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C#搞跨平台桌面UI，分别实现Windows，Mac，Linux屏幕截图
source link: https://www.cnblogs.com/dskin/p/14822862.html
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C#搞跨平台桌面UI，分别实现Windows，Mac，Linux屏幕截图 - DSkin - 博客园
随笔- 19 文章- 0 评论- 265 阅读-
13万
搞跨平台IM，截图功能少不了。
Windows
创建GDI的兼容位图，把桌面的图像通过BitBlt拷贝到兼容位图里，通过兼容位图的数据指针创建Bitmap对象，由于兼容位图的内存是非托管的，Bitmap无法释放该内存，拷贝一下，把兼容位图的释放掉，新的Bitmap的内存就可以由新Bitmap来自己托管释放。
public override Bitmap Screenshot()
{
var srcDC = GetDC(IntPtr.Zero);
var bounds = Bounds;
IntPtr memDc = CreateCompatibleDC(srcDC);
BITMAPINFOHEADER info = new BITMAPINFOHEADER();
info.biSize = (uint)Marshal.SizeOf(typeof(BITMAPINFOHEADER));
info.biBitCount = 32;
info.biHeight = -(int)bounds.Height;
info.biWidth = (int)bounds.Width;
info.biPlanes = 1;
var hBitmap = CreateDIBSection(memDc, ref info, 0, out var ppvBits, IntPtr.Zero, 0);
var oldBits = SelectObject(memDc, hBitmap);
BitBlt(memDc, 0, 0, (int)bounds.Width,
(int)bounds.Height, srcDC, (int)bounds.X, (int)bounds.Y, TernaryRasterOperations.SRCCOPY);
Bitmap temp = new Bitmap((int)bounds.Width, (int)bounds.Height, (int)bounds.Width * 4, PixelFormat.Bgra, ppvBits);
Bitmap bitmap = (Bitmap)temp.Clone();
temp.Dispose();
SelectObject(memDc, oldBits);
DeleteObject(hBitmap);
DeleteDC(memDc);
ReleaseDC(IntPtr.Zero, srcDC);
return bitmap;
}
直接使用Mac里的 CGWindowListCreateImage 来截图，由于数据格式不同，需要读取像素，一个个设置给Bitmap
Mac里在不同权限选项下截取的图片内容不同的，没有录制权限的情况下只能截取当前程序的界面和空的桌面。
public unsafe override Bitmap Screenshot()
{
using (var img = new CGImage(CGImage.CGWindowListCreateImage(screen.Frame, CGWindowListOption.All, 0, CGWindowImageOption.Default), owns: true))
{
//CGImage imageRef = CGImage.CGWindowListCreateImage(mainRect, kCGWindowListOptionOnScreenOnly, kCGNullWindowID, kCGWindowImageNominalResolution | kCGWindowImageShouldBeOpaque);
var height = img.Height;
var width = img.Width;
var bpr = img.BytesPerRow;
var bpp = img.BitsPerPixel;
var bpc = img.BitsPerComponent;
var bytes_per_pixel = bpp / bpc;
using (var data = img.DataProvider.CopyData())
{
var bitmap = new Bitmap(img.Width, img.Height);
var bytes = (byte*)data.Bytes;
using (var b = bitmap.Lock())
{
for (var row = 0; row < height; row++)
{
for (var col = 0; col < width; col++)
{
var pixel = &bytes[row * bpr + col * bytes_per_pixel];
b.SetPixel(col, row, pixel[3], pixel[2], pixel[1], pixel[0]);
}
}
}
return bitmap;
}
}
}
Linux
使用XGetImage来截图，同样需要转换一下位图格式
public override Bitmap Screenshot()
{
var bounds = Bounds;
var image = XGetImage(LinuxPlatform.Platform.Display, LinuxPlatform.Platform.Info.RootWindow, (int)bounds.X, (int)bounds.Y, (int)bounds.Width,
(int)bounds.Height, ~0, 2 /* ZPixmap*/);
if (image == IntPtr.Zero)
{
string s = String.Format("XGetImage returned NULL when asked to for a {0}x{1} region block",
bounds.Width, bounds.Height);
throw new InvalidOperationException(s);
}
Bitmap bmp = new Bitmap((int)bounds.Width, (int)bounds.Height);
var visual = LinuxPlatform.Platform.Info.TransparentVisualInfo;
int red, blue, green;
int red_mask = (int)visual.red_mask;
int blue_mask = (int)visual.blue_mask;
int green_mask = (int)visual.green_mask;
using (var b = bmp.Lock())
{
for (int y = 0; y < bounds.Height; y++)
{
for (int x = 0; x < bounds.Width; x++)
{
var pixel = XGetPixel(image, x, y);
switch (visual.depth)
{
case 16: /* 16bbp pixel transformation */
red = (int)((pixel & red_mask) >> 8) & 0xff;
green = (int)(((pixel & green_mask) >> 3)) & 0xff;
blue = (int)((pixel & blue_mask) << 3) & 0xff;
break;
case 24:
case 32:
red = (int)((pixel & red_mask) >> 16) & 0xff;
green = (int)(((pixel & green_mask) >> 8)) & 0xff;
blue = (int)((pixel & blue_mask)) & 0xff;
break;
default:
string text = string.Format("{0}bbp depth not supported.", visual.depth);
throw new NotImplementedException(text);
}
b.SetPixel(x, y, 255, (byte)red, (byte)green, (byte)blue);
}
}
}
XDestroyImage(image);
return bmp;
}
上面的就是CPF的内部实现，一般你不需要管这些细节，直接调用CPF的函数就行了。
最终封装到CPF就是一行代码就行
window.Screen.Screenshot();
要实现QQ截图的效果的话，先截图，再搞个全屏的窗体，把截图内容放到里面，再对屏幕截图进行裁剪，绘图处理。
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