opencv Mat显示到指定窗体 Direct2D实现

对于opencv的imshow函数，恐怕我们是再熟悉不过了，它会创建一个窗体，然后将mat显示到窗体中。

然而，实际开发程序中，会有这样一种需求：上层将创建好的窗体，传递给下层dll，下层dll将得到的一张张图像直接显示到窗体中去。

本文主要记录利用direct2d的实现方法。

1、在项目中添加 BaseFactory.h文件

// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF  // ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO  // THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A  // PARTICULAR PURPOSE.  //  // Copyright (c) Microsoft Corporation. All rights reserved  //  #pragma once  // Modify the following defines if you have to target a platform prior to the ones specified below.  // Refer to MSDN for the latest info on corresponding values for different platforms.  #ifndef WINVER              // Allow use of features specific to Windows 7 or later.  #define WINVER 0x0700       // Change this to the appropriate value to target other versions of Windows.  #endif  #ifndef _WIN32_WINNT        // Allow use of features specific to Windows 7 or later.  #define _WIN32_WINNT 0x0700 // Change this to the appropriate value to target other versions of Windows.  #endif  #ifndef UNICODE  #define UNICODE  #endif  // Exclude rarely-used items from Windows headers.  #include <d2d1.h>  //#include <d2d1helper.h>  /*******************************************************************                                                                 **  Macros                                                         **                                                                 *******************************************************************/template<class Interface>inline void SafeRelease(	Interface **ppInterfaceToRelease	){	if (*ppInterfaceToRelease != NULL)	{		(*ppInterfaceToRelease)->Release();		(*ppInterfaceToRelease) = NULL;	}}#ifndef Assert  #if defined( DEBUG ) || defined( _DEBUG )  #define Assert(b) do {if (!(b)) {OutputDebugStringA("Assert: " #b "/n");}} while(0)  #else  #define Assert(b)  #endif //DEBUG || _DEBUG  #endif  #ifndef HINST_THISCOMPONENT  EXTERN_C IMAGE_DOS_HEADER __ImageBase;#define HINST_THISCOMPONENT ((HINSTANCE)&__ImageBase)  #endif  class BaseFactory{public:	BaseFactory(void);	~BaseFactory(void);	bool Initialize(HWND hwnd, int width, int height);private:	// Initialize device-dependent resources.  	HRESULT CreateDeviceResources();	// Release device-dependent resource.  public:	//绘图  	void OnRender(char *data);	void DiscardDeviceResources();	//图片信息  	int imgwidth;	int imgheight;	D2D1_RECT_U imgrect;	char *imgdata;private:	RECT rc;	HWND m_hwnd;	ID2D1Factory* m_pDirect2dFactory;	ID2D1HwndRenderTarget* m_pRenderTarget;	ID2D1Bitmap* m_pBitmap;};
2、添加BaseFactory.cpp文件
