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