gpu: implement Device.nativeCreateSwapChain, SwapChain

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

gpu/src/SwapChain.zig

@@ -0,0 +1,44 @@
+const TextureUsage = @import("texture_usage.zig").TextureUsage;
+const TextureFormat = @import("texture_format.zig").TextureFormat;
+const PresentMode = @import("present_mode.zig").PresentMode;
+
+const SwapChain = @This();
+
+/// The type erased pointer to the SwapChain implementation
+/// Equal to c.WGPUSwapChain for NativeInstance.
+ptr: *anyopaque,
+vtable: *const VTable,
+
+pub const VTable = struct {
+    reference: fn (ptr: *anyopaque) void,
+    release: fn (ptr: *anyopaque) void,
+    // TODO:
+    // WGPU_EXPORT void wgpuSwapChainConfigure(WGPUSwapChain swapChain, WGPUTextureFormat format, WGPUTextureUsageFlags allowedUsage, uint32_t width, uint32_t height);
+    // WGPU_EXPORT WGPUTextureView wgpuSwapChainGetCurrentTextureView(WGPUSwapChain swapChain);
+    // WGPU_EXPORT void wgpuSwapChainPresent(WGPUSwapChain swapChain);
+};
+
+pub inline fn reference(swap_chain: SwapChain) void {
+    swap_chain.vtable.reference(swap_chain.ptr);
+}
+
+pub inline fn release(swap_chain: SwapChain) void {
+    swap_chain.vtable.release(swap_chain.ptr);
+}
+
+pub const Descriptor = struct {
+    label: ?[]const u8 = null,
+    usage: TextureUsage,
+    format: TextureFormat,
+    width: u32,
+    height: u32,
+    present_mode: PresentMode,
+    implementation: u64,
+};
+
+test "syntax" {
+    _ = VTable;
+    _ = reference;
+    _ = release;
+    _ = Descriptor;
+}