Introduces a new progress package that generates and displays progress updates on the Windows lock screen. The progress package uses the gg library to overlay text on a base image. The UI updates the lock screen by setting a registry policy and forcing a LogonUI refresh. Temporary image files can be cleaned up if required. Tests are added to verify image generation and cleanup behavior.

go.mod

@@ -5,23 +5,27 @@ go 1.23.0
 toolchain go1.24.4
 
 require (
-    github.com/StackExchange/wmi v1.2.1
-    github.com/capnspacehook/taskmaster v0.0.0-20210519235353-1629df7c85e9
-    github.com/go-ole/go-ole v1.3.0
-    github.com/google/deck v1.1.0
-    github.com/google/go-cmp v0.6.0
-    github.com/google/uuid v1.3.0
-    github.com/google/winops v0.0.0-20210803215038-c8511b84de2b
-    github.com/iamacarpet/go-win64api v0.0.0-20240507095429-873e84e85847
-    github.com/pkg/errors v0.9.1
-    github.com/scjalliance/comshim v0.0.0-20250111221056-b2ef9d8d7e0f
-    golang.org/x/sys v0.34.0
+	github.com/StackExchange/wmi v1.2.1
+	github.com/capnspacehook/taskmaster v0.0.0-20210519235353-1629df7c85e9
+	github.com/fogleman/gg v1.3.0
+	github.com/go-ole/go-ole v1.3.0
+	github.com/google/deck v1.1.0
+	github.com/google/go-cmp v0.6.0
+	github.com/google/uuid v1.3.0
+	github.com/google/winops v0.0.0-20210803215038-c8511b84de2b
+	github.com/iamacarpet/go-win64api v0.0.0-20240507095429-873e84e85847
+	github.com/pkg/errors v0.9.1
+	github.com/scjalliance/comshim v0.0.0-20250111221056-b2ef9d8d7e0f
+	golang.org/x/sys v0.34.0
 )
 
 require (
-    github.com/google/cabbie v1.0.5 // indirect
-    github.com/nu7hatch/gouuid v0.0.0-20131221200532-179d4d0c4d8d // indirect
-    github.com/rickb777/date v1.21.1 // indirect
-    github.com/rickb777/plural v1.4.4 // indirect
-    gopkg.in/toast.v1 v1.0.0-20180812000517-0a84660828b2 // indirect
-)
+	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 // indirect
+	github.com/google/cabbie v1.0.5 // indirect
+	github.com/nu7hatch/gouuid v0.0.0-20131221200532-179d4d0c4d8d // indirect
+	github.com/rickb777/date v1.21.1 // indirect
+	github.com/rickb777/plural v1.4.4 // indirect
+	golang.org/x/image v0.21.0 // indirect
+	golang.org/x/net v0.27.0 // indirect
+	gopkg.in/toast.v1 v1.0.0-20180812000517-0a84660828b2 // indirect
+)

go.sum

@@ -6,6 +6,8 @@ github.com/StackExchange/wmi v1.2.1/go.mod h1:rcmrprowKIVzvc+NUiLncP2uuArMWLCbu9
 github.com/capnspacehook/taskmaster v0.0.0-20210519235353-1629df7c85e9 h1:5jmtWADt5DzD8NnPxcqd1FzbFNZNfbJGNeDb+WKjoJ0=
 github.com/capnspacehook/taskmaster v0.0.0-20210519235353-1629df7c85e9/go.mod h1:257CYs3Wd/CTlLQ3c72jKv+fFE2MV3WPNnV5jiroYUU=
 github.com/creachadair/staticfile v0.1.3/go.mod h1:a3qySzCIXEprDGxk6tSxSI+dBBdLzqeBOMhZ+o2d3pM=
+github.com/fogleman/gg v1.3.0 h1:/7zJX8F6AaYQc57WQCyN9cAIz+4bCJGO9B+dyW29am8=
+github.com/fogleman/gg v1.3.0/go.mod h1:R/bRT+9gY/C5z7JzPU0zXsXHKM4/ayA+zqcVNZzPa1k=
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
 github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
 github.com/go-ole/go-ole v1.2.4/go.mod h1:XCwSNxSkXRo4vlyPy93sltvi/qJq0jqQhjqQNIwKuxM=
@@ -14,6 +16,8 @@ github.com/go-ole/go-ole v1.2.6/go.mod h1:pprOEPIfldk/42T2oK7lQ4v4JSDwmV0As9GaiU
 github.com/go-ole/go-ole v1.3.0 h1:Dt6ye7+vXGIKZ7Xtk4s6/xVdGDQynvom7xCFEdWr6uE=
 github.com/go-ole/go-ole v1.3.0/go.mod h1:5LS6F96DhAwUc7C+1HLexzMXY1xGRSryjyPPKW6zv78=
 github.com/godbus/dbus v4.1.0+incompatible/go.mod h1:/YcGZj5zSblfDWMMoOzV4fas9FZnQYTkDnsGvmh2Grw=
+github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 h1:DACJavvAHhabrF08vX0COfcOBJRhZ8lUbR+ZWIs0Y5g=
+github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0/go.mod h1:E/TSTwGwJL78qG/PmXZO1EjYhfJinVAhrmmHX6Z8B9k=
 github.com/golang/glog v0.0.0-20210429001901-424d2337a529/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/golang/protobuf v1.4.0-rc.1/go.mod h1:ceaxUfeHdC40wWswd/P6IGgMaK3YpKi5j83Wpe3EHw8=
@@ -72,6 +76,8 @@ github.com/scjalliance/comshim v0.0.0-20250111221056-b2ef9d8d7e0f h1:v+bqkkvZj6O
 github.com/scjalliance/comshim v0.0.0-20250111221056-b2ef9d8d7e0f/go.mod h1:Zt2M6t3i/fnWviIZkuw9wGn2E185P/rWZTqJkIrViGY=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/image v0.21.0 h1:c5qV36ajHpdj4Qi0GnE0jUc/yuo33OLFaa0d+crTD5s=
+golang.org/x/image v0.21.0/go.mod h1:vUbsLavqK/W303ZroQQVKQ+Af3Yl6Uz1Ppu5J/cLz78=
 golang.org/x/net v0.0.0-20180906233101-161cd47e91fd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20200520004742-59133d7f0dd7/go.mod h1:qpuaurCH72eLCgpAm/N6yyVIVM9cpaDIP3A8BGJEC5A=
@@ -122,4 +128,4 @@ gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7/go.mod h1:dt/ZhP58zS4L8KSrWD
 gopkg.in/yaml.v2 v2.2.4/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
-gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

