当我读取从相机拍摄的照片时，会出现透视图像问题。当方向为北时，图片看起来需要旋转270度。当方向为东方时，图片应旋转180度。但是当方向是西方时，它是好的。我在EncodedImage中尝试了getMetaData()。getKeyValue("orientation")来生成一个好的旋转公式，但它返回了空字符串。请帮我解决这个问题。
答案 0 :(得分：3)
在此找到解决方案： https://gist.github.com/3788313
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import javax.microedition.io.Connector;
import javax.microedition.io.file.FileConnection;
import net.rim.device.api.system.Bitmap;
import net.rim.device.api.system.EncodedImage;
public class ExifRotate {
/**
* Flip the image horizontally.
*/
public static final int FLIP_H = 1;
/**
* Flip the image vertically.
*/
public static final int FLIP_V = 2;
/**
* Flip the image horizontally and vertically.
*/
public static final int FLIP_HV = 3;
/**
* Rotate the image 90 degrees clockwise.
*/
public static final int FLIP_90CW = 4;
/**
* Rotate the image 90 degrees counter-clockwise.
*/
public static final int FLIP_90CCW = 5;
/**
* Rotate the image 180 degrees.
*/
public static final int FLIP_180 = 6;
private final static int read2bytes(InputStream in) throws IOException {
return in.read() << 8 | in.read();
}
private final static int readByte(InputStream in) throws IOException {
return in.read();
}
public static Bitmap readImageFromFile(String filename, int width, int height) throws IOException {
EncodedImage img = null;
byte[] data = null;
FileConnection file = null;
try {
file = (FileConnection) Connector.open(filename, Connector.READ);
int fileSize = (int) file.fileSize();
if (fileSize == 0) {
throw new IOException("File is empty");
}
data = new byte[fileSize];
InputStream input = file.openInputStream();
input.read(data);
input.close();
img = EncodedImage.createEncodedImage(data, 0, data.length);
int orientation = -1;
if ( filename.toLowerCase().endsWith(".jpg") || filename.toLowerCase().endsWith(".jpeg")) {
ByteArrayInputStream is = new ByteArrayInputStream( data );
orientation = getRotation(is);
}
if ( orientation == 2 ) {
return rotateBitmap(img.getBitmap(), ImageUtil.FLIP_H);
} else if ( orientation == 3 ) {
return rotateBitmap(img.getBitmap(), ImageUtil.FLIP_180);
} else if ( orientation == 4 ) {
return rotateBitmap(img.getBitmap(), ImageUtil.FLIP_V);
} else if ( orientation == 5 ) {
Bitmap tmp = rotateBitmap(img.getBitmap(), ImageUtil.FLIP_H);
tmp = rotateBitmap(tmp, ImageUtil.FLIP_90CCW);
return tmp;
} else if ( orientation == 6 ) {
return rotateBitmap(img.getBitmap(), ImageUtil.FLIP_90CW);
} else if ( orientation == 7 ) {
Bitmap tmp = rotateBitmap(img.getBitmap(), ImageUtil.FLIP_H);
tmp = rotateBitmap(tmp, ImageUtil.FLIP_90CW);
return tmp;
} else if ( orientation == 8 ) {
return rotateBitmap(img.getBitmap(), ImageUtil.FLIP_90CCW);
} else {
return img.getBitmap();
}
} finally {
if (file != null) {
try { file.close(); }
catch(Exception ex){}
}
}
}
public static int getRotation(InputStream in) throws IOException {
int [] exif_data = new int[100];
int n_flag = 0, set_flag = 0;
int is_motorola = 0;
/* Read File head, check for JPEG SOI + Exif APP1 */
for (int i = 0; i < 4; i++)
exif_data[i] = readByte(in);
if (exif_data[0] != 0xFF || exif_data[1] != 0xD8 || exif_data[2] != 0xFF || exif_data[3] != 0xE1)
return -2;
/* Get the marker parameter length count */
int length = read2bytes(in);
// exif_data = new int[length];
/* Length includes itself, so must be at least 2 */
/* Following Exif data length must be at least 6 */
if (length < 8)
return -1;
length -= 8;
/* Read Exif head, check for "Exif" */
for (int i = 0; i < 6; i++)
exif_data[i] = in.read();
if (exif_data[0] != 0x45 || exif_data[1] != 0x78 || exif_data[2] != 0x69 || exif_data[3] != 0x66 || exif_data[4] != 0 || exif_data[5] != 0)
return -1;
/* Read Exif body */
length = length > exif_data.length ? exif_data.length : length;
for (int i = 0; i < length; i++)
exif_data[i] = in.read();
if (length < 12)
return -1; /* Length of an IFD entry */
/* Discover byte order */
if (exif_data[0] == 0x49 && exif_data[1] == 0x49)
is_motorola = 0;
else if (exif_data[0] == 0x4D && exif_data[1] == 0x4D)
is_motorola = 1;
else
return -1;
/* Check Tag Mark */
if (is_motorola == 1) {
if (exif_data[2] != 0)
return -1;
if (exif_data[3] != 0x2A)
return -1;
} else {
if (exif_data[3] != 0)
return -1;
if (exif_data[2] != 0x2A)
return -1;
}
/* Get first IFD offset (offset to IFD0) */
int offset;
if (is_motorola == 1) {
if (exif_data[4] != 0)
return -1;
if (exif_data[5] != 0)
return -1;
offset = exif_data[6];
offset <<= 8;
offset += exif_data[7];
} else {
if (exif_data[7] != 0)
return -1;
if (exif_data[6] != 0)
return -1;
offset = exif_data[5];
