android中图片的处理（绘制圆形，圆角||缩略图）

/**
* 圆角处理
*
* @param bitmap
*            原图
* @param roundPx
*            角度
* @return
*/
public static Bitmap getCornerBitmap(Bitmap bitmap, float roundPx) {
if (bitmap == null)
return null;
// todo：to prevent memory overflow, suspend the processing of fillet
// 创建一个指定宽度和高度的空位图对象
Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
bitmap.getHeight(), Config.ARGB_8888);
// 用该位图创建画布
Canvas canvas = new Canvas(output);
// 画笔对象
final Paint paint = new Paint();
// 画笔的颜色
final int color = 0xff424242;
// 矩形区域对象
final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
// 未知
final RectF rectF = new RectF(rect);
// 拐角的半径
roundPx = roundPx == 0 ? (bitmap.getWidth() + bitmap.getHeight()) / 4
: roundPx;
// 消除锯齿
paint.setAntiAlias(true);
// 画布背景色
canvas.drawARGB(0, 0, 0, 0);
// 设置画笔颜色
paint.setColor(color);
// 绘制圆角矩形
canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
// 未知
paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
// 把该图片绘制在该圆角矩形区域中
canvas.drawBitmap(bitmap, rect, rect, paint);
// 最终在画布上呈现的就是该圆角矩形图片，然后我们返回该Bitmap对象
return output;
}

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/**
* 圆形处理
*
* @param bitmap
*            原图
* @return
*/
public static Bitmap getRoundBitmap(Bitmap bitmap) {
int width = bitmap.getWidth();
int height = bitmap.getHeight();
float roundPx;
float left, top, right, bottom, dst_left, dst_top, dst_right, dst_bottom;
if (width <= height) {
roundPx = width / 2;

left = 0;
top = 0;
right = width;
bottom = width;

height = width;

dst_left = 0;
dst_top = 0;
dst_right = width;
dst_bottom = width;
} else {
roundPx = height / 2;

float clip = (width - height) / 2;

left = clip;
right = width - clip;
top = 0;
bottom = height;
width = height;

dst_left = 0;
dst_top = 0;
dst_right = height;
dst_bottom = height;
}

Bitmap output = Bitmap.createBitmap(width, height, Config.ARGB_8888);
Canvas canvas = new Canvas(output);

final Paint paint = new Paint();
final Rect src = new Rect((int) left, (int) top, (int) right, (int) bottom);
final Rect dst = new Rect((int) dst_left, (int) dst_top, (int) dst_right, (int) dst_bottom);
final RectF rectF = new RectF(dst);

paint.setAntiAlias(true);// 设置画笔无锯齿

canvas.drawARGB(0, 0, 0, 0); // 填充整个Canvas

// 以下有两种方法画圆,drawRounRect和drawCircle
canvas.drawRoundRect(rectF, roundPx, roundPx, paint);// 画圆角矩形，第一个参数为图形显示区域，第二个参数和第三个参数分别是水平圆角半径和垂直圆角半径。
// canvas.drawCircle(roundPx, roundPx, roundPx, paint);

paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));// 设置两张图片相交时的模式,参考http://www.cnblogs.com/rayray/p/3670120.html
canvas.drawBitmap(bitmap, src, dst, paint); // 以Mode.SRC_IN模式合并bitmap和已经draw了的Circle

return output;
}

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/**
* 缩略图
*
* @param bitmap
*            原图
* @param thumbnailWidth
*            压缩宽
* @param thumbnailHeight
*            压缩高
* @return
*/
public static final Bitmap cropBitmap(final Bitmap bitmap,
final int thumbnailWidth, final int thumbnailHeight) {
if (bitmap == null)
return null;
final int width = bitmap.getWidth();
final int height = bitmap.getHeight();
int focusX = width / 2;
int focusY = height / 2;
int cropX;
int cropY;
int cropWidth;
int cropHeight;
float scaleFactor;
if (thumbnailWidth * height < thumbnailHeight * width) {
// Vertically constrained.
cropWidth = thumbnailWidth * height / thumbnailHeight;
cropX = Math.max(0,
Math.min(focusX - cropWidth / 2, width - cropWidth));
cropY = 0;
cropHeight = height;
scaleFactor = (float) thumbnailHeight / height;
} else {
// Horizontally constrained.
cropHeight = thumbnailHeight * width / thumbnailWidth;
cropY = Math.max(0,
Math.min(focusY - cropHeight / 2, height - cropHeight));
cropX = 0;
cropWidth = width;
scaleFactor = (float) thumbnailWidth / width;
}
final Bitmap finalBitmap = Bitmap.createBitmap(thumbnailWidth,
thumbnailHeight, Bitmap.Config.RGB_565);
final Canvas canvas = new Canvas(finalBitmap);
final Paint paint = new Paint();
paint.setDither(true);
paint.setFilterBitmap(true);
canvas.drawColor(0);
canvas.drawBitmap(bitmap, new Rect(cropX, cropY, cropX + cropWidth,
cropY + cropHeight), new Rect(0, 0, thumbnailWidth,
thumbnailHeight), paint);
bitmap.recycle();

// Store (long thumbnailId, short focusX, short focusY, JPEG data).
final ByteArrayOutputStream cacheOutput = new ByteArrayOutputStream(
16384);
final DataOutputStream dataOutput = new DataOutputStream(cacheOutput);
// byte[] retVal = null;
try {
dataOutput.writeShort((int) ((focusX - cropX) * scaleFactor));
dataOutput.writeShort((int) ((focusY - cropY) * scaleFactor));
dataOutput.flush();
finalBitmap.compress(Bitmap.CompressFormat.JPEG, 80, cacheOutput);
// retVal = cacheOutput.toByteArray();
cacheOutput.close();
// finalBitmap.recycle();
} catch (Exception e) {
;
}
return finalBitmap;
}