MFC TIMERS & PROGRESS BARS; WINDOWS MULTIMEDIA
THE WINDOWS TIMER--
An input device that notifies an app when a time interval has elapsed
Application starts it & tells Windows the interval with SetTimer()
Windows sends WM_TIMER message each time interval elapses
Application stops and removes timer with KillTimer()
Could be used to keep time--but not accurate
CTime class to the rescue!!
GetCurTime() member function returns hour, minute, and seconds
Member functions can retrieve these values:
GetHour(), GetMinute(), GetSecond()
Clock Application <Show program in action>
Use AppWizard to create a Dialog-Based MFC Application template
Add the following controls to the dialog box:
"Time:" static control
"Current Time" static control (IDC_STATICTIME)
(Will show the current time)
Remove the "Cancel" Button
Change the "OK" button to "Exit"
Add the timer ID:
In Resource View, right-click over "Clock" Resource Folder
Select "Resource Symbols"
Hit "New"
Enter ID_CLK_TIMER
Will assign an ID to the timer
Starting the Clock Timer with a one-second interval
In CClockDlg, Edit the OnInitDialog() function by adding:
// TODO: Add extra initialization here
SetTimer(ID_CLK_TIMER, 1000, NULL);
Use ClassWizard to add m_sTime variable to IDC_STATICTIME control
Type: CString
Use ClassWizard to set up a message handler for WM_TIMER:
Edit the resulting OnTimer() function:
// TODO: Add your message handler code here and/or call default
CTime t=CTime::GetCurrentTime();
m_sTime.Format("%d:%d:%d", t.GetHour(),
t.GetMinute(), t.GetSecond());
UpdateData(FALSE); //Send to Static Current Time control
Progress Bar Controls
Used to indicate progress of an operation
Lets user know what portion of an operation is not yet completed
Encapsulated in CProgressCtrl Class
Some Member Functions (kind of like Scroll bar functions):
SetRange() & GetRange() -- range of the progress bar
SetPos() & GetPos() -- current position
OffsetPos() -- to increment current progress bar position
SetStep() -- to set step amount for progress bar
StepIt() -- to increment position by step amount
TimerProgrss Application <Show program in action>
Set up an MFC Dialog-based Application template
Add the timer ID:
In Resource View, right-click over "TimerProgrss" Resource Folder
Select "Resource Symbols"
Hit "New"
Enter ID_CNT_TIMER
Will assign an ID to the timer
Add following controls:
"Interval:" static control
IDC_INTERVAL Edit box
"Max Count:" static control
IDC_MAXCNT Edit box
"Count:" static control
Static control to hold current count (IDC_STATICCNT, "0")
IDC_PROGCNT Progress Bar
Remove the "Cancel" Button
Change the "OK" button to "Exit"
Use ClassWizard to add the following variables for the controls:
Control ID Variable Name Variable Type
------------------------------------------------
IDC_PROGCNT m_Progress CProgressCtrl
IDC_START m_Start CButton
IDC_STATICCNT m_sCount CString
IDC_INTERVAL m_iInterval int
IDC_MAXCNT m_iMax int
Add m_iCount member variable (int private) to the TimerProgrssDlg class
(Right click on the clas)
Use ClassWizard to add the following Message Map handler functions:
CTimerProgrssDlcg -- WM_TIMER: OnTimer()
IDC_START -- BN_CLICKED: OnStart()
IDC_INTERVAL -- EN_CHANGE: OnChangeInterval()
IDC_MAXCNT -- EN_CHANGE: OnChangeMaxcnt()
Edit the OnInitDialog() function (initialization of controls):
// TODO: Add extra initialization here
m_iInterval=100;
m_iMax=1000;
UpdateData(FALSE); //Pass variable data to controls
Edit the OnStart() function (initialize progress bar & start timer):
// TODO: Add your control notification handler code here
UpdateData(TRUE); //Get data from controls
m_iCount=0;
m_sCount.Format("%d", m_iCount);
m_Progress.SetRange(0,m_iMax); //Set progress control
m_Progress.SetPos(0);
UpdateData(FALSE); //Pass new data back to controls
m_Start.EnableWindow(FALSE); //disable Start button
SetTimer(ID_CNT_TIMER,m_iInterval,NULL); //Start timer
Edit the OnTimer() function (timeout, so count and update progress bar):
// TODO: Add your message handler code here and/or call default
m_iCount+=m_iInterval; //Increment count
m_sCount.Format("%d", m_iCount);
m_Progress.SetPos(m_iCount); //Set new prog bar position
UpdateData(FALSE); //Pass data back to control
if(m_iCount>=m_iMax) //If done, kill timer
{
KillTimer(ID_CNTTIMER);
m_Start.EnableWindow(TRUE); // enable start button
}
Edit the OnChangeInterval() function (Get new interval from Interval control):
// TODO: Add your control notification handler code here
UpdateData(TRUE); // Get interval value from edit control
Edit the OnChangeMaxcnt() function (Get new Max from Maxcount control):
// TODO: Add your control notification handler code here
UpdateData(TRUE); // Get maxcount value from edit control
Build and Run the application.
