J2ME 中Image的操作很多，如：图片的存储，图片的缩放，图片的翻转等。
这里做一下小节!
1,
图片的存储，在实际的开发中，经常会遇到这样的问题，我们想把图片保存到rm中。方法肯定是将Image对象转化成imageByte[]再存储到
rms,到需要使用的时候再读出来，使用
Image.createImage(imageByte, 0, imageByte.length);
2,图片缩放：
直接按缩放的倍数：
/**
* 图片缩放
* @param src Image
* @param scales1 int
* @param scales2 int
* @return Image
*/
public Image scaleImage(Image src, int scales1, int scales2) {
return transImage(src, src.getWidth() * scales1 / scales2,
src.getHeight() * scales1 / scales2);
}
/**
* 图片参数设置
* @param src Image
* @param w int
* @param h int
* @return Image
*/
public Image transImage(Image src, int w, int h) {
int srcW = src.getWidth();
int srcH = src.getHeight();
int dstW = w, dstH = h;
Image tmp = Image.createImage(dstW, srcH);
Graphics g = tmp.getGraphics();
int scale = 16;
int delta = (srcW << scale) / dstW; //扫描长度
int pos = delta / 2; //扫描位置
for (int x = 0; x < dstW; x++) {
g.setClip(x, 0, 1, srcH);
g.drawImage(src, x - (pos >> scale), 0,
Graphics.LEFT | Graphics.TOP);
pos += delta;
}
Image newImage = Image.createImage(dstW, dstH);
g = newImage.getGraphics();
delta = (srcH << scale) / dstH;
pos = delta / 2;
for (int y = 0; y < dstH; y++) {
g.setClip(0, y, dstW, 1);
g.drawImage(tmp, 0, y - (pos >> scale),
Graphics.LEFT | Graphics.TOP);
pos += delta;
}
return newImage;
}
直接按图片的长宽实现缩放：
/**
* 按长宽实现缩放
* @param srcImage Image
* @param newW int
* @param newH int
* @return Image
*/
public Image scale(Image srcImage, int newW, int newH) {
int srcW = srcImage.getWidth();
int srcH = srcImage.getHeight();
//先做水平方向上的伸缩变换
Image tmp = Image.createImage(newW, srcH);
Graphics g = tmp.getGraphics();
for (int x = 0; x < newW; x++) {
g.setClip(x, 0, 1, srcH);
//按比例放缩
g.drawImage(srcImage, x - x * srcW / newW, 0,
Graphics.LEFT | Graphics.TOP);
}
//再做垂直方向上的伸缩变换
Image newImage = Image.createImage(newW, newH);
g = newImage.getGraphics();
for (int y = 0; y < newH; y++) {
g.setClip(0, y, newW, 1);
//按比例放缩
g.drawImage(tmp, 0, y - y * srcH / newH,
Graphics.LEFT | Graphics.TOP);
}
return newImage;
}
3，图片的翻转：
private static final int LEFT_RIGHT = 0;
private static final int UP_DOWN = 1;
private static final int HAIF_TURN = 2;
/**
* 图片的翻转初始化
* @param g1 Graphics
* @param image Image
* @param x int
* @param y int
* @param type int
*/
public void drawTransImage(Graphics g1, Image image, int x, int y,
int type) {
if (type == LEFT_RIGHT) { //左右翻转
for (int i = 0; i < image.getWidth(); i++) {
drawClipImage(g1, image, x + i, y, 1, image.getHeight(),
image.getWidth() - i, 0);
}
} else if (type == UP_DOWN) { //上下翻转
for (int i = 0; i < image.getHeight(); i++) {
drawClipImage(g1, image, x, y + i, image.getWidth(), 1, 0,
image.getHeight() - i);
}
} else if (type == HAIF_TURN) { //180度翻转
for (int i = 0; i < image.getWidth(); i++) {
for (int j = 0; j < image.getHeight(); j++) {
drawClipImage(g1, image, x + i, y + i, 1, 1,
image.getWidth() - i,
image.getHeight() - i);
}
}
}
}
/**
* 画图片
* @param g Graphics
* @param a Image
* @param clipx int
* @param clipy int
* @param clipw int
* @param cliph int
* @param offx int
* @param offy int
*/
public void drawClipImage(Graphics g, Image a, int clipx, int clipy,
int clipw, int cliph, int offx, int offy) {
int x, y, w, h;
x = g.getClipX();
y = g.getClipY();
w = g.getClipWidth();
h = g.getClipHeight();
g.setClip(clipx, clipy, clipw, cliph);
g.drawImage(a, clipx - offx, clipy - offy, 0);
g.setClip(x, y, w, h);
}
4，图片Image转换byte[]
/** * PngEncoder takes a Java Image object and creates a byte string which can
