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