1.主要代碼
廢話不多說,直接上代碼,具體請看注釋。
這個函數可以直接拿來用,通過設定想要的長邊長度按比例縮小圖檔。
/// <summary>
/// 處理并儲存圖檔
/// </summary>
/// <param name="inputFile">輸入檔案</param>
/// <param name="outputFile">輸出檔案</param>
/// <param name="longSide">長邊長度</param>
/// <returns>成功傳回true,否則false。</returns>
private async Task<bool> LoadSaveFileAsync(StorageFile inputFile, StorageFile outputFile, uint longSide)
{
try
{
Guid encoderId;
switch (outputFile.FileType)
{
case ".png":
encoderId = BitmapEncoder.PngEncoderId;
break;
case ".bmp":
encoderId = BitmapEncoder.BmpEncoderId;
break;
case ".jpg":
default:
encoderId = BitmapEncoder.JpegEncoderId;
break;
}
//圖檔處理部分
using (IRandomAccessStream inputStream = await inputFile.OpenAsync(FileAccessMode.Read),
outputStream = await outputFile.OpenAsync(FileAccessMode.ReadWrite))
{
//BitmapEncoder需要一個空的輸出流; 但是使用者可能已經選擇了預先存在的檔案,是以清零。
outputStream.Size = 0;
//從解碼器擷取像素資料。 我們對解碼的像素應用使用者請求的變換以利用解碼器中的潛在優化。
BitmapDecoder decoder = await BitmapDecoder.CreateAsync(inputStream);
BitmapTransform transform = new BitmapTransform();
//原圖尺寸比轉換尺寸更小
if (decoder.PixelHeight < longSide && decoder.PixelWidth < longSide)
throw new Exception("設定的尺寸大于原圖尺寸!");
// 判斷長邊并按原圖比例确定另一條邊的長度
if (decoder.PixelHeight > decoder.PixelWidth)
{
transform.ScaledHeight = longSide;
transform.ScaledWidth = (uint)(decoder.PixelWidth * ((float)longSide /decoder.PixelHeight));
}
else
{
transform.ScaledHeight = (uint)(decoder.PixelHeight * ((float)longSide/decoder.PixelWidth));
transform.ScaledWidth = longSide;
}
// Fant是相對高品質的插值模式。
transform.InterpolationMode = BitmapInterpolationMode.Fant;
// BitmapDecoder訓示最佳比對本地存儲的圖像資料的像素格式和alpha模式。 這可以提供高性能的與或品質增益。
BitmapPixelFormat format = decoder.BitmapPixelFormat;
BitmapAlphaMode alpha = decoder.BitmapAlphaMode;
// PixelDataProvider提供對位圖幀中像素資料的通路
PixelDataProvider pixelProvider = await decoder.GetPixelDataAsync(
format,
alpha,
transform,
ExifOrientationMode.RespectExifOrientation,
ColorManagementMode.ColorManageToSRgb
);
byte[] pixels = pixelProvider.DetachPixelData();
//将像素資料寫入編碼器。
BitmapEncoder encoder = await BitmapEncoder.CreateAsync(encoderId, outputStream);
//設定像素資料
encoder.SetPixelData(
format,
alpha,
transform.ScaledWidth,
transform.ScaledHeight,
decoder.DpiX,
decoder.DpiY,
pixels
);
await encoder.FlushAsync(); //異步送出和重新整理所有圖像資料(這一步儲存圖檔到檔案)
Debug.WriteLine("儲存成功:" + outputFile.Path);
return true;
}
}
catch (Exception err)
{
Debug.WriteLine(err.Message);
return false;
}
}
2.其他
1.打開圖檔檔案
FileOpenPicker picker = new FileOpenPicker();
picker.FileTypeFilter.Add(".jpg");
picker.FileTypeFilter.Add(".jpeg");
picker.FileTypeFilter.Add(".png");
picker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
//選取一個檔案
var file = await picker.PickSingleFileAsync();
if (file != null) //檔案不為空則進行下一步
{
_inputFile = file;
await LoadFileAsync(file);
}
2.顯示選取的圖檔
/// <summary>
/// 從檔案載入圖檔并顯示
/// </summary>
/// <param name="file">圖檔</param>
private async Task LoadFileAsync(StorageFile file)
{
try
{
// 顯示圖檔
BitmapImage src = new BitmapImage();
using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.Read))
{
await src.SetSourceAsync(stream);
}
MyImage.Source = src;
LongSide.IsEnabled = true;
SaveButton.IsEnabled = true;
}
catch (Exception err)
{
Debug.WriteLine(err.Message);
}
}
3.選擇儲存位置、調用函數處理并儲存圖檔
/// <summary>
/// 選擇檔案儲存位置并進行下一步處理
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private async void Save_Click(object sender, RoutedEventArgs e)
