(翻译）ZXing 解析二维码

package t1; import java.awt.Graphics2D; import java.awt.geom.AffineTransform; import java.awt.image.BufferedImage; import java.awt.image.WritableRaster; import com.google.zxing.LuminanceSource; /** * * 二维码的解析需要借助BufferedImageLuminanceSource类，该类是由Google提供的，可以将该类直接拷贝到源码中使用，当然你也可以自己写个 * 解析条形码的基类 */ public final class BufferedImageLuminanceSource extends LuminanceSource { private static final double MINUS_45_IN_RADIANS = -0.7853981633974483; // Math.toRadians(-45.0) private final BufferedImage image; private final int left; private final int top; private static final boolean EXPLICIT_LUMINANCE_CONVERSION; static { String property = System.getProperty("explicitLuminanceConversion"); if (property == null) { property = System.getenv("EXPLICIT_LUMINANCE_CONVERSION"); } EXPLICIT_LUMINANCE_CONVERSION = Boolean.parseBoolean(property); } public BufferedImageLuminanceSource(BufferedImage image) { this(image, 0, 0, image.getWidth(), image.getHeight()); } public BufferedImageLuminanceSource(BufferedImage image, int left, int top, int width, int height) { super(width, height); if (image.getType() == BufferedImage.TYPE_BYTE_GRAY) { this.image = image; } else { int sourceWidth = image.getWidth(); int sourceHeight = image.getHeight(); if (left + width > sourceWidth || top + height > sourceHeight) { throw new IllegalArgumentException("Crop rectangle does not fit within image data."); } this.image = new BufferedImage(sourceWidth, sourceHeight, BufferedImage.TYPE_BYTE_GRAY); if (EXPLICIT_LUMINANCE_CONVERSION) { WritableRaster raster = this.image.getRaster(); int[] buffer = new int[width]; for (int y = top; y < top + height; y++) { image.getRGB(left, y, width, 1, buffer, 0, sourceWidth); for (int x = 0; x < width; x++) { int pixel = buffer[x]; // see comments in implicit branch if ((pixel & 0xFF000000) == 0) { pixel = 0xFFFFFFFF; // = white } // .229R + 0.587G + 0.114B (YUV/YIQ for PAL and NTSC) buffer[x] = (306 * ((pixel >> 16) & 0xFF) + 601 * ((pixel >> 8) & 0xFF) + 117 * (pixel & 0xFF) + 0x200) >> 10; } raster.setPixels(left, y, width, 1, buffer); } } else { // The color of fully-transparent pixels is irrelevant. They are often, technically, fully-transparent // black (0 alpha, and then 0 RGB). They are often used, of course as the "white" area in a // barcode image. Force any such pixel to be white: if (image.getAlphaRaster() != null) { int[] buffer = new int[width]; for (int y = top; y < top + height; y++) { image.getRGB(left, y, width, 1, buffer, 0, sourceWidth); boolean rowChanged = false; for (int x = 0; x < width; x++) { if ((buffer[x] & 0xFF000000) == 0) { buffer[x] = 0xFFFFFFFF; // = white rowChanged = true; } } if (rowChanged) { image.setRGB(left, y, width, 1, buffer, 0, sourceWidth); } } } // Create a grayscale copy, no need to calculate the luminance manually this.image.getGraphics().drawImage(image, 0, 0, null); } } this.left = left; this.top = top; } @Override public byte[] getRow(int y, byte[] row) { if (y < 0 || y >= getHeight()) { throw new IllegalArgumentException("Requested row is outside the image: " + y); } int width = getWidth(); if (row == null || row.length < width) { row = new byte[width]; } // The underlying raster of image consists of bytes with the luminance values image.getRaster().getDataElements(left, top + y, width, 1, row); return row; } @Override public byte[] getMatrix() { int width = getWidth(); int height = getHeight(); int area = width * height; byte[] matrix = new byte[area]; // The underlying raster of image consists of area bytes with the luminance values image.getRaster().getDataElements(left, top, width, height, matrix); return matrix; } @Override public boolean isCropSupported() { return true; } @Override public LuminanceSource crop(int left, int top, int width, int height) { return new BufferedImageLuminanceSource(image, this.left + left, this.top + top, width, height); } /** * This is always true, since the image is a gray-scale image. * * @return true */ @Override public boolean isRotateSupported() { return true; } @Override public LuminanceSource rotateCounterClockwise() { int sourceWidth = image.getWidth(); int sourceHeight = image.getHeight(); // Rotate 90 degrees counterclockwise. AffineTransform transform = new AffineTransform(0.0, -1.0, 1.0, 0.0, 0.0, sourceWidth); // Note width/height are flipped since we are rotating 90 degrees. BufferedImage rotatedImage = new BufferedImage(sourceHeight, sourceWidth, BufferedImage.TYPE_BYTE_GRAY); // Draw the original image into rotated, via transformation Graphics2D g = rotatedImage.createGraphics(); g.drawImage(image, transform, null); g.dispose(); // Maintain the cropped region, but rotate it too. int width = getWidth(); return new BufferedImageLuminanceSource(rotatedImage, top, sourceWidth - (left + width), getHeight(), width); } @Override public LuminanceSource rotateCounterClockwise45() { int width = getWidth(); int height = getHeight(); int oldCenterX = left + width / 2; int oldCenterY = top + height / 2; // Rotate 45 degrees counterclockwise. AffineTransform transform = AffineTransform.getRotateInstance(MINUS_45_IN_RADIANS, oldCenterX, oldCenterY); int sourceDimension = Math.max(image.getWidth(), image.getHeight()); BufferedImage rotatedImage = new BufferedImage(sourceDimension, sourceDimension, BufferedImage.TYPE_BYTE_GRAY); // Draw the original image into rotated, via transformation Graphics2D g = rotatedImage.createGraphics(); g.drawImage(image, transform, null); g.dispose(); int halfDimension = Math.max(width, height) / 2; int newLeft = Math.max(0, oldCenterX - halfDimension); int newTop = Math.max(0, oldCenterY - halfDimension); int newRight = Math.min(sourceDimension - 1, oldCenterX + halfDimension); int newBottom = Math.min(sourceDimension - 1, oldCenterY + halfDimension); return new BufferedImageLuminanceSource(rotatedImage, newLeft, newTop, newRight - newLeft, newBottom - newTop); } }