Merge pull request #2178 from jcollie/kitty-graphics-performance

kitty graphics: performance enhancements

build.zig

@@ -1038,6 +1038,10 @@ fn addDeps(
         .images = false,
         .text_input = false,
     });
+    const wuffs_dep = b.dependency("wuffs", .{
+        .target = target,
+        .optimize = optimize,
+    });
 
     // Wasm we do manually since it is such a different build.
     if (step.rootModuleTarget().cpu.arch == .wasm32) {
@@ -1123,6 +1127,7 @@ fn addDeps(
     step.root_module.addImport("sentry", sentry_dep.module("sentry"));
     step.root_module.addImport("ziglyph", ziglyph_dep.module("ziglyph"));
     step.root_module.addImport("vaxis", vaxis_dep.module("vaxis"));
+    step.root_module.addImport("wuffs", wuffs_dep.module("wuffs"));
 
     // Mac Stuff
     if (step.rootModuleTarget().isDarwin()) {

build.zig.zon

@@ -40,6 +40,7 @@
         .sentry = .{ .path = "./pkg/sentry" },
         .simdutf = .{ .path = "./pkg/simdutf" },
         .utfcpp = .{ .path = "./pkg/utfcpp" },
+        .wuffs = .{ .path = "./pkg/wuffs" },
         .zlib = .{ .path = "./pkg/zlib" },
 
         // Shader translation

nix/zigCacheHash.nix

@@ -1,3 +1,3 @@
 # This file is auto-generated! check build-support/check-zig-cache-hash.sh for
 # more details.
-"sha256-mIUl5j3JxtydoV7ayy3aNrt/jR8+a68lQw6lQimLZEw="
+"sha256-YLopoyRgXV6GYiTiaKt64mH6lWjlKJbi61ck0fO4WvQ="

pkg/wuffs/build.zig

@@ -0,0 +1,33 @@
+const std = @import("std");
+
+pub fn build(b: *std.Build) !void {
+    const target = b.standardTargetOptions(.{});
+    const optimize = b.standardOptimizeOption(.{});
+
+    const wuffs = b.dependency("wuffs", .{});
+
+    const module = b.addModule("wuffs", .{
+        .root_source_file = b.path("src/main.zig"),
+        .target = target,
+        .optimize = optimize,
+        .link_libc = true,
+    });
+
+    if (target.result.isDarwin()) {
+        const apple_sdk = @import("apple_sdk");
+        try apple_sdk.addPaths(b, module);
+    }
+
+    var flags = std.ArrayList([]const u8).init(b.allocator);
+    defer flags.deinit();
+    try flags.append("-DWUFFS_IMPLEMENTATION");
+    inline for (@import("src/c.zig").defines) |key| {
+        try flags.append("-D" ++ key);
+    }
+
+    module.addIncludePath(wuffs.path("release/c"));
+    module.addCSourceFile(.{
+        .file = wuffs.path("release/c/wuffs-v0.4.c"),
+        .flags = flags.items,
+    });
+}

pkg/wuffs/build.zig.zon

@@ -0,0 +1,17 @@
+.{
+    .name = "wuffs",
+    .version = "0.0.0",
+    .dependencies = .{
+        .wuffs = .{
+            .url = "https://github.com/google/wuffs/archive/refs/tags/v0.4.0-alpha.8.tar.gz",
+            .hash = "12200984439edc817fbcbbaff564020e5104a0d04a2d0f53080700827052de700462",
+        },
+
+        .apple_sdk = .{ .path = "../apple-sdk" },
+    },
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "src",
+    },
+}

