Is there a way to capture CAEmitterCells (generated using a CAEmitterLayer) when capturing the ios device screen?
UIGetScreenImage() works, but since it's a private method im not allowed to use it.
UIGraphicsBeginImageContext doesn't seem to work, the particles are simply omitted from the resulting image.
EDIT:
Here is the code I'm currently using to capture the view. I'm actually recording a 30-second-long video of the screen, using the code provided by aroth at here. It works by recording 25 images of itself (its a UIView subclass) and its subviews (in our case including the UIView whose layer is the CAEmitterLayer) per second and uses AVAssetWriter to compose the recording.
It's quite a mouthful, so I'll just place the relevant lines here:
I ARC-ed the code using the ARC tool in XCode, so the code might be a bit different memory management wise.
- (CGContextRef) createBitmapContextOfSize:(CGSize) size {
CGContextRef context = NULL;
CGColorSpaceRef colorSpace;
int bitmapByteCount;
int bitmapBytesPerRow;
bitmapBytesPerRow = (size.width * 4);
bitmapByteCount = (bitmapBytesPerRow * size.height);
colorSpace = CGColorSpaceCreateDeviceRGB();
if (bitmapData != NULL) {
free(bitmapData);
}
bitmapData = malloc( bitmapByteCount );
if (bitmapData == NULL) {
fprintf (stderr, "Memory not allocated!");
return NULL;
}
context = CGBitmapContextCreate (bitmapData,
size.width,
size.height,
8, // bits per component
bitmapBytesPerRow,
colorSpace,
kCGImageAlphaNoneSkipFirst);
CGContextSetAllowsAntialiasing(context,NO);
if (context== NULL) {
free (bitmapData);
fprintf (stderr, "Context not created!");
return NULL;
}
CGColorSpaceRelease( colorSpace );
return context;
}
//static int frameCount = 0; //debugging
- (void) drawRect:(CGRect)rect {
NSDate* start = [NSDate date];
CGContextRef context = [self createBitmapContextOfSize:self.frame.size];
//not sure why this is necessary...image renders upside-down and mirrored
CGAffineTransform flipVertical = CGAffineTransformMake(1, 0, 0, -1, 0, self.frame.size.height);
CGContextConcatCTM(context, flipVertical);
[self.layer renderInContext:context];
CGImageRef cgImage = CGBitmapContextCreateImage(context);
UIImage* background = [UIImage imageWithCGImage: cgImage];
CGImageRelease(cgImage);
self.currentScreen = background;
//debugging
//if (frameCount < 40) {
// NSString* filename = [NSString stringWithFormat:@"Documents/frame_%d.png", frameCount];
// NSString* pngPath = [NSHomeDirectory() stringByAppendingPathComponent:filename];
// [UIImagePNGRepresentation(self.currentScreen) writeToFile: pngPath atomically: YES];
// frameCount++;
//}
//NOTE: to record a scrollview while it is scrolling you need to implement your UIScrollViewDelegate such that it calls
// 'setNeedsDisplay' on the ScreenCaptureView.
if (_recording) {
float millisElapsed = [[NSDate date] timeIntervalSinceDate:startedAt] * 1000.0;
[self writeVideoFrameAtTime:CMTimeMake((int)millisElapsed, 1000)];
}
float processingSeconds = [[NSDate date] timeIntervalSinceDate:start];
float delayRemaining = (1.0 / self.frameRate) - processingSeconds;
CGContextRelease(context);
//redraw at the specified framerate
[self performSelector:@selector(setNeedsDisplay) withObject:nil afterDelay:delayRemaining > 0.0 ? delayRemaining : 0.01];
}
Really hope this helps. Thanks for your support!
Did you try using
-[CALayer renderInContext:]
?