D2dengine edible tutorial (1) -- the simplest program

The goal is ： Create a window with a blue background

1. First the D2DEngine Four files of are added to the project

Right click on the item -> add to -> Existing items

2. Set the compliance mode to no (/permissive)

project -> attribute ->C/C+±> Language -> The compliance mode is set to no

If the mode is not set, an error will be reported . My understanding is that , Because Microsoft is VS2019 After starting, the requirements for value transfer become stricter , Image is not allowed by default char turn const char Such narrowing conversion , May cause memory leak . Here we don't need , Just turn it off .

3. Code

Let's start with Templates , This template is for all D2DEngine The programs are Universal

#include<windows.h>

#include"D2D_DRAW.h" // Directly reference the header file 




LRESULT CALLBACK CallBackFunc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    
	switch(message)
	{
    

	case WM_DESTROY:
		PostQuitMessage(0);
		break;

	default:
		return DefWindowProc(hwnd, message, wParam, lParam);
	}

	return 0;
}


int WINAPI WinMain(HINSTANCE hin, HINSTANCE, LPSTR, int CmdShow)
{
    

	MSG msg = {
    };
	WNDCLASSEX wcex = {
    };

	memset(&wcex, 0, sizeof(wcex));
	wcex.cbSize = sizeof(WNDCLASSEX);
	wcex.lpfnWndProc = CallBackFunc;
	wcex.lpszClassName = L"D2D";
	wcex.hInstance = hin;


	wcex.style = CS_GLOBALCLASS;  //  Get rid of ReDraw Redraw 
	wcex.hbrBackground = (HBRUSH)GetStockObject(NULL_BRUSH);
	//  Set to NULL_BRUSH, No need to come from GDI Any drawing of 

	RegisterClassEx(&wcex);

	HWND hwnd = CreateWindowW(wcex.lpszClassName, L"D2D",
		WS_OVERLAPPED | WS_SYSMENU, 
		// WS_OVERLAPPEDWINDOW  Will trigger OnSize news , Don't deal with this message for the time being 
		0, 0, 640, 480,
		nullptr,
		nullptr,
		hin,
		nullptr
	);

	ShowWindow(hwnd, CmdShow);
	//  because  CS_GLOBALCLASS, It must be used. ShowWindow Display window 


	//————————————————————————————————————————————————————————————————————





	//TODO: Do it here  Direct2D Rendering 





	//————————————————————————————————————————————————————————————————————
	

	while (GetMessage(&msg, NULL, 0, 0) > 0)
	{
    
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}

	return msg.wParam;
}

This program only needs to render in TODO part ( See note ) Just write it .

Member functions	effect
bool Initialize( hwnd, BrushColor)	D2DEngine Initialization of the device , Anything to do with D2DEngine All operations must go through this step first . Otherwise rendering fails . The parameters are ：hwnd Handle （ Required ）,BrushColor Brush color （ optional , Default white ）
void BeginDraw()	The signal that the program begins to draw ,D2DEngine The draw （ Rendering ） Operation can only be carried out after this function , Otherwise it will not work
void Clear(ClearColor)	（ Rendering ） Clear the screen and render the target background color , Parameters ：ClearColor Background color （ optional , Default white ）
void EndDraw()	The signal that the program stops drawing , Every time BeginDraw One time must end with this function .

Be careful ： belt ( Rendering ) The function of must be in BeginDraw() And EndDraw() It can only take effect between , Like the following code ：
Engine->BeginDraw();
Engine->Clear(); // Rendering function
Engine->EndDraw();

D2D.CPP

#include<windows.h>

#include"D2D_DRAW.h"

using namespace D2D1;



LRESULT CALLBACK CallBackFunc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    
	switch(message)
	{
    

	case WM_DESTROY:
		PostQuitMessage(0);
		break;

	default:
		return DefWindowProc(hwnd, message, wParam, lParam);
	}

	return 0;
}


int WINAPI WinMain(HINSTANCE hin, HINSTANCE, LPSTR, int CmdShow)
{
    

	MSG msg = {
    };
	WNDCLASSEX wcex = {
    };

	memset(&wcex, 0, sizeof(wcex));
	wcex.cbSize = sizeof(WNDCLASSEX);
	wcex.lpfnWndProc = CallBackFunc;
	wcex.lpszClassName = L"D2D";
	wcex.hInstance = hin;
	wcex.style = CS_GLOBALCLASS;
	wcex.hbrBackground = (HBRUSH)GetStockObject(NULL_BRUSH);

	RegisterClassEx(&wcex);

	HWND hwnd = CreateWindowW(wcex.lpszClassName, L"D2D",
		WS_OVERLAPPED | WS_SYSMENU,
		0, 0, 640, 480,
		nullptr,
		nullptr,
		hin,
		nullptr
	);

	ShowWindow(hwnd, CmdShow);


	//————————————————————————————————————————————————————————————————————

	D2DEngine* Engine = new D2DEngine; // establish  D2DEngine object 
	
	Engine->Initialize(hwnd); // Initialize with handle D2DEngine

	Engine->BeginDraw(); 

	Engine->Clear(ColorF::Blue);  // Empty the window and render it blue 

	Engine->EndDraw();

	//————————————————————————————————————————————————————————————————————


	while (GetMessage(&msg, NULL, 0, 0) > 0)
	{
    
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}

	return msg.wParam;
}

D2DEngine Resource link ：https://blog.csdn.net/DGAF2198588973/article/details/125909836

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