Midi Keyboard Program

[Tekkn0logik]

Here's a program I wrote. It lets you play the piano (or any MIDI instrument really - there's a nice dropdown to select the instrument) using the first 2 rows of your computer keyboard.

leet ascii diagram:

 2 3   5 6 7   9 0
q w e r t y u i o p

It's ANSI C and should compile on anything. Oh, and I put a bunch of comments in, so read the source if you want.

Not really game hacking related but I thought it was cool enough to post here.

/* A MIDI keyboard application for Windows. Controlled with the first 2 rows
   of the computer keyboard. Should compile on any Windows version down to 
   Windows 3.0 or 3.1. Doesn't use any fancy APIs. */
#include <Windows.h>

/* The keys used to control the keyboard. */
static const char *keys = "Q2W3ER5T6Y7UI9O0P";
/* Note value assigned to each key. */
static unsigned char values[256];
/* MIDI octave to play in. */
static unsigned char octave = 5;
/* Handle to the MIDI device. */
static HMIDIOUT hMidi;
/* Handle to the window. */
static HWND hWnd;
/* Handle to the drop-down list. */
static HWND hDropDown;

/* All the MIDI instruments. */
static char *patches[] = {
	"Acoustic Grand Piano",
	"Bright Acoustic Piano",
	"Electric Grand Piano",
	"Honky-tonk Piano",
	"Rhodes Piano",
	"Chorused Piano",
	"Harpsichord",
	"Clavinet",
	"Celesta",
	"Glockenspiel",
	"Music Box",
	"Vibraphone",
	"Marimba",
	"Xylophone",
	"Tubular Bells",
	"Dulcimer",
	"Hammond Organ",
	"Percussive Organ",
	"Rock Organ",
	"Church Organ",
	"Reed Organ",
	"Accordion",
	"Harmonica",
	"Tango Accordion",
	"Acoustic Guitar (nylon)",
	"Acoustic Guitar (steel)",
	"Electric Guitar (jazz)",
	"Electric Guitar (clean)",
	"Electric Guitar (muted)",
	"Overdriven Guitar",
	"Distortion Guitar",
	"Guitar Harmonics",
	"Acoustic Bass",
	"Electric Bass (finger)",
	"Electric Bass (pick)",
	"Fretless Bass",
	"Slap Bass 1",
	"Slap Bass 2",
	"Synth Bass 1",
	"Synth Bass 2",
	"Violin",
	"Viola",
	"Cello",
	"Contrabass",
	"Tremolo Strings",
	"Pizzicato Strings",
	"Orchestral Harp",
	"Timpani",
	"String Ensemble 1",
	"String Ensemble 2",
	"SynthStrings 1",
	"SynthStrings 2",
	"Choir Aahs",
	"Voice Oohs",
	"Synth Voice",
	"Orchestra Hit",
	"Trumpet",
	"Trombone",
	"Tuba",
	"Muted Trumpet",
	"French Horn",
	"Brass Section",
	"Synth Brass 1",
	"Synth Brass 2",
	"Soprano Sax",
	"Alto Sax",
	"Tenor Sax",
	"Baritone Sax",
	"Oboe",
	"English Horn",
	"Bassoon",
	"Clarinet",
	"Piccolo",
	"Flute",
	"Recorder",
	"Pan Flute",
	"Bottle Blow",
	"Shakuhachi",
	"Whistle",
	"Ocarina",
	"Lead 1 (square)",
	"Lead 2 (sawtooth)",
	"Lead 3 (calliope lead)",
	"Lead 4 (chiff lead)",
	"Lead 5 (charang)",
	"Lead 6 (voice)",
	"Lead 7 (fifths)",
	"Lead 8 (bass + lead)",
	"Pad 1 (new age)",
	"Pad 2 (warm)",
	"Pad 3 (polysynth)",
	"Pad 4 (choir)",
	"Pad 5 (bowed)",
	"Pad 6 (metallic)",
	"Pad 7 (halo)",
	"Pad 8 (sweep)",
	"FX 1 (rain)",
	"FX 2 (soundtrack)",
	"FX 3 (crystal)",
	"FX 4 (atmosphere)",
	"FX 5 (brightness)",
	"FX 6 (goblins)",
	"FX 7 (echoes)",
	"FX 8 (sci-fi)",
	"Sitar",
	"Banjo",
	"Shamisen",
	"Koto",
	"Kalimba",
	"Bagpipe",
	"Fiddle",
	"Shanai",
	"Tinkle Bell",
	"Agogo",
	"Steel Drums",
	"Woodblock",
	"Taiko Drum",
	"Melodic Tom",
	"Synth Drum",
	"Reverse Cymbal",
	"Guitar Fret Noise",
	"Breath Noise",
	"Seashore",
	"Bird Tweet",
	"Telephone Ring",
	"Helicopter",
	"Applause",
	"Gunshot"
};

