peftGDS=>PNG render improvement for GitHub Actions and local (#28)

* Add --create-png-preview option; more-robust GDS to PNG rendering for GHA

* Minor update to --create-png-preview

* Change --create-png-preview to just be a --create-png replacement

* Minor --create-png improvement

---------

Co-authored-by: Anton Maurovic <algo@foogle.com>

project.py

@@ -490,17 +490,113 @@ class Project():
         if p.returncode != 0:
             logging.error("pdf command failed")
     
-    # SVG and PNG renders of the GDS
+    # Read and return top-level GDS data from the final GDS file, using gdstk:
-    def create_svg(self):
+    def get_final_gds_top_cells(self):
         gds = glob.glob(os.path.join(self.local_dir, 'runs/wokwi/results/final/gds/*gds'))
         if self.args.openlane2:
             gds = glob.glob(os.path.join(self.local_dir, 'runs/wokwi/final/gds/*gds'))
         library = gdstk.read_gds(gds[0])
         top_cells = library.top_level()
-        top_cells[0].write_svg('gds_render.svg')
+        return top_cells[0]
+
+    # SVG render of the GDS.
+    # NOTE: This includes all standard GDS layers inc. text labels.
+    def create_svg(self):
+        top_cells = self.get_final_gds_top_cells()
+        top_cells.write_svg('gds_render.svg')
+
+    # Try various QUICK methods to create a more-compressed PNG render of the GDS,
+    # and fall back to cairosvg if it doesn't work. This is designed for speed,
+    # and in particular for use by the GitHub Actions.
+    # For more info, see:
+    # https://github.com/TinyTapeout/tt-gds-action/issues/8
+    def create_png(self):
+
+        logging.info('Loading GDS data...')
+        top_cells = self.get_final_gds_top_cells()
+
+        # Remove label layers (i.e. delete text), then generate SVG:
+        sky130_label_layers = [
+            (64,59),    # 64/59 - pwell.label
+            (64,5),     # 64/5  - nwell.label
+            (67,5),     # 67/5  - li1.label
+            (68,5),     # 68/5  - met1.label
+            (69,5),     # 69/5  - met2.label
+            (70,5),     # 70/5  - met3.label
+            (71,5),     # 71/5  - met4.label
+        ]
+        top_cells.filter(sky130_label_layers)
+        svg = 'gds_render_preview.svg'
+        logging.info('Rendering SVG without text label layers: {}'.format(svg))
+        top_cells.write_svg(svg, pad=0)
+        # We should now have gds_render_preview.svg
+
+        # Try converting using 'rsvg-convert' command-line utility.
+        # This should create gds_render_preview.png
+        png = 'gds_render_preview.png'
+        logging.info('Converting to PNG using rsvg-convert: {}'.format(png))
+
+        cmd = 'rsvg-convert --unlimited {} -o {} --no-keep-image-data'.format(svg, png)
+        logging.debug(cmd)
+        p = subprocess.run(cmd, shell=True, capture_output=True)
+
+        if p.returncode == 127:
+            logging.warning('rsvg-convert not found; is package "librsvg2-bin" installed? Falling back to cairosvg. This might take a while...')
+            # Fall back to cairosvg:
+            cairosvg.svg2png(url=svg, write_to=png)
+
+        elif p.returncode != 0 and b'cannot load more than' in p.stderr:
+            logging.warning('Too many SVG elements ("{}"). Reducing complexity...'.format(p.stderr.decode().strip()))
+            # Remove more layers that are hardly visible anyway:
+            sky130_buried_layers = [
+                (64,16), # 64/16 - nwell.pin
+                (65,44), # 65/44 - tap.drawing
+                (68,16), # 68/16 - met1.pin
+                (68,44), # 68/44 - via.drawing
+                (81,4 ), # 81/4  - areaid.standardc
+                (70,20), # 70/20 - met3.drawing
+                # Important:
+                # (68,20), # 68/20 - met1.drawing
+                # Less important, but keep for now:
+                # (69,20), # 69/20 - met2.drawing
+            ]
+            top_cells.filter(sky130_buried_layers)
+            svg_alt = 'gds_render_preview_alt.svg'
+            logging.info('Rendering SVG with more layers removed: {}'.format(svg_alt))
+            top_cells.write_svg(svg_alt, pad=0)
+            logging.info('Converting to PNG using rsvg-convert: {}'.format(png))
+
+            cmd = 'rsvg-convert --unlimited {} -o {} --no-keep-image-data'.format(svg_alt, png)
+            logging.debug(cmd)
+            p = subprocess.run(cmd, shell=True, capture_output=True)
+
+            if p.returncode != 0:
+                logging.warning('Still cannot convert to SVG ("{}"). Falling back to cairosvg. This might take a while...'.format(p.stderr.decode().strip()))
+                # Fall back to cairosvg, and since we're doing that, might as well use the original full-detail SVG anyway:
+                cairosvg.svg2png(url=svg, write_to=png)
+
+        # By now we should have gds_render_preview.png
+
+        # Compress with pngquant:
+        final_png = 'gds_render.png'
+        if self.yaml['project']['tiles'] == '8x2':
+            quality = '0-10' # Compress more for 8x2 tiles.
+        else:
+            quality = '0-30'
+        logging.info('Compressing PNG further with pngquant to: {}'.format(final_png))
+
+        cmd = 'pngquant --quality {} --speed 1 --nofs --strip --force --output {} {}'.format(quality, final_png, png)
+        logging.debug(cmd)
+        p = subprocess.run(cmd, shell=True, capture_output=True)
+        
+        if p.returncode == 127:
+            logging.warning('pngquant not found; is package "pngquant" installed? Using intermediate (uncompressed) PNG file')
+            os.rename(png, final_png)
+        elif p.returncode !=0:
+            logging.warning('pngquant error {} ("{}"). Using intermediate (uncompressed) PNG file'.format(p.returncode, p.stderr.decode().strip()))
+            os.rename(png, final_png)
+        logging.info('Final PNG is {} ({:,} bytes)'.format(final_png, os.path.getsize(final_png)))
 
-        if self.args.create_png:
-            cairosvg.svg2png(url='gds_render.svg', write_to='gds_render.png')
 
     def print_warnings(self):
         warnings = []

tt_tool.py

@@ -71,5 +71,8 @@ if __name__ == '__main__':
     if args.create_pdf:
         project.create_pdf()
 
-    if args.create_svg or args.create_png:
+    if args.create_png:
+        project.create_png()
+
+    if args.create_svg:
         project.create_svg()