pkg/wuffs/src/c.zig

@@ -0,0 +1,18 @@
+pub const c = @cImport({
+    for (defines) |d| @cDefine(d, "1");
+    @cInclude("wuffs-v0.4.c");
+});
+
+/// All the C macros defined so that the header matches the build.
+pub const defines: []const []const u8 = &[_][]const u8{
+    "WUFFS_CONFIG__MODULES",
+    "WUFFS_CONFIG__MODULE__AUX__BASE",
+    "WUFFS_CONFIG__MODULE__AUX__IMAGE",
+    "WUFFS_CONFIG__MODULE__BASE",
+    "WUFFS_CONFIG__MODULE__ADLER32",
+    "WUFFS_CONFIG__MODULE__CRC32",
+    "WUFFS_CONFIG__MODULE__DEFLATE",
+    "WUFFS_CONFIG__MODULE__JPEG",
+    "WUFFS_CONFIG__MODULE__PNG",
+    "WUFFS_CONFIG__MODULE__ZLIB",
+};

pkg/wuffs/src/error.zig

@@ -0,0 +1,3 @@
+const std = @import("std");
+
+pub const Error = std.mem.Allocator.Error || error{WuffsError};

pkg/wuffs/src/main.zig

@@ -0,0 +1,2 @@
+pub const png = @import("png.zig");
+pub const swizzle = @import("swizzle.zig");

pkg/wuffs/src/png.zig

@@ -0,0 +1,147 @@
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+const c = @import("c.zig").c;
+const Error = @import("error.zig").Error;
+
+const log = std.log.scoped(.wuffs_png);
+
+/// Decode a PNG image.
+pub fn decode(alloc: Allocator, data: []const u8) Error!struct {
+    width: u32,
+    height: u32,
+    data: []const u8,
+} {
+    // Work around some weirdness in WUFFS/Zig, there are some structs that
+    // are defined as "extern" by the Zig compiler which means that Zig won't
+    // allocate them on the stack at compile time. WUFFS has functions for
+    // dynamically allocating these structs but they use the C malloc/free. This
+    // gets around that by using the Zig allocator to allocate enough memory for
+    // the struct and then casts it to the appropriate pointer.
+
+    const decoder_buf = try alloc.alloc(u8, c.sizeof__wuffs_png__decoder());
+    defer alloc.free(decoder_buf);
+
+    const decoder: ?*c.wuffs_png__decoder = @ptrCast(decoder_buf);
+    {
+        const status = c.wuffs_png__decoder__initialize(
+            decoder,
+            c.sizeof__wuffs_png__decoder(),
+            c.WUFFS_VERSION,
+            0,
+        );
+        if (!c.wuffs_base__status__is_ok(&status)) {
+            const e = c.wuffs_base__status__message(&status);
+            log.warn("decode err={s}", .{e});
+            return error.WuffsError;
+        }
+    }
+
+    var source_buffer: c.wuffs_base__io_buffer = .{
+        .data = .{ .ptr = @constCast(@ptrCast(data.ptr)), .len = data.len },
+        .meta = .{
+            .wi = data.len,
+            .ri = 0,
+            .pos = 0,
+            .closed = true,
+        },
+    };
+
+    var image_config: c.wuffs_base__image_config = undefined;
+    {
+        const status = c.wuffs_png__decoder__decode_image_config(
+            decoder,
+            &image_config,
+            &source_buffer,
+        );
