#include<windows.h>

// winmm.lib をリンクする
#pragma comment(lib,"winmm")

#define SRATE	8000	//標本化周波数(1秒間のサンプル数)
#define F		400		//周波数(1秒間の波形数)

#define WIN_W	640		//横幅
#define WIN_H	480		//高さ

typedef struct _GCW{
	WORD nChannels;
	WORD wBitsPerSample;
	void *lpWave;
	DWORD sample_sum;
    DWORD win_r,win_b;
	POINT *left,*right;
	DWORD point_sum;
}GCW;

void GetCurrentWave(HWAVEOUT hWaveOut,DWORD sample,GCW *gcw)
{
	DWORD center_x=gcw->win_r/2;
	int left,right;
	for(DWORD i=0;i<gcw->point_sum;i++){
		if(gcw->nChannels==1){
			if(sample+i<center_x || (sample+i >= gcw->sample_sum+center_x)){
				gcw->left[i].y=gcw->win_b/2;
			}else{
				if(gcw->wBitsPerSample==8){
					left=((BYTE*)(gcw->lpWave))[(sample-center_x)+i];
					gcw->left[i].y=gcw->win_b*left/255;
				}else if(gcw->wBitsPerSample==16){
					left=((short*)(gcw->lpWave))[(sample-center_x)+i];
					gcw->left[i].y=gcw->win_b*(left+32768)/65536;
				}
			}
			gcw->left[i].y = gcw->win_b - gcw->left[i].y;		//上下反転
		}else if(gcw->nChannels==2){
			if(sample+i<center_x || (sample+i >= gcw->sample_sum+center_x)){
				gcw->left[i].y=gcw->win_b/2; gcw->right[i].y=gcw->win_b/2;
			}else{
				if(gcw->wBitsPerSample==8){
					left=((BYTE*)(gcw->lpWave))[(sample-center_x)*2 + 2*i];
					right=((BYTE*)(gcw->lpWave))[(sample-center_x)*2 + 2*i+1];
					gcw->left[i].y=gcw->win_b*left/255;
					gcw->right[i].y=gcw->win_b*right/255;
				}else if(gcw->wBitsPerSample==16){
					left=((short*)(gcw->lpWave))[(sample-center_x)*2 + 2*i];
					right=((short*)(gcw->lpWave))[(sample-center_x)*2 + 2*i+1];
					gcw->left[i].y=gcw->win_b*(left+32768)/65536;
					gcw->right[i].y=gcw->win_b*(right+32768)/65536;
				}
			}
			gcw->left[i].y = gcw->win_b - gcw->left[i].y;		//上下反転
			gcw->right[i].y = gcw->win_b - gcw->right[i].y;		//上下反転
		}
	}
}

LRESULT CALLBACK WindowProc(HWND hWnd,UINT uMsg,WPARAM wParam,LPARAM lParam)
{
	WAVEFORMATEX wfe;
	static HWAVEOUT hWaveOut;
	static WAVEHDR whdr;
	static LPBYTE lpWave;
	int i,len;

	HDC hdc;
	PAINTSTRUCT ps;
	static HPEN leftPen,rightPen;

	MMTIME mmt;
	DWORD sample;
	static GCW gcw;

	switch(uMsg){
		case WM_CREATE:
			wfe.wFormatTag=WAVE_FORMAT_PCM;
			wfe.nChannels=2;	//ステレオ
			wfe.wBitsPerSample=8;	//量子化ビット数
			wfe.nBlockAlign=wfe.nChannels * wfe.wBitsPerSample/8;
			wfe.nSamplesPerSec=SRATE;	//標本化周波数
			wfe.nAvgBytesPerSec=wfe.nSamplesPerSec * wfe.nBlockAlign;

			waveOutOpen(&hWaveOut,WAVE_MAPPER,&wfe,(DWORD)hWnd,0,CALLBACK_WINDOW);

			lpWave=(LPBYTE)calloc(wfe.nAvgBytesPerSec,2);	//2秒分

			len=SRATE/F;	//波長
			for(i=0;i<SRATE*2;i++){		//波形データ作成
				if(i%len < len/2){
					lpWave[2*i  ]=128+64;		//左
					lpWave[2*i+1]=128+32;		//右
				}else{
					lpWave[2*i  ]=128-64;		//左
					lpWave[2*i+1]=128-32;		//右
				}
			}
			/*for(i=0;i<SRATE*2;i++){	//波形データ作成
				if(i%len < len/2)	lpWave[i]=128+64;
				else				lpWave[i]=128-64;
			}*/

