Event Handler for Minimize and Maximize Window

Question

Hi,

I am developing an application for PocketPC. When the application starts the custom function SetScreenOrientation(270) is called which rotates the screen. When the application closes the function SetScreenOrientation(0) is called which restores the screen orientation.

This way the screen orientation isn't restored if the user minimizes the application and this is not acceptable.

Does anyone know where (in which event handlers) should SetScreenOrientation(int angle) be called to set the screen orientation on application start, restore orientation on minimize, set the orientation on maximize and restore the orientation on close?

Actually I don't know which event handler handles the Minimize and Maximize event.

Answer 1

I don't know what these are called in the C++ world, but in .NET Compact Framework your application form's Resize event would be called when you minimize/maximize a window, and then in the event code you would check the WindowState property of the form to see if its minimized or mazimized.

Altering the state of your PDA from within your application is risky (although there are lots of good reasons to do it), because if your app crashes it will leave the PDA in whatever state it was in. I've done a lot of kiosk-type (full-screen) apps in Windows Mobile, and one of the tricks to doing this effectively is to hide the WM title bar (the top row with the Windows start button) to keep it from flashing up for a split second every time you open a new form. If the app crashes, the windows bar remains invisible until you reset the device, which isn't good. At least with screen rotation the user can restore it manually.

Answer 2

Going from my Windows CE experience you should handle either the WM_SIZE or WM_WINDOWPOSCHANGED messages. If you're working on PocketPC I would suggest you take a look at the WM_WINDOWPOSCHANGED message first because I'm not sure the WM_SIZE has the right parameters that you need.

From the WM_WINDOWPOSCHANGED message's WINDOWPOS structure take a look at the flags member, specifically SWP_SHOWWINDOW and SWP_HIDEWINDOW.

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The specific version of the messages that you need to look at vary with what operating system you're using. The Pocket PC OS is built on Windows CE 3.0 (and lower), while Windows Mobile is now built on Windows CE 5.0 (even Windows Mobile 6), but was also built on Windows CE 4. (Source)

So just look under the relevant section in MSDN for the OS that you're writing for.

Answer 3

The correct message is WM_SIZE, but Daemin's answer points to the wrong WM_SIZE help topic. Check the wParam. Be careful as your window may be maximized but hidden.

Answer 4

It really depends on the platform, but I'd go with WM_WINDOWPOSCHANGED or the OnShow. It's not wm_size.. That one is not always thrown on all platforms. Casio's don't throw the size event when you'd expect them to. TDS and Symbol's do.

Even though the MSDN is a great sourse for info, remember not all OS's are created equal. In the PPC world the hardware provider gets to create their own OS and sometimes the miss things, or purposfully ignore things.

I've got a platform here (name withheld to protect... well me) that has left and right buttons.. When you press them, you'd expect to be able to catch VK_LEFT, VK_RIGHT.. You'd be wrong. You actually get ';' or ':'. How's that for a kick in the pants.