C#搞跨平臺桌面UI,分別實現Windows,Mac,Linux螢幕截圖
阿新 • • 發佈:2021-06-17
搞跨平臺IM,截圖功能少不了。
Windows
建立GDI的相容點陣圖,把桌面的影象通過BitBlt拷貝到相容位圖裡,通過相容點陣圖的資料指標建立Bitmap物件,由於相容點陣圖的記憶體是非託管的,Bitmap無法釋放該記憶體,拷貝一下,把相容點陣圖的釋放掉,新的Bitmap的記憶體就可以由新Bitmap來自己託管釋放。
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; }
Mac
直接使用Mac裡的 CGWindowListCreateImage 來截圖,由於資料格式不同,需要讀取畫素,一個個設定給Bitmap
Mac裡在不同許可權選項下擷取的圖片內容不同的,沒有錄製許可權的情況下只能擷取當前程式的介面和空的桌面。
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來截圖,同樣需要轉換一下點陣圖格式
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的內部實現,一般你不需要管這些細節,直接呼叫CPF的函式就行了。
最終封裝到CPF就是一行程式碼就行
window.Screen.Screenshot();
要實現QQ截圖的效果的話,先截圖,再搞個全屏的窗體,把截圖內容放到裡面,再對螢幕截圖進行裁剪,繪圖處理。