Android 图片操作（Bitmap）

/** * 将多个Bitmap合并成一个图片。 *  * @param int 将多个图合成多少列 * @param Bitmap... 要合成的图片 * @return */public static Bitmap combineBitmaps(int columns, Bitmap... bitmaps) {if (columns <= 0 || bitmaps == null || bitmaps.length == 0) {throw new IllegalArgumentException("Wrong parameters: columns must > 0 and bitmaps.length must > 0.");}int maxWidthPerImage = 0;int maxHeightPerImage = 0;for (Bitmap b : bitmaps) {maxWidthPerImage = maxWidthPerImage > b.getWidth() ? maxWidthPerImage : b.getWidth();maxHeightPerImage = maxHeightPerImage > b.getHeight() ? maxHeightPerImage : b.getHeight();}int rows = 0;if (columns >= bitmaps.length) {rows = 1;columns = bitmaps.length;} else {rows = bitmaps.length % columns == 0 ? bitmaps.length / columns : bitmaps.length / columns + 1;}Bitmap newBitmap = Bitmap.createBitmap(columns * maxWidthPerImage, rows * maxHeightPerImage, Config.RGB_565);for (int x = 0; x < rows; x++) {for (int y = 0; y < columns; y++) {int index = x * columns + y;if (index >= bitmaps.length)break;newBitmap = mixtureBitmap(newBitmap, bitmaps[index], new PointF(y * maxWidthPerImage, x * maxHeightPerImage));}}return newBitmap;}

/** * Mix two Bitmap as one. *  * @param bitmapOne * @param bitmapTwo * @param point *            where the second bitmap is painted. * @return */public static Bitmap mixtureBitmap(Bitmap first, Bitmap second, PointF fromPoint) {if (first == null || second == null || fromPoint == null) {return null;}Bitmap newBitmap = Bitmap.createBitmap(first.getWidth(), first.getHeight(), Config.ARGB_4444);Canvas cv = new Canvas(newBitmap);cv.drawBitmap(first, 0, 0, null);cv.drawBitmap(second, fromPoint.x, fromPoint.y, null);cv.save(Canvas.ALL_SAVE_FLAG);cv.restore();return newBitmap;}

//截屏public static Bitmap getScreenshotsForCurrentWindow(Activity activity) {View cv = activity.getWindow().getDecorView();Bitmap bmp = Bitmap.createBitmap(cv.getWidth(), cv.getHeight(), Bitmap.Config.ARGB_4444);cv.draw(new Canvas(bmp));return bmp;}

//旋转图片// Rotates the bitmap by the specified degree.// If a new bitmap is created, the original bitmap is recycled.public static Bitmap rotate(Bitmap b, int degrees) {if (degrees != 0 && b != null) {Matrix m = new Matrix();m.setRotate(degrees, (float) b.getWidth() / 2, (float) b.getHeight() / 2);try {b = Bitmap.createBitmap(b, 0, 0, b.getWidth(), b.getHeight(), m, true); if (b != b2) { b.recycle(); b = b2; }} catch (OutOfMemoryError ex) {// We have no memory to rotate. Return the original bitmap.}}return b;}