(You may have to make the some of the controls bigger)
WINDOWS MULTIMEDIA
Some multimedia devices:
Waveform audio device (sound card)
converts microphone & other analog audio to digitized samples
can be stored as .WAV files
can be played back
Usually has a MIDI device
plays music from short binary messages
can be attached to a MIDI input device (music keyboard)
CD Audio through the CD-ROM drive
Video for Windows device (AVI video device)
plays movie/animation files (.AVI)
Video capture boards (different compression schemes)
Laserdisc players & video cassette recorders
Others
Extensive Win32 API support for multimedia devices
Low-level support
High-level support
MSDN online documentaton:
Platform SDK/Graphics & Multimedia Services/Multimedia Reference
MCI (Media Control Interface)
High level multimedia control functions
Has commands common to all MM hardware
Possible since most use record/play metaphor
Open a device for input or output
If input, record
If output, play
When done, close
Two forms of MCI
Send command messages (like Windows messages) to MCI
(need to include bit-encoded flags and C data structures)
Send text strings to MCI
Good for use from scripting languages with string functionality
Simple to use
MCI converts them to command messages
mciSendString() function:
error = mciSendString(szCmd, szRetStr, cSzRetStr, hCallback)
szCmd--the mci command string (specifies command & device)
szRetStr--return string buffer (NULL if none used)
szSzRetStr--size of return string buffer (0 if none used)
szCallback--Handle to Callback function (NULL if none used)
Returns 0 if command is successful, error code if not
Usually used as parameter to mciGetErrorString()
Many command strings possible
See MSDN online help:
/ Platform SDK / Graphics & Multimedia Services / Multimedia Reference
/ Multiemedia Command Strings
Some Common MCI Command Strings:
open -- initializes a device
"open lpszDevice lpszOpenflags lpszFlags"
Some device types:
cdaudio -- Audio CD played on system's CD-ROM
waveaudio -- .WAV audio files
AVIVideo -- .AVI video files
Some Examples:
"open cdaudio"
"open new type waveaudio alias mysound" (for recording)
"open waveaudio!myclip.wav alias clip"
play -- plays from an open device
"play cdaudio"
stop -- stops playing from an open device
"stop clip"
close -- closes an open device
"close mysound"
PlayCD Application <show program in action>
Create an MFC AppWizard (.exe) Dialog-based application template
All Multimedia applications must #include the "mmsystem.h" header file
So add:
#include "mmsystem.h" at top of PlayCDDlg.h file
Must also link in the WINMM.LIB library--
Project / Settings / Link Tab / Category: Input / Object-Library Modules
Type in: WINMM.LIB
Add "Play CD" and "Stop CD" buttons (IDC_BPLAY and IDC_BSTOP)
Use ClassWizard to add Message Map BN_CLICKED handler functions for the two
new buttons --> OnBplay() & OnBstop()
Add code to OnBplay():
mciSendString("open cdaudio",NULL,0,NULL);
mciSendString("play cdaudio",NULL,0,NULL);
Add code to OnBstop():
mciSendString("stop cdaudio",NULL,0,NULL);
mciSendString("close cdaudio",NULL,0,NULL);
Build and run with an audio CD in the CD-ROM drive
You may have to shut down autostart app launched when audio CD is inserted
It may do stuff to "mute" & "volume" audio controls
You may have to adjust them
Recording and Playing Digital Sound (.WAV files)
RecPlay Application <show program in action>
Want to:
Begin and Stop recording
Begin and Stop playback
Save and read a .WAV file
Use mciSendString() to issue command strings
Keep track of what's happening with Booleans bRec and bPlay
Use 5 buttons: ("Begin Rec", "End Rec", "Begin Play", "End Play", "Exit")
