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 cx,cy = px(center.x), py(center.y)
 195     love.graphics.circle('line', cx,cy, geom.dist(cx,cy, App.mouse_x(),App.mouse_y()))
 196   elseif shape.mode == 'arc' then
 197     local center = drawing.points[shape.center]
 198     if mx < 0 or mx >= 256 or my < 0 or my >= drawing.h then
 199       return
 200     end
 201     shape.end_angle = geom.angle_with_hint(center.x,center.y, mx,my, shape.end_angle)
 202     local cx,cy = px(center.x), py(center.y)
 203     love.graphics.arc('line', 'open', cx,cy, Drawing.pixels(shape.radius, width), shape.start_angle, shape.end_angle, 360)
 204   elseif shape.mode == 'move' then
 205     -- nothing pending; changes are immediately committed
 206   elseif shape.mode == 'name' then
 207     -- nothing pending; changes are immediately committed
 208   else
 209     print(shape.mode)
 210     assert(false)
 211   end
 212 end
 213
 214 function Drawing.in_drawing(drawing, line_cache, x,y, left,right)
 215   if line_cache.starty == nil then return false end  -- outside current page
 216   local width = right-left
 217   return y >= line_cache.starty and y < line_cache.starty + Drawing.pixels(drawing.h, width) and x >= left and x < right
 218 end
 219
 220 function Drawing.mouse_press(State, drawing_index, x,y, mouse_button)
 221   local drawing = State.lines[drawing_index]
 222   local line_cache = State.line_cache[drawing_index]
 223   local cx = Drawing.coord(x-State.left, State.width)
 224   local cy = Drawing.coord(y-line_cache.starty, State.width)
 225   if State.current_drawing_mode == 'freehand' then
 226     drawing.pending = {mode=State.current_drawing_mode, points={{x=cx, y=cy}}}
 227   elseif State.current_drawing_mode == 'line' or State.current_drawing_mode == 'manhattan' then
 228     local j = Drawing.find_or_insert_point(drawing.points, cx, cy, State.width)
 229     drawing.pending = {mode=State.current_drawing_mode, p1=j}
 230   elseif State.current_drawing_mode == 'polygon' or State.current_drawing_mode == 'rectangle' or State.current_drawing_mode == 'square' then
 231     local j = Drawing.find_or_insert_point(drawing.points, cx, cy, State.width)
 232     drawing.pending = {mode=State.current_drawing_mode, vertices={j}}
 233   elseif State.current_drawing_mode == 'circle' then
 234     local j = Drawing.find_or_insert_point(drawing.points, cx, cy, State.width)
 235     drawing.pending = {mode=State.current_drawing_mode, center=j}
 236   elseif State.current_drawing_mode == 'move' then
 237     -- all the action is in mouse_release
 238   elseif State.current_drawing_mode == 'name' then
 239     -- nothing
 240   else
 241     print(State.current_drawing_mode)
 242     assert(false)
 243   end
 244 end
 245
 246 -- a couple of operations on drawings need to constantly check the state of the mouse
 247 function Drawing.update(State)
 248   if State.lines.current_drawing == nil then return end
 249   local drawing = State.lines.current_drawing
 250   local line_cache = State.line_cache[State.lines.current_drawing_index]
 251   assert(drawing.mode == 'drawing')
 252   local pmx, pmy = App.mouse_x(), App.mouse_y()
 253   local mx = Drawing.coord(pmx-State.left, State.width)
 254   local my = Drawing.coord(pmy-line_cache.starty, State.width)
 255   if App.mouse_down(1) then
 256     if Drawing.in_drawing(drawing, line_cache, pmx,pmy, State.left,State.right) then
 257       if drawing.pending.mode == 'freehand' then
 258         table.insert(drawing.pending.points, {x=mx, y=my})
 259       elseif drawing.pending.mode == 'move' then
 260         drawing.pending.target_point.x = mx
 261         drawing.pending.target_point.y = my
 262         Drawing.relax_constraints(drawing, drawing.pending.target_point_index)
 263       end
 264     end
 265   elseif State.current_drawing_mode == 'move' then
 266     if Drawing.in_drawing(drawing, line_cache, pmx, pmy, State.left,State.right) 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   else
 272     -- do nothing
 273   end
 274 end
 275
 276 function Drawing.relax_constraints(drawing, p)
 277   for _,shape in ipairs(drawing.shapes) do
 278     if shape.mode == 'manhattan' then
 279       if shape.p1 == p then
 280         shape.mode = 'line'
 281       elseif shape.p2 == p then
 282         shape.mode = 'line'