			whdr.lpData=(LPSTR)lpWave;
			whdr.dwBufferLength=wfe.nAvgBytesPerSec * 2;
			whdr.dwFlags=WHDR_BEGINLOOP | WHDR_ENDLOOP;
			whdr.dwLoops=1;

			waveOutPrepareHeader(hWaveOut,&whdr,sizeof(WAVEHDR));

			gcw.nChannels=wfe.nChannels;
			gcw.wBitsPerSample=wfe.wBitsPerSample;
			gcw.lpWave=whdr.lpData;
			gcw.sample_sum=SRATE*2;
			gcw.win_r=WIN_W-1;
			gcw.win_b=WIN_H-1;
			gcw.left=(POINT*)calloc(WIN_W+1,sizeof(POINT));
			gcw.right=(POINT*)calloc(WIN_W+1,sizeof(POINT));
			gcw.point_sum=WIN_W+1;

			for(i=0;i<gcw.point_sum;i++){
				gcw.left[i].x=i; gcw.left[i].y=gcw.win_b/2;
				gcw.right[i].x=i; gcw.right[i].y=gcw.win_b/2;
			}

			leftPen=CreatePen(PS_SOLID,1,RGB(0,255,0));
			rightPen=CreatePen(PS_SOLID,1,RGB(0,0,255));
			return 0;
		case WM_LBUTTONDOWN:
			waveOutWrite(hWaveOut,&whdr,sizeof(WAVEHDR));
			SetTimer(hWnd,1,50,NULL);
			return 0;
		case MM_WOM_DONE:
			waveOutReset((HWAVEOUT)wParam);
			KillTimer(hWnd,1);
			return 0;
		case WM_TIMER:
			mmt.wType=TIME_SAMPLES;
			waveOutGetPosition(hWaveOut,&mmt,sizeof(MMTIME));
			if(mmt.wType!=TIME_SAMPLES) return 0;
			sample=mmt.u.sample;

			GetCurrentWave(hWaveOut,sample,&gcw);
			InvalidateRect(hWnd,NULL,TRUE);
			return 0;
		case WM_PAINT:
			hdc=BeginPaint(hWnd,&ps);
			SelectObject(hdc,leftPen);
			Polyline(hdc,gcw.left,gcw.point_sum);
			if(gcw.nChannels==2){
                SelectObject(hdc,rightPen);
				Polyline(hdc,gcw.right,gcw.point_sum);
			}
			EndPaint(hWnd,&ps);
			return 0;
		case WM_DESTROY:
			waveOutReset(hWaveOut);
			waveOutUnprepareHeader(hWaveOut,&whdr,sizeof(WAVEHDR));
			waveOutClose(hWaveOut);
			free(lpWave);

			free(gcw.left);
			free(gcw.right);

			DeleteObject(leftPen);
			DeleteObject(rightPen);
			PostQuitMessage(0);
			return 0;
	}
	return DefWindowProc(hWnd,uMsg,wParam,lParam);
}

int WINAPI WinMain(
	HINSTANCE hInstance,HINSTANCE hPrevInstance,PSTR lpCmdLine,int nCmdShow)
{
	WNDCLASS wc;
	MSG msg;

	wc.style		 = CS_HREDRAW | CS_VREDRAW;
	wc.lpfnWndProc	 = WindowProc;
	wc.cbClsExtra	 = 0;
	wc.cbWndExtra	 = 0;
	wc.hInstance	 = hInstance;
	wc.hIcon		 = LoadIcon(NULL,IDI_APPLICATION);
	wc.hCursor		 = LoadCursor(NULL,IDC_ARROW);
	wc.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH);
	wc.lpszMenuName	 = NULL;
	wc.lpszClassName = __FILE__;
	if(!RegisterClass(&wc)) return 0;

	RECT rc={0,0,WIN_W,WIN_H};
	AdjustWindowRect(&rc,WS_OVERLAPPEDWINDOW,FALSE);

	HWND hWnd=CreateWindow(
		__FILE__,"波形を描画する",
		WS_OVERLAPPEDWINDOW | WS_VISIBLE,
		CW_USEDEFAULT,CW_USEDEFAULT,
		rc.right-rc.left,rc.bottom-rc.top, 
		NULL,NULL,hInstance,NULL);
	if(hWnd==NULL) return 0;

	BOOL bRet;
	while((bRet=GetMessage(&msg,NULL,0,0))!=0){
		if(bRet==-1) break;
		DispatchMessage(&msg);
	}

	return (int)msg.wParam;
}