转自：http://blog.sina.com.cn/s/blog_474928c90101dkvf.html
最近工作上遇到了一个将一个图片按照相框进行裁剪的问题，花了一个下午研究了下，在此整理一下，以便后用。
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（相片） （相框） （结果图）
一个按照边框裁剪的类，因为相框通体为蓝色，只是不同区域的透明度不同，所以，选用了根据透明度来筛选边界上的点的方法。
另外，这个类也提供了判断一个点是否是在相框内部的方法：
和当前像素点同一水平线上的各点，假如左右两侧均有相框蓝色边界上的点的话，并且当前点不在边框上则认为当前点在相框的内部。
反之，则认为当前点在相框的外部。
package com.example.test_filter;import android.graphics.Bitmap; import android.graphics.Color; import android.graphics.Matrix; import android.graphics.Bitmap.Config;public class AlphaFilter implements Filter{public static final int INSIDE_MODE = 0;public static final int EDGE_MODE = 1;public static final int OUTSIDE_MODE = 2;public int findNonOpaque(int x, int y, int width, int height, int[] srcPixels) {if(width < height) {return findNonOpaqueByX(x, y, width, height, srcPixels);} else {return findNonOpaqueByY(x, y, width, height, srcPixels);}}/** 横向检测左右两侧边界*/public int findNonOpaqueByX(int x, int y, int width, int height, int[] srcPixels) {int mode = OUTSIDE_MODE;//当前点左右两侧均有边界点出现，则认为当前点在内部或者边框中if(findNonOpaqueByXLeft(x, y, width, height, srcPixels) && findNonOpaqueByXRight(x, y, width, height, srcPixels)) {mode = INSIDE_MODE;}int pos = y*width+x;if(isMatch(pos, srcPixels)) {mode = EDGE_MODE;}return mode;}/** 检测与当前点y坐标相同的左侧各点是否有边界存在*/public boolean findNonOpaqueByXLeft(int x, int y, int width, int height, int[] srcPixels) {for(int i=0; i < x; i++) {int pos = y*width + i;if(isMatch(pos, srcPixels)) {return true;}}return false;}/** 检测与当前点y坐标相同的右侧各点是否有边界存在*/public boolean findNonOpaqueByXRight(int x, int y, int width, int height, int[] srcPixels) {for(int i= x+1; i < width; i++) {int pos = y*width + i;if(isMatch(pos, srcPixels)) {return true;}}return false;}/** 纵向检测上下两侧的边界*/public int findNonOpaqueByY(int x, int y, int width, int height, int[] srcPixels) {int mode = OUTSIDE_MODE;//当前点上下两侧均有边界点出现，则认为当前点在内部或者边框中if(findNonOpaqueByYTop(x, y, width, height, srcPixels) && findNonOpaqueByYBottom(x, y, width, height, srcPixels)) {mode = INSIDE_MODE;}int pos = y*width+x;if(isMatch(pos, srcPixels)) {mode = EDGE_MODE;}return mode;}/** 检测与当前点x坐标相同的上方各点是否有边界存在*/public boolean findNonOpaqueByYTop(int x, int y, int width, int height, int[] srcPixels) {for(int i=0; i < y; i++) {int pos = i*width + x;if(isMatch(pos, srcPixels)) {return true;}}return false;}/** 检测与当前点x坐标相同的下方各点是否有边界存在*/public boolean findNonOpaqueByYBottom(int x, int y, int width, int height, int[] srcPixels) {for(int i=y+1; i < height; i++) {int pos = i*width + x;if(isMatch(pos, srcPixels)) {return true;}}return false;}public boolean isMatch(int pos, int[]srcPixels) {int color = srcPixels[pos];int alpha = Color.alpha(color);//检测是否是边界，针对背景图片选用透明度进行过滤if(alpha >= 94 && alpha < 255) {return true;}return false;}/*** 图片效果叠加* @param bmp 要裁剪的图片* @param filter 边框* @return*/public Bitmap overlay(Bitmap bmp, Bitmap filter){int width = bmp.getWidth();int height = bmp.getHeight();Bitmap overlay = filter;Bitmap bitmap = Bitmap.createBitmap(width, height, Config.ARGB_4444);bitmap.setHasAlpha(true); // 对边框图片进行缩放int w = overlay.getWidth();int h = overlay.getHeight();float scaleX = width * 1F / w;float scaleY = height * 1F / h;Matrix matrix = new Matrix();matrix.postScale(scaleX, scaleY);Bitmap overlayCopy = Bitmap.createBitmap(overlay, 0, 0, w, h, matrix, true);int[] srcPixels = new int[width * height];int[] layPixels = new int[width * height];bmp.getPixels(srcPixels, 0, width, 0, 0, width, height);overlayCopy.getPixels(layPixels, 0, width, 0, 0, width, height);int pos = 0;for (int i = 0; i < height; i++){for (int k = 0; k < width; k++){pos = i * width + k;int mode = findNonOpaque(k, i, width, height, layPixels);if(mode == INSIDE_MODE) {srcPixels[pos] = srcPixels[pos];continue;} else if(mode == EDGE_MODE){srcPixels[pos] = layPixels[pos];} else{srcPixels[pos] = 0;continue;}}}bitmap.setPixels(srcPixels, 0, width, 0, 0, width, height);return bitmap;} }package com.example.test_filter;import android.os.AsyncTask; import android.os.Bundle; import android.app.Activity; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.widget.ImageView;public class MainActivity extends Activity {ImageView filter;AlphaFilter alphaFilter;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);filter = (ImageView) findViewById(R.id.filter);alphaFilter = new AlphaFilter();}@Overrideprotected void onResume() {Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.album_photo_0);Bitmap frame = BitmapFactory.decodeResource(getResources(), R.drawable.first_album_frame);new BitmapFilter().execute(bitmap, frame);super.onResume();}class BitmapFilter extends AsyncTask<Bitmap, Bitmap, Bitmap> {@Overrideprotected Bitmap doInBackground(Bitmap... params) {Bitmap bitmap = alphaFilter.overlay(params[0], params[1]);return bitmap;}@Overrideprotected void onPostExecute(Bitmap result) {filter.setImageBitmap(result);super.onPostExecute(result);}} }
