From 4904b7df7f0793654b0bc04c350cd73368db0d0f Mon Sep 17 00:00:00 2001
From: Dustin Swan <dustin@dustinswan.com>
Date: Thu, 26 Feb 2026 21:53:54 -0700
Subject: [PATCH] ctrl-d and ctrl-u for half scrolling

---
 src/cg/06-textEditor.cg | 43 +++++++++++++++++++++++++----------------
 1 file changed, 26 insertions(+), 17 deletions(-)

diff --git a/src/cg/06-textEditor.cg b/src/cg/06-textEditor.cg
index 7238a7e..215b632 100644
--- a/src/cg/06-textEditor.cg
+++ b/src/cg/06-textEditor.cg
@@ -1,6 +1,13 @@
 textEditor = name \
   # defaults = {};
   # c = { ...defaults, ...config };
+  scale = 2;
+  charH = 12;
+  charW = 5;
+  lineGap = 1;
+  charGap = 2;
+  lineH = charH * scale + lineGap;
+
   buffersKey = "textEditorBuffers";
 
   # load from staging buffers if it exists there. if not, load from source
@@ -116,19 +123,9 @@ textEditor = name \
     newState = clampCursor state.{ cursorCol = state.cursorCol + 1 };
     { state = newState, emit = [] };
 
-  # todo: scrollHalfDown = state \ ();
-  # todo: scrollHalfUp = state \ ();
-
   {
     view = ctx \
 
-      scale = 2;
-      charH = 12;
-      charW = 5;
-      lineGap = 1;
-      charGap = 2;
-      lineH = charH * scale + lineGap;
-
       autoScroll = state \
         cursorY = state.cursorRow * lineH;
         newScrollY = (cursorY < state.scrollY
@@ -143,11 +140,21 @@ textEditor = name \
           | False \ (cursorX + charW * scale > state.scrollX + ctx.w
             | True \ cursorX + charW * scale - ctx.w
             | False \ state.scrollX));
-        state.{ scrollY = newScrollY, cursorY = cursorY, scrollX = newScrollX, cursorX = cursorX };
+        state.{ scrollY = newScrollY, scrollX = newScrollX };
 
       withScroll = result \
         { state = autoScroll result.state, emit = result.emit };
 
+      scrollHalfUp = state ctx \ (
+        diff = floor ((ctx.h / 2) / lineH);
+        newRow = state.cursorRow - diff;
+        withScroll { state = clampCursor state.{ cursorRow = newRow }, emit = [] });
+
+      scrollHalfDown = state ctx \ (
+        diff = floor ((ctx.h / 2) / lineH);
+        newRow = state.cursorRow + diff;
+        withScroll { state = clampCursor state.{ cursorRow = newRow }, emit = [] });
+
       ui.stateful {
         focusable = True,
         autoFocus = True,
@@ -198,6 +205,9 @@ textEditor = name \
             | Insert \ insertChar "i" state
             | Normal \ insertMode state)
 
+          | Key { key = "d", ctrl = True } \ scrollHalfDown state ctx
+          | Key { key = "u", ctrl = True } \ scrollHalfUp state ctx
+
           | Key { key = "u" } \ (state.mode
             | Insert \ insertChar "u" state
             | Normal \ undo state)
@@ -218,9 +228,6 @@ textEditor = name \
             | Insert \ insertChar "A" state
             | Normal \ apply state)
 
-          | Key { key = "d", ctrl = True } \ scrollHalfDown state
-          | Key { key = "u", ctrl = True } \ scrollHalfUp state
-
           | Key { key = "Escape" } \ escape state
 
           | Key { key = "Backspace" } \ (state.mode
@@ -239,10 +246,12 @@ textEditor = name \
           | _ \ { state = state, emit = [] },
 
         view = state emit \
-          _ = debug! "here" state;
+          cursorX = state.cursorCol * charW * scale + charGap * state.cursorCol;
+          cursorY = state.cursorRow * lineH;
+
           cursor = ui.positioned {
-            x = state.cursorX,
-            y = state.cursorY,
+            x = cursorX,
+            y = cursorY,
             child = ui.rect { w = charW * scale, h = charH * scale, color = "rgba(255,255,255,0.5)" }
           };