+        if (!c.wuffs_base__status__is_ok(&status)) {
+            const e = c.wuffs_base__status__message(&status);
+            log.warn("decode err={s}", .{e});
+            return error.WuffsError;
+        }
+    }
+
+    const width = c.wuffs_base__pixel_config__width(&image_config.pixcfg);
+    const height = c.wuffs_base__pixel_config__height(&image_config.pixcfg);
+
+    c.wuffs_base__pixel_config__set(
+        &image_config.pixcfg,
+        c.WUFFS_BASE__PIXEL_FORMAT__RGBA_PREMUL,
+        c.WUFFS_BASE__PIXEL_SUBSAMPLING__NONE,
+        width,
+        height,
+    );
+
+    const destination = try alloc.alloc(
+        u8,
+        width * height * @sizeOf(c.wuffs_base__color_u32_argb_premul),
+    );
+    errdefer alloc.free(destination);
+
+    // temporary buffer for intermediate processing of image
+    const work_buffer = try alloc.alloc(
+        u8,
+
+        // The type of this is a u64 on all systems but our allocator
+        // uses a usize which is a u32 on 32-bit systems.
+        std.math.cast(
+            usize,
+            c.wuffs_png__decoder__workbuf_len(decoder).max_incl,
+        ) orelse return error.OutOfMemory,
+    );
+    defer alloc.free(work_buffer);
+
+    const work_slice = c.wuffs_base__make_slice_u8(
+        work_buffer.ptr,
+        work_buffer.len,
+    );
+
+    var pixel_buffer: c.wuffs_base__pixel_buffer = undefined;
+    {
+        const status = c.wuffs_base__pixel_buffer__set_from_slice(
+            &pixel_buffer,
+            &image_config.pixcfg,
+            c.wuffs_base__make_slice_u8(destination.ptr, destination.len),
+        );
+        if (!c.wuffs_base__status__is_ok(&status)) {
+            const e = c.wuffs_base__status__message(&status);
+            log.warn("decode err={s}", .{e});
+            return error.WuffsError;
+        }
+    }
+
+    var frame_config: c.wuffs_base__frame_config = undefined;
+    {
+        const status = c.wuffs_png__decoder__decode_frame_config(
+            decoder,
+            &frame_config,
+            &source_buffer,
+        );
+        if (!c.wuffs_base__status__is_ok(&status)) {
+            const e = c.wuffs_base__status__message(&status);
+            log.warn("decode err={s}", .{e});
+            return error.WuffsError;
+        }
+    }
+
+    {
+        const status = c.wuffs_png__decoder__decode_frame(
+            decoder,
+            &pixel_buffer,
+            &source_buffer,
+            c.WUFFS_BASE__PIXEL_BLEND__SRC_OVER,
+            work_slice,
+            null,
+        );
+        if (!c.wuffs_base__status__is_ok(&status)) {
+            const e = c.wuffs_base__status__message(&status);
+            log.warn("decode err={s}", .{e});
+            return error.WuffsError;
+        }
+    }
+
+    return .{
+        .width = width,
+        .height = height,
+        .data = destination,
+    };
+}