#include "BaseFactory.h"  BaseFactory::BaseFactory(void){}bool BaseFactory::Initialize(HWND hwnd, int width, int height){	imgheight = height;	imgwidth = width;	m_hwnd = hwnd;	m_pRenderTarget = nullptr;	m_pBitmap = nullptr;	CreateDeviceResources();	return true;}BaseFactory::~BaseFactory(void){}HRESULT BaseFactory::CreateDeviceResources(){	D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED, &m_pDirect2dFactory);	HRESULT hr = S_OK;	if (!m_pRenderTarget)	{		GetClientRect(m_hwnd, &rc);		D2D1_SIZE_U size = D2D1::SizeU			(			rc.right - rc.left,			rc.bottom - rc.top			);		// Create a Direct2D render target.  		hr = m_pDirect2dFactory->CreateHwndRenderTarget(			D2D1::RenderTargetProperties(),			D2D1::HwndRenderTargetProperties(m_hwnd, size, D2D1_PRESENT_OPTIONS_IMMEDIATELY),//第三个参数设置不等待垂直同步，默认垂直同步时最高刷新频率为显卡刷新频率，一般60FPS  			&m_pRenderTarget			);		//创建位图  		D2D1_SIZE_U imgsize = D2D1::SizeU(imgwidth, imgheight);		D2D1_PIXEL_FORMAT pixelFormat =  //位图像素格式描述  		{			DXGI_FORMAT_B8G8R8A8_UNORM, //该参数设置图像数据区的像素格式，现为RGBA，可根据需要改为别的格式，只是后面的数据拷贝要做相应的调整  			D2D1_ALPHA_MODE_IGNORE		};		D2D1_BITMAP_PROPERTIES prop =  //位图具体信息描述  		{			pixelFormat,			imgsize.width,			imgsize.height		};		long pitch = imgsize.width * 4;		imgdata = new char[imgsize.width * imgsize.height * 4];		memset(imgdata, 0, imgsize.width * imgsize.height * 4);		m_pRenderTarget->SetAntialiasMode(D2D1_ANTIALIAS_MODE_PER_PRIMITIVE);//设置图像为抗锯齿模式  		m_pRenderTarget->CreateBitmap(imgsize, imgdata, pitch, &prop, &m_pBitmap);		imgrect.left = 0;		imgrect.right = imgwidth;		imgrect.top = 0;		imgrect.bottom = imgheight;	}	return hr;}void BaseFactory::DiscardDeviceResources(){	delete[] imgdata;	SafeRelease(&m_pRenderTarget);	m_pDirect2dFactory->Release();	m_pBitmap->Release();}void BaseFactory::OnRender(char *data)//绘制图形到指定控件中  {	m_pRenderTarget->BeginDraw();//跟显示刷新频率有关系  	m_pBitmap->CopyFromMemory(&imgrect, data, imgwidth * 4);	m_pRenderTarget->DrawBitmap(m_pBitmap, D2D1::RectF(0, 0, rc.right - rc.left, rc.bottom - rc.top));//该矩形大小会受到"更改文本、应用和其他项目的大小:xxx%"的影响  	m_pRenderTarget->EndDraw();}
3、添加附加依赖项 d2d1.lib  和 程序运行所需要的d2d1.dll，d2d1.dll应该在电脑中能够搜索到。
4、使用示例
void test(HWND handle)//需要传入的窗体句柄{	HWND m_hWnd;	m_hWnd = HWND(handle);	string filename = "test.avi";//打开的视频文件  	VideoCapture capture;	capture.open(filename);		int image_width = 672;	int image_height = 378;		BaseFactory* m_BaseFactory = new BaseFactory();//创建Direct2D工厂对象   	m_BaseFactory->Initialize(m_hWnd, image_width, image_height);//初始化 	char *data = new char[image_width*image_height * 4];	while (true)	{		Mat image;		capture >> image;		if (image.empty()) break;		for (size_t row = 0; row < image_height; row++)			for (size_t col = 0; col < image_width; col++)			{				int point = col * 3 + row*image_width * 3;				int pointrbga = col * 4 + row*image_width * 4;				data[pointrbga + 0] = image.data[point + 0];				data[pointrbga + 1] = image.data[point + 1];				data[pointrbga + 2] = image.data[point + 2];			}		m_BaseFactory->OnRender(data);		Sleep(30);	}	//将rgb转为rgba 	//释放对象，回收内存  	if (m_BaseFactory != NULL)	{		m_BaseFactory->DiscardDeviceResources();		delete m_BaseFactory;		m_BaseFactory = NULL;	}	delete[]data;}5、以上四个步骤，就可以用起来了。可以在上层传入窗体的句柄，创建一个线程，下层就可以实时的把获取的照片显示到指定窗体了，同时不影响上层的任何操作。
但direct2d的方法，博主亲自使用后，发现d2d1.dll会在有的系统上报错，导致程序崩溃性错误。在Win7系统上，即使有serve pack1，也会无法使用，安装VS2013之后，就可以正常使用了，然而总不能够要求所有使用者的电脑都安装VS吧。
希望看到此博文的读者，有什么好的办法解决d2d1.dll报错问题，可以告诉我下，不胜感激。