本文使用C++雙快取進行指定視窗截圖。CreateDIBSection建立應用程式可以直接寫入的、與裝置無關的點陣圖(DIB)，它提供記憶體中點陣圖的指標，外部程式可以直接使用。

需要注意的是，PrintWindow方法能夠抓取使用D3D渲染的視窗（例如Excel、Win10自帶視訊播放器），如果抓取普通視窗則會附帶視窗陰影，可見視窗陰影是Windows使用D3D渲染出來的。

1、PrintCaptureHelper.h

#pragma once
 
#include <windows.h>
#include <string>
using std::string;
 
class PrintCaptureHelper
{
public:
  PrintCaptureHelper();
  virtual ~PrintCaptureHelper();
 
  bool Init(const string& windowName);
  bool Init(HWND hwnd);
  void Cleanup();
  bool RefreshWindow();
  bool ChangeWindowHandle(const string& windowName);
  bool ChangeWindowHandle(HWND hwnd);
  bool Capture() const;
 
  const RECT& GetWindowRect() const { return windowRect_; }
  const RECT& GetClientRect() const { return clientRect_; }
  int GetBitmapDataSize() const { return bmpDataSize_; }
  HBITMAP GetBitmap() const { return bitmap_; }
  void* GetBitmapAddress() const { return bitsPtr_; }
 
private:
  HWND hwnd_;
  HDC scrDc_;
  HDC memDc_;
  HBITMAP bitmap_;
  HBITMAP oldBitmap_;
  void* bitsPtr_;
 
  RECT windowRect_;
  RECT clientRect_;
  int bmpDataSize_;
};

2、PrintCaptureHelper.cpp

#include "stdafx.h"
#include "PrintCaptureHelper.h"
 
 
PrintCaptureHelper::PrintCaptureHelper()
  : hwnd_(nullptr),scrDc_(nullptr),memDc_(nullptr),bitmap_(nullptr),oldBitmap_(nullptr),bitsPtr_(nullptr),windowRect_{ 0,0 },clientRect_{ 0,bmpDataSize_(0)
{
 
}
 
PrintCaptureHelper::~PrintCaptureHelper()
{
  Cleanup();
}
 
bool PrintCaptureHelper::Init(const string& windowName)
{
  const auto handle = ::FindWindowA(nullptr,windowName.c_str());
  if (handle == nullptr)
  {
    return false;
  }
 
  return Init(handle);
}
 
bool PrintCaptureHelper::Init(HWND hwnd)
{
  hwnd_ = hwnd;
 
  //獲取視窗大小
  if (!::GetWindowRect(hwnd_,&windowRect_) || !::GetClientRect(hwnd_,&clientRect_))
  {
    return false;
  }
 
  const auto clientRectWidth = clientRect_.right - clientRect_.left;
  const auto clientRectHeight = clientRect_.bottom - clientRect_.top;
  bmpDataSize_ = clientRectWidth * clientRectHeight * 4;
 
  //點陣圖資訊
  BITMAPINFO bitmapInfo;
  bitmapInfo.bmiHeader.biSize = sizeof(bitmapInfo);
  bitmapInfo.bmiHeader.biWidth = clientRectWidth;
  bitmapInfo.bmiHeader.biHeight = clientRectHeight;
  bitmapInfo.bmiHeader.biPlanes = 1;
  bitmapInfo.bmiHeader.biBitCount = 32;
  bitmapInfo.bmiHeader.biSizeImage = clientRectWidth * clientRectHeight;
  bitmapInfo.bmiHeader.biCompression = BI_RGB;
 
  scrDc_ = ::GetWindowDC(hwnd_);
  memDc_ = ::CreateCompatibleDC(scrDc_);
  bitmap_ = ::CreateDIBSection(scrDc_,&bitmapInfo,DIB_RGB_COLORS,&bitsPtr_,nullptr,0);
  if (bitmap_ == nullptr)
  {
    ::DeleteDC(memDc_);
    ::ReleaseDC(hwnd_,scrDc_);
    return false;
  }
 
  oldBitmap_ = static_cast<HBITMAP>(::SelectObject(memDc_,bitmap_));
  return true;
}
 
void PrintCaptureHelper::Cleanup()
{
  if (bitmap_ == nullptr)
  {
    return;
  }
 
  //刪除用過的物件
  ::SelectObject(memDc_,oldBitmap_);
  ::DeleteObject(bitmap_);
  ::DeleteDC(memDc_);
  ::ReleaseDC(hwnd_,scrDc_);
 
  hwnd_ = nullptr;
  scrDc_ = nullptr;
  memDc_ = nullptr;
  bitmap_ = nullptr;
  oldBitmap_ = nullptr;
}
 
bool PrintCaptureHelper::RefreshWindow()
{
  const auto hwnd = hwnd_;
  Cleanup();
  return Init(hwnd);
}
 
bool PrintCaptureHelper::ChangeWindowHandle(const string& windowName)
{
  Cleanup();
  return Init(windowName);
}
 
bool PrintCaptureHelper::ChangeWindowHandle(HWND hwnd)
{
  Cleanup();
  return Init(hwnd);
}
 
bool PrintCaptureHelper::Capture() const
{
  if (bitmap_ == nullptr || memDc_ == nullptr || scrDc_ == nullptr)
  {
    return false;
  }
 
  const auto ret = ::PrintWindow(hwnd_,memDc_,PW_CLIENTONLY | PW_RENDERFULLCONTENT);
  return ret != 0;
}

以上就是C++ 使用PrintWindow實現視窗截圖功能的詳細內容，更多關於c++ 視窗截圖的資料請關注我們其它相關文章！