go/lockscreenui/README.md

@@ -0,0 +1,131 @@
+# Glazier Lock Screen UI Manager
+
+<!--* freshness: { owner: '@mjoliver' reviewed: '2026-06-11' } *-->
+
+`lockscreenui` is a robust, reusable Go library for displaying provisioning,
+installation, or configuration progress directly on the Windows lock screen
+(`LogonUI.exe`).
+
+It is fully configurable, supporting custom background images, solid background
+colors, tailored title prefixes, and custom footer messages.
+
+## Features
+
+*   **Seamless Lock Screen Integration**: Dynamically generates progress
+    wallpaper frames and applies them via Windows Group Policy registry keys
+    (`SOFTWARE\Policies\Microsoft\Windows\Personalization\LockScreenImage`).
+*   **Instant Visual Updates**: Safely refreshes the Windows logon screen
+    (`taskkill /F /IM LogonUI.exe`) to force immediate redraws without requiring
+    a reboot.
+*   **Reboot Resilient**: Because Group Policy registry keys persist across
+    restarts, Windows Winlogon automatically displays the latest progress screen
+    immediately upon bootup.
+*   **Flexible Overlay Positioning**: Supports placing the progress box in the
+    `center`, `top`, or `bottom` of the screen to avoid overlapping with active
+    Windows login credential tiles.
+*   **Distinct Error Alerting**: Provides a dedicated `UpdateLockScreenError`
+    API that renders a striking translucent dark red alert box to notify users
+    of failures and guide them on recovery steps.
+*   **Automatic Footprint Cleanup**: Includes a clean `Cleanup()` method to
+    remove Group Policy overrides and purge temporary image files once
+    provisioning is complete.
+
+## Usage Example
+
+```go
+package main
+
+import (
+    "context"
+    "image/color"
+    "log"
+
+    "github.com/google/glazier/go/lockscreenui"
+)
+
+func main() {
+    ctx := context.Background()
+
+    // 1. Define configuration
+    cfg := lockscreenui.Config{
+        TempDir:         `C:\Provisioning\TempScreens`,
+        BgColor:         color.RGBA{0, 120, 215, 255}, // Solid Windows Blue
+        TitlePrefix:     "System Setup: ",
+        FooterText:      "Please do not turn off your computer",
+        ErrorTitle:      "Setup Error (Step Failed)",
+        ErrorFooterText: "Please reboot the machine to retry setup",
+        OverlayPosition: lockscreenui.PositionBottom, // Position at the bottom to avoid credential tiles
+    }
+
+    // 2. Initialize UI Manager
+    ui, err := lockscreenui.NewProvisioningUI(ctx, cfg)
+    if err != nil {
+        log.Fatalf("Failed to initialize UI: %v", err)
+    }
+    defer ui.Cleanup(ctx) // Ensures policies and temp files are removed upon exit
+
+    // 3. Update Progress
+    if err := ui.UpdateLockScreen(ctx, 1, "Step 1 of 3: Installing system packages..."); err != nil {
+        log.Printf("Progress update failed: %v", err)
+    }
+
+    // 4. Report Error (if a step fails)
+    // ui.UpdateLockScreenError(ctx, 1, "Package download failed: network timeout")
+}
+```
+
+## Embedding a Custom Background Image
+
+You can bake a custom background image (JPEG or PNG) directly into your compiled
+Go binary using Go's native `//go:embed` directive. This ensures your tool
+remains a single standalone executable without relying on external asset files
+on the host machine.
+
+```go
+package main
+
+import (
+    "bytes"
+    "context"
+    "embed"
+    "image"
+    "log"
+
+    "github.com/google/glazier/go/lockscreenui"
+
+    _ "image/jpeg" // Essential for decoding embedded JPEG images
+)
+
+//go:embed assets/wallpaper.jpeg
+var embeddedFS embed.FS
+
+func main() {
+    ctx := context.Background()
+
+    // 1. Read and decode the embedded image
+    data, err := embeddedFS.ReadFile("assets/wallpaper.jpeg")
+    if err != nil {
+        log.Fatalf("Failed to read embedded image: %v", err)
+    }
+    img, _, err := image.Decode(bytes.NewReader(data))
+    if err != nil {
+        log.Fatalf("Failed to decode embedded image: %v", err)
+    }
+
+    // 2. Pass the decoded image to the configuration
+    cfg := lockscreenui.Config{
+        TempDir:         `C:\Provisioning\TempScreens`,
+        BaseImage:       img,
+        TitlePrefix:     "Setup: ",
+        OverlayPosition: lockscreenui.PositionBottom,
+    }
+
+    ui, err := lockscreenui.NewProvisioningUI(ctx, cfg)
+    if err != nil {
+        log.Fatalf("Failed to initialize UI: %v", err)
+    }
+    defer ui.Cleanup(ctx)
+
+    ui.UpdateLockScreen(ctx, 1, "Applying embedded background...")
+}
+```