kiloz

commit 5702e585fb5ef422e82aecc0653aeaa2c21da572
parent 4940f97f8cc9ad33079dec85720f8eef0f2a2a0f
Author: Martin Ashby <martin@ashbysoft.com>
Date:   Sat, 13 Jan 2024 20:01:17 +0000

Step 75

Diffstat:
D
src/c.zig
 | 
0

M
src/main.zig
 | 
35
++++++++++++++++++++++++-----------

2 files changed, 24 insertions(+), 11 deletions(-)
diff --git a/src/c.zig b/src/c.zig
diff --git a/src/main.zig b/src/main.zig
@@ -41,6 +41,7 @@ const EditorState = struct {
     cx: usize = 0,
     cy: usize = 0,
     rowoff: usize = 0,
+    coloff: usize = 0,
     erow: []ERow = &[_]ERow{},
 
     fn init(a: std.mem.Allocator) EditorState {
@@ -238,7 +239,7 @@ fn editorRefreshScreen(es: *EditorState) !void {
     //try wtr.writeAll("\x1b[2J");    // J clear 2 whole screen
     try wtr.writeAll("\x1b[H"); // Reset cursor (to 1:1)
     try editorDrawRows(es, wtr);
-    try std.fmt.format(wtr, "\x1b[{};{}H", .{ es.cy - es.rowoff + 1, es.cx + 1 }); // Move the cursor to our stored position
+    try std.fmt.format(wtr, "\x1b[{};{}H", .{ es.cy - es.rowoff + 1, es.cx - es.coloff + 1 }); // Move the cursor to our stored position
     try wtr.writeAll("\x1b[?25h"); // Show the cursor again
     try std.io.getStdOut().writeAll(es.screen_buf.items);
 }
@@ -247,7 +248,7 @@ fn editorDrawRows(es: *const EditorState, wtr: anytype) !void {
     for (0..es.screenrows) |y| {
         try wtr.writeAll("\x1b[K"); // Clear row before writing it
 
-        var lw = limitedWriter(wtr, es.screencols); // Never write more than we have columns
+        var lw = truncateWriter(wtr, es.screencols); // Never write more than we have columns
         const wtr2 = lw.writer();
         const filerow = y + es.rowoff;
         if (filerow >= es.erow.len) {
@@ -263,7 +264,13 @@ fn editorDrawRows(es: *const EditorState, wtr: anytype) !void {
                 try wtr2.writeAll("~");
             }
         } else {
-            try wtr2.writeAll(es.erow[filerow]);
+            var row = es.erow[filerow];
+            if (row.len < es.coloff) {
+                row = "";
+            } else {
+                row = row[es.coloff..];
+            }
+            try wtr2.writeAll(row);
         }
 
         if (y < es.screenrows-1) {
@@ -279,6 +286,12 @@ fn editorScroll(es: *EditorState) void {
     if (es.cy >= es.rowoff + es.screenrows) {
         es.rowoff = es.cy - es.screenrows + 1;
     }
+    if (es.cx < es.coloff) {
+        es.coloff = es.cx;
+    }
+    if (es.cx >= es.coloff + es.screencols) {
+        es.coloff = es.cx - es.screencols + 1;
+    }
 }
 
 //// Input
@@ -313,7 +326,7 @@ fn editorMoveCursor(key: editorKey, es: *EditorState) !void {
             if (es.cx > 0) es.cx -= 1;
         },
         .ARROW_RIGHT => {
-            if (es.cx < (es.screencols - 1)) es.cx += 1;
+            es.cx += 1;
         },
         .PAGE_UP => {
             es.cy = std.math.sub(usize, es.cy, es.screenrows) catch 0;
@@ -341,14 +354,14 @@ fn initEditor(es: *EditorState) !void {
 
 //// Extra stuff
 
-fn limitedWriter(base_writer: anytype, max: usize) LimitedWriter(@TypeOf(base_writer)) {
-    return LimitedWriter(@TypeOf(base_writer)){
+fn truncateWriter(base_writer: anytype, max: usize) TruncateWriter(@TypeOf(base_writer)) {
+    return TruncateWriter(@TypeOf(base_writer)){
         .base_writer = base_writer,
         .max = max,
     };
 }
 
-fn LimitedWriter(comptime BaseWriter: type) type {
+fn TruncateWriter(comptime BaseWriter: type) type {
     return struct {
         const Self = @This();
         const WriteError = BaseWriter.Error || error{NoSpaceLeft};
@@ -360,14 +373,14 @@ fn LimitedWriter(comptime BaseWriter: type) type {
 
         fn write(self: *Self, bytes: []const u8) WriteError!usize {
             const rem = self.max - self.written;
-            if (rem == 0) return error.NoSpaceLeft;
-
+            if (rem == 0) return bytes.len;
             var to_write = bytes;
             if (bytes.len > rem) {
                 to_write = bytes[0..rem];
             }
-            self.written += to_write.len;
-            return try self.base_writer.write(to_write);
+            const written = try self.base_writer.write(to_write);
+            self.written += written;
+            return written;
         }
 
         fn writer(self: *Self) Writer {