mouse events for scrollbar

You can either drag the scrollbar or click anywhere in the scrollbar
area.

It has this weird funkiness that the scrollbar shrinks as you get near
the bottom. But it feels.. weirdly satisfying?

0004-on.update

@@ -1,3 +1,6 @@
 on.update = function()
 	refresh_debug_animations()
-end
+	if Editor_scrollbar_drag then
+		adjust_scrollbar(App.mouse_y())
+	end
+end

0016-on.mouse_press

@@ -2,5 +2,11 @@ on.mouse_press = function(x,y, mouse_button)
 	if mouse_press_consumed_by_any_button_handler(Editor_state, x,y, mouse_button) then
 		return
 	end
-	edit.mouse_press(Editor_state, x,y, mouse_button)
+	if on_editor_scrollbar(x,y) then
+		Editor_scrollbar_drag = true
+	elseif on_editor_scrollbar_area(x,y) then
+		-- nothing
+	else
+		edit.mouse_press(Editor_state, x,y, mouse_button)
+	end
 end

0017-on.mouse_release

@@ -1,3 +1,10 @@
 on.mouse_release = function(x,y, mouse_button)
-	edit.mouse_release(Editor_state, x,y, mouse_button)
+	if Editor_scrollbar_drag then
+		adjust_scrollbar(y)
+		Editor_scrollbar_drag = nil
+	elseif on_editor_scrollbar_area(x,y) then
+		adjust_scrollbar(y)
+	else
+		edit.mouse_release(Editor_state, x,y, mouse_button)
+	end
 end

0034-draw_scrollbar

@@ -8,4 +8,6 @@ draw_scrollbar = function(Editor_state)
 	local boty = Editor_state.top +sbbot*(Editor_state.bottom - Editor_state.top)
 	App.color{r=0.6, g=0.6, b=0.8, a=0.5}
 	love.graphics.rectangle('fill', Editor_state.right+20, topy, 20, boty-topy)
+	Editor_scrollbar_top = topy
+	Editor_scrollbar_bottom = boty
 end

0036-adjust_scrollbar

@@ -0,0 +1,13 @@
+adjust_scrollbar = function(y)
+	local s = (y-Editor_state.top) / (Editor_state.bottom-Editor_state.top)
+	local screen_line = s*Editor_state.screen_line_count
+	local line = 1
+	for i=1,#Editor_state.lines do
+		if Editor_state.line_cache[i].start_screen_line_index > screen_line then
+			break
+		end
+		line = i
+	end
+	Editor_state.screen_top1 = {line=line, pos=1}
+	Editor_state.cursor1 = {line=line, pos=1}
+end

0037-Editor_scrollbar_top

@@ -0,0 +1,2 @@
+Editor_scrollbar_top = 0  -- in px
+Editor_scrollbar_bottom = 0

0038-on_editor_scrollbar

@@ -0,0 +1,7 @@
+on_editor_scrollbar = function(x,y)
+	if x < Editor_state.right+20 then return end
+	if x > Editor_state.right+40 then return end
+	if y < Editor_scrollbar_top then return end
+	if y > Editor_scrollbar_bottom then return end
+	return true
+end

0040-on_editor_scrollbar_area

@@ -0,0 +1,7 @@
+on_editor_scrollbar_area = function(x,y)
+	if x < Editor_state.right+20 then return end
+	if x > Editor_state.right+40 then return end
+	if y < Editor_state.top then return end
+	if y > Editor_state.bottom then return end
+	return true
+end

README.md

@@ -65,8 +65,6 @@ found anything amiss: http://akkartik.name/contact
 
 * Can't scroll while selecting text with mouse.
 
-* No scrollbars yet. That stuff is hard.
-
 ## Mirrors and Forks
 
 This repo is a fork of [lines.love](http://akkartik.name/lines.html), an