Android开发实现去除bitmap无用白色边框的方法示例

import android.graphics.Bitmap;public class BitmapDeleteNoUseSpaceUtil {    private static Bitmap getGrayImg(int imgTheWidth, int imgTheHeight, int[] imgThePixels) {    int alpha = 0xFF << 24; //设置透明度    for (int i = 0; i < imgTheHeight; i++) {      for (int j = 0; j < imgTheWidth; j++) {        int grey = imgThePixels[imgTheWidth * i + j];        int red = ((grey & 0x00FF0000) >> 16); //获取红色灰度值        int green = ((grey & 0x0000FF00) >> 8); //获取绿色灰度值        int blue = (grey & 0x000000FF);     //获取蓝色灰度值        grey = (int) ((float) red * 0.3 + (float) green * 0.59 + (float) blue * 0.11);        grey = alpha | (grey << 16) | (grey << 8) | grey; //添加透明度        imgThePixels[imgTheWidth * i + j] = grey;  //更改像素色值      }    }    Bitmap result =        Bitmap.createBitmap(imgTheWidth, imgTheHeight, Bitmap.Config.RGB_565);    result.setPixels(imgThePixels, 0, imgTheWidth, 0, 0, imgTheWidth, imgTheHeight);    return result;  }    public static Bitmap deleteNoUseWhiteSpace(Bitmap originBitmap) {    int[] imgThePixels = new int[originBitmap.getWidth() * originBitmap.getHeight()];    originBitmap.getPixels(        imgThePixels,        0,        originBitmap.getWidth(),        0,        0,        originBitmap.getWidth(),        originBitmap.getHeight());    // 灰度化 bitmap    Bitmap bitmap = getGrayImg(        originBitmap.getWidth(),        originBitmap.getHeight(),        imgThePixels);    int top = 0; // 上边框白色高度    int left = 0; // 左边框白色高度    int right = 0; // 右边框白色高度    int bottom = 0; // 底边框白色高度    for (int h = 0; h < bitmap.getHeight(); h++) {      boolean holdBlackPix = false;      for (int w = 0; w < bitmap.getWidth(); w++) {        if (bitmap.getPixel(w, h) != -1) { // -1 是白色          holdBlackPix = true; // 如果不是-1 则是其他颜色          break;        }      }      if (holdBlackPix) {        break;      }      top++;    }    for (int w = 0; w < bitmap.getWidth(); w++) {      boolean holdBlackPix = false;      for (int h = 0; h < bitmap.getHeight(); h++) {        if (bitmap.getPixel(w, h) != -1) {          holdBlackPix = true;          break;        }      }      if (holdBlackPix) {        break;      }      left++;    }    for (int w = bitmap.getWidth() - 1; w >= 0; w--) {      boolean holdBlackPix = false;      for (int h = 0; h < bitmap.getHeight(); h++) {        if (bitmap.getPixel(w, h) != -1) {          holdBlackPix = true;          break;        }      }      if (holdBlackPix) {        break;      }      right++;    }    for (int h = bitmap.getHeight() - 1; h >= 0; h--) {      boolean holdBlackPix = false;      for (int w = 0; w < bitmap.getWidth(); w++) {        if (bitmap.getPixel(w, h) != -1) {          holdBlackPix = true;          break;        }      }      if (holdBlackPix) {        break;      }      bottom++;    }    // 获取内容区域的宽高    int cropHeight = bitmap.getHeight() - bottom - top;    int cropWidth = bitmap.getWidth() - left - right;    // 获取内容区域的像素点    int[] newPix = new int[cropWidth * cropHeight];    int i = 0;    for (int h = top; h < top + cropHeight; h++) {      for (int w = left; w < left + cropWidth; w++) {        newPix[i++] = bitmap.getPixel(w, h);      }    }    // 创建切割后的 bitmap， 针对彩色图，把 newPix 替换为 originBitmap 的 pixs    return Bitmap.createBitmap(newPix, cropWidth, cropHeight, Bitmap.Config.ARGB_8888);  }}