Créer une bibliothèque dynamique
Bonjour,
Développeur Delphi, j'utilise Delphi XE2 depuis peu pour développer sur Mac OS (j'utilisais Lazarus avant). Certains framework Mac OS n'étant pas disponibles sur XE2, en particulier QTKit, il me faut écrire une partie du code sous XCODE en objective C...
Il m'arrive de développer quelques routines élémentaires en C, mais le C n'est vraiment pas mon élément et là, avec Objective-C je sèche.
Le but est en fait très simple : Récupérer une capture WebCam. J'ai trouvé ce bout de code qui semble faire ce que je cherche ici : http://erikrothoff.com/2011/07/captu...c-using-qtkit/
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//
// PhotoGrabber.h
// By Erik Rothoff Andersson <erikrothoff.com>
//
#import <Foundation/Foundation.h>
#import <QTKit/QTKit.h>
@protocol PhotoGrabberDelegate <NSObject>
- (void)photoGrabbed:(NSImage*)image;
@end
@interface PhotoGrabber : NSObject {
CVImageBufferRef currentImage;
QTCaptureDevice *video;
QTCaptureDecompressedVideoOutput *output;
QTCaptureInput *input;
QTCaptureSession *session;
id<PhotoGrabberDelegate> delegate;
}
@property (nonatomic, assign) id<PhotoGrabberDelegate> delegate;
- (void)grabPhoto;
- (NSString*)deviceName;
@end |
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//
// PhotoGrabber.m
// By Erik Rothoff Andersson <erikrothoff.com>
//
#import "PhotoGrabber.h"
@implementation PhotoGrabber
@synthesize delegate;
- (id)init
{
if ( (self = [super init]) )
{
NSError *error = nil;
// Acquire a device, we will also have objects for getting input
// from the device, and another for output
video = [QTCaptureDevice defaultInputDeviceWithMediaType:QTMediaTypeVideo];
BOOL success = [video open:&error];
if ( ! success || error )
{
NSLog(@"Did not succeed in acquire: %d", success);
NSLog(@"Error: %@", [error localizedDescription]);
return nil;
}
// QTCaptureDeviceInput is the object that will use the
// device as input, i.e. handle the photo-taking
input = [[QTCaptureDeviceInput alloc] initWithDevice:video];
// Session handles the input and output of both objects
session = [[QTCaptureSession alloc] init];
// Add our input object as input for this particular session
// (the code is pretty self-explanatory)
success = [session addInput:input error:&error];
if ( ! success || error )
{
NSLog(@"Did not succeed in connecting input to session: %d", success);
NSLog(@"Error: %@", [error localizedDescription]);
return nil;
}
// Create an object for outputing the video
// The input will tell the session object that it has taken
// some data, which will in turn send this to the output
// object, which has a delegate that you defined
output = [[QTCaptureDecompressedVideoOutput alloc] init];
// This is the delegate. Note the
// captureOutput:didOutputVideoFrame...-method of this
// object. That is the method which will be called when
// a photo has been taken.
[output setDelegate:self];
// Add the output-object for the session
success = [session addOutput:output error:&error];
if ( ! success || error )
{
NSLog(@"Did succeed in connecting output to session: %d", success);
NSLog(@"Error: %@", [error localizedDescription]);
return nil;
}
// Because the input stream is video we will be getting
// many frames after each other, we take the first one
// we get and store it, and don't accept any more after
// we already have one
currentImage = nil;
}
return self;
}
// This is the method to use when you want to initialize a grab
- (void)grabPhoto
{
[session startRunning];
}
// The device-name will most likely be "Built-in iSight camera"
- (NSString*)deviceName
{
return [video localizedDisplayName];
}
// QTCapture delegate method, called when a frame has been loaded by the camera
- (void)captureOutput:(QTCaptureOutput *)captureOutput didOutputVideoFrame:(CVImageBufferRef)videoFrame withSampleBuffer:(QTSampleBuffer *)sampleBuffer fromConnection:(QTCaptureConnection *)connection
{
// If we already have an image we should use that instead
if ( currentImage ) return;
// Retain the videoFrame so it won't disappear
// don't forget to release!
CVBufferRetain(videoFrame);
// The Apple docs state that this action must be synchronized
// as this method will be run on another thread
@synchronized (self) {
currentImage = videoFrame;
}
// As stated above, this method will be called on another thread, so
// we perform the selector that handles the image on the main thread
[self performSelectorOnMainThread:@selector(saveImage) withObject:nil waitUntilDone:NO];
}
// Called from QTCapture delegate method
- (void)saveImage
{
// Stop the session so we don't record anything more
[session stopRunning];
// Convert the image to a NSImage with JPEG representation
// This is a bit tricky and involves taking the raw data
// and turning it into an NSImage containing the image
// as JPEG
NSCIImageRep *imageRep = [NSCIImageRep imageRepWithCIImage:[CIImage imageWithCVImageBuffer:currentImage]];
NSImage *image = [[NSImage alloc] initWithSize:[imageRep size]];
[image addRepresentation:imageRep];
NSData *bitmapData = [image TIFFRepresentation];
NSBitmapImageRep *bitmapRep = [NSBitmapImageRep imageRepWithData:bitmapData];
NSData *imageData = [bitmapRep representationUsingType:NSJPEGFileType properties:nil];
[image release];
image = [[NSImage alloc] initWithData:imageData];
// Call delegate callback
if ( [self.delegate respondsToSelector:@selector(photoGrabbed:)] )
[self.delegate photoGrabbed:image];
// Clean up after us
[image release];
CVBufferRelease(currentImage);
currentImage = nil;
}
- (void)dealloc
{
self.delegate = nil;
// Just close/turn off everything if it's running
if ( [session isRunning] )
[session stopRunning];
if ( [video isOpen] )
[video close];
// Remove input/output
[session removeInput:input];
[session removeOutput:output];
[input release];
[session release];
[output release];
[super dealloc];
}
@end |
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// How to use the Gist from https://gist.github.com/1038480
// By Erik Rothoff Andersson <erikrothoff.com>
#import "PhotoGrabber.h"
@implementation MyClass
- (void)doSomething
{
PhotoGrabber *grabber = [[PhotoGrabber alloc] init];
grabber.delegate = self;
[grabber grabPhoto];
}
- (void)photoGrabbed:(NSImage*)image
{
// image is the image from the camera
// store it to a file or show, manipulate it, have fun
}
@end |
Ce que je souhaiterais, c'est faire de ce code une bibliothèque dynamique (.dylib) afin de pouvoir la charger et appeler la fonction qui me permet de récupérer une image prise par la webcam depuis mon code Delphi.
Mais l'objective C... 8O est encore plus abscond pour moi que le C.
Quelles fonctions faut-il exporter ? J'ajoute que si les 2 premiers morceaux de code compilent parfaitement, si j'ajoute le 3°, ça ne compile plus du tout sous XCode.
Quelqu'un pourrait-il m'éclairer ? Je ne parviens pas à comprendre ce code.
Merci d'avance,
André.
