关于WPF WriteableBitmap类直接操作像素点的问题

WPF（Windows Presentation Foundation）是微软推出的基于Windows 的用户界面框架，属于.NET Framework 3.0的一部分。它提供了统一的编程模型、语言和框架，真正做到了分离界面设计人员与开发人员的工作；同时它提供了全新的多媒体交互用户图形界面。

还是话不多说，直接上码：

1.新建WpfApp应用程序

2.MainWindow.xaml文件代码如下：

3.MainWindow.xaml.cs文件代码如下：

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Drawing;
using System.Drawing.Drawing2D;

namespace WpfApp1
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
public void Button_Click(object sender, RoutedEventArgs e)
WriteableBitmap wb = new WriteableBitmap((int)imgGrid.ActualWidth, (int)imgGrid.ActualHeight, 96, 96, PixelFormats.Pbgra32, null);
wb.Lock();
Bitmap backBitmap = new Bitmap((int)imgGrid.ActualWidth, (int)imgGrid.ActualHeight, wb.BackBufferStride, System.Drawing.Imaging.PixelFormat.Format32bppArgb, wb.BackBuffer);
Int32Rect rect = new Int32Rect(0, 0, (int)imgGrid.ActualWidth, (int)imgGrid.ActualHeight);
byte[] pixels = new byte[(int)imgGrid.ActualWidth * (int)imgGrid.ActualHeight * wb.Format.BitsPerPixel / 8];
Random rand = new Random();
for (int y = 0; y < wb.PixelHeight; y++)
{
for (int x = 0; x < wb.PixelWidth; x++)
{
int alpha = 0;
int red = 0;
int green = 0;
int blue = 0;
if ((x % 5 == 0) || (y % 7 == 0))
{
red = (int)((double)y / wb.PixelHeight * 255);
green = rand.Next(100, 255);
blue = (int)((double)x / wb.PixelWidth * 255);
alpha = 255;
}
else
red = (int)((double)x / wb.PixelWidth * 255);
blue = (int)((double)y / wb.PixelHeight * 255);
alpha = 50;
int pixeloffset = (x + y * wb.PixelWidth) * wb.Format.BitsPerPixel / 8;
pixels[pixeloffset] = (byte)blue;
pixels[pixeloffset + 1] = (byte)green;
pixels[pixeloffset + 2] = (byte)red;
pixels[pixeloffset + 3] = (byte)alpha;
}
int stride = (wb.PixelWidth * wb.Format.BitsPerPixel) / 8;
wb.WritePixels(rect, pixels, stride, 0);
}
wb.Unlock();
backBitmap.Dispose();
backBitmap = null;
img.Source = wb;
}
}