pkg/wuffs/src/swizzle.zig

@@ -0,0 +1,103 @@
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+const assert = std.debug.assert;
+const c = @import("c.zig").c;
+const Error = @import("error.zig").Error;
+
+const log = std.log.scoped(.wuffs_swizzler);
+
+pub fn gToRgba(alloc: Allocator, src: []const u8) Error![]u8 {
+    return swizzle(
+        alloc,
+        src,
+        c.WUFFS_BASE__PIXEL_FORMAT__Y,
+        c.WUFFS_BASE__PIXEL_FORMAT__RGBA_PREMUL,
+    );
+}
+
+pub fn gaToRgba(alloc: Allocator, src: []const u8) Error![]u8 {
+    return swizzle(
+        alloc,
+        src,
+        c.WUFFS_BASE__PIXEL_FORMAT__YA_PREMUL,
+        c.WUFFS_BASE__PIXEL_FORMAT__RGBA_PREMUL,
+    );
+}
+
+pub fn rgbToRgba(alloc: Allocator, src: []const u8) Error![]u8 {
+    return swizzle(
+        alloc,
+        src,
+        c.WUFFS_BASE__PIXEL_FORMAT__RGB,
+        c.WUFFS_BASE__PIXEL_FORMAT__RGBA_PREMUL,
+    );
+}
+
+fn swizzle(
+    alloc: Allocator,
+    src: []const u8,
+    comptime src_pixel_format: u32,
+    comptime dst_pixel_format: u32,
+) Error![]u8 {
+    const src_slice = c.wuffs_base__make_slice_u8(
+        @constCast(src.ptr),
+        src.len,
+    );
+
+    const dst_fmt = c.wuffs_base__make_pixel_format(
+        dst_pixel_format,
+    );
+
+    assert(c.wuffs_base__pixel_format__is_direct(&dst_fmt));
+    assert(c.wuffs_base__pixel_format__is_interleaved(&dst_fmt));
+    assert(c.wuffs_base__pixel_format__bits_per_pixel(&dst_fmt) % 8 == 0);
+
+    const dst_size = c.wuffs_base__pixel_format__bits_per_pixel(&dst_fmt) / 8;
+
+    const src_fmt = c.wuffs_base__make_pixel_format(
+        src_pixel_format,
+    );
+
+    assert(c.wuffs_base__pixel_format__is_direct(&src_fmt));
+    assert(c.wuffs_base__pixel_format__is_interleaved(&src_fmt));
+    assert(c.wuffs_base__pixel_format__bits_per_pixel(&src_fmt) % 8 == 0);
+
+    const src_size = c.wuffs_base__pixel_format__bits_per_pixel(&src_fmt) / 8;
+
+    assert(src.len % src_size == 0);
+
+    const dst = try alloc.alloc(u8, src.len * dst_size / src_size);
+    errdefer alloc.free(dst);
+
+    const dst_slice = c.wuffs_base__make_slice_u8(
+        dst.ptr,
+        dst.len,
+    );
+
+    var swizzler: c.wuffs_base__pixel_swizzler = undefined;
+    {
+        const status = c.wuffs_base__pixel_swizzler__prepare(
+            &swizzler,
+            dst_fmt,
+            c.wuffs_base__empty_slice_u8(),
+            src_fmt,
+            c.wuffs_base__empty_slice_u8(),
+            c.WUFFS_BASE__PIXEL_BLEND__SRC_OVER,
+        );
+        if (!c.wuffs_base__status__is_ok(&status)) {
+            const e = c.wuffs_base__status__message(&status);
+            log.warn("{s}", .{e});
+            return error.WuffsError;
+        }
+    }
+    {
+        _ = c.wuffs_base__pixel_swizzler__swizzle_interleaved_from_slice(
+            &swizzler,
+            dst_slice,
+            c.wuffs_base__empty_slice_u8(),
+            src_slice,
+        );
+    }
+
+    return dst;
+}

src/renderer/metal/image.zig

@@ -2,6 +2,7 @@ const std = @import("std");
 const Allocator = std.mem.Allocator;
 const assert = std.debug.assert;
 const objc = @import("objc");
+const wuffs = @import("wuffs");
 
 const mtl = @import("api.zig");
 
@@ -301,9 +302,8 @@ pub const Image = union(enum) {
             // RGB needs to be converted to RGBA because Metal textures
             // don't support RGB.
             .pending_rgb => |*p| {
-                // Note: this is the slowest possible way to do this...
                 const data = p.dataSlice(3);
-                const rgba = try rgbToRgba(alloc, data);
+                const rgba = try wuffs.swizzle.rgbToRgba(alloc, data);
                 alloc.free(data);
                 p.data = rgba.ptr;
                 self.* = .{ .pending_rgba = p.* };
@@ -311,7 +311,7 @@ pub const Image = union(enum) {
 
             .replace_rgb => |*r| {
                 const data = r.pending.dataSlice(3);
-                const rgba = try rgbToRgba(alloc, data);
+                const rgba = try wuffs.swizzle.rgbToRgba(alloc, data);
                 alloc.free(data);
                 r.pending.data = rgba.ptr;
                 self.* = .{ .replace_rgba = r.* };
@@ -320,7 +320,7 @@ pub const Image = union(enum) {
             // Gray and Gray+Alpha need to be converted to RGBA, too.
             .pending_gray => |*p| {
                 const data = p.dataSlice(1);
-                const rgba = try grayToRgba(alloc, data);
+                const rgba = try wuffs.swizzle.gToRgba(alloc, data);
                 alloc.free(data);
                 p.data = rgba.ptr;
                 self.* = .{ .pending_rgba = p.* };
@@ -328,7 +328,7 @@ pub const Image = union(enum) {
 