offset <<= 8;
offset += exif_data[4];
}
if (offset > length - 2)
return -1; /* check end of data segment */
/* Get the number of directory entries contained in this IFD */
int number_of_tags;
if (is_motorola == 1) {
number_of_tags = exif_data[offset];
number_of_tags <<= 8;
number_of_tags += exif_data[offset + 1];
} else {
number_of_tags = exif_data[offset + 1];
number_of_tags <<= 8;
number_of_tags += exif_data[offset];
}
if (number_of_tags == 0)
return -1;
offset += 2;
/* Search for Orientation Tag in IFD0 */
for (;;) {
if (offset > length - 12)
return -1; /* check end of data segment */
/* Get Tag number */
int tagnum;
if (is_motorola == 1) {
tagnum = exif_data[offset];
tagnum <<= 8;
tagnum += exif_data[offset + 1];
} else {
tagnum = exif_data[offset + 1];
tagnum <<= 8;
tagnum += exif_data[offset];
}
if (tagnum == 0x0112)
break; /* found Orientation Tag */
if (--number_of_tags == 0)
return -1;
offset += 12;
}
/*
* if (set_flag==1) { Set the Orientation value if (is_motorola==1) {
* exif_data[offset+2] = 0; Format = unsigned short (2 octets)
* exif_data[offset+3] = 3; exif_data[offset+4] = 0; Number Of
* Components = 1 exif_data[offset+5] = 0; exif_data[offset+6] = 0;
* exif_data[offset+7] = 1; exif_data[offset+8] = 0; exif_data[offset+9]
* = set_flag; exif_data[offset+10] = 0; exif_data[offset+11] = 0; }
* else { exif_data[offset+2] = 3; Format = unsigned short (2 octets)
* exif_data[offset+3] = 0; exif_data[offset+4] = 1; Number Of
* Components = 1 exif_data[offset+5] = 0; exif_data[offset+6] = 0;
* exif_data[offset+7] = 0; exif_data[offset+8] = set_flag;
* exif_data[offset+9] = 0; exif_data[offset+10] = 0;
* exif_data[offset+11] = 0; } }
*/
// else {
/* Get the Orientation value */
if (is_motorola == 1) {
if (exif_data[offset + 8] != 0)
return -1;
set_flag = exif_data[offset + 9];
} else {
if (exif_data[offset + 9] != 0)
return -1;
set_flag = exif_data[offset + 8];
}
if (set_flag > 8)
return -1;
// }
/* Write out Orientation value */
if (n_flag == 1)
System.out.println("set_flag " + set_flag);
else
System.out.println("set_flag " + set_flag);
return set_flag;
}
public static Bitmap rotateBitmap(Bitmap src, int operation) {
int width = src.getWidth();
int height = src.getHeight();
int[] inPixels = new int[width*height];
src.getARGB(inPixels, 0, width, 0, 0, width, height);
int x = 0, y = 0;
int w = width;
int h = height;
int newX = 0;
int newY = 0;
int newW = w;
int newH = h;
switch (operation) {
case FLIP_H:
newX = width - (x + w);
break;
case FLIP_V:
newY = height - (y + h);
break;
case FLIP_HV:
newW = h;
newH = w;
newX = y;
newY = x;
break;
case FLIP_90CW:
newW = h;
newH = w;
newX = height - (y + h);
newY = x;
break;
case FLIP_90CCW:
newW = h;
newH = w;
newX = y;
newY = width - (x + w);
break;
case FLIP_180:
newX = width - (x + w);
newY = height - (y + h);
break;
}
int[] newPixels = new int[newW * newH];
int index, newRow, newCol, newIndex;
if ( operation == FLIP_H ) {
for (int row = 0; row < h; row++) {
for (int col = 0; col < w; col++) {
index = row * width + col;
newRow = row;
newCol = w - col - 1;
newIndex = newRow * newW + newCol;
newPixels[newIndex] = inPixels[index];
}
}
} else if ( operation == FLIP_V ) {
for (int row = 0; row < h; row++) {
for (int col = 0; col < w; col++) {
index = row * width + col;
newRow = h - row - 1;
newCol = col;
newIndex = newRow * newW + newCol;
newPixels[newIndex] = inPixels[index];
}
}
} else if ( operation == FLIP_HV ) {
for (int row = 0; row < h; row++) {
for (int col = 0; col < w; col++) {
index = row * width + col;
newRow = col;
newCol = row;
newIndex = newRow * newW + newCol;
newPixels[newIndex] = inPixels[index];
}
}
} else if ( operation == FLIP_90CW ) {
for (int row = 0; row < h; row++) {
for (int col = 0; col < w; col++) {
index = row * width + col;
newRow = col;
newCol = h - row - 1;
newIndex = newRow * newW + newCol;
newPixels[newIndex] = inPixels[index];
}
}
} else if ( operation == FLIP_90CCW ) {
for (int row = 0; row < h; row++) {
for (int col = 0; col < w; col++) {
index = row * width + col;
newRow = w - col - 1;
newCol = row;
newIndex = newRow * newW + newCol;
newPixels[newIndex] = inPixels[index];
}
}
} else if ( operation == FLIP_180 ) {
for (int row = 0; row < h; row++) {
for (int col = 0; col < w; col++) {
index = row * width + col;
newRow = h - row - 1;
newCol = w - col - 1;
newIndex = newRow * newW + newCol;
newPixels[newIndex] = inPixels[index];
}
}
}
Bitmap dst = new Bitmap( newW, newH );
dst.setARGB(newPixels, 0, newW, 0, 0, newW, newH);
return dst;
}
}