feat: add memory frame buffer

Author: RossComputerGuy

src/phantom/painting/fb.zig

@@ -1,3 +1,4 @@
 pub const Base = @import("fb/base.zig");
 pub const AllocatedFrameBuffer = @import("fb/alloc.zig");
+pub const MemoryFrameBuffer = @import("fb/mem.zig");
 pub const FileDescriptorFrameBuffer = @import("fb/fd.zig");

src/phantom/painting/fb/mem.zig

@@ -0,0 +1,63 @@
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+const vizops = @import("vizops");
+const Base = @import("base.zig");
+const MemoryFrameBuffer = @This();
+
+base: Base,
+info: Base.Info,
+buffer: []u8,
+
+pub fn create(alloc: Allocator, info: Base.Info, ptr: [*]u8) !*Base {
+    const self = try alloc.create(MemoryFrameBuffer);
+    errdefer alloc.destroy(self);
+
+    self.* = .{
+        .info = info,
+        .buffer = ptr[0..(info.res.value[0] * info.res.value[1] * @divExact(info.colorFormat.width(), 8))],
+        .base = .{
+            .allocator = alloc,
+            .vtable = &.{
+                .addr = impl_addr,
+                .info = impl_info,
+                .dupe = impl_dupe,
+                .deinit = impl_deinit,
+                .blt = null,
+            },
+            .ptr = self,
+        },
+    };
+    return &self.base;
+}
+
+fn impl_addr(ctx: *anyopaque) anyerror!*anyopaque {
+    const self: *MemoryFrameBuffer = @ptrCast(@alignCast(ctx));
+    return @ptrCast(@alignCast(self.buffer));
+}
+
+fn impl_info(ctx: *anyopaque) Base.Info {
+    const self: *MemoryFrameBuffer = @ptrCast(@alignCast(ctx));
+    return self.info;
+}
+
+fn impl_dupe(ctx: *anyopaque) anyerror!*Base {
+    const self: *MemoryFrameBuffer = @ptrCast(@alignCast(ctx));
+    const d = try self.base.allocator.create(MemoryFrameBuffer);
+    errdefer self.base.allocator.destroy(d);
+
+    d.* = .{
+        .info = self.info,
+        .buffer = self.buffer,
+        .base = .{
+            .ptr = d,
+            .allocator = self.base.allocator,
+            .vtable = self.base.vtable,
+        },
+    };
+    return &d.base;
+}
+
+fn impl_deinit(ctx: *anyopaque) void {
+    const self: *MemoryFrameBuffer = @ptrCast(@alignCast(ctx));
+    self.base.allocator.destroy(self);
+}