keep text from overflowing right margin

I've been sloppy about this so far, and outside of tests I can't find
any examples where it matters, but it matters in a potential fork where
I'm rendering multiple columns of text.

It's unfortunate that my tests have this level of brittleness. What I'd
really like to assert in many of these changed lines is that the text
stays inside the margins and that more text would overflow margins.

2 files changed, 48 insertions, 41 deletions

diff --git a/text.lua b/text.lua
index e28a9dc..fdf2418 100644
--- a/text.lua
+++ b/text.lua
@@ -807,21 +807,23 @@ function Text.nearest_cursor_pos(line, x, left)
   assert(false)
 end
 
-function Text.nearest_pos_less_than(line, x)  -- x DOES NOT include left margin
+-- return the nearest index of line (in utf8 code points) which lies entirely
+-- within x pixels of the left margin
+function Text.nearest_pos_less_than(line, x)
+--?   print('-- nearest_pos_less_than', line, x)
   if x == 0 then
     return 1
   end
   local len = utf8.len(line)
-  local max_x = Text.x(line, len+1)
+  local max_x = Text.x_after(line, len)
   if x > max_x then
     return len+1
   end
   local left, right = 1, len+1
---?   print('--')
   while true do
     local curr = math.floor((left+right)/2)
-    local currxmin = Text.x(line, curr+1)
-    local currxmax = Text.x(line, curr+2)
+    local currxmin = Text.x_after(line, curr+1)
+    local currxmax = Text.x_after(line, curr+2)
 --?     print(x, left, right, curr, currxmin, currxmax)
     if currxmin <= x and x < currxmax then
       return curr
@@ -838,6 +840,14 @@ function Text.nearest_pos_less_than(line, x)  -- x DOES NOT include left margin
   assert(false)
 end
 
+function Text.x_after(s, pos)
+  local offset = Text.offset(s, math.min(pos+1, #s+1))
+  local s_before = s:sub(1, offset-1)
+--?   print('^'..s_before..'$')
+  local text_before = App.newText(love.graphics.getFont(), s_before)
+  return App.width(text_before)
+end
+
 function Text.x(s, pos)
   local offset = Text.offset(s, pos)
   local s_before = s:sub(1, offset-1)
diff --git a/text_tests.lua b/text_tests.lua
index c30f907..2d0edc6 100644
--- a/text_tests.lua
+++ b/text_tests.lua
@@ -338,9 +338,9 @@ function test_draw_wrapping_text()
   local y = Editor_state.top
   App.screen.check(y, 'abc', 'F - test_draw_wrapping_text/screen:1')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'def', 'F - test_draw_wrapping_text/screen:2')
+  App.screen.check(y, 'de', 'F - test_draw_wrapping_text/screen:2')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'gh', 'F - test_draw_wrapping_text/screen:3')
+  App.screen.check(y, 'fgh', 'F - test_draw_wrapping_text/screen:3')
 end
 
 function test_draw_word_wrapping_text()
@@ -414,9 +414,9 @@ function test_draw_text_wrapping_within_word()
   local y = Editor_state.top
   App.screen.check(y, 'abcd ', 'F - test_draw_text_wrapping_within_word/screen:1')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'e fghi', 'F - test_draw_text_wrapping_within_word/screen:2')
+  App.screen.check(y, 'e fgh', 'F - test_draw_text_wrapping_within_word/screen:2')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'jk', 'F - test_draw_text_wrapping_within_word/screen:3')
+  App.screen.check(y, 'ijk', 'F - test_draw_text_wrapping_within_word/screen:3')
 end
 
 function test_draw_wrapping_text_containing_non_ascii()
@@ -431,11 +431,11 @@ function test_draw_wrapping_text_containing_non_ascii()
   Editor_state.screen_bottom1 = {}
   edit.draw(Editor_state)
   local y = Editor_state.top
-  App.screen.check(y, 'mada', 'F - test_draw_wrapping_text_containing_non_ascii/screen:1')
+  App.screen.check(y, 'mad', 'F - test_draw_wrapping_text_containing_non_ascii/screen:1')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'm I’', 'F - test_draw_wrapping_text_containing_non_ascii/screen:2')
+  App.screen.check(y, 'am ', 'F - test_draw_wrapping_text_containing_non_ascii/screen:2')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'm ad', 'F - test_draw_wrapping_text_containing_non_ascii/screen:3')
+  App.screen.check(y, 'I’m ', 'F - test_draw_wrapping_text_containing_non_ascii/screen:3')
 end
 
