6838

Interestingly, erasing the screen partially looks better to me even though
it's clearly slower. The divider never being redrawn provides a sense of
stability.

2 files changed, 43 insertions, 1 deletions

diff --git a/apps/tile/box.mu b/apps/tile/box.mu
index 7cb69206..bc0f58e1 100644
--- a/apps/tile/box.mu
+++ b/apps/tile/box.mu
@@ -42,3 +42,44 @@ fn draw-vertical-line screen: (addr screen), row1: int, row2: int, col: int {
     loop
   }
 }
+
+# erase parts of screen the slow way
+fn clear-rect screen: (addr screen), row1: int, col1: int, row2: int, col2: int {
+  var i/eax: int <- copy row1
+  {
+    compare i, row2
+    break-if->
+    var j/ecx: int <- copy col1
+    move-cursor screen, i, j
+    {
+      compare j, col2
+      break-if->
+      print-grapheme screen 0x20  # space
+      j <- increment
+      loop
+    }
+    i <- increment
+    loop
+  }
+}
+
+fn clear-rect2 screen: (addr screen), row1: int, col1: int, w: int, h: int {
+  var i/eax: int <- copy 0
+  var curr-row/esi: int <- copy row1
+  {
+    compare i, w
+    break-if->=
+    move-cursor screen, curr-row, col1
+    var j/ecx: int <- copy 0
+    {
+      compare j, h
+      break-if->=
+      print-grapheme screen 0x20  # space
+      j <- increment
+      loop
+    }
+    i <- increment
+    curr-row <- increment
+    loop
+  }
+}
diff --git a/apps/tile/environment.mu b/apps/tile/environment.mu
index cd5721b4..5415bf6d 100644
--- a/apps/tile/environment.mu
+++ b/apps/tile/environment.mu
@@ -163,12 +163,13 @@ fn render _env: (addr environment) {
   var _screen/eax: (addr screen) <- lookup *screen-ah
   var screen/edi: (addr screen) <- copy _screen
   # prepare screen
-  clear-screen screen
   var nrows/eax: (addr int) <- get env, nrows
   var _repl-col/ecx: (addr int) <- get env, code-separator-col
   var repl-col/ecx: int <- copy *_repl-col
   draw-vertical-line screen, 1, *nrows, repl-col
   repl-col <- add 2  # repl-margin-left
+  var ncols/edx: (addr int) <- get env, ncols
+  clear-rect screen, 1, repl-col, *nrows, *ncols
   move-cursor screen, 5, repl-col  # input-row + stack-margin-top
   print-string screen, "stack:"
   move-cursor screen, 3, repl-col  # input-row, input-col