//The first step for using the fork/join framework is to write code
//that performs a segment of the work.
//Your code should look similar to the following pseudocode:
if (my portion of the work is small enough)
do the work directly
else
split my work into two pieces
invoke the two pieces and wait for the results
public class ForkBlur extends RecursiveAction {
private int[] mSource;
private int mStart;
private int mLength;
private int[] mDestination;
// Processing window size; should be odd.
private int mBlurWidth = 15;
public ForkBlur(int[] src, int start, int length, int[] dst) {
mSource = src;
mStart = start;
mLength = length;
mDestination = dst;
}
protected void computeDirectly() {
int sidePixels = (mBlurWidth - 1) / 2;
for (int index = mStart; index < mStart + mLength; index++) {
// Calculate average.
float rt = 0, gt = 0, bt = 0;
for (int mi = -sidePixels; mi <= sidePixels; mi++) {
int mindex = Math.min(Math.max(mi + index, 0),
mSource.length - 1);
int pixel = mSource[mindex];
rt += (float)((pixel & 0x00ff0000) >> 16)
/ mBlurWidth;
gt += (float)((pixel & 0x0000ff00) >> 8)
/ mBlurWidth;
bt += (float)((pixel & 0x000000ff) >> 0)
/ mBlurWidth;
}
// Reassemble destination pixel.
int dpixel = (0xff000000 ) |
(((int)rt) << 16) |
(((int)gt) << 8) |
(((int)bt) << 0);
mDestination[index] = dpixel;
}
}
protected static int sThreshold = 100000;
protected void compute() {
if (mLength < sThreshold) {
computeDirectly();
return;
}
int split = mLength / 2;
invokeAll(new ForkBlur(mSource, mStart, split, mDestination),
new ForkBlur(mSource, mStart + split, mLength - split,
mDestination));
}