c--exersize
/
第二章：图片
/
1.图片的读取和导入

---------------------------------图片绘制.CPP
// 图片绘制.cpp : 定义应用程序的入口点。
//
#pragma once
#include "framework.h"
#include "图片绘制.h"
#include "Canvas.h"
#include"Image.h"
#define MAX_LOADSTRING 100

// 全局变量:
HINSTANCE hInst;                                // 当前实例
WCHAR szTitle[MAX_LOADSTRING];                  // 标题栏文本
WCHAR szWindowClass[MAX_LOADSTRING];            // 主窗口类名

HWND hWnd;
HDC hDC;
HDC hMem;
int wWidth = 900;
int wHeight = 700;
GT::Canvas *  _canvas = NULL;
GT::Image* _image = NULL;

void Render();

// 此代码模块中包含的函数的前向声明:
ATOM                MyRegisterClass(HINSTANCE hInstance);
BOOL                InitInstance(HINSTANCE, int);
LRESULT CALLBACK    WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK    About(HWND, UINT, WPARAM, LPARAM);

int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
                     _In_opt_ HINSTANCE hPrevInstance,
                     _In_ LPWSTR    lpCmdLine,
                     _In_ int       nCmdShow)
{
    UNREFERENCED_PARAMETER(hPrevInstance);
    UNREFERENCED_PARAMETER(lpCmdLine);

    // TODO: 在此处放置代码。

    // 初始化全局字符串
    LoadStringW(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
    LoadStringW(hInstance, IDC_MY, szWindowClass, MAX_LOADSTRING);
    MyRegisterClass(hInstance);

    // 执行应用程序初始化:
    if (!InitInstance (hInstance, nCmdShow))
    {
        return FALSE;
    }

    HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_MY));


    //+++++++++++++创建绘图所需的位图
    void* buffer = 0;
    BITMAPINFO bmpInfo;
    hDC = GetDC(hWnd);
    hMem = CreateCompatibleDC(hDC);
    bmpInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
     bmpInfo.bmiHeader.biWidth = wWidth;
    bmpInfo.bmiHeader.biHeight = wHeight;
    bmpInfo.bmiHeader.biPlanes = 1;
    bmpInfo.bmiHeader.biBitCount = 32;
    bmpInfo.bmiHeader.biCompression = BI_RGB;
    bmpInfo.bmiHeader.biSizeImage = 0;
    bmpInfo.bmiHeader.biXPelsPerMeter = 0;
    bmpInfo.bmiHeader.biYPelsPerMeter = 0;
    bmpInfo.bmiHeader.biClrUsed = 0;
    bmpInfo.bmiHeader.biClrImportant = 0;

    HBITMAP hBmp = CreateDIBSection(hDC,&bmpInfo, DIB_RGB_COLORS, (void**)&buffer, 0, 0);
    SelectObject(hMem, hBmp);
    memset(buffer, 0, wWidth * wHeight * 4);
    MSG msg;
    //+++++++++++++创建绘图所需的位图
    _canvas = new  GT::Canvas( wWidth, wHeight, buffer);
    _image = GT::Image::readFromFile("res/x.png");//此处为读入图片的了路径

    // 主消息循环:
    while (GetMessage(&msg, nullptr, 0, 0))
    {
        if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
        {
            TranslateMessage(&msg);
             DispatchMessage(&msg);
        }

        Render();
     }

    return (int) msg.wParam;
  }

void Render()
{
    _canvas->drawImage(0, 0, _image);
    BitBlt(hDC, 0, 0, wWidth, wHeight, hMem, 0, 0, SRCCOPY);
}

//
//  函数: MyRegisterClass()
//
//  目标: 注册窗口类。
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
    WNDCLASSEXW wcex;

    wcex.cbSize = sizeof(WNDCLASSEX);

    wcex.style          = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = WndProc;
    wcex.cbClsExtra     = 0;
    wcex.cbWndExtra     = 0;
    wcex.hInstance      = hInstance;
    wcex.hIcon          = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_MY));
    wcex.hCursor        = LoadCursor(nullptr, IDC_ARROW);
    wcex.hbrBackground  = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName   = NULL;
    wcex.lpszClassName  = szWindowClass;
    wcex.hIconSm        = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

    return RegisterClassExW(&wcex);
}

//
//   函数: InitInstance(HINSTANCE, int)
//
//   目标: 保存实例句柄并创建主窗口
//
//   注释:
//
//        在此函数中，我们在全局变量中保存实例句柄并
//        创建和显示主程序窗口。
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
   hInst = hInstance; // 将实例句柄存储在全局变量中

    hWnd = CreateWindowW(szWindowClass, szTitle, WS_POPUP,
      CW_USEDEFAULT, 0, wWidth, wHeight, nullptr, nullptr, hInstance, nullptr);

