From 36b32c5a234a99e543b51a2de3d4f2fadfbc8774 Mon Sep 17 00:00:00 2001
From: Productive2 <48047721+Productive2@users.noreply.github.com>
Date: Sun, 21 Feb 2021 00:44:56 +0100
Subject: [PATCH] Added horizontal scrolling (for single/all line)

---
 examples/editor.nim   |  1 +
 src/jale/editor.nim   | 42 +++++++++++++++++++++++++++++++++++++-----
 src/jale/renderer.nim | 24 +++++++++++++-----------
 3 files changed, 51 insertions(+), 16 deletions(-)

diff --git a/examples/editor.nim b/examples/editor.nim
index d5a2918..a4fd24a 100644
--- a/examples/editor.nim
+++ b/examples/editor.nim
@@ -22,6 +22,7 @@ e.bindKey("ctrl+s"):
 
 e.prompt = ""
 e.populateDefaults(enterSubmits = false, ctrlForVerticalMove = false)
+e.scrollMode = sbAllScroll
 let result = e.read()
 if save and paramCount() > 0:
   writeFile(paramStr(1), result)
diff --git a/src/jale/editor.nim b/src/jale/editor.nim
index 83311c3..27e8c4d 100644
--- a/src/jale/editor.nim
+++ b/src/jale/editor.nim
@@ -16,11 +16,15 @@ type
   EditorState = enum
     esOutside, esTyping, esFinishing, esQuitting
 
+  ScrollBehavior* = enum
+    sbSingleScroll, sbAllScroll, sbWrap
+
   LineEditor* = ref object
     # permanents
     keystrokes*: Event[int]
     events*: Event[JaleEvent]
     prompt*: string
+    scrollMode*: ScrollBehavior
 
     # permanent internals: none
     
@@ -31,6 +35,7 @@ type
     state: EditorState
     rendered: int # how many lines were printed last full refresh
     forceRedraw: bool
+    hscroll: int
 
 # getter/setter sorts
 
@@ -61,6 +66,8 @@ proc newLineEditor*: LineEditor =
   result.lastKeystroke = -1
   result.forceRedraw = false
   result.state = esOutside
+  result.scrollMode = sbSingleScroll
+  result.hscroll = 0
   
 # priv/pub methods
 
@@ -72,20 +79,31 @@ proc reset(editor: LineEditor) =
   editor.content = newMultiline()
   editor.lastKeystroke = -1
   editor.forceRedraw = false
+  editor.hscroll = 0
 
-proc render(editor: LineEditor, line: int = -1, hscroll: bool = true) =
+proc render(editor: LineEditor, line: int = -1) =
+  ## Assumes that the cursor is already on the right line then
+  ## proceeds to render the line-th line of the editor (if -1, will check
+  ## the y).
   var y = line
   if y == -1:
     y = editor.content.Y
-
+ 
+  # the prompt's length is assumed to be always padded
   let prompt = if y == 0: editor.prompt else: " ".repeat(editor.prompt.len())
-  renderLine(prompt, editor.content.getLine(y), 0)
+  let content = editor.content.getLine(y)
+
+  if editor.scrollMode == sbAllScroll or 
+    (editor.scrollMode == sbSingleScroll and y == editor.content.Y):
+    renderLine(prompt, content, editor.hscroll)
+  else:
+    renderLine(prompt, content, 0)
 
 proc fullRender(editor: LineEditor) =
   # from the top cursor pos, it draws the entire multiline prompt, then
   # moves cursor to current y
   for i in countup(0, editor.content.high()):
-    editor.render(i, false)
+    editor.render(i)
     if i < editor.rendered:
       cursorDown(1)
     else:
@@ -118,7 +136,7 @@ proc read*(editor: LineEditor): string =
   while editor.state == esTyping:
 
     # refresh current line every time
-    setCursorXPos(editor.content.X + editor.prompt.len())
+    setCursorXPos(editor.content.X - editor.hscroll + editor.prompt.len())
     # get key (with escapes)
     let key = getKey()
     # record y pos
@@ -127,6 +145,20 @@ proc read*(editor: LineEditor): string =
     editor.lastKeystroke = key
     editor.keystrokes.call(key)
     editor.events.call(jeKeypress)
+    # autoscroll horizontally based on current scroll and x pos
+    
+    # last x rendered
+    let lastX = terminalWidth() - editor.prompt.len() + editor.hscroll - 1
+    # first x rendered
+    let firstX = editor.hscroll
+
+    # x squished into boundaries
+    let boundX = min(max(firstX, editor.content.X), lastX)
+    if editor.content.X != boundX:
+      editor.hscroll += editor.content.X - boundX
+      if editor.scrollMode == sbAllScroll:
+        editor.forceRedraw = true
+
     # redraw everything if y changed
     if editor.forceRedraw or preY != editor.content.Y:
       # move to the top
diff --git a/src/jale/renderer.nim b/src/jale/renderer.nim
index 3d5efa1..386fd44 100644
--- a/src/jale/renderer.nim
+++ b/src/jale/renderer.nim
@@ -5,16 +5,18 @@
 import strutils
 import terminal
 
-proc renderLine*(prompt: string, content: string, hscroll: int = 0) =
+proc renderLine*(prompt: string, text: string, hscroll: int = 0) =
+  eraseLine()
   setCursorXPos(0)
-  var content = prompt & content
-  if content.len() < terminalWidth():
-    content &= " ".repeat(terminalWidth() - content.len() - 1)
-  if content.len() > terminalWidth():
-    var lower = hscroll
-    var upper = hscroll + terminalWidth() - 1
-    if upper > content.high():
-      upper = content.high()
-    content = content[lower..upper]
-  write stdout, content
+  var lower = hscroll
+  var upper = hscroll + terminalWidth() - prompt.len() - 1
+  if upper > text.high():
+    upper = text.high()
+  if lower < -1:
+    raise newException(Defect, "negative hscroll submitted to renderLine")
+  if lower > text.high():
+    write stdout, prompt
+  else:
+    let content = prompt & text[lower..upper]
+    write stdout, content