//可用于生成缩略图。/** * Creates a centered bitmap of the desired size. Recycles the input. *  * @param source */public static Bitmap extractMiniThumb(Bitmap source, int width, int height) {return extractMiniThumb(source, width, height, true);}public static Bitmap extractMiniThumb(Bitmap source, int width, int height, boolean recycle) {if (source == null) {return null;}float scale;if (source.getWidth() < source.getHeight()) {scale = width / (float) source.getWidth();} else {scale = height / (float) source.getHeight();}Matrix matrix = new Matrix();matrix.setScale(scale, scale);Bitmap miniThumbnail = transform(matrix, source, width, height, false);if (recycle && miniThumbnail != source) {source.recycle();}return miniThumbnail;}public static Bitmap transform(Matrix scaler, Bitmap source, int targetWidth, int targetHeight, boolean scaleUp) {int deltaX = source.getWidth() - targetWidth;int deltaY = source.getHeight() - targetHeight;if (!scaleUp && (deltaX < 0 || deltaY < 0)) {/* * In this case the bitmap is smaller, at least in one dimension, * than the target. Transform it by placing as much of the image as * possible into the target and leaving the top/bottom or left/right * (or both) black. */Bitmap b2 = Bitmap.createBitmap(targetWidth, targetHeight, Bitmap.Config.ARGB_8888);Canvas c = new Canvas(b2);int deltaXHalf = Math.max(0, deltaX / 2);int deltaYHalf = Math.max(0, deltaY / 2);Rect src = new Rect(deltaXHalf, deltaYHalf, deltaXHalf + Math.min(targetWidth, source.getWidth()), deltaYHalf+ Math.min(targetHeight, source.getHeight()));int dstX = (targetWidth - src.width()) / 2;int dstY = (targetHeight - src.height()) / 2;Rect dst = new Rect(dstX, dstY, targetWidth - dstX, targetHeight - dstY);c.drawBitmap(source, src, dst, null);return b2;}float bitmapWidthF = source.getWidth();float bitmapHeightF = source.getHeight();float bitmapAspect = bitmapWidthF / bitmapHeightF;float viewAspect = (float) targetWidth / targetHeight;if (bitmapAspect > viewAspect) {float scale = targetHeight / bitmapHeightF;if (scale < .9F || scale > 1F) {scaler.setScale(scale, scale);} else {scaler = null;}} else {float scale = targetWidth / bitmapWidthF;if (scale < .9F || scale > 1F) {scaler.setScale(scale, scale);} else {scaler = null;}}Bitmap b1;if (scaler != null) {// this is used for minithumb and crop, so we want to filter here.b1 = Bitmap.createBitmap(source, 0, 0, source.getWidth(), source.getHeight(), scaler, true);} else {b1 = source;}int dx1 = Math.max(0, b1.getWidth() - targetWidth);int dy1 = Math.max(0, b1.getHeight() - targetHeight);Bitmap b2 = Bitmap.createBitmap(b1, dx1 / 2, dy1 / 2, targetWidth, targetHeight);if (b1 != source) {b1.recycle();}return b2;}

//图片剪切public static Bitmap cutBitmap(Bitmap mBitmap, Rect r, Bitmap.Config config) {int width = r.width();int height = r.height();Bitmap croppedImage = Bitmap.createBitmap(width, height, config);Canvas cvs = new Canvas(croppedImage);Rect dr = new Rect(0, 0, width, height);cvs.drawBitmap(mBitmap, r, dr, null);return croppedImage;}

//从任一Drawable得到Bitmappublic static Bitmap drawableToBitmap(Drawable drawable) {Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), Bitmap.Config.RGB_565);Canvas canvas = new Canvas(bitmap);drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());drawable.draw(canvas);return bitmap;}

/** * Save Bitmap to a file.保存图片到SD卡。 *  * @param bitmap * @param file * @return error message if the saving is failed. null if the saving is *         successful. * @throws IOException */public static void saveBitmapToFile(Bitmap bitmap, String _file) throws IOException {BufferedOutputStream os = null;try {File file = new File(_file);// String _filePath_file.replace(File.separatorChar +// file.getName(), "");int end = _file.lastIndexOf(File.separator);String _filePath = _file.substring(0, end);File filePath = new File(_filePath);if (!filePath.exists()) {filePath.mkdirs();}file.createNewFile();os = new BufferedOutputStream(new FileOutputStream(file));bitmap.compress(Bitmap.CompressFormat.PNG, 100, os);} finally {if (os != null) {try {os.close();} catch (IOException e) {Log.e(TAG_ERROR, e.getMessage(), e);}}}}