be saved as a PNG file. * The Image is presumed to use the DirectColorModel. * * Thanks to Jay Denny at KeyPoint Software * http://www.keypoint.com/ * who let me develop this code on company time. * * You may contact me with (probably very-much-needed) improvements, * comments, and bug fixes at: * * david@catcode.com * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * A copy of the GNU LGPL may be found at * http://www.gnu.org/copyleft/lesser.html, * * @author J. David Eisenberg * @version 1.4, 31 March 2000 */ import java.awt.*; import java.awt.image.*; import java.util.*; import java.util.zip.*; import java.io.*; public class PngEncoder extends Object { /** Constant specifying that alpha channel should be encoded. */ public static final boolean ENCODE_ALPHA = true; /** Constant specifying that alpha channel should not be encoded. */ public static final boolean NO_ALPHA = false; /** Constants for filters */ public static final int FILTER_NONE = 0; public static final int FILTER_SUB = 1; public static final int FILTER_UP = 2; public static final int FILTER_LAST = 2; protected byte[] pngBytes; protected byte[] priorRow; protected byte[] leftBytes; protected Image image; protected int width, height; protected int bytePos, maxPos; protected int hdrPos, dataPos, endPos; protected CRC32 crc = new CRC32(); protected long crcValue; protected boolean encodeAlpha; protected int filter; protected int bytesPerPixel; protected int compressionLevel; /** * Class constructor * */ public PngEncoder() { this(null, false, FILTER_NONE, 0); } /** * Class constructor specifying Image to encode, with no alpha channel encoding. * * @param image A Java Image object which uses the DirectColorModel * @see java.awt.Image */ public PngEncoder(Image image) { this(image, false, FILTER_NONE, 0); } /** * Class constructor specifying Image to encode, and whether to encode alpha. * * @param image A Java Image object which uses the DirectColorModel * @param encodeAlpha Encode the alpha channel? false=no; true=yes * @see java.awt.Image */ public PngEncoder(Image image, boolean encodeAlpha) { this(image, encodeAlpha, FILTER_NONE, 0); } /** * Class constructor specifying Image to encode, whether to encode alpha,
and filter to use. * * @param image A Java Image object which uses the DirectColorModel * @param encodeAlpha Encode the alpha channel? false=no; true=yes * @param whichFilter 0=none, 1=sub, 2=up * @see java.awt.Image */ public PngEncoder(Image image, boolean encodeAlpha, int whichFilter) { this(image, encodeAlpha, whichFilter, 0); } /** * Class constructor specifying Image source to encode, whether to encode alpha,
filter to use, and compression level. * * @param image A Java Image object * @param encodeAlpha Encode the alpha channel? false=no; true=yes * @param whichFilter 0=none, 1=sub, 2=up * @param compLevel 0..9 * @see java.awt.Image */ public PngEncoder(Image image, boolean encodeAlpha, int whichFilter, int compLevel) { this.image = image; this.encodeAlpha = encodeAlpha; setFilter(whichFilter); if (compLevel >= 0 && compLevel <= 9) { this.compressionLevel = compLevel; } } /** * Set the image to be encoded * * @param image A Java Image object which uses the DirectColorModel * @see java.awt.Image * @see java.awt.image.DirectColorModel */ public void setImage(Image image) { this.image = image; pngBytes = null; } /** * Creates an array of bytes that is the PNG equivalent of the current image,
