examples: add vaxis example

build.zig

@@ -46,6 +46,7 @@ pub fn build(b: *std.Build) void {
         shell,
         table,
         text_input,
+        vaxis,
     };
     const example_option = b.option(Example, "example", "Example to run (default: text_input)") orelse .text_input;
     const example_step = b.step("example", "Run example");

examples/vaxis.zig

@@ -0,0 +1,83 @@
+const std = @import("std");
+const vaxis = @import("vaxis");
+const Cell = vaxis.Cell;
+
+const Event = union(enum) {
+    key_press: vaxis.Key,
+    winsize: vaxis.Winsize,
+};
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer {
+        const deinit_status = gpa.deinit();
+        //fail test; can't try in defer as defer is executed after we return
+        if (deinit_status == .leak) {
+            std.log.err("memory leak", .{});
+        }
+    }
+    const alloc = gpa.allocator();
+
+    var vx = try vaxis.init(alloc, .{});
+    defer vx.deinit(alloc);
+
+    var loop: vaxis.Loop(Event) = .{ .vaxis = &vx };
+
+    try loop.run();
+    defer loop.stop();
+
+    try vx.enterAltScreen();
+    try vx.queryTerminal();
+
+    const lower_limit = 30;
+    var color_idx: u8 = lower_limit;
+    var dir: enum {
+        up,
+        down,
+    } = .up;
+
+    // block until we get a resize
+    while (true) {
+        const event = loop.nextEvent();
+        switch (event) {
+            .key_press => |key| if (key.matches('c', .{ .ctrl = true })) return,
+            .winsize => |ws| {
+                try vx.resize(alloc, ws);
+                break;
+            },
+        }
+    }
+
+    while (true) {
+        while (loop.tryEvent()) |event| {
+            switch (event) {
+                .key_press => |key| if (key.matches('c', .{ .ctrl = true })) return,
+                .winsize => |ws| try vx.resize(alloc, ws),
+            }
+        }
+
+        const win = vx.window();
+        win.clear();
+
+        const style: vaxis.Style = .{ .fg = .{ .rgb = [_]u8{ color_idx, color_idx, color_idx } } };
+
+        const segment: vaxis.Segment = .{
+            .text = vaxis.logo,
+            .style = style,
+        };
+        const center = vaxis.widgets.alignment.center(win, 28, 4);
+        _ = try center.printSegment(segment, .{ .wrap = .grapheme });
+        try vx.render();
+        std.time.sleep(8 * std.time.ns_per_ms);
+        switch (dir) {
+            .up => {
+                color_idx += 1;
+                if (color_idx == 255) dir = .down;
+            },
+            .down => {
+                color_idx -= 1;
+                if (color_idx == lower_limit) dir = .up;
+            },
+        }
+    }
+}