 function test_click_on_wrapping_line()
@@ -453,13 +453,13 @@ function test_click_on_wrapping_line()
   local y = Editor_state.top
   App.screen.check(y, 'madam ', 'F - test_click_on_wrapping_line/baseline/screen:1')
   y = y + Editor_state.line_height
-  App.screen.check(y, "I'm ada", 'F - test_click_on_wrapping_line/baseline/screen:2')
+  App.screen.check(y, "I'm ad", 'F - test_click_on_wrapping_line/baseline/screen:2')
   y = y + Editor_state.line_height
   -- click past end of second screen line
   edit.run_after_mouse_click(Editor_state, App.screen.width-2,y-2, 1)
   -- cursor moves to end of screen line
   check_eq(Editor_state.cursor1.line, 1, 'F - test_click_on_wrapping_line/cursor:line')
-  check_eq(Editor_state.cursor1.pos, 13, 'F - test_click_on_wrapping_line/cursor:pos')
+  check_eq(Editor_state.cursor1.pos, 12, 'F - test_click_on_wrapping_line/cursor:pos')
 end
 
 function test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen()
@@ -475,13 +475,13 @@ function test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen()
   Editor_state.screen_bottom1 = {}
   edit.draw(Editor_state)
   local y = Editor_state.top
-  App.screen.check(y, "I'm ada", 'F - test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen/baseline/screen:2')
+  App.screen.check(y, "I'm ad", 'F - test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen/baseline/screen:2')
   y = y + Editor_state.line_height
   -- click past end of second screen line
   edit.run_after_mouse_click(Editor_state, App.screen.width-2,y-2, 1)
   -- cursor moves to end of screen line
   check_eq(Editor_state.cursor1.line, 1, 'F - test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen/cursor:line')
-  check_eq(Editor_state.cursor1.pos, 13, 'F - test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen/cursor:pos')
+  check_eq(Editor_state.cursor1.pos, 12, 'F - test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen/cursor:pos')
 end
 
 function test_click_past_end_of_wrapping_line()
@@ -499,9 +499,9 @@ function test_click_past_end_of_wrapping_line()
   local y = Editor_state.top
   App.screen.check(y, 'madam ', 'F - test_click_past_end_of_wrapping_line/baseline/screen:1')
   y = y + Editor_state.line_height
-  App.screen.check(y, "I'm ada", 'F - test_click_past_end_of_wrapping_line/baseline/screen:2')
+  App.screen.check(y, "I'm ad", 'F - test_click_past_end_of_wrapping_line/baseline/screen:2')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'm', 'F - test_click_past_end_of_wrapping_line/baseline/screen:3')
+  App.screen.check(y, 'am', 'F - test_click_past_end_of_wrapping_line/baseline/screen:3')
   y = y + Editor_state.line_height
   -- click past the end of it
   edit.run_after_mouse_click(Editor_state, App.screen.width-2,y-2, 1)
@@ -509,8 +509,8 @@ function test_click_past_end_of_wrapping_line()
   check_eq(Editor_state.cursor1.pos, 15, 'F - test_click_past_end_of_wrapping_line/cursor')  -- one more than the number of UTF-8 code-points
 end
 
-function test_click_on_wrapping_line_containing_non_ascii()
-  io.write('\ntest_click_on_wrapping_line_containing_non_ascii')
+function test_click_past_end_of_wrapping_line_containing_non_ascii()
+  io.write('\ntest_click_past_end_of_wrapping_line_containing_non_ascii')
   -- display a wrapping line containing non-ASCII
   App.screen.init{width=75, height=80}
   Editor_state = edit.initialize_test_state()
@@ -522,16 +522,16 @@ function test_click_on_wrapping_line_containing_non_ascii()
   Editor_state.screen_bottom1 = {}
   edit.draw(Editor_state)
   local y = Editor_state.top
-  App.screen.check(y, 'madam ', 'F - test_click_on_wrapping_line_containing_non_ascii/baseline/screen:1')
+  App.screen.check(y, 'madam ', 'F - test_click_past_end_of_wrapping_line_containing_non_ascii/baseline/screen:1')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'I’m ada', 'F - test_click_on_wrapping_line_containing_non_ascii/baseline/screen:2')
+  App.screen.check(y, 'I’m ad', 'F - test_click_past_end_of_wrapping_line_containing_non_ascii/baseline/screen:2')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'm', 'F - test_click_on_wrapping_line_containing_non_ascii/baseline/screen:3')
+  App.screen.check(y, 'am', 'F - test_click_past_end_of_wrapping_line_containing_non_ascii/baseline/screen:3')
   y = y + Editor_state.line_height
   -- click past the end of it
   edit.run_after_mouse_click(Editor_state, App.screen.width-2,y-2, 1)
   -- cursor moves to end of line
-  check_eq(Editor_state.cursor1.pos, 15, 'F - test_click_on_wrapping_line_containing_non_ascii/cursor')  -- one more than the number of UTF-8 code-points
+  check_eq(Editor_state.cursor1.pos, 15, 'F - test_click_past_end_of_wrapping_line_containing_non_ascii/cursor')  -- one more than the number of UTF-8 code-points
 end
 