specifying whether to encode alpha or not. * * @param encodeAlpha boolean false=no alpha, true=encode alpha * @return an array of bytes, or null if there was a problem */ public byte[] pngEncode(boolean encodeAlpha) { byte[] pngIdBytes = { -119, 80, 78, 71, 13, 10, 26, 10}; int i; if (image == null) { return null; } width = image.getWidth(null); height = image.getHeight(null); this.image = image; /* * start with an array that is big enough to hold all the pixels * (plus filter bytes), and an extra 200 bytes for header info */ pngBytes = new byte[((width + 1) * height * 3) + 200]; /* * keep track of largest byte written to the array */ maxPos = 0; bytePos = writeBytes(pngIdBytes, 0); hdrPos = bytePos; writeHeader(); dataPos = bytePos; if (writeImageData()) { writeEnd(); pngBytes = resizeByteArray(pngBytes, maxPos); } else { pngBytes = null; } return pngBytes; } /** * Creates an array of bytes that is the PNG equivalent of the current image. * Alpha encoding is determined by its setting in the constructor. * * @return an array of bytes, or null if there was a problem */ public byte[] pngEncode() { return pngEncode(encodeAlpha); } /** * Set the alpha encoding on or off. * * @param encodeAlpha false=no, true=yes */ public void setEncodeAlpha(boolean encodeAlpha) { this.encodeAlpha = encodeAlpha; } /** * Retrieve alpha encoding status. * * @return boolean false=no, true=yes */ public boolean getEncodeAlpha() { return encodeAlpha; } /** * Set the filter to use * * @param whichFilter from constant list */ public void setFilter(int whichFilter) { this.filter = FILTER_NONE; if (whichFilter <= FILTER_LAST) { this.filter = whichFilter; } } /** * Retrieve filtering scheme * * @return int (see constant list) */ public int getFilter() { return filter; } /** * Set the compression level to use * * @param level 0 through 9 */ public void setCompressionLevel(int level) { if (level >= 0 && level <= 9) { this.compressionLevel = level; } } /** * Retrieve compression level * * @return int in range 0-9 */ public int getCompressionLevel() { return compressionLevel; } /** * Increase or decrease the length of a byte array. * * @param array The original array. * @param newLength The length you wish the new array to have. * @return Array of newly desired length. If shorter than the * original, the trailing elements are truncated. */ protected byte[] resizeByteArray(byte[] array, int newLength) { byte[] newArray = new byte[newLength]; int oldLength = array.length; System.arraycopy(array, 0, newArray, 0, Math.min(oldLength, newLength)); return newArray; } /** * Write an array of bytes into the pngBytes array. * Note: This routine has the side effect of updating * maxPos, the largest element written in the array. * The array is resized by 1000 bytes or the length * of the data to be written, whichever is larger. * * @param data The data to be written into pngBytes. * @param offset The starting point to write to. * @return The next place to be written to in the pngBytes array. */ protected int writeBytes(byte[] data, int offset) { maxPos = Math.max(maxPos, offset + data.length); if (data.length + offset > pngBytes.length) { pngBytes = resizeByteArray(pngBytes, pngBytes.length + Math.max(1000, data.length)); } System.arraycopy(data, 0, pngBytes, offset, data.length); return offset + data.length; } /** * Write an array of bytes into the pngBytes array, specifying number of bytes to write. * Note: This routine has the side effect of updating * maxPos, the largest element written in the array. * The array is resized by 1000 bytes or the length * of the data to be written, whichever is larger. * * @param data The data to be written into pngBytes. * @param nBytes The number of bytes to be written. * @param offset The starting point to write to. * @return The next place to be written to in the pngBytes array. */ protected int writeBytes(byte[] data, int nBytes, int offset) { maxPos = Math.max(maxPos, offset + nBytes); if (nBytes + offset > pngBytes.length) { pngBytes = resizeByteArray(pngBytes, pngBytes.length + Math.max(1000, nBytes)); } System.arraycopy(data, 0, pngBytes, offset, nBytes); return offset + nBytes; } /** * Write a two-byte integer into the pngBytes array at a given position. * * @param n The integer to be written into pngBytes. * @param offset The starting point to write to. * @return The next place to be written to in the pngBytes array. */ protected int writeInt2(int n, int offset) { byte[] temp = {(byte) ((n >> 8) & 0xff), (byte) (n & 0xff)}; return writeBytes(temp, offset); } /** * Write a four-byte integer into the pngBytes array at a given position. * * @param n The integer to be written into pngBytes. * @param offset The starting point to write to. * @return The next place to be written to in the pngBytes array. */ protected int writeInt4(int n, int offset) { byte[] temp = {(byte) ((n >> 24) & 0xff), (byte) ((n >> 16) & 0xff), (byte) ((n >> 8) & 0xff), (byte) (n & 0xff)}; return writeBytes(temp, offset); } /** * Write a single byte into the pngBytes array at a given position. * * @param n The integer to be written into pngBytes. * @param offset The starting point to write to. * @return The next place to be written to in the pngBytes array. */ protected int writeByte(int b, int offset) { byte[] temp = {(byte) b}; return writeBytes(temp, offset); } /** * Write a string into the pngBytes array at a given position. * This uses the getBytes method, so the encoding used will * be its default. * * @param n The integer to be written into pngBytes. * @param offset The starting point to write to. * @return The next place to be written to in the pngBytes array. * @see java.lang.String#getBytes() */ protected int writeString(String s, int offset) { return writeBytes(s.getBytes(), offset); } /** * Write a PNG "IHDR" chunk into the pngBytes array. */ protected void writeHeader() { int startPos; startPos = bytePos = writeInt4(13, bytePos); bytePos = writeString("IHDR", bytePos); width = image.getWidth(null); height = image.getHeight(null); bytePos = writeInt4(width, bytePos); bytePos = writeInt4(height, bytePos); bytePos = writeByte(8, bytePos); // bit depth bytePos = writeByte((encodeAlpha) ? 6 : 2, bytePos); // direct model bytePos = writeByte(0, bytePos); // compression method bytePos = writeByte(0, bytePos); // filter method bytePos = writeByte(0, bytePos); // no interlace crc.reset(); crc.update(pngBytes, startPos, bytePos - startPos); crcValue = crc.getValue(); bytePos = writeInt4((int) crcValue, bytePos); } /** * Perform "sub" filtering on the given row. * Uses temporary array leftBytes to store the original values * of the previous pixels. The array is 16 bytes long, which * will easily hold two-byte samples plus two-byte alpha. * * @param pixels The array holding the scan lines being built * @param startPos Starting position within pixels of bytes to be filtered. * @param width Width of a scanline in pixels. */ protected void filterSub(byte[] pixels, int startPos, int width) { int i; int offset = bytesPerPixel; int actualStart = startPos + offset; int nBytes = width * bytesPerPixel; int leftInsert = offset; int leftExtract = 0; byte current_byte; for (i = actualStart; i < startPos + nBytes; i++) { leftBytes[leftInsert] = pixels[i]; pixels[i] = (byte) ((pixels[i] - leftBytes[leftExtract]) % 256); leftInsert = (leftInsert + 1) % 0x0f; leftExtract = (leftExtract + 1) % 0x0f; } } /** * Perform "up" filtering on the given row. * Side effect: refills the prior row with current row * * @param pixels The array holding the scan lines being built * @param startPos Starting position within pixels of bytes to be filtered. * @param width Width of a scanline in pixels. */ protected void