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java.lang.Objectcom.google.zxing.common.GridSampler
public abstract class GridSampler
Implementations of this class can, given locations of finder patterns for a QR code in an
image, sample the right points in the image to reconstruct the QR code, accounting for
perspective distortion. It is abstracted since it is relatively expensive and should be allowed
to take advantage of platform-specific optimized implementations, like Sun's Java Advanced
Imaging library, but which may not be available in other environments such as J2ME, and vice
versa.
The implementation used can be controlled by calling setGridSampler(GridSampler)
with an instance of a class which implements this interface.
Constructor Summary | |
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GridSampler()
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Method Summary | |
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protected static void |
checkAndNudgePoints(BitMatrix image,
float[] points)
Checks a set of points that have been transformed to sample points on an image against the image's dimensions to see if the point are even within the image. |
static GridSampler |
getInstance()
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abstract BitMatrix |
sampleGrid(BitMatrix image,
int dimensionX,
int dimensionY,
float p1ToX,
float p1ToY,
float p2ToX,
float p2ToY,
float p3ToX,
float p3ToY,
float p4ToX,
float p4ToY,
float p1FromX,
float p1FromY,
float p2FromX,
float p2FromY,
float p3FromX,
float p3FromY,
float p4FromX,
float p4FromY)
Samples an image for a rectangular matrix of bits of the given dimension. |
abstract BitMatrix |
sampleGrid(BitMatrix image,
int dimensionX,
int dimensionY,
PerspectiveTransform transform)
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static void |
setGridSampler(GridSampler newGridSampler)
Sets the implementation of GridSampler used by the library. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public GridSampler()
Method Detail |
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public static void setGridSampler(GridSampler newGridSampler)
newGridSampler
- The platform-specific object to install.public static GridSampler getInstance()
public abstract BitMatrix sampleGrid(BitMatrix image, int dimensionX, int dimensionY, float p1ToX, float p1ToY, float p2ToX, float p2ToY, float p3ToX, float p3ToY, float p4ToX, float p4ToY, float p1FromX, float p1FromY, float p2FromX, float p2FromY, float p3FromX, float p3FromY, float p4FromX, float p4FromY) throws NotFoundException
image
- image to sampledimensionX
- width of BitMatrix
to sample from imagedimensionY
- height of BitMatrix
to sample from image
BitMatrix
representing a grid of points sampled from the image within a region
defined by the "from" parameters
NotFoundException
- if image can't be sampled, for example, if the transformation defined
by the given points is invalid or results in sampling outside the image boundariespublic abstract BitMatrix sampleGrid(BitMatrix image, int dimensionX, int dimensionY, PerspectiveTransform transform) throws NotFoundException
NotFoundException
protected static void checkAndNudgePoints(BitMatrix image, float[] points) throws NotFoundException
Checks a set of points that have been transformed to sample points on an image against the image's dimensions to see if the point are even within the image.
This method will actually "nudge" the endpoints back onto the image if they are found to be barely (less than 1 pixel) off the image. This accounts for imperfect detection of finder patterns in an image where the QR Code runs all the way to the image border.
For efficiency, the method will check points from either end of the line until one is found to be within the image. Because the set of points are assumed to be linear, this is valid.
image
- image into which the points should mappoints
- actual points in x1,y1,...,xn,yn form
NotFoundException
- if an endpoint is lies outside the image boundaries
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