Android 图片Bitmap的剪切的示例代码

一、什么是Android中的Bitmap

Bitmap是Android系统中的图像处理的最重要类之一。用它可以获取图像文件信息，进行图像剪切、旋转、缩放等操作，并可以指定格式保存图像文件。

二、Bitmap的剪切基本操作

代码如下:

public static Bitmap createBitmap (Bitmap source, int x, int y, int width, int height, Matrix m, boolean filter)

从原始位图剪切图像，这是一种高级的方式。可以用Matrix(矩阵)来实现旋转等高级方式截图

参数说明：

Bitmap source：要从中截图的原始位图

int x:起始x坐标

int y：起始y坐标

int width：要截的图的宽度

int height：要截的图的宽度

Bitmap.Config  config：一个枚举类型的配置，可以定义截到的新位图的质量

返回值：返回一个剪切好的Bitmap

三、Bitmap剪切的封装

实际使用中，因为项目需要时常需要对基本功能进行封装，下面是一段封装的代码，仅供参考。

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF; 

public class BitmapCut
{ 

 /**
 * 通过资源id转化成Bitmap
 *
 * @param context
 * @param resId
 * @return
 */
 public static Bitmap ReadBitmapById(Context context, int resId)
 {
 BitmapFactory.Options opt = new BitmapFactory.Options();
 opt.inPreferredConfig = Bitmap.Config.RGB_565;
 opt.inPurgeable = true;
 opt.inInputShareable = true; 

 InputStream is = context.getResources().openRawResource(resId);
 return BitmapFactory.decodeStream(is, null, opt);
 } 

 /**
 * 设置背景为圆角
 *
 * @param bitmap
 * @param pixels
 * @return
 */
 public static Bitmap removeYuanjiao(Bitmap bitmap, int pixels)
 {
 int width = bitmap.getWidth();
 int height = bitmap.getHeight(); 

 Bitmap creBitmap = Bitmap.createBitmap(width, height,
  android.graphics.Bitmap.Config.ARGB_8888);
 Canvas canvas = new Canvas(creBitmap); 

 Paint paint = new Paint();
 float roundPx = pixels;
 RectF rectF = new RectF(0, 0, bitmap.getWidth() - pixels,
  bitmap.getHeight() - pixels);
 paint.setAntiAlias(true); 

 canvas.drawARGB(0, 0, 0, 0);
 canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
 paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN)); 

 canvas.drawBitmap(bitmap, 0, 0, paint);
 if (!bitmap.isRecycled())
  bitmap.recycle(); 

 return creBitmap;
 } 

 /**
 * 按正方形裁切图片
 */
 public static Bitmap ImageCrop(Bitmap bitmap, boolean isRecycled)
 { 

 if (bitmap == null)
 {
  return null;
 } 

 int w = bitmap.getWidth(); // 得到图片的宽，高
 int h = bitmap.getHeight(); 

 int wh = w > h ? h : w;// 裁切后所取的正方形区域边长 

 int retX = w > h ? (w - h) / 2 : 0;// 基于原图，取正方形左上角x坐标
 int retY = w > h ? 0 : (h - w) / 2; 

 Bitmap bmp = Bitmap.createBitmap(bitmap, retX, retY, wh, wh, null,
  false);
 if (isRecycled && bitmap != null && !bitmap.equals(bmp)
  && !bitmap.isRecycled())
 {
  bitmap.recycle();
  bitmap = null;
 } 

 // 下面这句是关键
 return bmp;// Bitmap.createBitmap(bitmap, retX, retY, wh, wh, null,
   // false);
 } 

 /**
 * 按长方形裁切图片
 *
 * @param bitmap
 * @return
 */
 public static Bitmap ImageCropWithRect(Bitmap bitmap)
 {
 if (bitmap == null)
 {
  return null;
 } 

 int w = bitmap.getWidth(); // 得到图片的宽，高
 int h = bitmap.getHeight(); 

 int nw, nh, retX, retY;
 if (w > h)
 {
  nw = h / 2;
  nh = h;
  retX = (w - nw) / 2;
  retY = 0;
 } else
 {
  nw = w / 2;
  nh = w;
  retX = w / 4;
  retY = (h - w) / 2;
 } 

 // 下面这句是关键
 Bitmap bmp = Bitmap.createBitmap(bitmap, retX, retY, nw, nh, null,
  false);
 if (bitmap != null && !bitmap.equals(bmp) && !bitmap.isRecycled())
 {
  bitmap.recycle();
  bitmap = null;
 }
 return bmp;// Bitmap.createBitmap(bitmap, retX, retY, nw, nh, null,
   // false);
 } 

