golden/pdfxform a pdf rasterization server

go/pdf/pdfium.go

+// PDF Rasterizer
+package pdf
+
+import (
+        "fmt"
+        "os"
+        "os/exec"
+        "path/filepath"
+        "time"
+
+        "go.skia.org/infra/go/fileutil"
+        "go.skia.org/infra/go/util"
+)
+
+const pdfiumExecutable = "pdfium_test"
+
+type Pdfium struct{}
+
+func (Pdfium) String() string { return "Pdfium" }
+
+func (Pdfium) Enabled() bool {
+        return commandFound(pdfiumExecutable)
+}
+
+// Rasterize assumes that filepath.Dir(pdfInputPath) is writable
+func (Pdfium) Rasterize(pdfInputPath, pngOutputPath string) error {
+        if !(Pdfium{}).Enabled() {
+                return fmt.Errorf("pdfium_test is missing")
+        }
+
+        // Check input
+        if !fileutil.FileExists(pdfInputPath) {
+                return fmt.Errorf("Path '%s' does not exist", pdfInputPath)
+        }
+
+        // Remove any files created by pdfiumExecutable
+        defer func() {
+                // Assume pdfInputPath has glob characters.
+                matches, _ := filepath.Glob(fmt.Sprintf("%s.*.png", pdfInputPath))
+                for _, match := range matches {
+                        util.Remove(match)
+                }
+        }()
+
+        command := exec.Command(pdfiumExecutable, "--png", pdfInputPath)
+        if err := command.Start(); err != nil {
+                return err
+        }
+        go func() {
+                time.Sleep(5 * time.Second)
+                _ = command.Process.Kill()
+        }()
+        if err := command.Wait(); err != nil {
+                return err
+        }
+
+        firstPagePath := fmt.Sprintf("%s.0.png", pdfInputPath)
+        if !fileutil.FileExists(firstPagePath) {
+                return fmt.Errorf("First rasterized page (%s) not found.", firstPagePath)
+        }
+        if err := os.Rename(firstPagePath, pngOutputPath); err != nil {
+                return err
+        }
+        return nil
+}