feat(notify): parse the image hints and encode them to PNG

image-data (and the deprecated icon_data) is the (iiibiiay) struct; the
PNG encoder honours rowstride and both 3- and 4-channel data. The path
and data readers are pure, so the service can apply the spec's priority
and the store stays free of image handling.

1 files changed, 101 insertions, 0 deletions

diff --git a/internal/notify/image_test.go b/internal/notify/image_test.go
new file mode 100644
index 0000000..2db4c75
--- /dev/null
+++ b/internal/notify/image_test.go
@@ -0,0 +1,101 @@
+// Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+package notify
+
+import (
+	"bytes"
+	"image/png"
+	"testing"
+
+	"github.com/godbus/dbus/v5"
+)
+
+// rawVariant builds the (iiibiiay) struct the bus delivers for image-data.
+func rawVariant(w, h, stride int, alpha bool, ch int, data []byte) dbus.Variant {
+	return dbus.MakeVariant([]interface{}{
+		int32(w), int32(h), int32(stride), alpha, int32(8), int32(ch), data,
+	})
+}
+
+func TestImageDataFromHints(t *testing.T) {
+	// 2x1 RGBA: red, green.
+	rgba := []byte{255, 0, 0, 255, 0, 255, 0, 255}
+	cases := []struct {
+		name  string
+		hints map[string]dbus.Variant
+		wantW int
+		want  bool
+	}{
+		{"image-data wins", map[string]dbus.Variant{
+			"image-data": rawVariant(2, 1, 8, true, 4, rgba),
+			"image-path": dbus.MakeVariant("/tmp/x.png"),
+		}, 2, true},
+		{"icon_data fallback", map[string]dbus.Variant{
+			"icon_data": rawVariant(2, 1, 8, true, 4, rgba),
+		}, 2, true},
+		{"image_data alias", map[string]dbus.Variant{
+			"image_data": rawVariant(2, 1, 8, true, 4, rgba),
+		}, 2, true},
+		{"absent", map[string]dbus.Variant{}, 0, false},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			got, ok := ImageDataFromHints(c.hints)
+			if ok != c.want {
+				t.Fatalf("ok = %v, want %v", ok, c.want)
+			}
+			if ok && got.Width != c.wantW {
+				t.Fatalf("width = %d, want %d", got.Width, c.wantW)
+			}
+		})
+	}
+}
+
+func TestImagePathFromHints(t *testing.T) {
+	got, ok := ImagePathFromHints(map[string]dbus.Variant{"image-path": dbus.MakeVariant("/tmp/shot.png")})
+	if !ok || got != "/tmp/shot.png" {
+		t.Fatalf("got %q ok=%v", got, ok)
+	}
+	if _, ok := ImagePathFromHints(map[string]dbus.Variant{}); ok {
+		t.Fatal("empty hints must not report a path")
+	}
+}
+
+func TestRawImagePNG(t *testing.T) {
+	// 2x1 RGBA on a rowstride wider than the data, to prove stride is honoured.
+	r := &RawImage{Width: 2, Height: 1, RowStride: 12, HasAlpha: true, BitsPerSample: 8, Channels: 4,
+		Data: []byte{255, 0, 0, 255, 0, 255, 0, 255, 9, 9, 9, 9}}
+	data, err := r.PNG()
+	if err != nil {
+		t.Fatalf("PNG: %v", err)
+	}
+	img, err := png.Decode(bytes.NewReader(data))
+	if err != nil {
+		t.Fatalf("decode: %v", err)
+	}
+	if img.Bounds().Dx() != 2 || img.Bounds().Dy() != 1 {
+		t.Fatalf("bounds = %v", img.Bounds())
+	}
+	r0, g0, b0, a0 := img.At(0, 0).RGBA()
+	if r0>>8 != 255 || g0>>8 != 0 || b0>>8 != 0 || a0>>8 != 255 {
+		t.Fatalf("pixel 0 = %d %d %d %d", r0>>8, g0>>8, b0>>8, a0>>8)
+	}
+}
+
+func TestRawImagePNGRejectsBadData(t *testing.T) {
+	if _, err := (&RawImage{Width: 0, Height: 1, Channels: 4, BitsPerSample: 8}).PNG(); err == nil {
+		t.Fatal("zero width must error")
+	}
+	if _, err := (&RawImage{Width: 1, Height: 1, Channels: 2, BitsPerSample: 8}).PNG(); err == nil {
+		t.Fatal("channels 2 must error")
+	}
+}