 function test_click_past_end_of_word_wrapping_line()
@@ -735,15 +735,12 @@ function test_edit_wrapping_text()
   Editor_state.screen_bottom1 = {}
   edit.draw(Editor_state)
   edit.run_after_textinput(Editor_state, 'g')
-  edit.run_after_textinput(Editor_state, 'h')
-  edit.run_after_textinput(Editor_state, 'i')
-  edit.run_after_textinput(Editor_state, 'j')
   local y = Editor_state.top
   App.screen.check(y, 'abc', 'F - test_edit_wrapping_text/screen:1')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'def', 'F - test_edit_wrapping_text/screen:2')
+  App.screen.check(y, 'de', 'F - test_edit_wrapping_text/screen:2')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'ghij', 'F - test_edit_wrapping_text/screen:3')
+  App.screen.check(y, 'fg', 'F - test_edit_wrapping_text/screen:3')
 end
 
 function test_insert_newline()
@@ -1158,18 +1155,18 @@ function test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_
   y = y + Editor_state.line_height
   App.screen.check(y, 'def', 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/baseline/screen:2')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'ghijk', 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/baseline/screen:3')
+  App.screen.check(y, 'ghij', 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/baseline/screen:3')
   -- after hitting the down arrow the screen scrolls down by one line
   edit.run_after_keychord(Editor_state, 'down')
   check_eq(Editor_state.screen_top1.line, 2, 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/screen_top')
   check_eq(Editor_state.cursor1.line, 3, 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/cursor:line')
-  check_eq(Editor_state.cursor1.pos, 6, 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/cursor:pos')
+  check_eq(Editor_state.cursor1.pos, 5, 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/cursor:pos')
   y = Editor_state.top
   App.screen.check(y, 'def', 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/screen:1')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'ghijk', 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/screen:2')
+  App.screen.check(y, 'ghij', 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/screen:2')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'l', 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/screen:3')
+  App.screen.check(y, 'kl', 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/screen:3')
 end
 
 function test_page_down_followed_by_down_arrow_does_not_scroll_screen_up()
@@ -1187,7 +1184,7 @@ function test_page_down_followed_by_down_arrow_does_not_scroll_screen_up()
   y = y + Editor_state.line_height
   App.screen.check(y, 'def', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline/screen:2')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'ghijk', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline/screen:3')
+  App.screen.check(y, 'ghij', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline/screen:3')
   -- after hitting pagedown the screen scrolls down to start of a long line
   edit.run_after_keychord(Editor_state, 'pagedown')
   check_eq(Editor_state.screen_top1.line, 3, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline2/screen_top')
@@ -1197,11 +1194,11 @@ function test_page_down_followed_by_down_arrow_does_not_scroll_screen_up()
   edit.run_after_keychord(Editor_state, 'down')
   check_eq(Editor_state.screen_top1.line, 3, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/screen_top')
   check_eq(Editor_state.cursor1.line, 3, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/cursor:line')
-  check_eq(Editor_state.cursor1.pos, 6, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/cursor:pos')
+  check_eq(Editor_state.cursor1.pos, 5, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/cursor:pos')
   y = Editor_state.top
-  App.screen.check(y, 'ghijk', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/screen:1')
+  App.screen.check(y, 'ghij', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/screen:1')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'l', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/screen:2')
+  App.screen.check(y, 'kl', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/screen:2')
   y = y + Editor_state.line_height
   App.screen.check(y, 'mno', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/screen:3')
 end
@@ -1538,9 +1535,9 @@ function test_typing_on_bottom_line_scrolls_down()
   y = Editor_state.top
   App.screen.check(y, 'def', 'F - test_typing_on_bottom_line_scrolls_down/screen:1')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'ghijk', 'F - test_typing_on_bottom_line_scrolls_down/screen:2')
+  App.screen.check(y, 'ghij', 'F - test_typing_on_bottom_line_scrolls_down/screen:2')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'l', 'F - test_typing_on_bottom_line_scrolls_down/screen:3')
+  App.screen.check(y, 'kl', 'F - test_typing_on_bottom_line_scrolls_down/screen:3')
 end
 
 function test_left_arrow_scrolls_up_in_wrapped_line()
@@ -1747,9 +1744,9 @@ function test_backspace_can_scroll_up_screen_line()
   -- after hitting backspace the screen scrolls up by one screen line
   edit.run_after_keychord(Editor_state, 'backspace')
   y = Editor_state.top
-  App.screen.check(y, 'ghijk', 'F - test_backspace_can_scroll_up_screen_line/screen:1')
+  App.screen.check(y, 'ghij', 'F - test_backspace_can_scroll_up_screen_line/screen:1')
   y = y + Editor_state.line_height
-  App.screen.check(y, 'l', 'F - test_backspace_can_scroll_up_screen_line/screen:2')
+  App.screen.check(y, 'kl', 'F - test_backspace_can_scroll_up_screen_line/screen:2')
   y = y + Editor_state.line_height
   App.screen.check(y, 'mno', 'F - test_backspace_can_scroll_up_screen_line/screen:3')
   check_eq(Editor_state.screen_top1.line, 3, 'F - test_backspace_can_scroll_up_screen_line/screen_top')