 /**
 * Bitmap --> byte[]
 *
 * @param bmp
 * @return
 */
 public static byte[] readBitmap(Bitmap bmp)
 {
 ByteArrayOutputStream baos = new ByteArrayOutputStream();
 bmp.compress(Bitmap.CompressFormat.JPEG, 60, baos);
 try
 {
  baos.flush();
  baos.close();
 } catch (IOException e)
 {
  e.printStackTrace();
 }
 return baos.toByteArray();
 } 

 /**
 * 将图像裁剪成圆形
 *
 * @param bitmap
 * @return
 */
 public static Bitmap toRoundBitmap(Bitmap bitmap)
 {
 if (bitmap == null)
 {
  return null;
 } 

 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;
  top = 0;
  bottom = width;
  left = 0;
  right = 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 int color = 0xff424242;
 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); 

 canvas.drawARGB(0, 0, 0, 0);
 paint.setColor(color);
 canvas.drawRoundRect(rectF, roundPx, roundPx, paint); 

 paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
 canvas.drawBitmap(bitmap, src, dst, paint);
 if (bitmap != null && !bitmap.isRecycled())
 {
  bitmap.recycle();
  bitmap = null;
 }
 return output;
 } 

 // 将图片变成带圆边的圆形图片
 public static Bitmap getRoundBitmap(Bitmap bitmap, int width, int height)
 {
 if (bitmap == null)
 {
  return null;
 }
 // 将图片变成圆角
 Bitmap roundBitmap = Bitmap.createBitmap(width, height,
  Config.ARGB_8888);
 Canvas canvas = new Canvas(roundBitmap);
 Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
 int len = (width > height) ? height : width;
 canvas.drawCircle(width / 2, height / 2, len / 2 - 8, paint);
 paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
 Bitmap scaledBitmap = Bitmap.createScaledBitmap(bitmap, len, len, true);
 canvas.drawBitmap(scaledBitmap, 0, 0, paint);
 // 将图片加圆边
 Bitmap outBitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);
 canvas = new Canvas(outBitmap);
 paint = new Paint(Paint.ANTI_ALIAS_FLAG);
 paint.setColor(0xffffffff);
 canvas.drawCircle(width / 2, height / 2, len / 2 - 4, paint);
 paint.setXfermode(new PorterDuffXfermode(Mode.SRC_OVER));
 canvas.drawBitmap(roundBitmap, 0, 0, paint);
 bitmap.recycle();
 bitmap = null;
 roundBitmap.recycle();
 roundBitmap = null;
 scaledBitmap.recycle();
 scaledBitmap = null;
 return outBitmap;
 } 

 // 将图片变成带圆边的圆形图片
 public static Bitmap getRoundBitmap(Bitmap bitmap, int width, int height,
  int color)
 {
 if (bitmap == null)
 {
  return null;
 }
 // 将图片变成圆角
 Bitmap roundBitmap = Bitmap.createBitmap(width, height,
  Config.ARGB_8888);
 Canvas canvas = new Canvas(roundBitmap);
 Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
 int len = (width > height) ? height : width;
 canvas.drawCircle(width / 2, height / 2, len / 2 - 8, paint);
 paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
 Bitmap scaledBitmap = Bitmap.createScaledBitmap(bitmap, len, len, true);
 canvas.drawBitmap(scaledBitmap, 0, 0, paint);
 // 将图片加圆边
 Bitmap outBitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);
 canvas = new Canvas(outBitmap);
 paint = new Paint(Paint.ANTI_ALIAS_FLAG);
 paint.setColor(color);
 canvas.drawCircle(width / 2, height / 2, len / 2 - 4, paint);
 paint.setXfermode(new PorterDuffXfermode(Mode.SRC_OVER));
 canvas.drawBitmap(roundBitmap, 0, 0, paint);
 bitmap.recycle();
 bitmap = null;
 roundBitmap.recycle();
 roundBitmap = null;
 scaledBitmap.recycle();
 scaledBitmap = null;
 return outBitmap;
 } 

 /**
 * function:图片转圆角
 *
 * @param bitmap
 *  需要转的bitmap
 * @param pixels
 *  转圆角的弧度
 * @return 转圆角的bitmap
 */
 public static Bitmap toRoundCorner(Bitmap bitmap, int pixels)
 {
 Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
  bitmap.getHeight(), Config.ARGB_8888);
 Canvas canvas = new Canvas(output);
 final int color = 0xff424242;
 final Paint paint = new Paint();
 final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
 final RectF rectF = new RectF(rect);
 final float roundPx = pixels;
 paint.setAntiAlias(true);
 canvas.drawARGB(0, 0, 0, 0);
 paint.setColor(color);
 canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
 paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
 canvas.drawBitmap(bitmap, rect, rect, paint);
 if (bitmap != null && !bitmap.isRecycled())
 {
  bitmap.recycle();
 }
 return output;
 } 

