[GH-ISSUE #674] Renderer alpha blends against black when root is transparent #952

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opened 2026-03-14 09:08:11 +03:00 by kerem · 1 comment

kerem commented

2026-03-14 09:08:11 +03:00

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Originally created by @akronb on GitHub (Feb 12, 2026).
Original GitHub issue: https://github.com/anomalyco/opentui/issues/674

Problem\nWhen the root renderable uses a transparent background, semi-transparent overlays (e.g., dialog dimmers) blend against black rather than the terminal's real background. This makes overlays appear black on light terminal themes.\n\n## Expected\nAlpha blending should composite against the terminal background, or the renderer should allow configuring a clear/composite base color.\n\n## Impact\nApps like OpenCode need transparency for system theme, but overlays become unreadable on light terminals unless we force an opaque backdrop while dialogs are open.\n\n## Possible solutions\n- Add a renderer option to composite transparent cells against the terminal background\n- Expose a configurable framebuffer clear color for alpha blending\n- Provide a hook to supply a background color when blending\n

Originally created by @akronb on GitHub (Feb 12, 2026). Original GitHub issue: https://github.com/anomalyco/opentui/issues/674 ## Problem\nWhen the root renderable uses a transparent background, semi-transparent overlays (e.g., dialog dimmers) blend against black rather than the terminal's real background. This makes overlays appear black on light terminal themes.\n\n## Expected\nAlpha blending should composite against the terminal background, or the renderer should allow configuring a clear/composite base color.\n\n## Impact\nApps like OpenCode need transparency for system theme, but overlays become unreadable on light terminals unless we force an opaque backdrop while dialogs are open.\n\n## Possible solutions\n- Add a renderer option to composite transparent cells against the terminal background\n- Expose a configurable framebuffer clear color for alpha blending\n- Provide a hook to supply a background color when blending\n