feat(render): implement direct rendering

src/layout/HStack.zig

@@ -78,8 +78,34 @@ pub fn Layout(comptime Event: type, comptime Renderer: type) type {
                 .resize => |size| {
                     this.size = size;
                     // adjust size according to the containing elements
+                    log.debug("Event .resize: {{ .anchor = {{ .col = {d}, .row = {d} }}, .cols = {d}, .rows = {d} }}", .{
+                        size.anchor.col,
+                        size.anchor.row,
+                        size.cols,
+                        size.rows,
+                    });
+                    const len: u16 = @truncate(this.elements.items.len);
+                    const element_cols = @divTrunc(size.cols, len);
+                    var overflow = size.cols % len;
+                    var offset: u16 = 0;
+                    // adjust size according to the containing elements
                     for (this.elements.items) |*element| {
-                        const sub_event = event;
+                        var cols = element_cols;
+                        if (overflow > 0) {
+                            overflow -|= 1;
+                            cols += 1;
+                        }
+                        const sub_event: Event = .{
+                            .resize = .{
+                                .anchor = .{
+                                    .col = size.anchor.col + offset,
+                                    .row = size.anchor.row,
+                                },
+                                .cols = cols,
+                                .rows = size.rows,
+                            },
+                        };
+                        offset += cols;
                         switch (element.*) {
                             .layout => |*layout| {
                                 const events = try layout.handle(sub_event);
@@ -113,17 +139,13 @@ pub fn Layout(comptime Event: type, comptime Renderer: type) type {
         }
 
         pub fn render(this: *@This(), renderer: Renderer) !void {
-            // TODO: concat contents accordingly to create a horizontal stack
             for (this.elements.items) |*element| {
                 switch (element.*) {
                     .layout => |*layout| {
                         try layout.render(renderer);
                     },
                     .widget => |*widget| {
-                        // TODO: clear per widget if necessary (i.e. can I query that?)
-                        // TODO: render using `renderer`
-                        const content = try widget.content();
-                        _ = try terminal.write(content);
+                        try widget.render(renderer);
                     },
                 }
             }

src/layout/VStack.zig

@@ -25,10 +25,7 @@ pub fn Layout(comptime Event: type, comptime Renderer: type) type {
     const Events = std.ArrayList(Event);
     return struct {
         // TODO: current focused `Element`?
-        // FIX: this should not be 'hardcoded' but dynamically be calculated and updated (i.e. through the event system)
-        anchor: terminal.Position = .{ .col = 1, .row = 1 },
         size: terminal.Size = undefined,
-        element_rows: u16 = undefined,
         elements: Elements = undefined,
         events: Events = undefined,
 
@@ -87,12 +84,12 @@ pub fn Layout(comptime Event: type, comptime Renderer: type) type {
                         size.rows,
                     });
                     const len: u16 = @truncate(this.elements.items.len);
-                    this.element_rows = @divTrunc(size.rows, len);
-                    var overflow = this.size.rows % len;
+                    const element_rows = @divTrunc(size.rows, len);
+                    var overflow = size.rows % len;
                     var offset: u16 = 0;
                     // adjust size according to the containing elements
                     for (this.elements.items) |*element| {
-                        var rows = this.element_rows;
+                        var rows = element_rows;
                         if (overflow > 0) {
                             overflow -|= 1;
                             rows += 1;
@@ -141,7 +138,6 @@ pub fn Layout(comptime Event: type, comptime Renderer: type) type {
         }
 
         pub fn render(this: *@This(), renderer: Renderer) !void {
-            // FIX: renderer should clear only what is going to change! (i.e. the 'active' widget / layout)
             for (this.elements.items) |*element| {
                 switch (element.*) {
                     .layout => |*layout| {

src/main.zig

@@ -3,7 +3,7 @@ const zterm = @import("zterm");
 
 const App = zterm.App(
     union(enum) {},
-    zterm.Renderer.Plain,
+    zterm.Renderer.Direct,
     true,
 );
 const Key = zterm.Key;
@@ -31,7 +31,7 @@ pub fn main() !void {
     // -> size hint how much should it use?
 
     var layout = Layout.createFrom(layout: {
-        var vstack = Layout.VStack.init(allocator, .{
+        var vstack = Layout.HStack.init(allocator, .{
             Widget.createFrom(blk: {
                 const file = try std.fs.cwd().openFile("./src/app.zig", .{});
                 defer file.close();
@@ -59,6 +59,7 @@ pub fn main() !void {
     // App.Event loop
     while (true) {
         const event = app.nextEvent();
+        log.debug("received event: {s}", .{@tagName(event)});
 
         switch (event) {
             .quit => break,

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..]);
+            }
         }
     };
 }

src/widget/RawText.zig

@@ -78,20 +78,21 @@ pub fn Widget(comptime Event: type, comptime Renderer: type) type {
         pub fn render(this: *@This(), renderer: Renderer) !void {
             try renderer.clear(this.size);
             try terminal.setCursorPosition(this.size.anchor);
-            // TODO: render `this.contents`
             if (this.size.rows >= this.line_index.items.len) {
-                _ = try terminal.write(this.contents.items);
+                log.debug("render: {s}", .{this.contents.items});
+                try renderer.render(this.size, this.contents.items);
             } else {
                 // more rows than we can display
                 const i = this.line_index.items[this.line];
                 const e = this.size.rows + this.line;
                 if (e > this.line_index.items.len) {
-                    _ = try terminal.write(this.contents.items[i..]);
+                    log.debug("render: {s}", .{this.contents.items[i..]});
+                    try renderer.render(this.size, this.contents.items[i..]);
+                    return;
                 }
-                // last line should not end with the last character (likely a newline character)
-                // FIX: what about files which do not end with a newline?
-                const x = this.line_index.items[e] - 1;
-                _ = try terminal.write(this.contents.items[i..x]);
+                const x = this.line_index.items[e];
+                log.debug("render: {s}", .{this.contents.items[i..x]});
+                try renderer.render(this.size, this.contents.items[i..x]);
             }
         }
     };