 283       end
 284     elseif shape.mode == 'rectangle' or shape.mode == 'square' then
 285       for _,v in ipairs(shape.vertices) do
 286         if v == p then
 287           shape.mode = 'polygon'
 288         end
 289       end
 290     end
 291   end
 292 end
 293
 294 function Drawing.mouse_release(State, x,y, mouse_button)
 295   if State.current_drawing_mode == 'move' then
 296     State.current_drawing_mode = State.previous_drawing_mode
 297     State.previous_drawing_mode = nil
 298     if State.lines.current_drawing then
 299       State.lines.current_drawing.pending = {}
 300       State.lines.current_drawing = nil
 301     end
 302   elseif State.lines.current_drawing then
 303     local drawing = State.lines.current_drawing
 304     local line_cache = State.line_cache[State.lines.current_drawing_index]
 305     if drawing.pending then
 306       if drawing.pending.mode == nil then
 307         -- nothing pending
 308       elseif drawing.pending.mode == 'freehand' then
 309         -- the last point added during update is good enough
 310         Drawing.smoothen(drawing.pending)
 311         table.insert(drawing.shapes, drawing.pending)
 312       elseif drawing.pending.mode == 'line' then
 313         local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 314         if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
 315           drawing.pending.p2 = Drawing.find_or_insert_point(drawing.points, mx,my, State.width)
 316           table.insert(drawing.shapes, drawing.pending)
 317         end
 318       elseif drawing.pending.mode == 'manhattan' then
 319         local p1 = drawing.points[drawing.pending.p1]
 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           if math.abs(mx-p1.x) > math.abs(my-p1.y) then
 323             drawing.pending.p2 = Drawing.find_or_insert_point(drawing.points, mx, p1.y, State.width)
 324           else
 325             drawing.pending.p2 = Drawing.find_or_insert_point(drawing.points, p1.x, my, State.width)
 326           end
 327           local p2 = drawing.points[drawing.pending.p2]
 328           App.mouse_move(State.left+Drawing.pixels(p2.x, State.width), line_cache.starty+Drawing.pixels(p2.y, State.width))
 329           table.insert(drawing.shapes, drawing.pending)
 330         end
 331       elseif drawing.pending.mode == 'polygon' then
 332         local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 333         if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
 334           table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, mx,my, State.width))
 335           table.insert(drawing.shapes, drawing.pending)
 336         end
 337       elseif drawing.pending.mode == 'rectangle' then
 338         assert(#drawing.pending.vertices <= 2)
 339         if #drawing.pending.vertices == 2 then
 340           local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 341           if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
 342             local first = drawing.points[drawing.pending.vertices[1]]
 343             local second = drawing.points[drawing.pending.vertices[2]]
 344             local thirdx,thirdy, fourthx,fourthy = Drawing.complete_rectangle(first.x,first.y, second.x,second.y, mx,my)
 345             table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, thirdx,thirdy, State.width))
 346             table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, fourthx,fourthy, State.width))
 347             table.insert(drawing.shapes, drawing.pending)
 348           end
 349         else
 350           -- too few points; draw nothing
 351         end
 352       elseif drawing.pending.mode == 'square' then
 353         assert(#drawing.pending.vertices <= 2)
 354         if #drawing.pending.vertices == 2 then
 355           local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 356           if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
 357             local first = drawing.points[drawing.pending.vertices[1]]
 358             local second = drawing.points[drawing.pending.vertices[2]]
 359             local thirdx,thirdy, fourthx,fourthy = Drawing.complete_square(first.x,first.y, second.x,second.y, mx,my)
 360             table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, thirdx,thirdy, State.width))
