Develop Reference

LeJOS GyroSensor sample always 0

I would like to read the current angle from my Ev3GyroSensor, however the returned value is always 0.
I tested multiple Ports nothing worked.
If I test the sensor with the LeJOS integrated Tool, everything works fine.
EV3GyroSensor ev3GyroSensor = new EV3GyroSensor(SensorPort.S4);
SampleProvider sampleProvider = ev3GyroSensor.getAngleAndRateMode();
float[] sample = new float[sampleProvider.sampleSize()];
sampleProvider.fetchSample(sample, 0);
System.out.println(sample[0]);
//I move the robot with my hand
Delay.msDelay(3000);
sampleProvider.fetchSample(sample, 0);
System.out.println(sample[0]);
ev3GyroSensor.close();

try using only angle mode, from my experience, angle and rate mode doesn't always work correctly.
There is also a possibility that you are reading the rate from the sample, but I'm not really sure.

How can I prevent the Charm bar from showing up in my Java application?

I've got a Java swing program that runs in full screen mode. It's effectively a kiosk program in that I want it to lock out everything else while it's running. This is running on a Windows 8.1 tablet, so of course the tablet is touchscreen, and therefore if you do an "edge swipe" (drag your finger from the right) the charms bar pops up and you can get to the Start screen from there. Is there some way to disable this from happening in Java? (Or is there some third-party solution not involving Java that can work in tandem to achieve the same result?)

You can disable edge gestures while your app is active and full screen by setting the System.EdgeGesture.DisableTouchWhenFullScreen property on the window.
I don't know if Java provides a direct way to set this (probably not), but you should be able to set this from a JNI.
Here's a C++ snippet from the DisableTouchWhenFullScreen docs:
HRESULT SetTouchDisableProperty(HWND hwnd, BOOL fDisableTouch)
{
IPropertyStore* pPropStore;
HRESULT hrReturnValue = SHGetPropertyStoreForWindow(hwnd, IID_PPV_ARGS(&pPropStore));
if (SUCCEEDED(hrReturnValue))
{
PROPVARIANT var;
var.vt = VT_BOOL;
var.boolVal = fDisableTouch ? VARIANT_TRUE : VARIANT_FALSE;
hrReturnValue = pPropStore->SetValue(PKEY_EdgeGesture_DisableTouchWhenFullscreen, var);
pPropStore->Release();
}
return hrReturnValue;
}

What I ended up doing was to write a batch script that kills explorer.exe and then re-spawns it after the app exits, based on this answer on Super User.

Set the initial directory in SWT FileDialog

I'm working on an Eclipse RCP project and need to let the user select some file.
For convenience, based on some conditions, the initial directory of the file choosing dialog should be set prior to opening it.
As I'm bound to Eclipse RCP / SWT, I am working with the org.eclipse.swt.widgets.FileDialog.
The documentation of this FileDialog points out to use the setFilterPath(String string)-method which should do exactly what I need (see documentation).
FileDialog dialog = new FileDialog(shell, SWT.OPEN);
dialog.setFilterExtensions(new String [] {"*.html"});
dialog.setFilterPath("c:\\temp");
String result = dialog.open();
Unfortunately it is not working, at least not "every time".
I have currently no installation to check on it, but I'm quite sure that the feature would work totally fine on a Windows 200/XP/Vista machine.
I am working with a Windows 7 machine and I think I am suffering from the behaviour described here for lpstrInitialDir.
At least, this is exactly the behaviour I am facing: The path is good the first time I open the dialog, but the second time, the path is initially set to the last chosen path.
This seems to be convenient in most cases, but it is not in mine.
Can this be right?
If so, have I any chance on changing the behaviour according to my needs?
Thanks for any helping answer!

I ran into the same problem on Windows 10 and found a solution that seems to be working for me. A code snippet from the DirectoryDialog led to the right direction:
if (filterPath != null && filterPath.length() > 0) {
String path = filterPath.replace('/', '\\');
char[] buffer = new char[path.length() + 1];
path.getChars(0, path.length(), buffer, 0);
if (COM.SHCreateItemFromParsingName(buffer, 0, COM.IID_IShellItem, ppv) == OS.S_OK) {
IShellItem psi = new IShellItem(ppv[0]);
/*
* SetDefaultDirectory does not work if the dialog has
* persisted recently used folder. The fix is to clear the
* persisted data.
*/
fileDialog.ClearClientData();
fileDialog.SetDefaultFolder(psi);
psi.Release();
}
}
The FileDialog misses this statement 'fileDialog.ClearClientData()'. My solution is to execute the following code before setting the path and open the dialog:
long [] ppv = new long [1];
if (COM.CoCreateInstance(COM.CLSID_FileOpenDialog, 0, COM.CLSCTX_INPROC_SERVER, COM.IID_IFileOpenDialog, ppv) == OS.S_OK) {
IFileDialog fileDialog = new IFileDialog(ppv[0]);
fileDialog.ClearClientData();
fileDialog.Release();
}
Now you can set the filterpath without Windows messing things up.

