From d7061cbfefe9a8a1f6a799931707f54d370e4052 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Mon, 2 Jun 2025 23:02:48 +0300
Subject: [PATCH] examples: add a small memory game (#24643)

---
 examples/gg/memory.v | 137 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 examples/gg/memory.v

diff --git a/examples/gg/memory.v b/examples/gg/memory.v
new file mode 100644
index 0000000000..9a00f0a676
--- /dev/null
+++ b/examples/gg/memory.v
@@ -0,0 +1,137 @@
+module main
+
+import gg
+import gx
+import rand
+import time
+
+const cover = gx.rgba(85, 200, 85, 255)
+const csize = 120 // cell size in pixels
+const letters = 'AABBOOCCVVXXYYZZMMKKHHTT'.runes().map(it.str())
+const header_size = 30
+
+struct Cell {
+mut:
+	is_open bool
+	letter  string
+}
+
+struct Game {
+mut:
+	ctx       &gg.Context = unsafe { nil }
+	cells     []Cell
+	card1_idx ?int
+	card2_idx ?int
+	size      int // in cells
+	remaining int
+	sw        time.StopWatch = time.new_stopwatch()
+	revert_sw time.StopWatch = time.new_stopwatch(auto_start: false)
+}
+
+fn (mut g Game) restart() {
+	ncells := g.size * g.size
+	g.remaining = ncells
+	g.cells = []Cell{len: ncells, init: Cell{
+		letter: letters[index % letters.len]
+	}}
+	rand.shuffle(mut g.cells) or {}
+	g.sw = time.new_stopwatch()
+	g.card1_idx = none
+	g.card2_idx = none
+}
+
+fn (mut g Game) draw_cell(i int, cell Cell) {
+	x, y := i % g.size, i / g.size
+	rect_x, rect_y := x * csize, header_size + y * csize
+	dt := g.sw.elapsed().milliseconds()
+	if g.cells[i].is_open || dt <= 1000 {
+		lsize := 96
+		g.ctx.draw_rect_empty(rect_x + 6, rect_y + 6, csize - 10, csize - 10, gx.light_gray)
+		g.ctx.draw_text(rect_x + csize / 2 - lsize / 3, rect_y + csize / 2 - lsize / 2,
+			g.cells[i].letter, color: gx.yellow, size: lsize)
+	} else {
+		g.ctx.draw_rect_filled(rect_x + 6, rect_y + 6, csize - 10, csize - 10, cover)
+	}
+}
+
+fn on_frame(mut g Game) {
+	ws := gg.window_size()
+	g.ctx.begin()
+	message := '(r)estart (esc)ape | remaining: ${g.remaining:02} | time: ${f64(g.sw.elapsed().milliseconds()) / 1000.0:06.1f}s'
+	g.ctx.draw_text(ws.width / 2, 7, message, color: gx.light_gray, size: 22, align: .center)
+	for i, cell in g.cells {
+		g.draw_cell(i, cell)
+	}
+	dt := g.revert_sw.elapsed().milliseconds()
+	if dt > 750 {
+		g.revert_sw = time.new_stopwatch(auto_start: false)
+		if g.card1_idx != none {
+			if g.card2_idx != none {
+				g.cells[g.card1_idx].is_open = false
+				g.cells[g.card2_idx].is_open = false
+				g.card1_idx = none
+				g.card2_idx = none
+				g.remaining = g.cells.count(!it.is_open)
+			}
+		}
+	}
+	g.ctx.end()
+}
+
+fn on_event(e &gg.Event, mut g Game) {
+	if e.typ == .key_down {
+		match e.key_code {
+			.escape { g.ctx.quit() }
+			.r { g.restart() }
+			else {}
+		}
+		return
+	}
+	if e.typ != .mouse_down {
+		return
+	}
+	x, y := int(e.mouse_x / csize), int((e.mouse_y - header_size) / csize)
+	if e.mouse_button == .left && g.card2_idx == none {
+		if g.remaining == 0 {
+			g.restart()
+			return
+		}
+		i := y * g.size + x
+		if !g.cells[i].is_open {
+			g.cells[i].is_open = true
+			if g.card1_idx == none {
+				g.card1_idx = i
+			} else {
+				g.card2_idx = i
+				if g.cells[g.card1_idx].letter == g.cells[i].letter {
+					g.card1_idx = none
+					g.card2_idx = none
+				} else {
+					// start a timer, that will be checked in the on_frame callback
+					g.revert_sw.start()
+				}
+			}
+		}
+	}
+	g.remaining = g.cells.count(!it.is_open)
+	if g.remaining == 0 {
+		g.sw.stop()
+	}
+}
+
+mut g := &Game{
+	// the CLI argument should be number of pairs, so `size` is even, and the puzzle can be solved:
+	size: arguments()[1] or { '3' }.int() * 2
+}
+g.restart()
+g.ctx = gg.new_context(
+	bg_color:     gx.black
+	width:        g.size * csize
+	height:       header_size + g.size * csize
+	window_title: 'V Memory ${g.size} x ${g.size}'
+	user_data:    g
+	frame_fn:     on_frame
+	event_fn:     on_event
+	sample_count: 2
+)
+g.ctx.run()