Added build pipeline process for generating fonts

.github/workflows/build_fonts.yml

@@ -0,0 +1,59 @@
+# Script to build font files.
+
+name: Build Fonts
+
+on:
+  # Triggers the workflow on pull request events but only for the "main" branch
+  pull_request:
+    branches: [ "main" ]
+  push:
+    branches: [ "*" ]
+
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+jobs:
+  build_fonts:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set Up Python 3.10
+        uses: actions/setup-python@v4
+        with:
+          python-version: '3.10'
+
+      - name: install Python dependencies
+        run: |
+          python -m pip install -U pip
+          python -m pip install -U fonttools[ufo,woff]
+          python -m pip install git+https://github.com/prasannagunuru/nanoemoji.git@PrasannaG/rules_into_feature_file
+      - name: build Color font
+        run: |
+          python scripts/copy_assets.py assets --style="Color" --popular=20
+          nanoemoji --color_format="glyf_colr_1" --output_file="font_color.ttf" --width=0 --noclip_to_viewbox --family="Emoji Color" svgs/*.svg
+          mv build/font_color.otf .
+          rm -rf svgs
+          rm -rf build
+      - name: build Flat font
+        run: |
+          python scripts/copy_assets.py assets --style="Flat" --popular=20
+          nanoemoji --color_format="glyf_colr_0" --output_file="font_flat.ttf" --width=0 --noclip_to_viewbox --family="Emoji Flat" svgs/*.svg
+          mv build/font_flat.otf .
+          rm -rf svgs
+          rm -rf build
+      - name: build High Contrast font
+        run: |
+          python scripts/copy_assets.py assets --style="High Contrast" --popular=20
+          nanoemoji --color_format="glyf" --output_file="font_hc.ttf" --width=0 --noclip_to_viewbox --family="Emoji High Contrast" svgs/*.svg
+          mv build/font_hc.otf .
+          rm -rf svgs
+          rm -rf build
+
+      - name: attach fonts as build artifacts
+        uses: actions/upload-artifact@v3
+        with:
+          name: font_package
+          path: |
+            font_*.ttf