             .replace_gray => |*r| {
                 const data = r.pending.dataSlice(2);
-                const rgba = try grayToRgba(alloc, data);
+                const rgba = try wuffs.swizzle.gToRgba(alloc, data);
                 alloc.free(data);
                 r.pending.data = rgba.ptr;
                 self.* = .{ .replace_rgba = r.* };
@@ -336,7 +336,7 @@ pub const Image = union(enum) {
 
             .pending_gray_alpha => |*p| {
                 const data = p.dataSlice(2);
-                const rgba = try gaToRgba(alloc, data);
+                const rgba = try wuffs.swizzle.gaToRgba(alloc, data);
                 alloc.free(data);
                 p.data = rgba.ptr;
                 self.* = .{ .pending_rgba = p.* };
@@ -344,7 +344,7 @@ pub const Image = union(enum) {
 
             .replace_gray_alpha => |*r| {
                 const data = r.pending.dataSlice(2);
-                const rgba = try gaToRgba(alloc, data);
+                const rgba = try wuffs.swizzle.gaToRgba(alloc, data);
                 alloc.free(data);
                 r.pending.data = rgba.ptr;
                 self.* = .{ .replace_rgba = r.* };
@@ -352,56 +352,6 @@ pub const Image = union(enum) {
         }
     }
 
-    fn grayToRgba(alloc: Allocator, data: []const u8) ![]u8 {
-        const pixels = data.len;
-        var rgba = try alloc.alloc(u8, pixels * 4);
-        errdefer alloc.free(rgba);
-        var i: usize = 0;
-        while (i < pixels) : (i += 1) {
-            const rgba_i = i * 4;
-            rgba[rgba_i] = data[i];
-            rgba[rgba_i + 1] = data[i];
-            rgba[rgba_i + 2] = data[i];
-            rgba[rgba_i + 3] = 255;
-        }
-
-        return rgba;
-    }
-
-    fn gaToRgba(alloc: Allocator, data: []const u8) ![]u8 {
-        const pixels = data.len / 2;
-        var rgba = try alloc.alloc(u8, pixels * 4);
-        errdefer alloc.free(rgba);
-        var i: usize = 0;
-        while (i < pixels) : (i += 1) {
-            const data_i = i * 2;
-            const rgba_i = i * 4;
-            rgba[rgba_i] = data[data_i];
-            rgba[rgba_i + 1] = data[data_i];
-            rgba[rgba_i + 2] = data[data_i];
-            rgba[rgba_i + 3] = data[data_i + 1];
-        }
-
-        return rgba;
-    }
-
-    fn rgbToRgba(alloc: Allocator, data: []const u8) ![]u8 {
-        const pixels = data.len / 3;
-        var rgba = try alloc.alloc(u8, pixels * 4);
-        errdefer alloc.free(rgba);
-        var i: usize = 0;
-        while (i < pixels) : (i += 1) {
-            const data_i = i * 3;
-            const rgba_i = i * 4;
-            rgba[rgba_i] = data[data_i];
-            rgba[rgba_i + 1] = data[data_i + 1];
-            rgba[rgba_i + 2] = data[data_i + 2];
-            rgba[rgba_i + 3] = 255;
-        }
-
-        return rgba;
-    }
-
     /// Upload the pending image to the GPU and change the state of this
     /// image to ready.
     pub fn upload(

src/renderer/opengl/image.zig

@@ -2,6 +2,7 @@ const std = @import("std");
 const Allocator = std.mem.Allocator;
 const assert = std.debug.assert;
 const gl = @import("opengl");
+const wuffs = @import("wuffs");
 
