WP7 - 載入圖片速度比較 | Help - 點部落

2011-03-24

WP7 - 載入圖片速度比較

目前對於從IsolatedStorageFile裡存取圖片

我所知道的有幾種方法

儲存的方法有Extensions.SaveJpeg和IsolatedStorageFileStream.Write

載入的方法有Extensions.LoadJpeg和BitmapImage.SetSource

因為最近的APP必須大量存取IsolatedStorageFile裡的圖

所以做了一個效能測試

測試方法:

首先選擇一個圖片

然後儲存此圖到IsolatedStorage一百次~檔名用流水號

再從IsolatedStorage取得此一百張圖

最後全部刪除

時間計算就用簡單的DataTime來計算毫秒

第一種模式

使用Extensions.SaveJpeg 和 Extensions.LoadJpeg

程式碼片段如下

   1:  Result.Text += "Begin Mode 1\r\n";

   2:  using (var appStorage = IsolatedStorageFile.GetUserStoreForApplication()) {

   3:      DateTime start = DateTime.Now;

   4:      for (int i = 0; i < MaxCount; i++) {

   5:          using (var file = appStorage.OpenFile(string.Format("m1_{0}", i), System.IO.FileMode.OpenOrCreate)) {

   6:              image.SaveJpeg(file, image.PixelWidth, image.PixelHeight, 0, 75);

   7:              size += file.Length;

   8:          }

   9:      }

  10:      TimeSpan ts = DateTime.Now - start;

  11:      Result.Text += string.Format("Save MS={0} Size={1}\r\n", ts.TotalMilliseconds, size / MaxCount);

  12:      size = 0;

  13:      start = DateTime.Now;

  14:      for (int i = 0; i < MaxCount; i++) {

  15:          using (var file = appStorage.OpenFile(string.Format("m1_{0}", i), System.IO.FileMode.OpenOrCreate)) {

  16:              image.LoadJpeg(file);

  17:              size += file.Length;

  18:          }

  19:      }

  20:      ts = DateTime.Now - start;

  21:      Result.Text += string.Format("Load MS={0} Size={1}\r\n", ts.TotalMilliseconds, size / MaxCount);

  22:      start = DateTime.Now;

  23:      for (int i = 0; i < MaxCount; i++) {

  24:          appStorage.DeleteFile(string.Format("m1_{0}", i));

  25:      }

  26:      ts = DateTime.Now - start;

  27:      Result.Text += string.Format("Delete MS={0}\r\n", ts.TotalMilliseconds);

28:

  29:  }

第二種模式

使用IsolatedStorageFileStream.Write 和BitmapImage.SetSource

程式碼片段如下

   1:  Result.Text += "Begin mode 2\r\n";

   2:  using (var appStorage = IsolatedStorageFile.GetUserStoreForApplication()) {

   3:      DateTime start = DateTime.Now;

   4:      for (int i = 0; i < MaxCount; i++) {

   5:          using (var file = appStorage.OpenFile(string.Format("m2_{0}", i), System.IO.FileMode.OpenOrCreate)) {

   6:              byte[] bytes;

   7:              using (MemoryStream stream = new MemoryStream()) {

   8:                  image.SaveJpeg(stream, image.PixelWidth, image.PixelHeight, 0, 75);

   9:                  bytes = stream.ToArray();

  10:              }

  11:              file.Write(bytes, 0, bytes.Length);

  12:              size += file.Length;

  13:          }

  14:      }

  15:      TimeSpan ts = DateTime.Now - start;

  16:      Result.Text += string.Format("Save MS={0} Size={1}\r\n", ts.TotalMilliseconds, size / MaxCount);

  17:      size = 0;

  18:      start = DateTime.Now;

  19:      for (int i = 0; i < MaxCount; i++) {

  20:          using (var file = appStorage.OpenFile(string.Format("m2_{0}", i), System.IO.FileMode.OpenOrCreate)) {

  21:              BitmapImage bb = new BitmapImage();

  22:              bb.SetSource(file);

  23:              size += file.Length;

  24:          }

  25:      }

  26:      ts = DateTime.Now - start;

  27:      Result.Text += string.Format("Load MS={0} Size={1}\r\n", ts.TotalMilliseconds, size / MaxCount);

  28:      start = DateTime.Now;

  29:      for (int i = 0; i < MaxCount; i++) {

  30:          appStorage.DeleteFile(string.Format("m2_{0}", i));

  31:      }

  32:      ts = DateTime.Now - start;

  33:      Result.Text += string.Format("Delete MS={0}\r\n", ts.TotalMilliseconds);

  34:  }

第三種模式

和第一種一樣~但是載入的時候選擇比較小的SIZE

   1:  Result.Text += "Begin Mode 3\r\n";

   2:  using (var appStorage = IsolatedStorageFile.GetUserStoreForApplication()) {

   3:      DateTime start = DateTime.Now;

   4:      for (int i = 0; i < MaxCount; i++) {

   5:          using (var file = appStorage.OpenFile(string.Format("m3_{0}", i), System.IO.FileMode.OpenOrCreate)) {

   6:              image.SaveJpeg(file, image.PixelWidth, image.PixelHeight, 0, 75);

   7:              size += file.Length;

   8:          }

   9:      }

  10:      TimeSpan ts = DateTime.Now - start;

  11:      Result.Text += string.Format("Save MS={0} Size={1}\r\n", ts.TotalMilliseconds, size / MaxCount);

  12:      size = 0;

  13:      start = DateTime.Now;

  14:      for (int i = 0; i < MaxCount; i++) {

  15:          using (var file = appStorage.OpenFile(string.Format("m3_{0}", i), System.IO.FileMode.OpenOrCreate)) {

  16:              WriteableBitmap bit = new WriteableBitmap(150, 150);

  17:              bit.LoadJpeg(file);

  18:              size += file.Length;

  19:          }

  20:      }

  21:      ts = DateTime.Now - start;

  22:      Result.Text += string.Format("Load MS={0} Size={1}\r\n", ts.TotalMilliseconds, size / MaxCount);

  23:      start = DateTime.Now;

  24:      for (int i = 0; i < MaxCount; i++) {

  25:          appStorage.DeleteFile(string.Format("m3_{0}", i));

  26:      }

  27:      ts = DateTime.Now - start;

  28:      Result.Text += string.Format("Delete MS={0}\r\n", ts.TotalMilliseconds);

29:

  30:  }

接著是測試結果

上面每個數據都是用HD7實機測試~OS:7.0.7008.0

單位都是毫秒

可以看的出來M2的儲存方式雖然是先用Extensions.SaveJpeg存到Memory裡再用IsolatedStorageFile.Write

卻還是比直接用Extensions.SaveJpeg還要快~雖然只快一點

而差異比較大的是Extensions.LoadJpeg 和 BitmapImage.SetSource

幾乎差了一倍的效能

而載入的時候把圖縮小是有提升些許效能的

雖然Extensions.LoadJpeg 和 BitmapImage.SetSource效能差一倍

但是Extensions.LoadJpeg 可以在非主執行續使用

BitmapImage.SetSource就一定要在主執行續使用

但是~~效能還是比不上Pucture Hub載入圖片的速度啊!

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