   if (!hWnd)
   {
      return FALSE;
   }

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   return TRUE;
}

//
//  函数: WndProc(HWND, UINT, WPARAM, LPARAM)
//
//  目标: 处理主窗口的消息。
//
//  WM_COMMAND  - 处理应用程序菜单
//  WM_PAINT    - 绘制主窗口
//  WM_DESTROY  - 发送退出消息并返回
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
    case WM_COMMAND:
        {
            int wmId = LOWORD(wParam);
            // 分析菜单选择:
            switch (wmId)
            {
            case IDM_ABOUT:
                DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
                break;
            case IDM_EXIT:
                DestroyWindow(hWnd);
                break;
            default:
                return DefWindowProc(hWnd, message, wParam, lParam);
            }
        }
        break;
    case WM_PAINT:
        {
            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(hWnd, &ps);
            // TODO: 在此处添加使用 hdc 的任何绘图代码...
            EndPaint(hWnd, &ps);
        }
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

// “关于”框的消息处理程序。
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
    UNREFERENCED_PARAMETER(lParam);
    switch (message)
    {
    case WM_INITDIALOG:
        return (INT_PTR)TRUE;

    case WM_COMMAND:
        if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
        {
            EndDialog(hDlg, LOWORD(wParam));
            return (INT_PTR)TRUE;
        }
        break;
    }
    return (INT_PTR)FALSE;
}


Canvas.h
#pragma once
#include"GTMATH.hpp"
#include"Image.h"

namespace GT {
	class Canvas
	{
	public:
		int m_width;
		int m_height;
		RGBA* m_buffer;


		Canvas(int _width, int _height, void* _buffer) {
			if (_height <= 0 || _width <= 0)
			{
				m_height = -1;
				m_width = -1;
				m_buffer = nullptr;
			}
			m_width = _width;
			m_height = _height;
			m_buffer = (RGBA*) _buffer;
		}
		~Canvas() {}
		void drawPoint(int x, int y, RGBA _color)
		{

			if (x<0 || y<0 || x>=m_width || y>=m_height )
			{
				return;
			}
			 m_buffer[y * m_width + x]= _color;
		}
		void drawImage(int _x, int _y, Image* _image);
	};

}


-------------------------------------------------Canvas.cpp
#include "Canvas.h"
namespace GT {
	void Canvas::drawImage(int _x, int _y, Image* _image)
	{
		for (int u = 0; u < _image->GetWidth(); u ++) {
			for (int v = 0; v < _image->GetHeight(); v++) {

				RGBA _color = _image->GetColor(u, v);
				drawPoint(_x + u, _y + v,_color);
			}
		}
	}
}


------------------------------Image.h
#pragma once
#include"GTMATH.hpp"
#include"Image.h"

namespace GT {
	class Canvas
	{
	public:
		int m_width;
		int m_height;
		RGBA* m_buffer;


		Canvas(int _width, int _height, void* _buffer) {
			if (_height <= 0 || _width <= 0)
			{
				m_height = -1;
				m_width = -1;
				m_buffer = nullptr;
			}
			m_width = _width;
			m_height = _height;
			m_buffer = (RGBA*) _buffer;
		}
		~Canvas() {}
		void drawPoint(int x, int y, RGBA _color)
		{

			if (x<0 || y<0 || x>=m_width || y>=m_height )
			{
				return;
			}
			 m_buffer[y * m_width + x]= _color;
		}
		void drawImage(int _x, int _y, Image* _image);
	};

}


-------------------------------------Image.cpp

#pragma once
#include"Image.h"
#define STB_IMAGE_IMPLEMENTATION
#include"stb_image.h"
namespace GT {

	 Image* Image::readFromFile(const char* _fileName)
	{
		int _picType=0 ;
		int _width= 0;
		int  _height=0 ;
		stbi_set_flip_vertically_on_load(true);
		byte* bits = stbi_load(_fileName, &_width, &_height, &_picType, STBI_rgb_alpha);
		//调整颜色
		for (int i = 0; i < _width * _height * 4; i += 4)
		{
			byte tmp = bits[i];
			bits[i] = bits[i + 2];
			bits[i + 2] = tmp;
		}
		//构造一个Image
		Image* _image = new Image(_width, _height, bits);
		stbi_image_free(bits);
		return _image;
	 }
}


----------------GTMATH.hpp
#pragma once
namespace GT {
	typedef unsigned char byte;

	class RGBA {
	public:
		byte m_r;
		byte m_g;
		byte m_b;
		byte m_a;
		RGBA(byte _r = 255,
			byte _g = 255,
			byte _b = 255,
			byte _a = 255)
		{
			m_b = _b;
			m_g = _g;
			m_r = _r;
			m_a = _a;
		}
		~RGBA() {}
	};
}


------stb.image.h：库下载地址：stb_image.h：https://github.com/nothings/stb/blob/master/stb_image.h