In this post, I will show you how to read WMF images in Java. We also have a related article covering how to convert WMF to SVG files in Java that might interest you.
ImageIO does not support WMF file types by default so you will need to use an ImageIO plugin or an external library. I will demonstrate using an Open source ImageIO plugin called TwelveMonkeys (which extends ImageIO to provide WMF reading support), and using the JDeli Image Library.
What is WMF?
Windows Metafile (WMF for short) is an image file format developed by Microsoft, which has the capabilities for both vector and bitmap images. It is more commonly used for its vector capabilities, similar to a file format such as SVG. Note that once you have loaded a WMF file into a BufferedImage, it has been converted into a bitmap image and is no longer a vector format.
The file name extension for WMF files is:
How to read a WMF image in Java with ImageIO
Step 1 Download TwelveMonkeys plugin and add to class path.
Step 2 Create a File handle, InputStream or URL pointing to the raw WMF image.
Step 3 ImageIO will now be able to read a WMF file into a BufferedImage. This syntax is like so:
BufferedImage image = ImageIO.read(wmfFileOrInputStreamOrURL)
How to read a WMF image in Java with JDeli
Step 1 Add JDeli to your class or module path. (download the trial jar).
Step 2 Create a File handle, InputStream pointing to the raw WMF image. You can also use a byte containing the image data.
Step 3 Read the WMF image into a BufferedImage
BufferedImage image = JDeli.read(wmfFile);
Why use JDeli to read WMF?
JDeli offers a range of advantages over ImageIO and alternatives, including:
- Prevents heap related JVM crashes from ImageIO use of native memory
- The option to convert directly to SVG format, retaining Vector format
- Improved read performance
- Support for threading
- Support for later versions of Java and Java modules