golden/pdfxform a pdf rasterization server

go/pdf/pdf.go

+/* PDF Rasterizer Package
+
+This package provides the Pdfium and Poppler rasterizers.  Pdfium
+requires the `pdfium_test` executable be located in the PATH.  Poppler
+requires `pdftoppm` (provided by poppler-utils) and `pnmtopng`
+(provided by netpbm). */
+
+package pdf
+
+type Rasterizer interface {
+        // Rasterize will take the path to a PDF file and rasterize the
+        // file.  If the file has multiple pages, discard all but the first
+        // page.  The output file will be in PNG format.
+        Rasterize(pdfInputPath, pngOutputPath string) error
+        // Return the name of this rasterizer.
+        String() string
+        // Return false if the rasterizer is found.
+        Enabled() bool
+}