base.h

#pragma once

#include<iostream>
#include<vector>
#include<map>
#include<cmath>
#include<assert.h>

#define PI					3.14159265358979323
#define DEG2RAD(theta)		(0.01745329251994329 * (theta))
#define FRACTION(v)			((v) - (int)(v))

using byte = unsigned char;

struct RGBA {
	byte mB;
	byte mG;
	byte mR;
	byte mA;

	RGBA(
		byte r = 255,
		byte g = 255,
		byte b = 255,
		byte a = 255)
	{
		mR = r;
		mG = g;
		mB = b;
		mA = a;
	}
};

struct Point {
	int32_t x;
	int32_t y;
	RGBA color;
};

application.h

#pragma once
#include "../global/base.h"
#include<Windows.h>

#define app Application::getInstance()

class Application {
public:
	static Application* getInstance();
	Application();
	~Application();

	//注册窗体类，创建一个窗体，显示
	bool initApplication(HINSTANCE hInstance, const uint32_t& width = 800, const uint32_t& height = 600);

	//托管了wndProc捕获的消息，并且进行处理
	void handleMessage(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);

	//每一帧/每一次循环，都会调用，捕获以及分发窗体消息
	bool peekMessage();

	void show();

	uint32_t getWidth() const { return mWidth; }
	uint32_t getHeight() const { return mHeight; }
	void* getCanvas() const { return mCanvasBuffer; }

private:
	BOOL createWindow(HINSTANCE hInstance);
	ATOM registerWindowClass(HINSTANCE hInstance);

private:
	static Application* mInstance;

	//为true表示当前窗体仍然在继续显示，程序一直在跑
	//为false表示窗体已经被命令关闭，程序需要退出
	bool		mAlive{ true };

	HINSTANCE	mWindowInst;
	WCHAR		mWindowClassName[100] = L"AppWindow";
	HWND		mHwnd;

	int			mWidth = 800;
	int			mHeight = 600;

	HDC			mhDC;//当前窗口主dc
	HDC			mCanvasDC;//创建的于mhDC相兼容的绘图用的dc
	HBITMAP		mhBmp;//mCanvasDC内部生成的bitmap
	void*		mCanvasBuffer{ nullptr };//mhBmp对应的内存起始位置指针
};

application.cpp

#include"application.h"

Application* Application::mInstance = nullptr;
Application* Application::getInstance() {
	if (mInstance == nullptr) {
		mInstance = new Application();
	}

	return mInstance;
}

Application::Application() {}
Application::~Application() {}

LRESULT CALLBACK Wndproc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) {
	Application::getInstance()->handleMessage(hWnd, message, wParam, lParam);
	return(DefWindowProc(hWnd, message, wParam, lParam));
}

bool Application::initApplication(HINSTANCE hInstance, const uint32_t& width, const uint32_t& height) {
	mWidth = width;
	mHeight = height;

	//初始化窗体类型，并且注册
	registerWindowClass(hInstance);

	//生成一个窗体，并且显示
	if (!createWindow(hInstance)) {
		return false;
	}

	//初始化画布
	/*
	* DC：Device Context 设备上下文描述对象
	* 每个窗口都有自己对应的设备区域映射，即mhDC
	* 这里创建一个与本窗口兼容的DC，mCanvasDC
	* 可以从mCanvasDC向mhDC拷贝绘图数据内容
	*/
	mhDC = GetDC(mHwnd);
	mCanvasDC = CreateCompatibleDC(mhDC);

	BITMAPINFO  bmpInfo{};
	bmpInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
	bmpInfo.bmiHeader.biWidth = mWidth;
	bmpInfo.bmiHeader.biHeight = mHeight;
	bmpInfo.bmiHeader.biPlanes = 1;
	bmpInfo.bmiHeader.biBitCount = 32;
	bmpInfo.bmiHeader.biCompression = BI_RGB; //实际上存储方式为bgra

	//创建与mhMem兼容的位图,其实实在mhMem指代的设备上划拨了一块内存，让mCanvasBuffer指向它
	mhBmp = CreateDIBSection(mCanvasDC, &bmpInfo, DIB_RGB_COLORS, (void**)&mCanvasBuffer, 0, 0);//在这里创建buffer的内存