 361             table.insert(drawing.pending.vertices, Drawing.find_or_insert_point(drawing.points, fourthx,fourthy, State.width))
 362             table.insert(drawing.shapes, drawing.pending)
 363           end
 364         end
 365       elseif drawing.pending.mode == 'circle' then
 366         local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 367         if mx >= 0 and mx < 256 and my >= 0 and my < drawing.h then
 368           local center = drawing.points[drawing.pending.center]
 369           drawing.pending.radius = round(geom.dist(center.x,center.y, mx,my))
 370           table.insert(drawing.shapes, drawing.pending)
 371         end
 372       elseif drawing.pending.mode == 'arc' 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.end_angle = geom.angle_with_hint(center.x,center.y, mx,my, drawing.pending.end_angle)
 377           table.insert(drawing.shapes, drawing.pending)
 378         end
 379       elseif drawing.pending.mode == 'name' then
 380         -- drop it
 381       else
 382         print(drawing.pending.mode)
 383         assert(false)
 384       end
 385       State.lines.current_drawing.pending = {}
 386       State.lines.current_drawing = nil
 387     end
 388   end
 389 end
 390
 391 function Drawing.keychord_press(State, chord)
 392   if chord == 'C-p' and not App.mouse_down(1) then
 393     State.current_drawing_mode = 'freehand'
 394   elseif App.mouse_down(1) and chord == 'l' then
 395     State.current_drawing_mode = 'line'
 396     local _,drawing = Drawing.current_drawing(State)
 397     if drawing.pending.mode == 'freehand' then
 398       drawing.pending.p1 = Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)
 399     elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
 400       drawing.pending.p1 = drawing.pending.vertices[1]
 401     elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
 402       drawing.pending.p1 = drawing.pending.center
 403     end
 404     drawing.pending.mode = 'line'
 405   elseif chord == 'C-l' and not App.mouse_down(1) then
 406     State.current_drawing_mode = 'line'
 407   elseif App.mouse_down(1) and chord == 'm' then
 408     State.current_drawing_mode = 'manhattan'
 409     local drawing = Drawing.select_drawing_at_mouse(State)
 410     if drawing.pending.mode == 'freehand' then
 411       drawing.pending.p1 = Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)
 412     elseif drawing.pending.mode == 'line' then
 413       -- do nothing
 414     elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
 415       drawing.pending.p1 = drawing.pending.vertices[1]
 416     elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
 417       drawing.pending.p1 = drawing.pending.center
 418     end
 419     drawing.pending.mode = 'manhattan'
 420   elseif chord == 'C-m' and not App.mouse_down(1) then
 421     State.current_drawing_mode = 'manhattan'
 422   elseif chord == 'C-g' and not App.mouse_down(1) then
 423     State.current_drawing_mode = 'polygon'
 424   elseif App.mouse_down(1) and chord == 'g' then
 425     State.current_drawing_mode = 'polygon'
 426     local _,drawing = Drawing.current_drawing(State)
 427     if drawing.pending.mode == 'freehand' then
 428       drawing.pending.vertices = {Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)}
 429     elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
 430       if drawing.pending.vertices == nil then
 431         drawing.pending.vertices = {drawing.pending.p1}
 432       end
 433     elseif drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
 434       -- reuse existing vertices
 435     elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
 436       drawing.pending.vertices = {drawing.pending.center}
 437     end
 438     drawing.pending.mode = 'polygon'
 439   elseif chord == 'C-r' and not App.mouse_down(1) then
 440     State.current_drawing_mode = 'rectangle'
 441   elseif App.mouse_down(1) and chord == 'r' then
 442     State.current_drawing_mode = 'rectangle'
 443     local _,drawing = Drawing.current_drawing(State)
 444     if drawing.pending.mode == 'freehand' then
 445       drawing.pending.vertices = {Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)}
 446     elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
 447       if drawing.pending.vertices == nil then
