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I am working on a project which involves Rust and Java. I need to be able to use the JNI from the Rust side, without the Java side calling invoking it (because it is not my code). So far, I have been able to ensure my DLL is injected (open a small window on keypress, I have been using this for debugging).
A shortened example of the relevant code is the following:
use jni::sys::{JNI_GetCreatedJavaVMs, JNIInvokeInterface_};
let jvm_ptr = null_mut() as *mut *mut *const JNIInvokeInterface_;
let count = null_mut();
// hasn't crashed
JNI_GetCreatedJavaVMs(jvm_ptr, 1, count); // https://docs.rs/jni/latest/jni/sys/fn.JNI_GetCreatedJavaVMs.html
// crashes
My question is this: is it possible to/how do I get a JNI environment in this situation?
With the help of the comments, I got that crash to stop happening. The trick was to pre-allocate an array.
let jvm_ptr = Vec::with_capacity(1).as_mut_ptr();
let count = null_mut();
JNI_GetCreatedJavaVMs(jvm_ptr, 1, count);
You can't chunk a null pointer into the vmBuf parameter and then tell it that vmBuf points to an array of length 1 via bufLen. Translating the C++ code linked above, I would do something like
let mut count: jint = 0;
let check = JNI_GetCreatedJavaVMs(null_mut(), 0, &mut count);
assert!(check == JNI_OK);
let mut vms = vec![null_mut(); count as usize];
let check = JNI_GetCreatedJavaVMs(vms.as_mut_ptr(), vms.len() as i32, &mut count);
assert!(check == JNI_OK);
assert!(vms.len() == count as usize);
though that's probably a bit overkill since there can only be one VM. Still, checking the count is probably a good idea.
I have been using this many years. It can be polished....
try {
// how many JVMs is there?
JNI_GetCreatedJavaVMs(NULL, 0, &number_of_JVMs);
}
catch (exception e)
{
int x = 0;
}
if (number_of_JVMs > 0)
{
JavaVM** buffer = new JavaVM * [number_of_JVMs];
JNI_GetCreatedJavaVMs(buffer, number_of_JVMs, &number_of_JVMs);
// 2. get the data
jvm_handle = buffer[0];
if (!jvm_handle == 0)
return true;
else return false;
}
I'm new to rust and having trouble with the scope of objects/variables in GTK. I have the following code, which works, but I need to set a label in the GTK Window to the text of the variable watch_text. Here is the code:
use adw::subclass::prelude::AdwApplicationWindowImpl;
use gtk::prelude::*;
use gtk::subclass::prelude::*;
use gtk::{gio, glib, CompositeTemplate};
use glib::{clone, DateTime, timeout_add};
use std::time::Duration;
use std::sync::{Arc, Mutex};
fn setup_signals(&self) {
let imp = imp::FurWindow::from_instance(self);
let running = Arc::new(Mutex::new(false));
imp.start_button.connect_clicked(clone!(#weak self as this, #strong running => move |_| {
if !*running.lock().unwrap() {
let mut secs: u32 = 0;
let mut mins: u32 = 0;
let mut hrs: u32 = 0;
this.inapp_notification("Starting Timer!");
*running.lock().unwrap() = true;
let stopwatch = DateTime::now_local();
let duration = Duration::new(1,0);
let timer_repeat = timeout_add(duration, clone!(#strong running as running_clone => move || {
if *running_clone.lock().unwrap() {
secs += 1;
if secs > 59 {
secs = 0;
mins += 1;
if mins > 59 {
mins = 0;
hrs += 1;
}
}
let watch_text: &str = &format!("{:02}:{:02}:{:02}", hrs, mins, secs).to_string();
println!("{}",watch_text);
// **Here the println works, everything prints correctly,
// but I need to add watch_text to the label "watch"
// this.set_watch_time(watch_text);
}
Continue(*running_clone.lock().unwrap())
}));
} else {
this.inapp_notification("Stopping Timer!");
*running.lock().unwrap() = false;
}
}));
}
The issue is that in the commented section, no matter how I try to access or clone imp.watch, I get an error NonNull<GObject> cannot be sent between threads safely. How can I set the label text to watch_text?
The issue is that timeout_add() requires the passed callback to be Send, which is nice, because with this function you can pass values from one working thread to the GUI thread, to be processed and update the interface accordingly.
But GUI objects are not Send, because they live in the GUI thread and must be used only from the GUI thread, so they cannot be used for timeout_add().
But that is precisely why there is this other timeout_add_local(), that works just like the other one, except that it does not require Send, and that it must be called from the GUI thread, or else it will panic.
