From a8f63313ee5f729b6cbc8e38a151c05cef454291 Mon Sep 17 00:00:00 2001
From: kdx <kikoodx@paranoici.org>
Date: Wed, 31 May 2023 21:59:22 +0200
Subject: draw begin+end

---
 src/main.zig |  3 +++
 src/zxc.zig  | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 84 insertions(+), 4 deletions(-)

diff --git a/src/main.zig b/src/main.zig
index 4a5c92c..ea12f00 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -8,4 +8,7 @@ pub fn main() !void {
         .target_fps = 60,
     });
     defer z.deinit();
+
+    try z.drawBegin();
+    try z.drawEnd();
 }
diff --git a/src/zxc.zig b/src/zxc.zig
index f394f7d..599dfaa 100644
--- a/src/zxc.zig
+++ b/src/zxc.zig
@@ -6,13 +6,14 @@ const Config = struct {
     const RenderMode = enum {
         Pixel,
         PixelPerfect,
-        HdRender,
+        Hd,
     };
 
     width: usize,
     height: usize,
     scale: usize = 1,
-    target_fps: usize,
+    target_fps: ?u31,
+    show_cursor: bool = false,
     render: RenderMode = .Pixel,
     title: [:0]const u8 = "ZXC",
 };
@@ -20,12 +21,20 @@ const Config = struct {
 config: Config,
 window: sdl.Window,
 renderer: sdl.Renderer,
+target: ?sdl.Texture,
+min_dt: u64,
+next_time: u64,
+tick: u64,
 
 pub fn init(config: Config) !Self {
     var self = Self{
         .config = config,
         .window = undefined,
         .renderer = undefined,
+        .target = null,
+        .min_dt = undefined,
+        .next_time = undefined,
+        .tick = 0,
     };
 
     try sdl.init(.{ .video = true });
@@ -54,17 +63,85 @@ pub fn init(config: Config) !Self {
         sdl.RendererFlags{ .accelerated = true },
     );
     errdefer self.renderer.destroy();
+    try self.renderer.setDrawBlendMode(.blend);
+
+    if (config.render != .Hd) {
+        self.target = try sdl.createTexture(
+            self.renderer,
+            .rgb888,
+            .target,
+            config.width,
+            config.height,
+        );
+    }
+    errdefer if (self.target != null) self.target.?.destroy();
+
+    if (!config.show_cursor)
+        _ = try sdl.showCursor(false);
 
     _ = sdl.setHint(
         sdl.hint.render_scale_quality,
-        if (config.render == .HdRender) "1" else "0",
+        if (config.render == .Hd) "1" else "0",
     );
 
+    if (config.target_fps != null) {
+        self.min_dt = 1000 / config.target_fps.?;
+        self.next_time = sdl.getTicks64();
+    }
+
     return self;
 }
 
-pub fn deinit(self: Self) void {
+pub fn deinit(self: *const Self) void {
+    if (self.target != null)
+        self.target.?.destroy();
     self.renderer.destroy();
     self.window.destroy();
     sdl.quit();
 }
+
+pub fn drawBegin(self: *const Self) !void {
+    if (self.config.render == .Hd)
+        return;
+
+    try self.renderer.setTarget(self.target);
+}
+
+pub fn drawEnd(self: *Self) !void {
+    if (self.config.render != .Hd) {
+        try self.renderer.setTarget(null);
+        try self.renderer.setColorRGBA(0, 0, 0, 255);
+        try self.renderer.clear();
+
+        const size = self.window.getSize();
+        const scw = @intToFloat(f64, self.config.width);
+        const sch = @intToFloat(f64, self.config.height);
+
+        const scale = brk: {
+            const ratio_w = @intToFloat(f64, size.width) / scw;
+            const ratio_h = @intToFloat(f64, size.height) / sch;
+            const ratio = if (ratio_w < ratio_h) ratio_w else ratio_h;
+            break :brk if (ratio > 1) std.math.floor(ratio) else ratio;
+        };
+
+        const dst_rect = sdl.Rectangle{
+            .x = size.width - @floatToInt(c_int, scw * scale),
+            .y = size.height - @floatToInt(c_int, sch * scale),
+            .width = @floatToInt(c_int, scw * scale),
+            .height = @floatToInt(c_int, sch * scale),
+        };
+        try self.renderer.copy(self.target.?, dst_rect, null);
+    }
+
+    if (self.config.target_fps != null) {
+        self.next_time += self.min_dt;
+        const cur_time = sdl.getTicks64();
+        if (self.next_time <= cur_time)
+            self.next_time = cur_time
+        else
+            sdl.delay(@truncate(u32, self.next_time - cur_time));
+    }
+
+    self.renderer.present();
+    self.tick += 1;
+}
-- 
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