 /// Represents a single image placement on the grid. A placement is a
 /// request to render an instance of an image.
@@ -300,9 +301,8 @@ pub const Image = union(enum) {
             // RGB needs to be converted to RGBA because Metal textures
             // don't support RGB.
             .pending_rgb => |*p| {
-                // Note: this is the slowest possible way to do this...
                 const data = p.dataSlice(3);
-                const rgba = try rgbToRgba(alloc, data);
+                const rgba = try wuffs.swizzle.rgbToRgba(alloc, data);
                 alloc.free(data);
                 p.data = rgba.ptr;
                 self.* = .{ .pending_rgba = p.* };
@@ -310,7 +310,7 @@ pub const Image = union(enum) {
 
             .replace_rgb => |*r| {
                 const data = r.pending.dataSlice(3);
-                const rgba = try rgbToRgba(alloc, data);
+                const rgba = try wuffs.swizzle.rgbToRgba(alloc, data);
                 alloc.free(data);
                 r.pending.data = rgba.ptr;
                 self.* = .{ .replace_rgba = r.* };
@@ -319,7 +319,7 @@ pub const Image = union(enum) {
             // Gray and Gray+Alpha need to be converted to RGBA, too.
             .pending_gray => |*p| {
                 const data = p.dataSlice(1);
-                const rgba = try grayToRgba(alloc, data);
+                const rgba = try wuffs.swizzle.gToRgba(alloc, data);
                 alloc.free(data);
                 p.data = rgba.ptr;
                 self.* = .{ .pending_rgba = p.* };
@@ -327,7 +327,7 @@ pub const Image = union(enum) {
 
             .replace_gray => |*r| {
                 const data = r.pending.dataSlice(2);
-                const rgba = try grayToRgba(alloc, data);
+                const rgba = try wuffs.swizzle.gToRgba(alloc, data);
                 alloc.free(data);
                 r.pending.data = rgba.ptr;
                 self.* = .{ .replace_rgba = r.* };
@@ -335,7 +335,7 @@ pub const Image = union(enum) {
 
             .pending_gray_alpha => |*p| {
                 const data = p.dataSlice(2);
-                const rgba = try gaToRgba(alloc, data);
+                const rgba = try wuffs.swizzle.gaToRgba(alloc, data);
                 alloc.free(data);
                 p.data = rgba.ptr;
                 self.* = .{ .pending_rgba = p.* };
@@ -343,7 +343,7 @@ pub const Image = union(enum) {
 
             .replace_gray_alpha => |*r| {
                 const data = r.pending.dataSlice(2);
-                const rgba = try gaToRgba(alloc, data);
+                const rgba = try wuffs.swizzle.gaToRgba(alloc, data);
                 alloc.free(data);
                 r.pending.data = rgba.ptr;
                 self.* = .{ .replace_rgba = r.* };
@@ -351,56 +351,6 @@ pub const Image = union(enum) {
         }
     }
 
-    fn grayToRgba(alloc: Allocator, data: []const u8) ![]u8 {
-        const pixels = data.len;
-        var rgba = try alloc.alloc(u8, pixels * 4);
-        errdefer alloc.free(rgba);
-        var i: usize = 0;
-        while (i < pixels) : (i += 1) {
-            const rgba_i = i * 4;
-            rgba[rgba_i] = data[i];
-            rgba[rgba_i + 1] = data[i];
-            rgba[rgba_i + 2] = data[i];
-            rgba[rgba_i + 3] = 255;
-        }
-
-        return rgba;
-    }
-
-    fn gaToRgba(alloc: Allocator, data: []const u8) ![]u8 {
-        const pixels = data.len / 2;
-        var rgba = try alloc.alloc(u8, pixels * 4);
-        errdefer alloc.free(rgba);
-        var i: usize = 0;
-        while (i < pixels) : (i += 1) {
-            const data_i = i * 2;
-            const rgba_i = i * 4;
-            rgba[rgba_i] = data[data_i];
-            rgba[rgba_i + 1] = data[data_i];
-            rgba[rgba_i + 2] = data[data_i];
-            rgba[rgba_i + 3] = data[data_i + 1];
-        }
-
-        return rgba;
-    }
-
-    fn rgbToRgba(alloc: Allocator, data: []const u8) ![]u8 {
-        const pixels = data.len / 3;
-        var rgba = try alloc.alloc(u8, pixels * 4);
-        errdefer alloc.free(rgba);
-        var i: usize = 0;
-        while (i < pixels) : (i += 1) {
-            const data_i = i * 3;
-            const rgba_i = i * 4;
-            rgba[rgba_i] = data[data_i];
-            rgba[rgba_i + 1] = data[data_i + 1];
-            rgba[rgba_i + 2] = data[data_i + 2];
-            rgba[rgba_i + 3] = 255;
-        }
-
-        return rgba;
-    }
-
     /// Upload the pending image to the GPU and change the state of this
     /// image to ready.
     pub fn upload(

