gfx/wr/wrench/reftests/blend/difference-transparent-ref.yaml
author Kartikaya Gupta <kgupta@mozilla.com>
Thu, 22 Nov 2018 21:47:48 +0000
changeset 447760 89caaea53d18aaf2d4b90b98a2f989a8cdc7062b
permissions -rw-r--r--
Bug 1507524 - Move webrender to gfx/wr. r=jrmuizel This patch copies the webrender repository contents into gfx/wr. The existing files from gfx/webrender, gfx/webrender_api, and gfx/wrench are moved, and the remaining files are added. The revision being used is the same as before. In addition, the mozilla-central top-level Cargo.toml and the gfx/webrender_bindings/Cargo.toml files are updated to reflect the new structure. Differential Revision: https://phabricator.services.mozilla.com/D12059

---
root:
  items:
        - type: rect
          bounds: [0, 0, 100, 100]

          # First blend black rect with green in place
          #  Cs = (1 - αb) x Cs + αb x B(Cb, Cs)
          #  B(Cb, Cs) = | Cb - Cs | = (0, 0, 0)
          #  0.5 * (0, 255, 0) + 0.5 * (0, 0, 0) = (0, 127.5, 0)
          #
          #  Now, composite the resulting color with src-over; the alpha is the original alpha for the top layer
          #  while the color is the blending result
          #  co = αs x Fa x Cs + αb x Fb x Cb  - this is premultiplied 
          #  αo = αs + αb x (1 – αs) 
          #  Source over:     Fa = 1; Fb = 1 – αs 
          # co = 0.5 * 1 * (0, 127.5, 0) + 0.5 * 0.5 * (0, 255, 0) = (0, 63.5, 0) + 0.25 * (0, 255, 0) = (0, 127.5, 0)
          # ao = 0.5 + 0.5 * 0.5 = 0.75
          #  Co = co/ao = (0, 127.5, 0) / 0.75
          #
          #  Now alpha composite on white background
          # co = 0.75 * 1 * (0, 127.5, 0) / 0.75 + 1 * 0.25 * (255, 255, 255) = (0, 127.5, 0) + (63.75, 63.75, 63.75) = (63.75, 159, 63.75) = (64, 191, 64) 
          color: [64, 191, 64]