filterUp(byte[] pixels, int startPos, int width) { int i, nBytes; byte current_byte; nBytes = width * bytesPerPixel; for (i = 0; i < nBytes; i++) { current_byte = pixels[startPos + i]; pixels[startPos + i] = (byte) ((pixels[startPos + i] - priorRow[i]) % 256); priorRow[i] = current_byte; } } /** * Write the image data into the pngBytes array. * This will write one or more PNG "IDAT" chunks. In order * to conserve memory, this method grabs as many rows as will * fit into 32K bytes, or the whole image; whichever is less. * * * @return true if no errors; false if error grabbing pixels */ protected boolean writeImageData() { int rowsLeft = height; // number of rows remaining to write int startRow = 0; // starting row to process this time through int nRows; // how many rows to grab at a time byte[] scanLines; // the scan lines to be compressed int scanPos; // where we are in the scan lines int startPos; // where this line's actual pixels start (used for filtering) byte[] compressedLines; // the resultant compressed lines int nCompressed; // how big is the compressed area? int depth; // color depth ( handle only 8 or 32 ) PixelGrabber pg; bytesPerPixel = (encodeAlpha) ? 4 : 3; Deflater scrunch = new Deflater(compressionLevel); ByteArrayOutputStream outBytes = new ByteArrayOutputStream(1024); DeflaterOutputStream compBytes = new DeflaterOutputStream(outBytes, scrunch); try { while (rowsLeft > 0) { nRows = Math.min(32767 / (width * (bytesPerPixel + 1)), rowsLeft); // nRows = rowsLeft; int[] pixels = new int[width * nRows]; pg = new PixelGrabber(image, 0, startRow, width, nRows, pixels, 0, width); try { pg.grabPixels(); } catch (Exception e) { System.err.println("interrupted waiting for pixels!"); return false; } if ((pg.getStatus() & ImageObserver.ABORT) != 0) { System.err.println("image fetch aborted or errored"); return false; } /* * Create a data chunk. scanLines adds "nRows" for * the filter bytes. */ scanLines = new byte[width * nRows * bytesPerPixel + nRows]; if (filter == FILTER_SUB) { leftBytes = new byte[16]; } if (filter == FILTER_UP) { priorRow = new byte[width * bytesPerPixel]; } scanPos = 0; startPos = 1; for (int i = 0; i { if (i % width == 0) { scanLines[scanPos++] = (byte) filter; startPos = scanPos; } scanLines[scanPos++] = (byte) ((pixels[i] >> 16) & 0xff); scanLines[scanPos++] = (byte) ((pixels[i] >> 8) & 0xff); scanLines[scanPos++] = (byte) ((pixels[i]) & 0xff); if (encodeAlpha) { scanLines[scanPos++] = (byte) ((pixels[i] >> 24) & 0xff); } if ((i % width == width - 1) && (filter != FILTER_NONE)) { if (filter == FILTER_SUB) { filterSub(scanLines, startPos, width); } if (filter == FILTER_UP) { filterUp(scanLines, startPos, width); } } } /* * Write these lines to the output area */ compBytes.write(scanLines, 0, scanPos); startRow += nRows; rowsLeft -= nRows; } compBytes.close(); /* * Write the compressed bytes */ compressedLines = outBytes.toByteArray(); nCompressed = compressedLines.length; crc.reset(); bytePos = writeInt4(nCompressed, bytePos); bytePos = writeString("IDAT", bytePos); crc.update("IDAT".getBytes()); bytePos = writeBytes(compressedLines, nCompressed, bytePos); crc.update(compressedLines, 0, nCompressed); crcValue = crc.getValue(); bytePos = writeInt4((int) crcValue, bytePos); scrunch.finish(); return true; } catch (IOException e) { System.err.println(e.toString()); return false; } } /** * Write a PNG "IEND" chunk into the pngBytes array. */ protected void writeEnd() { bytePos = writeInt4(0, bytePos); bytePos = writeString("IEND", bytePos); crc.reset(); crc.update("IEND".getBytes()); crcValue = crc.getValue(); bytePos = writeInt4((int) crcValue, bytePos); } }