{
FileSavePicker picker = new FileSavePicker();
picker.FileTypeChoices.Add("JPEG image", new string[] { ".jpg" });
picker.FileTypeChoices.Add("PNG image", new string[] { ".png" });
picker.FileTypeChoices.Add("BMP image", new string[] { ".bmp" });
picker.DefaultFileExtension = ".png";
picker.SuggestedFileName = "Output file";
picker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
var file = await picker.PickSaveFileAsync();
if (file != null && !String.IsNullOrEmpty(LongSide.Text))
{
uint longSide = uint.Parse(LongSide.Text);
if (await LoadSaveFileAsync(_inputFile, file, longSide)) //處理圖檔
MsgBox.Text = "轉換成功!" + file.Path;
else
MsgBox.Text = "失敗";
}
}
3.完整Demo
<Page
x:Class="ImageDemo.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:ImageDemo"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Grid.RowDefinitions>
<RowDefinition Height="auto"/>
<RowDefinition Height="auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Image Name="MyImage" Height="300" Grid.Row="0"/>
<StackPanel Orientation="Horizontal" Grid.Row="1" HorizontalAlignment="Left" Margin="10">
<TextBlock Text="目标長邊長度:" VerticalAlignment="Center"/>
<TextBox Name="LongSide" IsEnabled="False" Margin="10,0,0,0"/>
</StackPanel>
<TextBlock Name="MsgBox" Grid.Row="2" VerticalAlignment="Center"/>
<StackPanel Grid.Row="2" Orientation="Horizontal"
HorizontalAlignment="Right" VerticalAlignment="Top">
<Button Content="擷取圖檔" Click="Get_Click"/>
<Button Content="儲存" Click="Save_Click" Name="SaveButton"
IsEnabled="False" Margin="10"/>
</StackPanel>
</Grid>
</Page>
using System;
using System.Diagnostics;
using System.Threading.Tasks;
using Windows.Graphics.Imaging;
using Windows.Storage;
using Windows.Storage.Pickers;
using Windows.Storage.Streams;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Media.Imaging;
// https://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x804 上介紹了“空白頁”項模闆
namespace ImageDemo
{
/// <summary>
/// 可用于自身或導航至 Frame 内部的空白頁。
/// </summary>
public sealed partial class MainPage : Page
{
private StorageFile _inputFile;
public MainPage()
{
this.InitializeComponent();
}
/// <summary>
/// 點選“擷取圖檔”
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private async void Get_Click(object sender, RoutedEventArgs e)
{
FileOpenPicker picker = new FileOpenPicker();
picker.FileTypeFilter.Add(".jpg");
picker.FileTypeFilter.Add(".jpeg");
picker.FileTypeFilter.Add(".png");
picker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
//選取一個檔案
var file = await picker.PickSingleFileAsync();
if (file != null) //檔案不為空則進行下一步
{
_inputFile = file;
await LoadFileAsync(file);
}
}
/// <summary>
/// 從檔案載入圖檔并顯示
/// </summary>
/// <param name="file">圖檔</param>
private async Task LoadFileAsync(StorageFile file)
{
try
{
// 顯示圖檔
BitmapImage src = new BitmapImage();
using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.Read))
{
await src.SetSourceAsync(stream);
}
MyImage.Source = src;
LongSide.IsEnabled = true;
SaveButton.IsEnabled = true;
}
catch (Exception err)
{
Debug.WriteLine(err.Message);
}
}
/// <summary>
/// 選擇檔案儲存位置并進行下一步處理
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private async void Save_Click(object sender, RoutedEventArgs e)
{
FileSavePicker picker = new FileSavePicker();
picker.FileTypeChoices.Add("JPEG image", new string[] { ".jpg" });
picker.FileTypeChoices.Add("PNG image", new string[] { ".png" });
