Easyx无边窗口画笔：鼠标按下+鼠标移动

#include <windows.h>
#include <iostream>
#include<stdio.h>
#include <graphics.h>

using namespace std;


struct Point
{
	int x;    //存储鼠标坐标
	int y;
};


struct LineTool
{
	int size;
	COLORREF color;
	struct Point begin;
	struct Point end;
	int isDown;               //鼠标 按下 和 弹起 的变量
};


struct LineTool linetool = { 5,WHITE,{0,0},{0,0},0};


void drawLine(ExMessage msg)
{
	if (msg.message == WM_LBUTTONDOWN)  //左键按下
	{
		linetool.isDown = 1;
		linetool.begin.x = msg.x;
		linetool.begin.y = msg.y;
    }

	if (msg.message == WM_LBUTTONUP)   //鼠标弹起
	{
		linetool.isDown = 0;
	}

	if (linetool.isDown == 1 && msg.message == WM_MOUSEMOVE)  //鼠标移动
	{
		setlinestyle(PS_SOLID,5);
		line(linetool.begin.x,linetool.begin.y,msg.x,msg.y);

	}
         
    //鼠标不移动，终点为设为鼠标起点
 
	linetool.begin.x = msg.x;
	linetool.begin.y = msg.y;

}



int main()
{



	initgraph(640, 480, SH