Delphi Notes

Useful website: http://www.delphitips.com/

Even better tip website: Torry Delphi

Delphi Basics Website - excellent site for critical info (the documentation that should be included with Delphi!)

Converting Integers to Strings:

Use "IntToStr" from the SysUtils unit.

  uses SysUtils;
  aString := IntToStr(i);

To play a sound file:

uses MMSystem;

PlaySound('example.wav',0,snd_Async);

Delphi Threads

To create a thread use File; New; Other; ThreadObject - this will create a unit that encapsulates your thread class.

A thread class has the following functions and procedures:

• Create(boolean) - used to actually create the thread; if the boolean value is true it starts "suspended", if the boolean value is false it starts and runs immediately.
• Execute() - this code is run when the thread is created/run
• Synchronize(method) - executes a procedure such that it can access VCL and other things safely.
• Suspend() - pause?
• Resume() - continue?
• WaitFor() - waits for this thread to finish before continuing (i.e. spawn you can spawn a thread and then wait for it to complete before your main logic continues - this could be handy to launch several threads and then wait for them all to complete before your main logic continues.
• Priority - variable that can be set (or read) to "tpIdle, tpLowest, tpLower, tpNormal, tpHigher, tpHighest, tptimeCritical". This adjusts the relative priority of the thread (to set the main priority of a process use "SetPriorityClass(GetCurrentProcess,HIGH_PRIORITY_CLASS)"

Sleep(DWORD) - Win32 API procedure to pause a thread for the specified number of milliseconds.

GetThreadTimes can be used to get timing information for a thread (when created, exit time, kernel time and user time).

To Execute an external application use the Windows API "ShellAPI" to provide "ShellExecute":

  ShellExecute(handle, operation, filename, parameters, folder, show command);

Where:

• handle is the handle of your parent application
• operation is nil; edit; explore; find; open, print; properties; (nil essentially means "open")
• filename - the program to be run (or file to be processed)
• parameters to be passed to the application
• folder - default execution path
• show command - an integer; common values: SW_HIDE; SW_SHOWNORMAL; SW_SHOWMAXIMIZED

Example:

  ShellExecute(Form1.Handle, nil, 'c:\windows\notepad.exe','c:\windows\general.txt', nil, SW_SHOWMAXIMIZED);

ShellExecute spawns a separate process (thread) for the application so it runs in parallel with your Delphi application that executed it.

If it fails it will return a longword error code between 0 to 32 (or if higher is the handle of the other application). Try RaiseLastWin32Error() (part of SysUtils) for more error info.

See: http://delphi.about.com/library/weekly/aa082499.htm or http://www.latiumsoftware.com/en/delphi/00002.php