picker.FileTypeChoices.Add("BMP image", new string[] { ".bmp" });
picker.DefaultFileExtension = ".png";
picker.SuggestedFileName = "Output file";
picker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
var file = await picker.PickSaveFileAsync();
if (file != null && !String.IsNullOrEmpty(LongSide.Text))
{
uint longSide = uint.Parse(LongSide.Text);
if (await LoadSaveFileAsync(_inputFile, file, longSide))
MsgBox.Text = "轉換成功!" + file.Path;
else
MsgBox.Text = "失敗";
}
}
/// <summary>
/// 處理并儲存圖檔
/// </summary>
/// <param name="inputFile">輸入檔案</param>
/// <param name="outputFile">輸出檔案</param>
/// <param name="longSide">長邊長度</param>
/// <returns>成功傳回true,否則false。</returns>
private async Task<bool> LoadSaveFileAsync(StorageFile inputFile, StorageFile outputFile, uint longSide)
{
try
{
Guid encoderId;
switch (outputFile.FileType)
{
case ".png":
encoderId = BitmapEncoder.PngEncoderId;
break;
case ".bmp":
encoderId = BitmapEncoder.BmpEncoderId;
break;
case ".jpg":
default:
encoderId = BitmapEncoder.JpegEncoderId;
break;
}
//圖檔處理部分
using (IRandomAccessStream inputStream = await inputFile.OpenAsync(FileAccessMode.Read),
outputStream = await outputFile.OpenAsync(FileAccessMode.ReadWrite))
{
//BitmapEncoder需要一個空的輸出流; 但是使用者可能已經選擇了預先存在的檔案,是以清零。
outputStream.Size = 0;
//從解碼器擷取像素資料。 我們對解碼的像素應用使用者請求的變換以利用解碼器中的潛在優化。
BitmapDecoder decoder = await BitmapDecoder.CreateAsync(inputStream);
BitmapTransform transform = new BitmapTransform();
//原圖尺寸比轉換尺寸更小
if (decoder.PixelHeight < longSide && decoder.PixelWidth < longSide)
throw new Exception("設定的尺寸大于原圖尺寸!");
// 判斷長邊并按原圖比例确定另一條邊的長度
if (decoder.PixelHeight > decoder.PixelWidth)
{
transform.ScaledHeight = longSide;
transform.ScaledWidth = (uint)(decoder.PixelWidth * ((float)longSide /decoder.PixelHeight));
}
else
{
transform.ScaledHeight = (uint)(decoder.PixelHeight * ((float)longSide/decoder.PixelWidth));
transform.ScaledWidth = longSide;
}
// Fant是相對高品質的插值模式。
transform.InterpolationMode = BitmapInterpolationMode.Fant;
// BitmapDecoder訓示最佳比對本地存儲的圖像資料的像素格式和alpha模式。 這可以提供高性能的與或品質增益。
BitmapPixelFormat format = decoder.BitmapPixelFormat;
BitmapAlphaMode alpha = decoder.BitmapAlphaMode;
// PixelDataProvider提供對位圖幀中像素資料的通路
PixelDataProvider pixelProvider = await decoder.GetPixelDataAsync(
format,
alpha,
transform,
ExifOrientationMode.RespectExifOrientation,
ColorManagementMode.ColorManageToSRgb
);
byte[] pixels = pixelProvider.DetachPixelData();
//将像素資料寫入編碼器。
BitmapEncoder encoder = await BitmapEncoder.CreateAsync(encoderId, outputStream);
//設定像素資料
encoder.SetPixelData(
format,
alpha,
transform.ScaledWidth,
transform.ScaledHeight,
decoder.DpiX,
decoder.DpiY,
pixels
);
await encoder.FlushAsync(); //異步送出和重新整理所有圖像資料(這一步儲存圖檔到檔案)
Debug.WriteLine("儲存成功:" + outputFile.Path);
return true;
}
}
catch (Exception err)
{
Debug.WriteLine(err.Message);
return false;
}
}
}
}
![](https://img.laitimes.com/img/__Qf2AjLwojIjJCLyojI0JCLiIXZ05WZD9CX5RXa2Fmcn9CXwczLcVmds92czlGZvwVP9EUTDZ0aRJkSwk0LcxGbpZ2LcBDM08CXlpXazRnbvZ2LcRlMMVDT2EWNvwFdu9mZvwFMjpXTwEkeOJTT6hVaWhUYwwmMaZXUYpVd1kmYr50MZV3YyI2cKJDT29GRjBjUIF2LcRHelR3LcJzLctmch1mclRXY39jN0UzNwcTNwIjNxMDM3EDMy8CX0Vmbu4GZzNmLn9Gbi1yZtl2Lc9CX6MHc0RHaiojIsJye.jpg)
話說這個Demo還挺有用,平時壓縮一個什麼圖檔就這麼一下子搞定了。
注,這個方法我是從微軟的官方示例裡學到的,并修改了一下,位址 https://github.com/Microsoft/Windows-universal-samples/tree/master/Samples/SimpleImaging