I am trying to set up a global hotkey on Linux.
I had initially used x11 (libX11.so) however I had to do this from a thread. I tried it but the XPendingEvent and XNextEvent would eventually crash the app.
So I switched to xcb (libxcb.so.1). There is no errors, I even check with xcb_request_check however the event loop is not picking anything up. As soon as I start the loop, I get only one event which looks like this:
{
response_type: 0,
pad0: 10,
sequence: 2,
pad: [620, 2162688, 0, 0, 0, 0, 0],
full_sequence: 2
}
Here is my code, I actually do this in js-ctypes, but I cut down all the stuff to just show simple agnostic as possible code:
conn = xcb_connect(null, null);
keysyms = xcb_key_symbols_alloc(conn);
keycodesPtr = xcb_key_symbols_get_keycode(keysyms, XK_Space);
setup = xcb_get_setup(conn);
screens = xcb_setup_roots_iterator(setup);
screensCnt = screens.rem;
for (var i=0; i<screensCnt; i++) {
rez_grab = xcb_grab_key(conn, 1, screens.data.root, XCB_MOD_MASK_ANY, keycodesPtr[0], XCB_GRAB_MODE_ASYNC, XCB_GRAB_MODE_ASYNC);
rez_err = xcb_request_check(conn, rez_grab);
// rez_err is null
xcb_screen_next(&screens);
}
xcb_flush(conn);
// start event loop
while (true) {
ev = xcb_poll_for_event(conn);
console.log(ev);
if (ev != null) {
free(ev);
}
Sleep(50);
}
console.log(ev) gives me what I posted above earlier, response_type of 0 and then forever after that ev is just null.
Does anyone know what's up? rez_grab as a raw string is xcb_void_cookie_t(2)
Thanks much
Figured it out at long last!! Ah figured this one out! I was using XCB_MOD_MASK_ANY and this constant works on Debian but not on Ubuntu, which is what I was using to test. I switched that up to use num lock, caps lock etc and now it works! :)
ostypes.API('xcb_grab_key')(conn, 1, screens.data.contents.root, ostypes.CONST.XCB_MOD_MASK_LOCK, keycodesArr[j], ostypes.CONST.XCB_GRAB_MODE_ASYNC, ostypes.CONST.XCB_GRAB_MODE_ASYNC); // caps lock
ostypes.API('xcb_grab_key')(conn, 1, screens.data.contents.root, ostypes.CONST.XCB_MOD_MASK_2, keycodesArr[j], ostypes.CONST.XCB_GRAB_MODE_ASYNC, ostypes.CONST.XCB_GRAB_MODE_ASYNC); // num lock
ostypes.API('xcb_grab_key')(conn, 1, screens.data.contents.root, ostypes.CONST.XCB_MOD_MASK_LOCK | ostypes.CONST.XCB_MOD_MASK_2, keycodesArr[j], ostypes.CONST.XCB_GRAB_MODE_ASYNC, ostypes.CONST.XCB_GRAB_MODE_ASYNC); // caps lock AND num lock
that was very very crazy i had no idea the XCB_MOD_MASK_ANY constant didnt work on Ubuntu -
var rez_grab = ostypes.API('xcb_grab_key')(conn, 1, screens.data.contents.root, ostypes.CONST.XCB_MOD_MASK_ANY, keycodesArr[j], ostypes.CONST.XCB_GRAB_MODE_ASYNC, ostypes.CONST.XCB_GRAB_MODE_ASYNC);
I also tried #n.m's code. On ubuntu it didnt work, but worked on debian -
#include <xcb/xcb.h>
#define XK_LATIN1
#include <xcb/xcb_keysyms.h>
#include <X11/keysymdef.h>
#include <stdio.h>
#include <stdlib.h>
int
main ()
{
xcb_connection_t *conn;
conn = xcb_connect (NULL, NULL);
xcb_key_symbols_t * keysyms = xcb_key_symbols_alloc(conn);
xcb_keycode_t * keycodesPtr = xcb_key_symbols_get_keycode(keysyms, XK_space);
const xcb_setup_t* setup = xcb_get_setup(conn);
xcb_screen_iterator_t screens = xcb_setup_roots_iterator(setup);
int screensCnt = screens.rem;
for (int i=0; i<screensCnt; i++) {
xcb_void_cookie_t rez_grab = xcb_grab_key(conn, 1, screens.data->root, XCB_MOD_MASK_ANY, keycodesPtr[0], XCB_GRAB_MODE_ASYNC, XCB_GRAB_MODE_ASYNC);
const static uint32_t values[] = { XCB_EVENT_MASK_EXPOSURE | XCB_EVENT_MASK_BUTTON_PRESS };
xcb_change_window_attributes (conn, screens.data->root, XCB_CW_EVENT_MASK, values);
xcb_screen_next(&screens);
}
xcb_flush(conn);
// start event loop
while (1) {
xcb_generic_event_t *ev = xcb_wait_for_event(conn);
if (ev && ((ev->response_type & ~0x80) == XCB_KEY_PRESS))
{
xcb_key_press_event_t *kp = (xcb_key_press_event_t *)ev;
printf ("Got key press %d\n", (int)kp->event);
}
if (ev != NULL) {
free(ev);
}
}
return 0;
}
I'm trying to figure out how to call this AVFoundation function in Swift. I've spent a ton of time fiddling with declarations and syntax, and got this far. The compiler is mostly happy, but I'm left with one last quandary.
