What is the difference between SendMessage and postMessage?
postMessage: Sends a message in the message queue associated with the thread and returns without waiting for the thread to process that messaage. SendMessage: calls the window procedure for the specified window and does not return until the window procedure has processed the message.
Is postMessage thread safe?
This method is a thread-safe solution to send messages to windows. Those messages will be handled in the message loop of the application and therefore can be sent from any thread. The difference between SendMessage and PostMessage is the way that they return control to the calling thread.
How do you send iframe to postMessage?
postMessage – To: Information and samples for HTML5 and related APIs
- window.onload = function () {
- var iframeWin = document. getElementById( “da-iframe” ).
- form = document. getElementById( “the-form” ),
- myMessage = document. getElementById( “my-message” );
- myMessage. select();
- form.onsubmit = function () {
What is postMessage?
postMessage() The window. postMessage() method safely enables cross-origin communication between Window objects; e.g., between a page and a pop-up that it spawned, or between a page and an iframe embedded within it. The receiving window is then free to handle this event as needed.
What is Lresult?
LRESULT is an integer value that your program returns to Windows. It contains your program’s response to a particular message. Additional data for the message is contained in the lParam and wParam parameters. Both parameters are integer values the size of a pointer width (32 bits or 64 bits).
What type is Wparam?
WPARAM is a typedef for UINT_PTR which is an unsigned int (unsigned 32-bit) on win32 and unsigned __int64 (unsigned 64-bit) on x86_64.
What is BroadcastChannel?
The BroadcastChannel interface represents a named channel that any browsing context of a given origin can subscribe to. It allows communication between different documents (in different windows, tabs, frames or iframes) of the same origin.
Can two iFrames communicate?
1 Answer. Why do you say that the child iframes can’t communicate directly? Actually, they can. What you can do within a child iframe is use the window.
Is postMessage asynchronous?
The postMessage() function is asynchronous, meaning it will return immediately. So you can not do synchronous communication with it. In your example, the posted message will vanish in the void, because there is no listener for the message event at the time the postMessage() function is executed.
Can two iframes communicate?
What is Lparam and Wparam in VC ++?
According to this, LPARAM is defined as LONG_PTR , which in 64-bit Windows is a signed, 64-bit value. WPARAM is defined as UINT_PTR , which in 64-bit Windows is an unsigned, 64-bit value. If you are defining your own message, you might want to assign its parameters accordingly.
What is WinMain?
WinMain() is the C entry point function of any windows application. Like normal DOS/console based application which has main() function as C entry point, in windows we have WinMain() instead. WinMain() is a function which is called by system during creation of a process.
How does the SendMessage function in Win32 work?
SendMessage function. Sends the specified message to a window or windows. The SendMessage function calls the window procedure for the specified window and does not return until the window procedure has processed the message. To send a message and return immediately, use the SendMessageCallback or SendNotifyMessage function.
How to use the postMessage function in Windows?
The following example shows how to post a private window message using the PostMessage function. Assume you defined a private window message called WM_COMPLETE: You can post a message to the message queue associated with the thread that created the specified window as shown below: For more examples, see Initiating a Data Link.
How to post a private window message in Win32?
The following example shows how to post a private window message using the PostMessage function. Assume you defined a private window message called WM_COMPLETE: C++. #define WM_COMPLETE (WM_USER + 0) You can post a message to the message queue associated with the thread that created the specified window as shown below: C++.
How is the SendMessage function used in Notepad?
There are a set of predefined properties that the message can relate to, and these can be used to send messages to existing applications to perform all sorts of useful functions such as changing the font in notepad, or bringing a window to the fore. For more information of the wider use of the SendMessage function, have a look at: