Added support for mouse double/triple click+drag selection

Resolves #159
Resolves #161

data/core/docview.lua

···
 end
 
 
+local function mouse_selection(doc, clicks, line1, col1, line2, col2)
+  local swap = line2 < line1 or line2 == line1 and col2 <= col1
+  if swap then
+    line1, col1, line2, col2 = line2, col2, line1, col1
+  end
+  if clicks == 2 then
+    line1, col1 = translate.start_of_word(doc, line1, col1)
+    line2, col2 = translate.end_of_word(doc, line2, col2)
+  elseif clicks == 3 then
+    if line2 == #doc.lines and doc.lines[#doc.lines] ~= "\n" then
+      doc:insert(math.huge, math.huge, "\n")
+    end
+    line1, col1, line2, col2 = line1, 1, line2 + 1, 1
+  end
+  if swap then
+    return line2, col2, line1, col1
+  end
+  return line1, col1, line2, col2
+end
+
+
 function DocView:on_mouse_pressed(button, x, y, clicks)
   local caught = DocView.super.on_mouse_pressed(self, button, x, y, clicks)
   if caught then
     return
   end
-  local line, col = self:resolve_screen_position(x, y)
-  if clicks == 2 then
-    local line1, col1 = translate.start_of_word(self.doc, line, col)
-    local line2, col2 = translate.end_of_word(self.doc, line, col)
-    self.doc:set_selection(line2, col2, line1, col1)
-  elseif clicks == 3 then
-    if line == #self.doc.lines then
-      self.doc:insert(math.huge, math.huge, "\n")
+  if keymap.modkeys["shift"] then
+    if clicks == 1 then
+      local line, col = self.doc:get_selection()
+      self.mouse_selecting = { line, col, clicks = 1 }
+      self:on_mouse_moved(x, y)
     end
-    self.doc:set_selection(line + 1, 1, line, 1)
   else
-    local line2, col2
-    if keymap.modkeys["shift"] then
-      line2, col2 = select(3, self.doc:get_selection())
-    end
-    self.doc:set_selection(line, col, line2, col2)
-    self.mouse_selecting = true
+    local line, col = self:resolve_screen_position(x, y)
+    self.doc:set_selection(mouse_selection(self.doc, clicks, line, col, line, col))
+    self.mouse_selecting = { line, col, clicks = clicks }
   end
   self.blink_timer = 0
 end
···
   end
 
   if self.mouse_selecting then
-    local _, _, line2, col2 = self.doc:get_selection()
-    local line1, col1 = self:resolve_screen_position(x, y)
-    self.doc:set_selection(line1, col1, line2, col2)
+    local l1, c1 = self:resolve_screen_position(x, y)
+    local l2, c2 = table.unpack(self.mouse_selecting)
+    local clicks = self.mouse_selecting.clicks
+    self.doc:set_selection(mouse_selection(self.doc, clicks, l1, c1, l2, c2))
   end
 end
 
 
 function DocView:on_mouse_released(button)
   DocView.super.on_mouse_released(self, button)
-  self.mouse_selecting = false
+  self.mouse_selecting = nil
 end