[BUG] device.Render does not handle transparency

[dillonkh]

Description

Using device.Render to convert a page of a pdf to an image does so without transparency.

Expected Behavior

When the input PDF has transparency, the image rendered should have the same transparency.

Actual Behavior

Running the following PDF (or any PDF with transparency) through the device.Render gives me an image that does not respect the transparency of the original PDF.

Attachments

Here is my code for an example:

func pdfToImage(file io.ReadSeeker) error {
    // create a new reader
    pdfReader, err := pdf.NewPdfReader(file)
    if err != nil {
        return err
    }

    // get total number of pages
    numPages, err := pdfReader.GetNumPages()
    if err != nil {
        return err
    }

    // for each page
    for i := 1; i <= numPages; i++ {
        // get specific page by number
        page, err := pdfReader.GetPage(i)
        if err != nil {
            return err
        }

        // create device to render page onto
        device := render.NewImageDevice()

        // render image to path
        err = device.RenderToPath(page, "some/path.png")
        if err != nil {
            return err
        }
    }

    return nil
}

Original PDF: transparent_watermark.pdf

Output image:

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[anovik]

@dillonkh Hello, we have fixed this transparency issue and it will be included in the next release of UniPDF.

We will notify you when the next release will be available.

Thanks for reporting the issue.

[anovik]

@dillonkh The UniPDF version 3.57 https://github.com/unidoc/unipdf/releases/tag/v3.57.0 is available and it fixes your issue.

Closing this ticket, feel free to re-open it or open a new one in case of any problems.