 448         drawing.pending.vertices = {drawing.pending.p1}
 449       end
 450     elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'square' then
 451       -- reuse existing (1-2) vertices
 452     elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
 453       drawing.pending.vertices = {drawing.pending.center}
 454     end
 455     drawing.pending.mode = 'rectangle'
 456   elseif chord == 'C-s' and not App.mouse_down(1) then
 457     State.current_drawing_mode = 'square'
 458   elseif App.mouse_down(1) and chord == 's' then
 459     State.current_drawing_mode = 'square'
 460     local _,drawing = Drawing.current_drawing(State)
 461     if drawing.pending.mode == 'freehand' then
 462       drawing.pending.vertices = {Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)}
 463     elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
 464       if drawing.pending.vertices == nil then
 465         drawing.pending.vertices = {drawing.pending.p1}
 466       end
 467     elseif drawing.pending.mode == 'polygon' then
 468       while #drawing.pending.vertices > 2 do
 469         table.remove(drawing.pending.vertices)
 470       end
 471     elseif drawing.pending.mode == 'rectangle' then
 472       -- reuse existing (1-2) vertices
 473     elseif drawing.pending.mode == 'circle' or drawing.pending.mode == 'arc' then
 474       drawing.pending.vertices = {drawing.pending.center}
 475     end
 476     drawing.pending.mode = 'square'
 477   elseif App.mouse_down(1) and chord == 'p' and State.current_drawing_mode == 'polygon' then
 478     local _,drawing,line_cache = Drawing.current_drawing(State)
 479     local mx,my = Drawing.coord(App.mouse_x()-State.left, State.width), Drawing.coord(App.mouse_y()-line_cache.starty, State.width)
 480     local j = Drawing.find_or_insert_point(drawing.points, mx,my, State.width)
 481     table.insert(drawing.pending.vertices, j)
 482   elseif App.mouse_down(1) and chord == 'p' and (State.current_drawing_mode == 'rectangle' or State.current_drawing_mode == 'square') then
 483     local _,drawing,line_cache = Drawing.current_drawing(State)
 484     local mx,my = Drawing.coord(App.mouse_x()-State.left, State.width), Drawing.coord(App.mouse_y()-line_cache.starty, State.width)
 485     local j = Drawing.find_or_insert_point(drawing.points, mx,my, State.width)
 486     while #drawing.pending.vertices >= 2 do
 487       table.remove(drawing.pending.vertices)
 488     end
 489     table.insert(drawing.pending.vertices, j)
 490   elseif chord == 'C-o' and not App.mouse_down(1) then
 491     State.current_drawing_mode = 'circle'
 492   elseif App.mouse_down(1) and chord == 'a' and State.current_drawing_mode == 'circle' then
 493     local _,drawing,line_cache = Drawing.current_drawing(State)
 494     drawing.pending.mode = 'arc'
 495     local mx,my = Drawing.coord(App.mouse_x()-State.left, State.width), Drawing.coord(App.mouse_y()-line_cache.starty, State.width)
 496     local center = drawing.points[drawing.pending.center]
 497     drawing.pending.radius = round(geom.dist(center.x,center.y, mx,my))
 498     drawing.pending.start_angle = geom.angle(center.x,center.y, mx,my)
 499   elseif App.mouse_down(1) and chord == 'o' then
 500     State.current_drawing_mode = 'circle'
 501     local _,drawing = Drawing.current_drawing(State)
 502     if drawing.pending.mode == 'freehand' then
 503       drawing.pending.center = Drawing.find_or_insert_point(drawing.points, drawing.pending.points[1].x, drawing.pending.points[1].y, State.width)
 504     elseif drawing.pending.mode == 'line' or drawing.pending.mode == 'manhattan' then
 505       drawing.pending.center = drawing.pending.p1
 506     elseif drawing.pending.mode == 'polygon' or drawing.pending.mode == 'rectangle' or drawing.pending.mode == 'square' then
 507       drawing.pending.center = drawing.pending.vertices[1]
 508     end
 509     drawing.pending.mode = 'circle'
 510   elseif chord == 'C-u' and not App.mouse_down(1) then
 511     local drawing_index,drawing,line_cache,i,p = Drawing.select_point_at_mouse(State)
 512     if drawing then
 513       if State.previous_drawing_mode == nil then
 514         State.previous_drawing_mode = State.current_drawing_mode
 515       end
 516       State.current_drawing_mode = 'move'
 517       drawing.pending = {mode=State.current_drawing_mode, target_point=p, target_point_index=i}
