在android webview实现截屏的手动tounchmove裁剪图片

1. first,import phonegap.
2. js

   1. var isSelect = false;
      var w, h;
      function capturePhoto(){
      var mask = $("<div></div>");
          mask.css({
              'filter': 'alpha(opacity=80)',
              'opacity': 0.5,
              'background-color': 'gray',
              'width': '100%',
              'height': '100%',
              'position': 'fixed',
              'left': 0,
              'top': 0,
              'z-index': 99998,
              'text-align': 'center',
              'vertical-align': 'middle'
          });
          area = $("<div></div>").css({
              'display': 'none'
          });
          $(document.body).append(area);
          $(document.body).append(mask);
          mask.bind({
              "touchstart mousedown": function(e){
                  e.preventDefault();
      // Handle the start
      var event = e.originalEvent, touch = event.targetTouches ? event.targetTouches[0] : e;
                  xStart = touch.pageX;
                  yStart = touch.pageY;
              },
              "touchend mouseup": function(e){
      // Handle the end
                  e.preventDefault();
      var event = e.originalEvent;
      var touch = event.changedTouches ? event.changedTouches[0] : e;
      
                  w = touch.pageX - xStart;
                  h = touch.pageY - yStart;
      if (isSelect) {
      if (window.confirm("are you sure save?")) {
                          mask.css({
                              "display": "none"
                          });
                          alert(window.MyCls.capturePicture(xStart, yStart, w, h));
                      }
      else {
                          isSelect = false;
                      }
                  }
                  area.fadeOut();
      
              },
              "touchmove": function(e){
                  e.preventDefault();
      var event = e.originalEvent;
      var touch = event.changedTouches ? event.changedTouches[0] : e;
      var width = touch.pageX - xStart;
      var height = touch.pageY - yStart;
      if (width > 0 && height > 0) {
                      isSelect = true;
                  }
                  area.css({
                      'background-color': '#fff',
                      'opacity': 0.1,
                      'width': width + "px",
                      'height': height + "px",
                      'position': 'fixed',
                      'left': xStart + "px",
                      'top': yStart + "px",
                      'z-index': 99999,
                      'display': 'none'
                  }).show();
              }
          });
      
      }

      
      
      
3. java

package com.sangeco.plant;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Picture;
import android.os.Bundle;
import android.webkit.WebView;

import com.phonegap.DroidGap;

public class MainActivity extends DroidGap {
    /** Called when the activity is first created. */
    private JavaScriptInterface jsGap;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        super.init();
        // WebSettings ws = super.appView.getSettings();
        jsGap = new JavaScriptInterface(this, appView);
        appView.addJavascriptInterface(jsGap, "MyCls");

        super.loadUrl("file:///android_asset/html/index.html");
    }

    public class JavaScriptInterface {
        private WebView mAppView;
        private DroidGap mGap;

        public JavaScriptInterface(DroidGap gap, WebView view) {
            mAppView = view;
            mGap = gap;
        }

        public String getTelephoneNumber(String msg) {
            return msg;
        }

        public String capturePicture(String x,String y,String w,String h) {
            int left = Integer.parseInt(x);
            int top = Integer.parseInt(y);
            int width = Integer.parseInt(w);
            int height = Integer.parseInt(h);
            String path = "photo saved as ";
            Bitmap bitmap2=Bitmap.createBitmap(getScreenShot(), left, top, width, height);
            try {
                String filename=System.currentTimeMillis()+".jpg";
                path += saveImage(filename, bitmap2)+"\n";
            } catch (IOException e) {
                path=e.getLocalizedMessage();
                e.printStackTrace();
            }
            return path;

        }
        
        public String cutScreen() {
            String path = "photo saved as ";
            Picture picture = mAppView.capturePicture();
            Bitmap bitmap = Bitmap.createBitmap(picture.getWidth(),
                    picture.getHeight(), Config.ARGB_8888);
            Canvas canvas = new Canvas(bitmap);
            picture.draw(canvas);
            try {
                String filename = System.currentTimeMillis() + ".jpg";
                path += saveImage(filename, bitmap);
            } catch (IOException e) {
                // TODO Auto-generated catch block
                path = e.getLocalizedMessage();
                e.printStackTrace();
            }
            return path;
        }
        
        private Bitmap getScreenShot(){
            Picture picture = mAppView.capturePicture();
            Bitmap bitmap = Bitmap.createBitmap(picture.getWidth(),
                    picture.getHeight(), Config.ARGB_8888);
            Canvas canvas = new Canvas(bitmap);
            picture.draw(canvas);
            return bitmap;
        }
        
        private String saveImage(String filename, Bitmap bitmap) throws IOException {
            String sdState = android.os.Environment.getExternalStorageState();
            String img = null;
            if (sdState.equals(android.os.Environment.MEDIA_MOUNTED)) {
                File SDFile = android.os.Environment.getExternalStorageDirectory();
                img=SDFile.getAbsolutePath() + File.separator
                        + filename;
                File myFile = new File(img);
                if (!myFile.exists()) {
                    myFile.createNewFile();
                }
                BufferedOutputStream os = new BufferedOutputStream(
                        new FileOutputStream(myFile));
                bitmap.compress(Bitmap.CompressFormat.PNG, 100, os);
                os.flush();
                os.close();
            }
            return img;
        }
        
    }
}