feat(render): implement direct rendering

src/render.zig

@@ -6,16 +6,17 @@ const Contents = std.ArrayList(u8);
 const Position = terminal.Position;
 const Size = terminal.Size;
 
-pub fn Buffered(comptime fullscreen: bool) type {
+pub fn Buffered(comptime _: bool) type {
     return struct {
         refresh: bool = false,
         size: terminal.Size = undefined,
-        screen: Contents = undefined,
+        next_frame: Contents = undefined,
+        frame: Contents = undefined,
 
         pub fn init(allocator: std.mem.Allocator) @This() {
             return .{
-                .fullscreen = fullscreen,
-                .screen = Contents.init(allocator),
+                .next_frame = Contents.init(allocator),
+                .frame = Contents.init(allocator),
             };
         }
 
@@ -41,7 +42,7 @@ pub fn Buffered(comptime fullscreen: bool) type {
     };
 }
 
-pub fn Plain(comptime _: bool) type {
+pub fn Direct(comptime _: bool) type {
     return struct {
         pub fn clear(this: @This(), size: Size) !void {
             _ = this;
@@ -52,12 +53,52 @@ pub fn Plain(comptime _: bool) type {
             }
         }
 
-        pub fn render(this: @This(), anchor: Position, size: Size, contents: *Contents) !void {
+        pub fn render(this: @This(), size: Size, contents: []u8) !void {
             _ = this;
-            _ = size;
-            // FIXME: this should respect the given `size`
-            try terminal.setCursorPosition(anchor);
-            _ = try terminal.write(contents.items);
+            try terminal.setCursorPosition(size.anchor);
+            var row: u16 = 0;
+            var idx: usize = 0;
+            var skip_next_line = false;
+            for (contents, 0..) |item, i| {
+                if (item == '\n') { // do not print newlines
+                    if (!skip_next_line) {
+                        _ = try terminal.write(contents[idx..i]); // does not include '\n' at position _i_
+                        row += 1;
+                        if (row >= size.rows) {
+                            return; // we are done
+                        }
+                        try terminal.setCursorPosition(.{
+                            .col = size.anchor.col,
+                            .row = size.anchor.row + row,
+                        });
+                    }
+                    skip_next_line = false;
+                    idx = i + 1; // skip over '\n'
+                    continue;
+                }
+                if (i - idx == size.cols) {
+                    // FIXME: this will introduce another additional line which is not accounted for and will cut off these lines in the end from rendering
+                    // -> *current solution*: cut of the line and skip that remaining content (not sure if that should be done)
+                    //   - however the widget has actually knowledge about the size and could change the reported contents which fit to the size or simply don't care and leave it to the renderer?
+                    // flush line
+                    if (!skip_next_line) {
+                        _ = try terminal.write(contents[idx..i]);
+                        row += 1;
+                        if (row >= size.rows) {
+                            return; // we are done
+                        }
+                        try terminal.setCursorPosition(.{
+                            .col = size.anchor.col,
+                            .row = size.anchor.row + row,
+                        });
+                    }
+                    skip_next_line = true;
+                    idx = i;
+                }
+            }
+            if (idx < contents.len) {
+                _ = try terminal.write(contents[idx..]);
+            }
         }
     };
 }