Forms Android Bitmap 处理

forms 接口定义

using System;
using System.Collections.Generic;
using System.IO;

namespace
{
    public interface IUtilPicture
    {
        List<string> ResizeBitmap(string imagePath); //图片采样缩小    
        //删除图片
        void DeletePicture(string imagePath);
    }
}


平台实现
using System;
using System.Collections.Generic;
using System.IO;
using System.Diagnostics;

using Xamarin.Forms;

using.TDroid;

using Android.Graphics;

[assembly:Dependency (typeof(UtilPicture))]
namespace.TDroid
{
    public class UtilPicture : Java.Lang.Object,IUtilPicture
    {
        public UtilPicture ()
        {        

        }

        public List<string> ResizeBitmap (string imagePath)
        {
            List<string> listImagePath = new List<string> ();
            BitmapFactory.Options newOptions = new BitmapFactory.Options ();
            //开始du图片
            newOptions.InJustDecodeBounds = true;
            Bitmap bitmap = BitmapFactory.DecodeFile (imagePath, newOptions);
            newOptions.InJustDecodeBounds = false;
            int be = calculateInSampleSize (newOptions,700,700);            
            newOptions.InSampleSize = be;
            bitmap = BitmapFactory.DecodeFile (imagePath, newOptions);
            Bitmap tempBitOne = compressImage (bitmap,60);
            bitmap.Recycle ();
            string shinkOne = SaveCompressImage (tempBitOne, imagePath,"");
            listImagePath.Add (shinkOne);
            string shinkTwo = SaveShinkImage (shinkOne);
            listImagePath.Add (shinkTwo);
            return listImagePath;
        }
                

        public void DeletePicture (string imagePath)
        {
            if (File.Exists (imagePath)) {
                try {
                    File.Delete (imagePath);
                } catch (IOException ex) {
                    Debug.WriteLine ("DeleteFile:" + ex.Message);
                    return;
                }
            }
        }

        private Bitmap compressImage (Bitmap bitmap,int byteCount)
        {
            MemoryStream mStrean = new MemoryStream ();
            bitmap.Compress (Bitmap.CompressFormat.Jpeg, 100, mStrean);        
            int options = 100;
            while (mStrean.ToArray ().Length / 1024 > byteCount) {
                mStrean.SetLength (0);
                mStrean.Position = 0;
                bitmap.Compress (Bitmap.CompressFormat.Jpeg, options, mStrean);
                options -= 10;
            }
            bitmap.Recycle ();
            Bitmap tempBit = BitmapFactory.DecodeByteArray (mStrean.ToArray (), 0, mStrean.ToArray ().Length);
            mStrean.SetLength (0);
            mStrean.Position = 0;
            return tempBit;            
        }

        private string SaveCompressImage (Bitmap mBitmap, string path,string fileShink)  //上传图片
        {
            MemoryStream mStrean = new MemoryStream ();
            mBitmap.Compress (Bitmap.CompressFormat.Jpeg, 100, mStrean);
            var image1Path = Environment.GetFolderPath (Environment.SpecialFolder.Personal);
            ///data/data/PocketDoctor.TDroid/files
            string mPath = Android.OS.Environment.ExternalStorageDirectory + "/FDEKYYYG/MemoImages";    
            mPath += fileShink;
            if (!Directory.Exists (mPath)) {
                Directory.CreateDirectory (mPath);
            }
            string fileName = path.Substring (path.LastIndexOf ('/') + 1);
            string imageFilePath = mPath + "/" + fileName;
            FileInfo fileInfo;        
            fileInfo = new FileInfo (imageFilePath);
            try {
                FileStream fStream = fileInfo.Create ();                
                fStream.Write (mStrean.ToArray (), 0, mStrean.ToArray ().Length);
                mStrean.SetLength (0);
                mStrean.Position = 0;            
                fStream.Close ();
                mBitmap.Recycle ();
            } catch (Exception ex) {            
                Debug.WriteLine ("DeleteFile:" + ex.Message);
            }                        
            return imageFilePath;
        }

        private string SaveShinkImage (string imagePath) //缩略图
        {
            BitmapFactory.Options newOptions = new BitmapFactory.Options ();
            //开始du图片
            newOptions.InJustDecodeBounds = true;
            Bitmap bitmap = BitmapFactory.DecodeFile (imagePath, newOptions);
            newOptions.InJustDecodeBounds = false;        
            int beTwo =  calculateInSampleSize (newOptions,70,70);
            newOptions.InSampleSize = beTwo;
            bitmap = BitmapFactory.DecodeFile (imagePath, newOptions);
            Bitmap tempBitTwo = compressImage (bitmap,5);
            bitmap.Recycle ();
            string shinkOne = SaveCompressImage (tempBitTwo, imagePath,"Thumbnail");
            return shinkOne;
        }

        private  int calculateInSampleSize (
            BitmapFactory.Options options, int reqWidth, int reqHeight)
        {
            // Raw height and width of image
            int height = options.OutHeight;
            int width = options.OutWidth;
            int inSampleSize = 1;

            if (height > reqHeight || width > reqWidth) {

                int halfHeight = height / 2;
                int halfWidth = width / 2;

                // Calculate the largest inSampleSize value that is a power of 2 and keeps both
                // height and width larger than the requested height and width.
                while ((halfHeight / inSampleSize) > reqHeight
                       && (halfWidth / inSampleSize) > reqWidth) {
                    inSampleSize *= 2;
                }
            }
            return inSampleSize;
        }
    
    }
}