 /**
 * 获取指定的圆角图片
 *
 * @param bitmap
 * @return
 */
 public static Bitmap getRadiusBitmap(Bitmap bitmap)
 {
 Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
 paint.setColor(0xffffffff);
 Bitmap radiusBitmap = Bitmap.createBitmap(bitmap.getWidth(),
  bitmap.getHeight(), Config.ARGB_8888);
 Canvas canvas = new Canvas(radiusBitmap);
 RectF rectF = new RectF(0, 0, bitmap.getWidth(), bitmap.getHeight());
 canvas.drawRoundRect(rectF, 7, 7, paint);
 paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
 canvas.drawBitmap(bitmap, 0, 0, paint);
 if (bitmap != null && !bitmap.isRecycled())
 {
  bitmap.recycle();
 }
 return radiusBitmap;
 } 

 // 获得指定大小的圆边的bitmap数组
 public static ArrayList<Bitmap> getRadiusBitmapList(String[] pathArray,
  int size, int len, float radius, int color)
 {
 Bitmap canvasBitmap = null;
 Canvas canvas = null;
 Paint paint = null;
 RectF rectF = new RectF(0, 0, len - radius, len - radius);
 File file = null;
 FileInputStream fis = null;
 Bitmap bitmap = null;
 Bitmap scaledBitmap = null; 

 ArrayList<Bitmap> list = new ArrayList<Bitmap>();
 for (int i = 0; i < pathArray.length; i++)
 {
  file = new File(pathArray[i]);
  if (!file.exists())
  continue;
  try
  {
  fis = new FileInputStream(file);
  bitmap = BitmapFactory.decodeStream(fis);
  if (bitmap != null)
  {
   canvasBitmap = Bitmap.createBitmap(len, len,
    Config.ARGB_8888);
   canvas = new Canvas(canvasBitmap);
   paint = new Paint(Paint.ANTI_ALIAS_FLAG);
   paint.setColor(color);
   canvas.drawRoundRect(rectF, radius, radius, paint);
   paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN)); 

   scaledBitmap = Bitmap.createScaledBitmap(bitmap, len, len,
    true);
   canvas.drawBitmap(scaledBitmap, 0, 0, paint);
   list.add(canvasBitmap);
  }
  } catch (FileNotFoundException e)
  {
  } finally
  {
  if (fis != null)
  {
   try
   {
   fis.close();
   } catch (IOException e1)
   {
   }
  }
  }
  if (list.size() == size)
  break;
 }
 if (scaledBitmap != null && !scaledBitmap.isRecycled())
 {
  scaledBitmap.recycle();
  scaledBitmap = null;
 }
 if (bitmap != null && !bitmap.isRecycled())
 {
  bitmap.recycle();
  bitmap = null;
 }
 return list;
 } 

 /**
 * 按照一定的宽高比例裁剪图片
 *
 * @param bitmap
 * @param num1
 *  长边的比例
 * @param num2
 *  短边的比例
 * @return
 */
 public static Bitmap ImageCrop(Bitmap bitmap, int num1, int num2,
  boolean isRecycled)
 {
 if (bitmap == null)
 {
  return null;
 }
 int w = bitmap.getWidth(); // 得到图片的宽，高
 int h = bitmap.getHeight();
 int retX, retY;
 int nw, nh;
 if (w > h)
 {
  if (h > w * num2 / num1)
  {
  nw = w;
  nh = w * num2 / num1;
  retX = 0;
  retY = (h - nh) / 2;
  } else
  {
  nw = h * num1 / num2;
  nh = h;
  retX = (w - nw) / 2;
  retY = 0;
  }
 } else
 {
  if (w > h * num2 / num1)
  {
  nh = h;
  nw = h * num2 / num1;
  retY = 0;
  retX = (w - nw) / 2;
  } else
  {
  nh = w * num1 / num2;
  nw = w;
  retY = (h - nh) / 2;
  retX = 0;
  }
 }
 Bitmap bmp = Bitmap.createBitmap(bitmap, retX, retY, nw, nh, null,
  false);
 if (isRecycled && bitmap != null && !bitmap.equals(bmp)
  && !bitmap.isRecycled())
 {
  bitmap.recycle();
  bitmap = null;
 }
 return bmp;// Bitmap.createBitmap(bitmap, retX, retY, nw, nh, null,
   // false);
 }
}

示例代码：Bitmaptest_jb51.rar

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