 518       State.lines.current_drawing_index = drawing_index
 519       State.lines.current_drawing = drawing
 520     end
 521   elseif chord == 'C-n' and not App.mouse_down(1) then
 522     local drawing_index,drawing,line_cache,point_index,p = Drawing.select_point_at_mouse(State)
 523     if drawing then
 524       if State.previous_drawing_mode == nil then
 525         -- don't clobber
 526         State.previous_drawing_mode = State.current_drawing_mode
 527       end
 528       State.current_drawing_mode = 'name'
 529       p.name = ''
 530       drawing.pending = {mode=State.current_drawing_mode, target_point=point_index}
 531       State.lines.current_drawing_index = drawing_index
 532       State.lines.current_drawing = drawing
 533     end
 534   elseif chord == 'C-d' and not App.mouse_down(1) then
 535     local _,drawing,_,i,p = Drawing.select_point_at_mouse(State)
 536     if drawing then
 537       for _,shape in ipairs(drawing.shapes) do
 538         if Drawing.contains_point(shape, i) then
 539           if shape.mode == 'polygon' then
 540             local idx = table.find(shape.vertices, i)
 541             assert(idx)
 542             table.remove(shape.vertices, idx)
 543             if #shape.vertices < 3 then
 544               shape.mode = 'deleted'
 545             end
 546           else
 547             shape.mode = 'deleted'
 548           end
 549         end
 550       end
 551       drawing.points[i].deleted = true
 552     end
 553     local drawing,_,_,shape = Drawing.select_shape_at_mouse(State)
 554     if drawing then
 555       shape.mode = 'deleted'
 556     end
 557   elseif chord == 'C-h' and not App.mouse_down(1) then
 558     local drawing = Drawing.select_drawing_at_mouse(State)
 559     if drawing then
 560       drawing.show_help = true
 561     end
 562   elseif chord == 'escape' and App.mouse_down(1) then
 563     local _,drawing = Drawing.current_drawing(State)
 564     drawing.pending = {}
 565   end
 566 end
 567
 568 function Drawing.complete_rectangle(firstx,firsty, secondx,secondy, x,y)
 569   if firstx == secondx then
 570     return x,secondy, x,firsty
 571   end
 572   if firsty == secondy then
 573     return secondx,y, firstx,y
 574   end
 575   local first_slope = (secondy-firsty)/(secondx-firstx)
 576   -- slope of second edge:
 577   --    -1/first_slope
 578   -- equation of line containing the second edge:
 579   --    y-secondy = -1/first_slope*(x-secondx)
 580   -- => 1/first_slope*x + y + (- secondy - secondx/first_slope) = 0
 581   -- now we want to find the point on this line that's closest to the mouse pointer.
 582   -- https://en.wikipedia.org/wiki/Distance_from_a_point_to_a_line#Line_defined_by_an_equation
 583   local a = 1/first_slope
 584   local c = -secondy - secondx/first_slope
 585   local thirdx = round(((x-a*y) - a*c) / (a*a + 1))
 586   local thirdy = round((a*(-x + a*y) - c) / (a*a + 1))
 587   -- slope of third edge = first_slope
 588   -- equation of line containing third edge:
 589   --     y - thirdy = first_slope*(x-thirdx)
 590   --  => -first_slope*x + y + (-thirdy + thirdx*first_slope) = 0
 591   -- now we want to find the point on this line that's closest to the first point
 592   local a = -first_slope
 593   local c = -thirdy + thirdx*first_slope
 594   local fourthx = round(((firstx-a*firsty) - a*c) / (a*a + 1))
 595   local fourthy = round((a*(-firstx + a*firsty) - c) / (a*a + 1))
 596   return thirdx,thirdy, fourthx,fourthy
 597 end
 598
 599 function Drawing.complete_square(firstx,firsty, secondx,secondy, x,y)
 600   -- use x,y only to decide which side of the first edge to complete the square on
 601   local deltax = secondx-firstx
 602   local deltay = secondy-firsty
 603   local thirdx = secondx+deltay
 604   local thirdy = secondy-deltax
 605   if not geom.same_side(firstx,firsty, secondx,secondy, thirdx,thirdy, x,y) then
 606     deltax = -deltax
 607     deltay = -deltay
 608     thirdx = secondx+deltay
 609     thirdy = secondy-deltax
 610   end
 611   local fourthx = firstx+deltay
 612   local fourthy = firsty-deltax
 613   return thirdx,thirdy, fourthx,fourthy
 614 end
 615
 616 function Drawing.current_drawing(State)
 617   local x, y = App.mouse_x(), App.mouse_y()
 618   for drawing_index,drawing in ipairs(State.lines) do
