Spyglass
Render Compose UI @Preview functions to PNG and compare them against design mocks without an IDE, emulator, or build modifications.
Spyglass provides automated visual feedback for Jetpack Compose and Compose Multiplatform without needing Android Studio or an emulator. It inspects compiled classes, renders @Preview functions into cropped PNG images via an offscreen Skia canvas on the project's own classpath, and compares them against target design mockups. Designed specifically to close the feedback loop for AI coding agents, developers, and CI pipelines, it reports structural similarity scores, visual diff heatmaps, and bounding-box coordinates in pixels and density-independent pixels (dp), enabling automated or manual visual correction with zero permanent modifications to the build configuration.