experimental approach to combining keyboard and mouse while drawing

Desired properties:
  - fluently draw lots of precise drawings
    - requires expressing lots of different kinds of constraints
  - always know what pressing a key is going to do
  - when typing, don't care where the mouse pointer is

Less important:
  - discoverability, learnability. Provide a hotkey for help.

Current plan:
  - chorded keys to modify drawings while mouse button is not pressed
  - unchorded keys to modify drawings only while mouse button is pressed
  - make changes while drawing a shape by pressing a key while mouse
    button is pressed
  - make changes to a drawing by hovering mouse pointer at a shape and
    pressing a key (unary operators)
  - add constraints after drawing by hovering mouse pointer at a shape,
    pressing a key and moving mouse pointer to a second shape (binary
    operators)
  - almost any change can be made to a shape after it's drawn (inspired
    by Sketchpad)
  - keys pressed while drawing a shape act as abbreviations to
    performing the action after drawing

First example in this PR:
  - you press mouse button, start drawing freehand
  - you realize you want a simple line, not a freehand stroke
  - without releasing the mouse button, you press 'l'
  - now you're drawing a straight line

You could also release the mouse button and finish the stroke, then
press 'ctrl-l' while hovering the mouse pointer on the stroke to turn it
into a line.

There's an asymmetry here. Strokes require a lot more information, so
while you can turn a stroke into a line, you can't turn a line into a
stroke.

Strokes are an exception where you can't switch to freehand mode after
you start drawing. You have to press C-f before drawing.

1 files changed, 36 insertions, 0 deletions

diff --git a/main.lua b/main.lua
index 234ac2a..aa1053b 100644
--- a/main.lua
+++ b/main.lua
@@ -229,6 +229,8 @@ function on_line(x,y, shape)
 end
 
 function love.textinput(t)
+  if love.mouse.isDown('1') then return end
+  if in_drawing() then return end
   lines[#lines] = lines[#lines]..t
 end
 
@@ -250,7 +252,17 @@ function keychord_pressed(chord)
     lines[#lines+1] = ''
   elseif chord == 'C-d' then
     parse_into_exec_payload(lines[#lines])
+  elseif chord == 'C-f' then
+    current_mode = 'freehand'
+  elseif love.mouse.isDown('1') and chord == 'l' then
+    current_mode = 'line'
+    local drawing = current_drawing()
+    assert(drawing.pending.mode == 'freehand')
+    drawing.pending.mode = 'line'
+    drawing.pending.x1 = drawing.pending.points[1].x
+    drawing.pending.y1 = drawing.pending.points[1].y
   elseif chord == 'C-l' then
+    current_mode = 'line'
     local drawing,i,shape = select_shape_at_mouse()
     if drawing then
       convert_line(shape)
@@ -268,6 +280,30 @@ function keychord_pressed(chord)
   end
 end
 
+function in_drawing()
+  local x, y = love.mouse.getX(), love.mouse.getY()
+  for _,drawing in ipairs(lines) do
+    if type(drawing) == 'table' then
+      if y >= drawing.y and y < drawing.y + pixels(drawing.h) and x >= 12 and x < 12+drawingw then
+        return true
+      end
+    end
+  end
+  return false
+end
+
+function current_drawing()
+  local x, y = love.mouse.getX(), love.mouse.getY()
+  for _,drawing in ipairs(lines) do
+    if type(drawing) == 'table' then
+      if y >= drawing.y and y < drawing.y + pixels(drawing.h) and x >= 12 and x < 12+drawingw then
+        return drawing
+      end
+    end
+  end
+  return nil
+end
+
 function select_shape_at_mouse()
   for _,drawing in ipairs(lines) do
     if type(drawing) == 'table' then