1 files changed, 62 insertions, 0 deletions
diff --git a/share/extensions/raster_output_png.py b/share/extensions/raster_output_png.py
new file mode 100755
index 0000000..b70baa0
--- /dev/null
+++ b/share/extensions/raster_output_png.py
@@ -0,0 +1,62 @@
+#!/usr/bin/env python
+"""
+Optimise PNG file using optipng
+"""
+
+import os
+import inkex
+from inkex.extensions import TempDirMixin
+from inkex.command import ProgramRunError, call
+
+
+class PngOutput(TempDirMixin, inkex.RasterOutputExtension):
+    def add_arguments(self, pars):
+        pars.add_argument("--tab")
+        # Lossless options
+        pars.add_argument("--interlace", type=inkex.Boolean, default=False)
+        pars.add_argument("--level", type=int, default=0)
+        # Lossy options
+        pars.add_argument("--bitdepth", type=inkex.Boolean, default=False)
+        pars.add_argument("--color", type=inkex.Boolean, default=False)
+        pars.add_argument("--palette", type=inkex.Boolean, default=False)
+
+    def load(self, stream):
+        """Load the PNG file (prepare it for optipng)"""
+        self.png_file = os.path.join(self.tempdir, "input.png")
+        with open(self.png_file, "wb") as fhl:
+            fhl.write(stream.read())
+
+    def save(self, stream):
+        """Pass the PNG file to optipng with the options"""
+        options = {
+            "o": self.options.level,
+            "i": int(self.options.interlace),
+            "nb": not self.options.bitdepth,
+            "nc": not self.options.color,
+            "np": not self.options.palette,
+        }
+        try:
+            call("optipng", self.png_file, oldie=True, clobber=True, **options)
+        except ProgramRunError as err:
+            if "IDAT recoding is necessary" in err.stderr.decode("utf-8"):
+                raise inkex.AbortExtension(
+                    _(
+                        "The optipng command failed, possibly due to a mismatch of the"
+                        "interlacing and compression level options. Please try to disable "
+                        '"Interlaced" or set "Level" to 1 or higher.'
+                    )
+                )
+            else:
+                raise inkex.AbortExtension(
+                    _("The optipng command failed with the following message:")
+                    + "\n"
+                    + err.stderr.decode("utf-8")
+                )
+
+        if os.path.isfile(self.png_file):
+            with open(self.png_file, "rb") as fhl:
+                stream.write(fhl.read())
+
+
+if __name__ == "__main__":
+    PngOutput().run()