public func captureOutput(
captureOutput: AVCaptureOutput!,
didOutputSampleBuffer sampleBuffer: CMSampleBuffer!,
fromConnection connection: AVCaptureConnection!
) {
let samplesInBuffer = CMSampleBufferGetNumSamples(sampleBuffer)
var audioBufferList: AudioBufferList
var buffer: Unmanaged<CMBlockBuffer>? = nil
CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(
sampleBuffer,
nil,
&audioBufferList,
UInt(sizeof(audioBufferList.dynamicType)),
nil,
nil,
UInt32(kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment),
&buffer
)
// do stuff
}
The compiler complains for the 3rd and 4th arguments:
Address of variable 'audioBufferList' taken before it is initialized
and
Variable 'audioBufferList' used before being initialized
So what am I supposed to do here?
I'm working off of this StackOverflow answer but it's Objective-C. I'm trying to translate it into Swift, but run into this problem.
Or is there possibly a better approach? I need to read the data from the buffer, one sample at a time, so I'm basically trying to get an array of the samples that I can iterate over.
Disclaimer: I have just tried to translate the code from Reading audio samples via AVAssetReader to Swift, and verified that it compiles. I have not
tested if it really works.
// Needs to be initialized somehow, even if we take only the address
var audioBufferList = AudioBufferList(mNumberBuffers: 1,
mBuffers: AudioBuffer(mNumberChannels: 0, mDataByteSize: 0, mData: nil))
var buffer: Unmanaged<CMBlockBuffer>? = nil
CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(
sampleBuffer,
nil,
&audioBufferList,
UInt(sizeof(audioBufferList.dynamicType)),
nil,
nil,
UInt32(kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment),
&buffer
)
// Ensure that the buffer is released automatically.
let buf = buffer!.takeRetainedValue()
// Create UnsafeBufferPointer from the variable length array starting at audioBufferList.mBuffers
let audioBuffers = UnsafeBufferPointer<AudioBuffer>(start: &audioBufferList.mBuffers,
count: Int(audioBufferList.mNumberBuffers))
for audioBuffer in audioBuffers {
// Create UnsafeBufferPointer<Int16> from the buffer data pointer
var samples = UnsafeMutableBufferPointer<Int16>(start: UnsafeMutablePointer(audioBuffer.mData),
count: Int(audioBuffer.mDataByteSize)/sizeof(Int16))
for sample in samples {
// ....
}
}
Swift3 solution:
func loopAmplitudes(audioFileUrl: URL) {
let asset = AVAsset(url: audioFileUrl)
let reader = try! AVAssetReader(asset: asset)
let track = asset.tracks(withMediaType: AVMediaTypeAudio)[0]
let settings = [
AVFormatIDKey : kAudioFormatLinearPCM
]
let readerOutput = AVAssetReaderTrackOutput(track: track, outputSettings: settings)
reader.add(readerOutput)
reader.startReading()
while let buffer = readerOutput.copyNextSampleBuffer() {
var audioBufferList = AudioBufferList(mNumberBuffers: 1, mBuffers: AudioBuffer(mNumberChannels: 0, mDataByteSize: 0, mData: nil))
var blockBuffer: CMBlockBuffer?
CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(
buffer,
nil,
&audioBufferList,
MemoryLayout<AudioBufferList>.size,
nil,
nil,
kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment,
&blockBuffer
);
let buffers = UnsafeBufferPointer<AudioBuffer>(start: &audioBufferList.mBuffers, count: Int(audioBufferList.mNumberBuffers))
for buffer in buffers {
let samplesCount = Int(buffer.mDataByteSize) / MemoryLayout<Int16>.size
let samplesPointer = audioBufferList.mBuffers.mData!.bindMemory(to: Int16.self, capacity: samplesCount)
let samples = UnsafeMutableBufferPointer<Int16>(start: samplesPointer, count: samplesCount)
for sample in samples {
//do something with you sample (which is Int16 amplitude value)
}
}
}
}
The answers posted here make assumptions about the size of the necessary AudioBufferList -- which may have allowed them to have work in their particular circumstance, but didn't work for me when receiving audio from a AVCaptureSession. (Apple's own sample code didn't work either.)
The documentation on CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer is not obvious, but it turns out you can ask the function it how big AudioListBuffer item should be first, and then call it a second time with an AudioBufferList allocated to the size it wants.
Below is a C++ example (sorry, don't know Swift) that shows a more general solution that worked for me.
// ask the function how big the audio buffer list should be for this
// sample buffer ref
size_t requiredABLSize = 0;
err = CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(sampleBuffer,
&requiredABLSize,
NULL,
NULL,
kCFAllocatorSystemDefault,
kCFAllocatorSystemDefault,
kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment,
NULL);
// allocate an audio buffer list of the required size
AudioBufferList* audioBufferList = (AudioBufferList*) malloc(requiredABLSize);
// ensure that blockBuffer is NULL in case the function fails
CMBlockBufferRef blockBuffer = NULL;
// now let the function allocate fill in the ABL for you
err = CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(sampleBuffer,
NULL,
audioBufferList,
requiredABLSize,
kCFAllocatorSystemDefault,
kCFAllocatorSystemDefault,
kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment,
&blockBuffer);
// if we succeeded...
if (err == noErr) {
// la la la... read your samples...
}
// release the allocated block buffer
if (blockBuffer != NULL) {
CFRelease(blockBuffer);
blockBuffer = NULL;
}
// release the allocated ABL
if (audioBufferList != NULL) {
free(audioBufferList);
audioBufferList = NULL;
}
I'll leave it up to the Swift experts to offer an implementation in that language.
Martin's answer works and does exactly what I asked in the question, however, after posting the question and spending more time with the problem (and before seeing Martin's answer), I came up with this:
public func captureOutput(
captureOutput: AVCaptureOutput!,
didOutputSampleBuffer sampleBuffer: CMSampleBuffer!,
fromConnection connection: AVCaptureConnection!
) {
let samplesInBuffer = CMSampleBufferGetNumSamples(sampleBuffer)
self.currentZ = Double(samplesInBuffer)
let buffer: CMBlockBufferRef = CMSampleBufferGetDataBuffer(sampleBuffer)
var lengthAtOffset: size_t = 0
var totalLength: size_t = 0
var data: UnsafeMutablePointer<Int8> = nil
if( CMBlockBufferGetDataPointer( buffer, 0, &lengthAtOffset, &totalLength, &data ) != noErr ) {
println("some sort of error happened")
} else {
for i in stride(from: 0, to: totalLength, by: 2) {
// do stuff
}
}
}
This is a slightly different approach, and probably still has room for improvement, but the main point here is that at least on an iPad Mini (and probably other devices), each time this method is called, we get 1,024 samples. But those samples come in an array of 2,048 Int8 values. Every other one is the left/right byte that needs to be combined into to make an Int16 to turn the 2,048 half-samples into 1,024 whole samples.
it works for me. try it:
let musicUrl: NSURL = mediaItemCollection.items[0].valueForProperty(MPMediaItemPropertyAssetURL) as! NSURL
let asset: AVURLAsset = AVURLAsset(URL: musicUrl, options: nil)
let assetOutput = AVAssetReaderTrackOutput(track: asset.tracks[0] as! AVAssetTrack, outputSettings: nil)
var error : NSError?
let assetReader: AVAssetReader = AVAssetReader(asset: asset, error: &error)
if error != nil {
print("Error asset Reader: \(error?.localizedDescription)")
}
assetReader.addOutput(assetOutput)
assetReader.startReading()
let sampleBuffer: CMSampleBufferRef = assetOutput.copyNextSampleBuffer()
var audioBufferList = AudioBufferList(mNumberBuffers: 1, mBuffers: AudioBuffer(mNumberChannels: 0, mDataByteSize: 0, mData: nil))
var blockBuffer: Unmanaged<CMBlockBuffer>? = nil
CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(
sampleBuffer,
nil,
&audioBufferList,
sizeof(audioBufferList.dynamicType), // instead of UInt(sizeof(audioBufferList.dynamicType))
nil,
nil,
UInt32(kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment),
&blockBuffer
)
I do this (swift 4.2):
let n = CMSampleBufferGetNumSamples(audioBuffer)
let format = CMSampleBufferGetFormatDescription(audioBuffer)!
