很实用的图片处理算法
这些天一直为android程序如何压缩图片烦恼，上网找了很多资料，整理了一下，经过测试，都是可用的，
/**
* 压缩图片
* @param bitmap 源图片
* @param width 想要的宽度
* @param height 想要的高度
* @param isAdjust 是否自动调整尺寸, true图片就不会拉伸，false严格按照你的尺寸压缩
* @return Bitmap
*/
public Bitmap reduce(Bitmap bitmap, int width, int height, boolean isAdjust) {
// 如果想要的宽度和高度都比源图片小，就不压缩了，直接返回原图
if (bitmap.getWidth() < width && bitmap.getHeight() < height) {return bitmap;}
// 根据想要的尺寸精确计算压缩比例, 方法详解：public BigDecimal divide(BigDecimal divisor, int scale, int roundingMode);
// scale表示要保留的小数位, roundingMode表示如何处理多余的小数位，BigDecimal.ROUND_DOWN表示自动舍弃
float sx = new BigDecimal(width).divide(new BigDecimal(bitmap.getWidth()), 4, BigDecimal.ROUND_DOWN).floatValue();
float sy = new BigDecimal(height).divide(new BigDecimal(bitmap.getHeight()), 4, BigDecimal.ROUND_DOWN).floatValue();
if (isAdjust) {// 如果想自动调整比例，不至于图片会拉伸
sx = (sx < sy ? sx : sy);sy = sx;// 哪个比例小一点，就用哪个比例
}
Matrix matrix = new Matrix();
matrix.postScale(sx, sy);// 调用api中的方法进行压缩，就大功告成了
return Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
}
旋转图片：
/**
* 旋转图片
* @param bitmap 源图片
* @param angle 旋转角度(90为顺时针旋转,-90为逆时针旋转)
* @return Bitmap
*/
public Bitmap rotate(Bitmap bitmap, float angle) {
Matrix matrix = new Matrix();
matrix.postRotate(angle);
return Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
}
放大或缩小图片：
/**
* 放大或缩小图片
* @param bitmap 源图片
* @param ratio 放大或缩小的倍数，大于1表示放大，小于1表示缩小
* @return Bitmap
*/
public Bitmap zoom(Bitmap bitmap, float ratio) {
if (ratio < 0f) {return bitmap;}
Matrix matrix = new Matrix();
matrix.postScale(ratio, ratio);
return Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
}
在图片上印字：
/**
* 在图片上印字
* @param bitmap 源图片
* @param text 印上去的字
* @param param 字体参数分别为：颜色,大小,是否加粗,起点x,起点y; 比如：{color : 0xFF000000, size : 30, bold : true, x : 20, y : 20}
* @return Bitmap
*/
public Bitmap printWord(Bitmap bitmap, String text, Map<String, Object> param) {
if (ToolUtil.get().isBlank(text) || null == param) {return bitmap;}
Bitmap newBitmap = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(newBitmap);
canvas.drawBitmap(bitmap, 0, 0, null);canvas.save(Canvas.ALL_SAVE_FLAG);canvas.restore();
Paint paint = new Paint();
paint.setColor(null != param.get("color") ? (Integer) param.get("color") : Color.BLACK);
paint.setTextSize(null != param.get("size") ? (Integer) param.get("size") : 20);
paint.setFakeBoldText(null != param.get("bold") ? (Boolean) param.get("bold") : false);
canvas.drawText(text, null != param.get("x") ? (Integer) param.get("x") : 0, null != param.get("y") ? (Integer) param.get("y") : 0, paint);
canvas.save(Canvas.ALL_SAVE_FLAG);canvas.restore();
return newBitmap;
}
创建logo(给图片加水印), ：
/**
* 创建logo(给图片加水印),
* @param bitmaps 原图片和水印图片
* @param left 左边起点坐标
* @param top 顶部起点坐标t
* @return Bitmap
*/
public Bitmap createLogo(Bitmap[] bitmaps, int left, int top) {
Bitmap newBitmap = Bitmap.createBitmap(bitmaps[0].getWidth(), bitmaps[0].getHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(newBitmap);
for (int i = 0; i < bitmaps.length; i++) {
if (i == 0) {
canvas.drawBitmap(bitmaps[0], 0, 0, null);
} else {
canvas.drawBitmap(bitmaps[i], left, top, null);
}
canvas.save(Canvas.ALL_SAVE_FLAG);canvas.restore();
}
return newBitmap;
}
产生一个4位随机数字的图片验证码：
private int width = 140, height = 40, codeLen = 4;
private String checkCode = "";
private Random random = new Random();
/**
* 产生一个4位随机数字的图片验证码
* @return Bitmap
*/
public Bitmap createCode() {
checkCode = "";
String[] chars = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9" };
for (int i = 0; i < codeLen; i++) {checkCode += chars[random.nextInt(chars.length)];}
Bitmap bitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);canvas.drawColor(Color.WHITE);
Paint paint = new Paint();paint.setTextSize(30);paint.setColor(Color.BLUE);
for (int i = 0; i < checkCode.length(); i++) {
paint.setColor(randomColor(1));paint.setFakeBoldText(random.nextBoolean());
float skewX = random.nextInt(11) / 10;
paint.setTextSkewX(random.nextBoolean() ? skewX : -skewX);
int x = width / codeLen * i + random.nextInt(10);
canvas.drawText(String.valueOf(checkCode.charAt(i)), x, 28, paint);
}
for (int i = 0; i < 3; i++) {drawLine(canvas, paint);}
for (int i = 0; i < 255; i++) {drawPoints(canvas, paint);}
canvas.save(Canvas.ALL_SAVE_FLAG);canvas.restore();
return bitmap;
}
/**
* 获得一个随机的颜色
* @param rate
* @return
*/
public int randomColor(int rate) {
int red = random.nextInt(256) / rate, green = random.nextInt(256) / rate, blue = random.nextInt(256) / rate;
return Color.rgb(red, green, blue);
}
/**
* 画随机线条
* @param canvas
* @param paint
*/
public void drawLine(Canvas canvas, Paint paint) {
int startX = random.nextInt(width), startY = random.nextInt(height);
int stopX = random.nextInt(width), stopY = random.nextInt(height);
paint.setStrokeWidth(1);paint.setColor(randomColor(1));
canvas.drawLine(startX, startY, stopX, stopY, paint);
}
/**
* 画随机干扰点
* @param canvas
* @param paint
*/
public void drawPoints(Canvas canvas, Paint paint) {
int stopX = random.nextInt(width), stopY = random.nextInt(height);
paint.setStrokeWidth(1);
paint.setColor(randomColor(1));
canvas.drawPoint(stopX, stopY, paint);
}
/**
* 返回真实验证码字符串
* @return String
*/
public String getCheckCode() {
return checkCode;
}