From f768942015b2ae40e7ea75e35ad3af8f15812fbd Mon Sep 17 00:00:00 2001
From: Travis Shears <t@travisshears.com>
Date: Sun, 11 Jan 2026 11:21:55 +0100
Subject: [PATCH] Remove pixel offset so x,y values are zero based

---
 README.md           |  2 ++
 one_line_canvas.tal | 35 ++++++++++++++++-------------------
 tasks.txt           |  7 +++++--
 3 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/README.md b/README.md
index b9fad3b..b16f583 100644
--- a/README.md
+++ b/README.md
@@ -4,6 +4,8 @@ This is an art project drawing canvas tool that enables drawing low resolution
 pixel images. The project includes a file specification for the drawings and a canvas
 app for making the files.
 
+Press "e" to export the drawing to .1line file.
+
 
 ## Dev
 
diff --git a/one_line_canvas.tal b/one_line_canvas.tal
index 5e23784..cd4cf62 100644
--- a/one_line_canvas.tal
+++ b/one_line_canvas.tal
@@ -43,19 +43,23 @@
 	#65 EQU ?write-drawing-file-to-disk
 	BRK
 
+@on-mouse ( -> )
+    .Mouse/x DEI2 LIT2 =canvas-width SUB2 .x STZ2
+    .Mouse/y DEI2 LIT2 =canvas-height SUB2 .y STZ2
+    .Mouse/x DEI2  .Mouse/y DEI2  ( y x )
+	draw-cursor
+	add-px-to-drawing
+	BRK
+
 @add-px-to-drawing
     ( figure out if px on on canvas )
-    ( x too small )
-    LIT2 =canvas-width .x LDZ2 GTH2 ?/end
     ( x too big )
-    LIT2 =canvas-width #0002 MUL2 .x LDZ2 LTH2 ?/end
-    ( y too small )
-    LIT2 =canvas-height .y LDZ2 GTH2 ?/end
+    LIT2 =canvas-width .x LDZ2 LTH2 ?/end
     ( y too big )
-    LIT2 =canvas-height #0002 MUL2 .y LDZ2 LTH2 ?/end
+    LIT2 =canvas-height .y LDZ2 LTH2 ?/end
     ( draw px to screen )
-    .x LDZ2 .Screen/x DEO2
-	.y LDZ2 .Screen/y DEO2
+    .x LDZ2 LIT2 =canvas-width ADD2 .Screen/x DEO2
+	.y LDZ2 LIT2 =canvas-height ADD2 .Screen/y DEO2
 	#01 .Screen/pixel DEO
     ( set local pt to start of pixels )
     !{ &local-pt $2 }
@@ -94,21 +98,16 @@
 	JMP2r
     &filename "drawing.1line $1
 
-@on-mouse ( -> )
-	.Mouse/x DEI2 .x STZ2
-	.Mouse/y DEI2 .y STZ2
-	draw-cursor
-	add-px-to-drawing
-	BRK
 
-@draw-cursor
+
+@draw-cursor ( y x -- )
 	( clear fg )
 	LIT2 0000 .Screen/x DEO2
 	LIT2 0000 .Screen/y DEO2
 	#c0 .Screen/pixel DEO
 	( draw cursor sprite to fg )
-	.x LDZ2 #0002 SUB2 .Screen/x DEO2
-	.y LDZ2 #0002 SUB2 .Screen/y DEO2
+	#0002 SUB2 .Screen/y DEO2 ( x )
+	#0002 SUB2 .Screen/x DEO2
 	;cursor-sprite .Screen/addr DEO2
 	#41 .Screen/sprite DEO
 	JMP2r
@@ -120,7 +119,6 @@
     ( store vars )
     !{ &y $1 &l $1 }
     ,/y STR ,/l STR
-
     &loop
         ( set y )
         ,/y LDR DUP ( y y )
@@ -144,7 +142,6 @@
     ( store vars )
     !{ &x $1 &l $1 }
     ,/x STR ,/l STR
-
     &loop
         ( set x )
         ,/x LDR DUP ( x x )
diff --git a/tasks.txt b/tasks.txt
index 44b94b9..a6e02c4 100644
--- a/tasks.txt
+++ b/tasks.txt
@@ -1,3 +1,6 @@
-task: include header in generated .1line file as spec in ./one_line_file_type_spec.ms
-task: shift pixel x,y to be zero based
 task: set terminal byte
+
+-------------------------
+
+DONE: include header in generated .1line file as spec in ./one_line_file_type_spec.ms
+DONE: shift pixel x,y to be zero based