我创建了一个小小的wpf测试应用程序,它使用 System.Drawing.Graphics 和wpf的 InteropBitmap 每30毫秒渲染一些随机矩形。我以为InteropBitmap会比WriteableBitmap快:它具有从内存部分更新自身的能力。
在执行应用程序(屏幕尺寸1600 * 1200)时,应用程序的CPU使用率仅为 2-10%(双核3GHz)。但是总体CPU使用率约为 80-90%,因为“系统(NT内核和系统)”进程最多上升了70%! 编辑:我注意到RAM使用率在15秒内定期增加超过1 GB,然后突然回落到其正常水平,依此类推。
也许以下代码可以优化? :
namespace InteropBitmapTest{
using System;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Interop;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using Color = System.Drawing.Color;
public partial class Window1 : Window
{
private System.Drawing.Bitmap gdiBitmap;
private Graphics graphics;
InteropBitmap interopBitmap;
const uint FILE_MAP_ALL_ACCESS = 0xF001F;
const uint PAGE_READWRITE = 0x04;
private int bpp = PixelFormats.Bgr32.BitsPerPixel / 8;
private Random random;
private System.Windows.Forms.Timer timer = new System.Windows.Forms.Timer();
SolidBrush[] brushes = new SolidBrush[] { new SolidBrush(Color.Lime), new SolidBrush(Color.White) };
[DllImport("kernel32.dll", SetLastError = true)]
static extern IntPtr CreateFileMapping(IntPtr hFile,
IntPtr lpFileMappingAttributes,
uint flProtect,
uint dwMaximumSizeHigh,
uint dwMaximumSizeLow,
string lpName);
[DllImport("kernel32.dll", SetLastError = true)]
static extern IntPtr MapViewOfFile(IntPtr hFileMappingObject,
uint dwDesiredAccess,
uint dwFileOffsetHigh,
uint dwFileOffsetLow,
uint dwNumberOfBytesToMap);
public Window1()
{
InitializeComponent();
Loaded += Window1_Loaded;
WindowState = WindowState.Maximized;
timer.Tick += timer_Tick;
timer.Interval = 30;
random = new Random();
}
void Window1_Loaded(object sender, RoutedEventArgs e)
{
// create interopbitmap, gdi bitmap, get Graphics object
CreateBitmaps();
// start drawing 100 gdi+ rectangles every 30 msec:
timer.Start();
}
void timer_Tick(object sender, EventArgs e)
{
int width = 50;
// Draw 100 gdi+ rectangles :
for (int i = 0; i < 100; i++)
{
int left = random.Next((int)(ActualWidth - width));
int top = random.Next((int)(ActualHeight - width));
graphics.FillRectangle(brushes[left % 2], left, top, width, width);
}
interopBitmap.Invalidate(); // should only update video memory (and not copy the whole bitmap to video memory before)
}
void CreateBitmaps()
{
uint byteCount = (uint) (ActualWidth * ActualHeight * bpp);
//Allocate/reserve memory to write to
var sectionPointer = CreateFileMapping(new IntPtr(-1), IntPtr.Zero, PAGE_READWRITE, 0, byteCount, null);
var mapPointer = MapViewOfFile(sectionPointer, FILE_MAP_ALL_ACCESS, 0, 0, byteCount);
var format = PixelFormats.Bgr32;
//create the InteropBitmap
interopBitmap = Imaging.CreateBitmapSourceFromMemorySection(sectionPointer, (int)ActualWidth, (int)ActualHeight, format,
(int)(ActualWidth * format.BitsPerPixel / 8), 0) as InteropBitmap;
//create the GDI Bitmap
gdiBitmap = new System.Drawing.Bitmap((int)ActualWidth, (int)ActualHeight,
(int)ActualWidth * bpp,
System.Drawing.Imaging.PixelFormat.Format32bppPArgb,
mapPointer);
// Get good old GDI Graphics
graphics = Graphics.FromImage(gdiBitmap);
// set the interopbitmap as Source to the wpf image defined in XAML
wpfImage.Source = (BitmapSource) interopBitmap;
}
}}
XAML:
<Window x:Class="InteropBitmapTest.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="300">
<Image Name="wpfImage" Stretch="None" />
</Window>
最佳答案
WTF:这是一个 InteropBitmap内存泄漏,这是.NET 4.0中的新功能:
http://connect.microsoft.com/VisualStudio/feedback/details/603004/massive-gpu-memory-leak-with-interopbitmap
https://connect.microsoft.com/VisualStudio/feedback/details/585875/interopbitmap-is-way-less-performant-in-net-4-0-vs-net-3-5
将目标框架设置为3.5,一切正常!
另一种选择是放置“GC.Collect();”。在每个“interopBitmap.Invalidate();”之后称呼。
关于c# - WPF的InteropBitmap与GDI + : high cpu usage,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/4473515/