let asbd = CMAudioFormatDescriptionGetStreamBasicDescription(format)!.pointee
let nChannels = Int(asbd.mChannelsPerFrame) // probably 2
let bufferlistSize = AudioBufferList.sizeInBytes(maximumBuffers: nChannels)
let abl = AudioBufferList.allocate(maximumBuffers: nChannels)
for i in 0..<nChannels {
abl[i] = AudioBuffer(mNumberChannels: 0, mDataByteSize: 0, mData: nil)
}
var block: CMBlockBuffer?
var status = CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(audioBuffer, bufferListSizeNeededOut: nil, bufferListOut: abl.unsafeMutablePointer, bufferListSize: bufferlistSize, blockBufferAllocator: nil, blockBufferMemoryAllocator: nil, flags: 0, blockBufferOut: &block)
assert(noErr == status)
// use AudioBufferList here (abl.unsafePointer), e.g. with ExtAudioFileWrite or what have you
I'm new in OpenGL.
I want to draw somethink using OpenGL in Windows Forms.
If I use Win32 application with WinMain method, application working.
In WinMain method, I fill HWND with CreateWindow() function and ı give WinMain parameters to CreateWindows.
But I want to get Handle from Windows form i cant get this. Everytime
wglCreateContext(hdc) return NULL
there is a example which is I take
public:
COpenGL(System::Windows::Forms::Form ^ parentForm, GLsizei iWidth, GLsizei iHeight)
{
CreateParams^ cp = gcnew CreateParams;
// Set the position on the form
cp->X = 0;
cp->Y = 0;
cp->Height = iHeight;
cp->Width = iWidth;
// Specify the form as the parent.
cp->Parent = parentForm->Handle;
// Create as a child of the specified parent and make OpenGL compliant (no clipping)
cp->Style = WS_CHILD | WS_VISIBLE | WS_CLIPSIBLINGS | WS_CLIPCHILDREN;
// Create the actual window
this->CreateHandle(cp);
m_hDC = GetDC((HWND)this->Handle.ToPointer());
if(m_hDC)
{
MySetPixelFormat(m_hDC);
ReSizeGLScene(iWidth, iHeight);
InitGL();
}
rtri = 0.0f;
rquad = 0.0f;
}
GLint MySetPixelFormat(HDC hdc)
{
static PIXELFORMATDESCRIPTOR pfd=
{
sizeof(PIXELFORMATDESCRIPTOR),
1,
PFD_DRAW_TO_WINDOW |
PFD_SUPPORT_OPENGL |
PFD_DOUBLEBUFFER,
PFD_TYPE_RGBA,
16,
0, 0, 0, 0, 0, 0,
0,
0,
0,
0, 0, 0, 0,
16,
0,
0,
PFD_MAIN_PLANE,
0,
0, 0, 0
};
GLint iPixelFormat;
// get the device context's best, available pixel format match
if((iPixelFormat = ChoosePixelFormat(hdc, &pfd)) == 0)
{
MessageBox::Show("ChoosePixelFormat Failed");
return 0;
}
// make that match the device context's current pixel format
if(SetPixelFormat(hdc, iPixelFormat, &pfd) == FALSE)
{
MessageBox::Show("SetPixelFormat Failed");
return 0;
}
if((m_hglrc = wglCreateContext(hdc)) == NULL)
{
MessageBox::Show("wglCreateContext Failed");
return 0;
}
if((wglMakeCurrent(hdc, m_hglrc)) == NULL)
{
MessageBox::Show("wglMakeCurrent Failed");
return 0;
}
return 1;
}
Have can I solve this problem?
Here, change in the constructor :
m_hDC = GetDC((HWND)this->Handle.ToPointer());
if(m_hDC)
{
wglMakeCurrent(m_hDC, NULL);
MySetPixelFormat(m_hDC);
ReSizeGLScene(iWidth, iHeight);
InitGL();
}
You must call wglMakeCurrent after m_hDC has been setup. I reply to the first article of the example. Here Creating an OpenGL view on a Windows Form
That solve my problem :)
you can check what glGetLastError value and mostly it is because you choose wrong or incompatible pixel format, you can try with other format, then your window class should be flagged CS_OWNDC and set DoubleBuffering to false.