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Rationalize the black-run counting to avoid AIOOBE but also get the right answer still

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git-svn-id: https://zxing.googlecode.com/svn/trunk@1820 59b500cc-1b3d-0410-9834-0bbf25fbcc57
This commit is contained in:
srowen 2011-06-10 08:43:38 +00:00
parent f17a43df81
commit 7f06b18976
1 changed files with 46 additions and 47 deletions
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93
core/src/com/google/zxing/qrcode/detector/Detector.java
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@ -256,33 +256,35 @@ public class Detector {
*/ */
private float sizeOfBlackWhiteBlackRunBothWays(int fromX, int fromY, int toX, int toY) { private float sizeOfBlackWhiteBlackRunBothWays(int fromX, int fromY, int toX, int toY) {
float result = sizeOfBlackWhiteBlackRun(fromX, fromY, toX, toY); float result = sizeOfBlackWhiteBlackRun(fromX, fromY, toX, toY);
// Now count other way -- don't run off image though of course // Now count other way -- don't run off image though of course
float scale = 1.0f; float scale = 1.0f;
int otherToX = fromX - (toX - fromX); int otherToX = fromX - (toX - fromX);
if (otherToX < 0) { if (otherToX < 0) {
scale = (float) fromX / (float) (fromX - otherToX); scale = (float) fromX / (float) (fromX - otherToX);
otherToX = 0; otherToX = 0;
} else if (otherToX > image.getWidth()) { } else if (otherToX >= image.getWidth()) {
scale = (float) (image.getWidth() - fromX) / (float) (otherToX - fromX); scale = (float) (image.getWidth() - 1 - fromX) / (float) (otherToX - fromX);
otherToX = image.getWidth(); otherToX = image.getWidth() - 1;
} }
int otherToY = (int) (fromY - (toY - fromY) * scale); int otherToY = (int) (fromY - (toY - fromY) * scale);
scale = 1.0f; scale = 1.0f;
if (otherToY < 0) { if (otherToY < 0) {
scale = (float) fromY / (float) (fromY - otherToY); scale = (float) fromY / (float) (fromY - otherToY);
otherToY = 0; otherToY = 0;
} else if (otherToY > image.getHeight()) { } else if (otherToY >= image.getHeight()) {
scale = (float) (image.getHeight() - fromY) / (float) (otherToY - fromY); scale = (float) (image.getHeight() - 1 - fromY) / (float) (otherToY - fromY);
otherToY = image.getHeight(); otherToY = image.getHeight() - 1;
} }
otherToX = (int) (fromX + (otherToX - fromX) * scale); otherToX = (int) (fromX + (otherToX - fromX) * scale);
result += sizeOfBlackWhiteBlackRun(fromX, fromY, otherToX, otherToY); result += sizeOfBlackWhiteBlackRun(fromX, fromY, otherToX, otherToY);
return result;
} // Middle pixel is double-counted this way; subtract 1
return result - 1.0f;
}
/** /**
* <p>This method traces a line from a point in the image, in the direction towards another point. * <p>This method traces a line from a point in the image, in the direction towards another point.
@ -313,32 +315,22 @@ public class Detector {
// In black pixels, looking for white, first or second time. // In black pixels, looking for white, first or second time.
int state = 0; int state = 0;
for (int x = fromX, y = fromY; x != toX; x += xstep) { // Loop up until x == toX, but not beyond
int xLimit = toX + xstep;
for (int x = fromX, y = fromY; x != xLimit; x += xstep) {
int realX = steep ? y : x; int realX = steep ? y : x;
int realY = steep ? x : y; int realY = steep ? x : y;
// In white pixels, looking for black. // Does current pixel mean we have moved white to black or vice versa?
// FIXME(dswitkin): This method seems to assume square images, which can cause these calls to if (!(state == 1 ^ image.get(realX, realY))) {
// BitMatrix.get() to throw ArrayIndexOutOfBoundsException. if (state == 2) {
if (state == 1) { int diffX = x - fromX;
if (image.get(realX, realY)) { int diffY = y - fromY;
state++; return (float) Math.sqrt((double) (diffX * diffX + diffY * diffY));
}
} else {
if (!image.get(realX, realY)) {
state++;
} }
state++;
} }
// Found black, white, black, and stumbled back onto white, so we're done.
if (state == 3) {
int diffX = x - fromX;
int diffY = y - fromY;
if (xstep < 0) {
diffX++;
}
return (float) Math.sqrt((double) (diffX * diffX + diffY * diffY));
}
error += dy; error += dy;
if (error > 0) { if (error > 0) {
if (y == toY) { if (y == toY) {
@ -348,9 +340,16 @@ public class Detector {
error -= dx; error -= dx;
} }
} }
int diffX = toX - fromX; // Found black-white-black; give the benefit of the doubt that the next pixel outside the image
int diffY = toY - fromY; // is "white" so this last point at (toX+xStep,toY) is the right ending. This is really a
return (float) Math.sqrt((double) (diffX * diffX + diffY * diffY)); // small approximation; (toX+xStep,toY+yStep) might be really correct. Ignore this.
if (state == 2) {
int diffX = toX + xstep - fromX;
int diffY = toY - fromY;
return (float) Math.sqrt((double) (diffX * diffX + diffY * diffY));
}
// else we didn't find even black-white-black; no estimate is really possible
return Float.NaN;
} }
/** /**