I found a simple Solution for the Problem you described (I had the exact same Problem).
Just rearrange the your code like this:
FileDialog dialog = new FileDialog(shell, SWT.OPEN);
dialog.setFilterPath("c:\\temp"); // This line is switched with the following line
dialog.setFilterExtensions(new String [] {"*.html"});
String result = dialog.open();
Somehow the Order of the methods called is relevant.

Are you using the same FileDialog object when you re-open it?
I ran a few quick tests and found that, if you re-set the filterPath, the dialog opens in the correct location.
If I open the same object again, it starts in the previously selected location.

How to disable "Window animation scale" programmatically on Android 4.0+ devices?

I'm using a Service that displays a view using WindowManager, and animation occurs every time I change the view's size using
windowManagerLayoutParams.height = newHeight;
((WindowManager) getSystemService(WINDOW_SERVICE)).updateViewLayout(mMainLayout, windowManagerLayoutParams);
If I disable manually the scale animations, no animation occurs.
Scale animation disabled manually like so:
http://www.cultofandroid.com/11143/android-4-0-tip-how-to-find-and-disable-animations-for-a-snappier-experience/
Is there a way to disable the window scale animations for my application programmatically?

I just had this same problem while working on a system overlay in the SystemUI package and decided to dig through the source to see if I could find a solution. WindowManager.LayoutParams has some hidden goodies that can solve this problem. The trick is to use the privateFlags member of WindowManager.LayoutParams like so:
windowManagerLayoutParams.privateFlags |= 0x00000040;
If you look at line 1019 of WindowManager.java you'll see that 0x00000040 is the value for PRIVATE_FLAG_NO_MOVE_ANIMATION. For me this did stop window animations from occurring on my view when I change the size via updateViewLayout()
I had the advantage of working on a system package so I am able to access privateFlags directly in my code but you are going to need to use reflection if you want to access this field.

As #clark stated this can be changed using reflection:
private void disableAnimations() {
try {
int currentFlags = (Integer) mLayoutParams.getClass().getField("privateFlags").get(mLayoutParams);
mLayoutParams.getClass().getField("privateFlags").set(mLayoutParams, currentFlags|0x00000040);
} catch (Exception e) {
//do nothing. Probably using other version of android
}
}

Did you try Activity#overridePendingTransition(0, 0)?
Check out the documentation:
Call immediately after one of the flavors of startActivity(Intent) or finish() to specify an explicit transition animation to perform next.

How to get supported video camera resolutions in android?

I am writing an app where I am allowing the user to capture video using the phones camera. I am using my own code to record the video as opposed to Androids built in camera app.
Everything is working OK except I need to be able to access the list of supported camera resolutions so I can choose at runtime which one to use. I am looking for something like getSupportedPictureSizes() but for video. Android 3.0 has this functionality but I am looking for something for 2.2.
As of right now I am using CamcorderProfile.QUALITY_HIGH / QUALITY_LOW, but this only gives me two options and on the phones I have been testing on, the file sizes are at each extreme.(QUALITY_LOW is 216 kb/s and QUALITY_HIGH is > 3 MB/s)
Any help would be greatly appreciated,
Thank You!

Did you try to use the getSupportedVideoSizes() method from Camera.Parameters class?
public List<Camera.Size> getSupportedVideoSizes()
This method returns a list of Size objects. It will return null if the camera does not have separate preview and video output. The answer here indicates that when this returns null you may use the getSupportedPreviewSizes() list.

Ok I think I figured it out. It seems to work correctly on the phones I have been testing on.
List<Size> tmpList = camera.getParameters().getSupportedPreviewSizes();
final List<Size> sizeList = new Vector<Size>();
//compair the apsect ratio of the candidate sizes against the real ratio
Double aspectRatio = (Double.valueOf(getWindowManager().getDefaultDisplay().getHeight()) / getWindowManager().getDefaultDisplay().getWidth());
for(int i=0; i<tmpList.size(); i++){
Double tmpRatio = Double.valueOf(tmpList.get(i).height) / tmpList.get(i).width;
if(Math.abs(aspectRatio - tmpRatio) < .15){
sizeList.add(tmpList.get(i));
}
}