 619     if drawing.mode == 'drawing' then
 620       local line_cache = State.line_cache[drawing_index]
 621       if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
 622         return drawing_index,drawing,line_cache
 623       end
 624     end
 625   end
 626   return nil
 627 end
 628
 629 function Drawing.select_shape_at_mouse(State)
 630   for drawing_index,drawing in ipairs(State.lines) do
 631     if drawing.mode == 'drawing' then
 632       local x, y = App.mouse_x(), App.mouse_y()
 633       local line_cache = State.line_cache[drawing_index]
 634       if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
 635         local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 636         for i,shape in ipairs(drawing.shapes) do
 637           assert(shape)
 638           if geom.on_shape(mx,my, drawing, shape) then
 639             return drawing,line_cache,i,shape
 640           end
 641         end
 642       end
 643     end
 644   end
 645 end
 646
 647 function Drawing.select_point_at_mouse(State)
 648   for drawing_index,drawing in ipairs(State.lines) do
 649     if drawing.mode == 'drawing' then
 650       local x, y = App.mouse_x(), App.mouse_y()
 651       local line_cache = State.line_cache[drawing_index]
 652       if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
 653         local mx,my = Drawing.coord(x-State.left, State.width), Drawing.coord(y-line_cache.starty, State.width)
 654         for i,point in ipairs(drawing.points) do
 655           assert(point)
 656           if Drawing.near(point, mx,my, State.width) then
 657             return drawing_index,drawing,line_cache,i,point
 658           end
 659         end
 660       end
 661     end
 662   end
 663 end
 664
 665 function Drawing.select_drawing_at_mouse(State)
 666   for drawing_index,drawing in ipairs(State.lines) do
 667     if drawing.mode == 'drawing' then
 668       local x, y = App.mouse_x(), App.mouse_y()
 669       local line_cache = State.line_cache[drawing_index]
 670       if Drawing.in_drawing(drawing, line_cache, x,y, State.left,State.right) then
 671         return drawing
 672       end
 673     end
 674   end
 675 end
 676
 677 function Drawing.contains_point(shape, p)
 678   if shape.mode == 'freehand' then
 679     -- not supported
 680   elseif shape.mode == 'line' or shape.mode == 'manhattan' then
 681     return shape.p1 == p or shape.p2 == p
 682   elseif shape.mode == 'polygon' or shape.mode == 'rectangle' or shape.mode == 'square' then
 683     return table.find(shape.vertices, p)
 684   elseif shape.mode == 'circle' then
 685     return shape.center == p
 686   elseif shape.mode == 'arc' then
 687     return shape.center == p
 688     -- ugh, how to support angles
 689   elseif shape.mode == 'deleted' then
 690     -- already done
 691   else
 692     print(shape.mode)
 693     assert(false)
 694   end
 695 end
 696
 697 function Drawing.smoothen(shape)
 698   assert(shape.mode == 'freehand')
 699   for _=1,7 do
 700     for i=2,#shape.points-1 do
 701       local a = shape.points[i-1]
 702       local b = shape.points[i]
 703       local c = shape.points[i+1]
 704       b.x = round((a.x + b.x + c.x)/3)
 705       b.y = round((a.y + b.y + c.y)/3)
 706     end
 707   end
 708 end
 709
 710 function round(num)
 711   return math.floor(num+.5)
 712 end
 713
 714 function Drawing.find_or_insert_point(points, x,y, width)
 715   -- check if UI would snap the two points together
 716   for i,point in ipairs(points) do
 717     if Drawing.near(point, x,y, width) then
 718       return i
 719     end
 720   end
 721   table.insert(points, {x=x, y=y})
 722   return #points
 723 end
 724
 725 function Drawing.near(point, x,y, width)
 726   local px,py = Drawing.pixels(x, width),Drawing.pixels(y, width)
 727   local cx,cy = Drawing.pixels(point.x, width), Drawing.pixels(point.y, width)
 728   return (cx-px)*(cx-px) + (cy-py)*(cy-py) < Same_point_distance*Same_point_distance
 729 end
 730
 731 function Drawing.pixels(n, width)  -- parts to pixels
 732   return math.floor(n*width/256)
 733 end
 734 function Drawing.coord(n, width)  -- pixels to parts
 735   return math.floor(n*256/width)
 736 end
 737
 738 function table.find(h, x)
 739   for k,v in pairs(h) do
 740     if v == x then
 741       return k
 742     end
 743   end
 744 end