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// +build !cgo
package helper
import (
"io/ioutil"
"os"
"os/exec"
"github.com/sirupsen/logrus"
)
// CanConvertTgsToX Checks whether the external command necessary for ConvertTgsToX works.
func CanConvertTgsToX() error {
// We depend on the fact that `lottie_convert.py --help` has exit status 0.
// Hyrum's Law predicted this, and Murphy's Law predicts that this will break eventually.
// However, there is no alternative like `lottie_convert.py --is-properly-installed`
cmd := exec.Command("lottie_convert.py", "--help")
return cmd.Run()
}
// ConvertTgsToWebP convert input data (which should be tgs format) to WebP format
// This relies on an external command, which is ugly, but works.
func ConvertTgsToX(data *[]byte, outputFormat string, logger *logrus.Entry) error {
// lottie can't handle input from a pipe, so write to a temporary file:
tmpInFile, err := ioutil.TempFile(os.TempDir(), "matterbridge-lottie-input-*.tgs")
if err != nil {
return err
}
tmpInFileName := tmpInFile.Name()
defer func() {
if removeErr := os.Remove(tmpInFileName); removeErr != nil {
logger.Errorf("Could not delete temporary (input) file %s: %v", tmpInFileName, removeErr)
}
}()
// lottie can handle writing to a pipe, but there is no way to do that platform-independently.
// "/dev/stdout" won't work on Windows, and "-" upsets Cairo for some reason. So we need another file:
tmpOutFile, err := ioutil.TempFile(os.TempDir(), "matterbridge-lottie-output-*.data")
if err != nil {
return err
}
tmpOutFileName := tmpOutFile.Name()
defer func() {
if removeErr := os.Remove(tmpOutFileName); removeErr != nil {
logger.Errorf("Could not delete temporary (output) file %s: %v", tmpOutFileName, removeErr)
}
}()
if _, writeErr := tmpInFile.Write(*data); writeErr != nil {
return writeErr
}
// Must close before calling lottie to avoid data races:
if closeErr := tmpInFile.Close(); closeErr != nil {
return closeErr
}
// Call lottie to transform:
cmd := exec.Command("lottie_convert.py", "--input-format", "lottie", "--output-format", outputFormat, tmpInFileName, tmpOutFileName)
cmd.Stdout = nil
cmd.Stderr = nil
// NB: lottie writes progress into to stderr in all cases.
_, stderr := cmd.Output()
if stderr != nil {
// 'stderr' already contains some parts of Stderr, because it was set to 'nil'.
return stderr
}
dataContents, err := ioutil.ReadFile(tmpOutFileName)
if err != nil {
return err
}
*data = dataContents
return nil
}
func SupportsFormat(format string) bool {
switch format {
case "png":
fallthrough
case "webp":
return true
default:
return false
}
return false
}
func LottieBackend() string {
return "lottie_convert.py"
}
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