/* Sets the key notes based on the octave */
void setKeyValues(void) {
	int k, len = strlen(keys);
	for(k = 0; k < len; k++) {
		values[keys[k]] = k + (octave * 12);
	}
	/* Force a redraw of the window */
	InvalidateRect(hWnd, NULL, FALSE);
}

void populateList(void)
{
	int k;

	/* Add all the instruments to the list box. */
	for(k = 0; k < 128; k++)
		SendMessage(hDropDown, CB_ADDSTRING, (WPARAM) 0, (LPARAM) patches[k]);
	/* Set the highlighted item to the first one. */
	SendMessage(hDropDown, CB_SETCURSEL, (WPARAM) 0, (LPARAM) 0);
}

/* Sends a message to the MIDI output. */
void sendMIDIMessage(int status, int channel, int data1, int data2)
{
	midiOutShortMsg(hMidi, (data2 << 16) | (data1 << 8) | status | channel);
}

/* Called when a key is pressed down */
void onKeyDown(unsigned char key)
{
	if(key == VK_ESCAPE) { /* exit */
		PostQuitMessage(0);
	} else if(key == VK_OEM_COMMA) { /* octave down */
		if(octave > 1) octave--;
		setKeyValues();
	} else if(key == VK_OEM_PERIOD) { /* octave up */
		if(octave < 10) octave++;
		setKeyValues();
	} else if(values[key] != 0) { /* some note key */
		sendMIDIMessage(0x90, 0, values[key], 127);
		/* Force a redraw of the window */
		InvalidateRect(hWnd, NULL, FALSE);
	}
}

/* Called when a key is released */
void onKeyUp(unsigned char key)
{
	if(values[key] != 0) { /* end the note by sending a velocity of 0 */
		sendMIDIMessage(0x90, 0, values[key], 0);
		/* Force a redraw of the window */
		InvalidateRect(hWnd, NULL, FALSE);
	}
}

/* Returns 1 if the key (0 to 11) is an accidental */
int isAccidental(unsigned char key)
{
	int pos = key % 12;
	return pos == 1 || pos == 3 || pos == 6 || pos == 8 || pos == 10;
}

/* Draws the keyboard on the window. */
void drawKeyboard(HDC hdc)
{
	int k, x = 0, y, len = strlen(keys);

	/* Draw the octave */
	TextOut(hdc, 200, 165, "Octave: ", 8);
	/* Small note: this next line uses a trick to convert an int to its char
	   representation. It treats the string "0123456789" as an array of chars
	   (since that's what strings are) and then uses the octave as an index
	   into this array. Then, since the TextOut function wants a pointer to
	   the text, it takes the address of that character. */
	TextOut(hdc, 260, 165, &"0123456789"[octave - 1], 1);
	TextOut(hdc, 280, 165, "(< and > to change)", 19);

	for(k = 0; k < len; k++) {
		if(GetAsyncKeyState(keys[k]) & 0x80000000) {
			/* Set the background of the note to red */
			SetDCBrushColor(hdc, RGB(255, 0, 0));
			SelectObject(hdc, GetStockObject(DC_BRUSH));
			/* Set the text foreground color to white */
			SetTextColor(hdc, RGB(255, 255, 255));
			/* Set the text background color to red */
			SetBkColor(hdc, RGB(255, 0, 0));
		} else if(isAccidental(k)) {
			/* Set the background of the note to black */
			SelectObject(hdc, GetStockObject(BLACK_BRUSH));
			/* Set the text foreground color to white */
			SetTextColor(hdc, RGB(255, 255, 255));
			/* Set the text background color to black */
			SetBkColor(hdc, RGB(0, 0, 0));
		} else {
			/* Set the background of the note to white */
			SelectObject(hdc, GetStockObject(WHITE_BRUSH));
			/* Set the text foreground color to black */
			SetTextColor(hdc, RGB(0, 0, 0));
			/* Set the text background color to white */
			SetBkColor(hdc, RGB(255, 255, 255));
		}

		/* If the note is a white key, draw it lower */
		if(!isAccidental(k))
			y = 80;
		else y = 0;

		/* Draw the actual key */
		Rectangle(hdc, x, y, x + 59, y + 79);
		/* Set the text font to something less ugly than SYSTEM_FONT */
		SelectObject(hdc, GetStockObject(DEFAULT_GUI_FONT));
		/* Draw the letter which controls this key */
		TextOut(hdc, x + 10, y + 10, &keys[k], 1);

		/* Increment the position for the next key. If there are 2 white
		   keys in a row (E to F or B to C), make the gap bigger so they
		   don't run into each other, otherwise only offset a bit so the
		   keys overlap. */
		if(!isAccidental(k) && !isAccidental(k + 1))
			x += 60;
		else x += 30;
	}
}

/* Called when the window receives a message */
LRESULT CALLBACK WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
	PAINTSTRUCT ps;

	switch(msg) {
		case WM_COMMAND:
			if(HIWORD(wParam) == CBN_SELCHANGE) { /* New item selected from the listbox */
				/* Send the MIDI message to change the instrument. The 'patch number'
				   that the instrument is changed to is queried from the dropdown list. */
				sendMIDIMessage(0xC0, 0, SendMessage(hDropDown, CB_GETCURSEL, 0, 0), 0);
				/* Set the focus back to the main window so we can still get key events */
				SetFocus(hWnd);
			} else if(HIWORD(wParam) == CBN_SELENDCANCEL) {
				/* The user clicked out of the combo box without selecting anything.
				   Set the focus back to the main window so we can still get key events */
				SetFocus(hWnd);
			}
			break;
		case WM_DESTROY: /* Window is being closed */
			PostQuitMessage(0);
			break;
		case WM_KEYDOWN: /* Key press */
			/* Only call the function if it's not a 'held down' key event.
			   Otherwise, the notes would repeat and it'd sound bad. */
			if(((lParam >> 30) & 0x01) == 0)
				onKeyDown((unsigned char) wParam);
			break;
		case WM_KEYUP: /* Key release */
			onKeyUp((unsigned char) wParam);
			break;
		case WM_PAINT: /* Window is being redrawn */
			BeginPaint(hWnd, &ps);
			/* draw the keyboard */
			drawKeyboard(ps.hdc);
			EndPaint(hWnd, &ps);
			break;
		default:
			/* Make Windows handle all messages that we don't. */
			return DefWindowProc(hWnd, msg, wParam, lParam);
	}

	return 0;
}

/* Main entry point. */
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, 
	LPSTR lpCmdLine, int nCmdShow)
{
	WNDCLASSEX wc;
	MSG msg;
	RECT rct;

	/* Create and register the window type */
	wc.cbSize = sizeof(WNDCLASSEX);
	wc.style = 0;
	wc.lpfnWndProc = WndProc;
	wc.cbClsExtra = 0;
	wc.cbWndExtra = 0;
	wc.hInstance = hInstance;
	wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
	wc.hCursor = LoadCursor(NULL, IDC_ARROW);
	wc.hbrBackground = (HBRUSH) (COLOR_WINDOW + 1);
	wc.lpszMenuName = NULL;
	wc.lpszClassName = "MidiKeyboard";
	wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);

	RegisterClassEx(&wc);

	/* Calculate the width/height of the window based on the 
	   width/height of the canvas area */
	rct.left = 0;
	rct.top = 0;
	rct.right = 600;
	rct.bottom = 185;
	AdjustWindowRect(&rct, WS_OVERLAPPEDWINDOW, FALSE);

	/* Actually create/show the window */
	hWnd = CreateWindow("MidiKeyboard", "Keyboard", WS_OVERLAPPED | WS_CAPTION 
		| WS_MINIMIZEBOX | WS_SYSMENU, CW_USEDEFAULT, CW_USEDEFAULT, 
		rct.right - rct.left, rct.bottom - rct.top, 0, 0, hInstance, 0);
	hDropDown = CreateWindow("COMBOBOX", NULL, CBS_DROPDOWNLIST 
		| WS_VISIBLE | WS_VSCROLL | WS_CHILD, 0, 160, 200, 200, hWnd, 0, hInstance, 0);
	populateList();
	ShowWindow(hWnd, nCmdShow);
	UpdateWindow(hWnd);
	
	/* Set up the MIDI stuff */
	midiOutOpen(&hMidi, MIDIMAPPER, 0, 0, 0);
	setKeyValues();

	/* Message loop */
	while(GetMessage(&msg, NULL, 0, 0) > 0) {
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}

	/* Release the MIDI resources. */
	midiOutClose(hMidi);

	return msg.wParam;
}

[zhaoyun333]

I just wasted an hour of my life playing with this xD

[tchdavid]

I've tried this code, but it can't compile.
Here are error messenges:

main.c||In function 'onKeyDown':|
main.c|185|error: 'VK_OEM_COMMA' undeclared (first use in this function)|
main.c|185|error: (Each undeclared identifier is reported only once|
main.c|185|error: for each function it appears in.)|
main.c|188|error: 'VK_OEM_PERIOD' undeclared (first use in this function)|
main.c||In function 'drawKeyboard':|
main.c|234|error: 'DC_BRUSH' undeclared (first use in this function)|
||=== Build finished: 5 errors, 0 warnings ==

I just open a new empty project and a new file "main.c" contain those codes.
And I can't compile this file.

Sorry that I'm new in midi program.
Thank you.

[Jason]

Very nice! I had to manually pragma the winmm.lib to clear up some unresolved externals (thanks @Hell_Demon)

#pragma comment(lib, "winmm.lib")

Other than than, this is awesome!

I did find a small bug, if you hold down a note, then change the octave, the note is never released. It's quite cool for combining a variety of sounds though