point_distance
 736 end
 737
 738 function Drawing.pixels(n, width)  -- parts to pixels
 739   return math.floor(n*width/256)
 740 end
 741 function Drawing.coord(n, width)  -- pixels to parts
 742   return math.floor(n*256/width)
 743 end
 744
 745 function table.find(h, x)
 746   for k,v in pairs(h) do
 747     if v == x then
 748       return k
 749     end
 750   end
 751 end