src/terminal/kitty/graphics_image.zig

@@ -10,7 +10,7 @@ const command = @import("graphics_command.zig");
 const point = @import("../point.zig");
 const PageList = @import("../PageList.zig");
 const internal_os = @import("../../os/main.zig");
-const stb = @import("../../stb/main.zig");
+const wuffs = @import("wuffs");
 
 const log = std.log.scoped(.kitty_gfx);
 
@@ -412,47 +412,30 @@ pub const LoadingImage = struct {
     fn decodePng(self: *LoadingImage, alloc: Allocator) !void {
         assert(self.image.format == .png);
 
-        // Decode PNG
-        var width: c_int = 0;
-        var height: c_int = 0;
-        var bpp: c_int = 0;
-        const data = stb.stbi_load_from_memory(
-            self.data.items.ptr,
-            @intCast(self.data.items.len),
-            &width,
-            &height,
-            &bpp,
-            0,
-        ) orelse return error.InvalidData;
-        defer stb.stbi_image_free(data);
-        const len: usize = @intCast(width * height * bpp);
-        if (len > max_size) {
-            log.warn("png image too large size={} max_size={}", .{ len, max_size });
-            return error.InvalidData;
-        }
+        const result = wuffs.png.decode(
+            alloc,
+            self.data.items,
+        ) catch |err| switch (err) {
+            error.WuffsError => return error.InvalidData,
+            error.OutOfMemory => return error.OutOfMemory,
+        };
+        defer alloc.free(result.data);
 
-        // Validate our bpp
-        if (bpp < 1 or bpp > 4) {
-            log.warn("png with unsupported bpp={}", .{bpp});
-            return error.UnsupportedDepth;
+        if (result.data.len > max_size) {
+            log.warn("png image too large size={} max_size={}", .{ result.data.len, max_size });
+            return error.InvalidData;
         }
 
         // Replace our data
         self.data.deinit(alloc);
         self.data = .{};
-        try self.data.ensureUnusedCapacity(alloc, len);
-        try self.data.appendSlice(alloc, data[0..len]);
+        try self.data.ensureUnusedCapacity(alloc, result.data.len);
+        try self.data.appendSlice(alloc, result.data[0..result.data.len]);
 
         // Store updated image dimensions
-        self.image.width = @intCast(width);
-        self.image.height = @intCast(height);
-        self.image.format = switch (bpp) {
-            1 => .gray,
-            2 => .gray_alpha,
-            3 => .rgb,
-            4 => .rgba,
-            else => unreachable, // validated above
-        };
+        self.image.width = result.width;
+        self.image.height = result.height;
+        self.image.format = .rgba;
     }
 };
 
@@ -792,6 +775,6 @@ test "image load: png, not compressed, regular file" {
     var img = try loading.complete(alloc);
     defer img.deinit(alloc);
     try testing.expect(img.compression == .none);
-    try testing.expect(img.format == .rgb);
+    try testing.expect(img.format == .rgba);
     try tmp_dir.dir.access(path, .{});
 }