	//一个设备可以创建多个位图，本设备使用mhBmp作为激活位图，对mCanvasDC的内存拷出，其实就是拷出了mhBmp的数据
	SelectObject(mCanvasDC, mhBmp);//选择位图mCanvasDC给作画
	memset(mCanvasBuffer, 0, mWidth * mHeight * 4); //清空buffer为0

	return true;
}

ATOM Application::registerWindowClass(HINSTANCE hInstance)
{
	WNDCLASSEXW wndClass;

	wndClass.cbSize = sizeof(WNDCLASSEX);
	wndClass.style = CS_HREDRAW | CS_VREDRAW;	//水平/垂直大小发生变化重绘窗口
	wndClass.lpfnWndProc = Wndproc;
	wndClass.cbClsExtra = 0;
	wndClass.cbWndExtra = 0;
	wndClass.hInstance = hInstance;		//应用程序句柄
	wndClass.hIcon = LoadIcon(NULL, IDI_APPLICATION);//应用程序图标,即任务栏的大图标
	wndClass.hCursor = LoadCursor(NULL, IDC_ARROW);//鼠标图标
	wndClass.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH);//窗口背景色
	wndClass.lpszMenuName = NULL;
	wndClass.lpszClassName = mWindowClassName;//窗口类名
	wndClass.hIconSm = LoadIcon(NULL, IDI_WINLOGO);//窗口标题图标

	return RegisterClassExW(&wndClass);
}

BOOL Application::createWindow(HINSTANCE hInstance)
{
	mWindowInst = hInstance;

	/*
	* WS_POPUP:不需要标题栏，则不需要边框
	* WS_OVERLAPPEDWINDOW：拥有普通程序主窗口的所有特点，必须有标题且有边框
	*
	* WS_CLIPSIBLINGS:被兄弟窗口挡住区域不绘制
	* WS_CLIPCHILDREN:被子窗口遮挡住的区域不绘制
	*/

	auto dwExStyle = WS_EX_APPWINDOW;
	auto dwStyle = WS_OVERLAPPEDWINDOW | WS_CLIPSIBLINGS | WS_CLIPCHILDREN;

	//由于存在标题栏等，所以需要计算中间显示区域的大小,比如PopUp的窗体，就没有标题栏，则不会改变
	RECT windowRect;
	windowRect.left = 0L;
	windowRect.top = 0L;
	windowRect.right = (long)mWidth;
	windowRect.bottom = (long)mHeight;
	AdjustWindowRectEx(&windowRect, dwStyle, FALSE, dwExStyle);

	mHwnd = CreateWindowW(
		mWindowClassName,
		(LPCWSTR)"GraphicLearning",	//窗体标题
		dwStyle,
		500,//x位置，相对左上角
		500,//y位置，相对左上角
		windowRect.right - windowRect.left,
		windowRect.bottom - windowRect.top,
		nullptr,//父窗体
		nullptr,//菜单栏
		hInstance,//程序实例
		nullptr);//额外参数


	if (!mHwnd)
	{
		return FALSE;
	}

	ShowWindow(mHwnd, true);
	UpdateWindow(mHwnd);

	return TRUE;
}

bool Application::peekMessage() {
	MSG msg;
	if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
	{
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}

	return mAlive;
}

void Application::handleMessage(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) {
	switch (message)
	{
	case WM_CLOSE: {
		DestroyWindow(hWnd);//此处销毁窗体,会自动发出WM_DESTROY
		break;
	}
	case WM_PAINT:
	{
		PAINTSTRUCT ps;
		HDC hdc = BeginPaint(hWnd, &ps);
		EndPaint(hWnd, &ps);
	}
	break;
	case WM_DESTROY: {
		PostQuitMessage(0);//发出线程终止请求
		mAlive = false;
		break;
	}
	}
}

void Application::show() {
	BitBlt(mhDC, 0, 0, mWidth, mHeight, mCanvasDC, 0, 0, SRCCOPY);
}