JavaFX-屏幕关闭时的绘图组件

Question

My application works on tablet (with Windows 7) which sometimes turns off its display in order to save battery. After touching the screen, it turns on again.

Application should remain operational even after turning off the screen, what is, in general, accomplished (ie sounds are played). The only problem is the fact that when screen is turned off and application tries to add new component to the scene (technically - add children to the displayed GridPane ), the newly added component is not visible when I touch the screen (and it turns on).

It is just like there was a cache which stores and restores displayed content when screen is turning on/off. After turning screen on - when I click windows button (keyboard) or or change focus to another application - newly added component appears.

I have tried setting -Dprism.dirtyopts=false but it did not change anything.

My Java is 7u67.

Is it known bug? Is there any programming workaround? I have tought about using WinAPI to force redraw/refresh of the application window but it seems too big for this case.

Answer 1

I have just figured out "simple" workaround:

import com.sun.jna.Pointer;
import com.sun.jna.platform.win32.Kernel32;
import com.sun.jna.platform.win32.User32;
import com.sun.jna.platform.win32.WinDef;
import com.sun.jna.platform.win32.WinUser;
import com.sun.jna.ptr.IntByReference;

/** WINAPI CONSTANTS **/
private static final int RDW_UPDATENOW = 0x0100;

/**
* Redraws all windows associated with currently running process.
*/
public static void redrawApplicationWindows() {
    final int processId = Kernel32.INSTANCE.GetCurrentProcessId();
    User32.INSTANCE.EnumWindows(
        new WinUser.WNDENUMPROC() {
          @Override
          public boolean callback(WinDef.HWND hwnd, Pointer pointer) {
            IntByReference someProcessId = new IntByReference();
            User32.INSTANCE.GetWindowThreadProcessId(hwnd, someProcessId);
            if (someProcessId.getValue() == processId) {
              User32.INSTANCE.RedrawWindow(hwnd, null, null, new User32.DWORD(RDW_UPDATENOW));
            }
            return true;
          }
        }, Pointer.NULL);
}

It requires you to have jna and jna-platform in dependencies.

This method should be called after drawing when the screen is turned off (it is another problem how to detect it). As my application rarely draws automatically (without user input), I have placed its call after every drawing happening automatically.

It works in Win7.