Enable or Disable according to what's happening==>
Need Button control variables (to access EnableWindow() function)
Requirements:
When app begins execution:
Set bRec and bPlay to FALSE
Disable "End Record", "End Play" buttons
"Begin Rec" button pressed==>
open new waveaudio device & record
set bRec to TRUE
disable: "Begin Rec", "Begin Play", "End Play" buttons
enable: "End Rec" button
"End Rec" button pressed==>
stop device, save as .WAV file, close device
set bRec to FALSE
disable: "End Rec", "End Play" buttons
enable: "Begin Rec", "Begin Play" buttons
"Begin Play" button pressed==>
open .WAV file & play
set bPlay to TRUE
disable: "Begin Rec", "Enc Rec", Begin Play" buttons
enable: "End Play" button
"End Play" button pressed==>
stop & close device
set bPlay to FALSE
disable: "End Rec", "End Play" buttons
enable: "Begin Rec", "Begin Play" buttons
"Exit" button pressed==>
if bPlay is TRUE: execute "End Play" button command function
if bRec is TRUE: stop & close device (don't save incomplete recording)
Exit
RecPlay Application Details:
Create an MFC AppWizard (.exe) Dialog-based application template
Add: #include "mmsystem.h" at top of RecPlayDlg.h file
Link in the WINMM.LIB library--
Project / Settings / Link Tab / Category: Input / Object-Library Modules
Type in: WINMM.LIB
Create Buttons:
"Begin Rec" (IDC_REC_BEG), "End Rec" (IDC_REC_END)
"Begin Play" (IDC_PLAY_BEG), "End Play" (IDC_PLAY_END)
Add private BOOL variables: bPlay, bRec (Right click class)
Use ClassWizard to attach Command member variables to the buttons:
m_cRecBeg, m_cRecEnd, m_ cPlayBeg, m_cPlayEnd (CButton derived)
USe ClassWizard to add Message Map BN_CLICKED handler functions to each button -->
OnRecBeg(), OnRecEnd(), OnPlayBeg(), OnPlayEnd(), OnOK()
Edit OnInitDialog():
// TODO: Add extra initialization here
bPlay=bRec=FALSE;
m_cRecEnd.EnableWindow(FALSE);
m_cPlayEnd.EnableWindow(FALSE);
Edit OnRecBeg():
// TODO: Add your control notification handler code here
mciSendString("open new type waveaudio alias myvoice",NULL,0,NULL);
mciSendString("record myvoice",NULL,0,NULL);
bRec=TRUE;
m_cRecBeg.EnableWindow(FALSE);
m_cRecEnd.EnableWindow(TRUE);
m_cPlayBeg.EnableWindow(FALSE);
m_cPlayEnd.EnableWindow(FALSE);
Edit OnRecEnd():
// TODO: Add your control notification handler code here
mciSendString("stop myvoice",NULL,0,NULL);
mciSendString("save myvoice test.wav",NULL,0,NULL);
mciSendString("close mysound",NULL,0,NULL);
bRec=FALSE;
m_cRecBeg.EnableWindow(TRUE);
m_cRecEnd.EnableWindow(FALSE);
m_cPlayBeg.EnableWindow(TRUE);
m_cPlayEnd.EnableWindow(FALSE);
Edit OnPlayBeg():
// TODO: Add your control notification handler code here
mciSendString("open test.wav alias myvoice",NULL,0,NULL);
mciSendString("play myvoice",NULL,0,NULL);
bPlay=TRUE;
m_cRecBeg.EnableWindow(FALSE);
m_cRecEnd.EnableWindow(FALSE);
m_cPlayBeg.EnableWindow(FALSE);
m_cPlayEnd.EnableWindow(TRUE);
Edit OnPlayEnd():
// TODO: Add your control notification handler code here
mciSendString("stop myvoice",NULL,0,NULL);
mciSendString("close myvoice",NULL,0,NULL);
bPlay=FALSE;
m_cRecBeg.EnableWindow(TRUE);
m_cRecEnd.EnableWindow(FALSE);
m_cPlayBeg.EnableWindow(TRUE);
m_cPlayEnd.EnableWindow(FALSE);
Edit OnOK():
// TODO: Add extra validation here
if (bPlay)
OnPlayEnd();
if(bRecording)
{
mciSendString("stop myvoice",NULL,0,NULL);
mciSendString("close myvoice",NULL,0,NULL);
}
Build and run the application
You may need to attach an external microphone and
fool around with audio control and microphone settings
Best to run "Sound Recorder" app first to make sure things are working:
Start / Programs / Accessories / Entertainment / Sound Recorder