I am attempting to create a memory mapped region so that I can read
the contents of the frame buffer. I have changed the permission
accordingly so that I can access the framebuffer. (things work fine if
I just use the random access file directly, however I assume it's
slower)
When I run the following lines:
RandomAccessFile fin = new RandomAccessFile("/dev/graphics/fb0", "r");
IntBuffer ib = fin.getChannel().map(
FileChannel.MapMode.READ_ONLY, 0, 4 * screenWidth *
screenHeight)
.asIntBuffer();
I get the following error:
java.io.IOException: Invalid argument
at org.apache.harmony.luni.platform.OSFileSystem.truncate(Native
Method)
at
org.apache.harmony.nio.internal.FileChannelImpl.mapImpl(FileChannelImpl.java:
195)
at
org.apache.harmony.nio.internal.ReadOnlyFileChannel.map(ReadOnlyFileChannel.java:
95)
at ...
When I run the equivalent thing in C using mmap the code executes
fine. One thing I have noticed is that the size() method of the file
channel returned from fin.getChannel() is 0 (which doesn't seem
right).
Does anyone have any idea what is going on here and if I can make this
work somehow?
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