I have been using UIImagePickerController for my application preview purpose, I have customized and zoom in/out buttons, I didn't used CGAffineTransformScale before, however I have googled and implemented zoom in functionality using CGAffineTransformScale like this...
- (void) zoom_in_clkd
{
preview_picker.cameraViewTransform = CGAffineTransformScale(preview_picker.cameraViewTransform, 1.0, 1.2499);
}
It seems fine, however I want to implement zoom out functionality, I don't have any idea what should be its sx,sy values in CGAffineTransformScale.
Can anyone please tell a good tutorial or sample code to use CGAffineTransformScale?
sx and sy suggests the zoom factor on x and y values respectively.
If you want zoom out the view provide the sx and sy < 1.0
Download the sample code from this link.
I have simulated zoom out functionality in different way, What I have done is I reset to identity(bringing back to original size) and zooming in again to what position I want like this..
if (cameraTransformX == 2.0) {
preview_picker.cameraViewTransform = CGAffineTransformIdentity;
cameraTransformX -= 1.0;
} else if (cameraTransformX == 3.0) {
preview_picker.cameraViewTransform = CGAffineTransformIdentity;
preview_picker.cameraViewTransform = CGAffineTransformScale(preview_picker.cameraViewTransform, 1.0, 1.2499);
cameraTransformX -= 1.0;
} else if (cameraTransformX == 4.0) {
preview_picker.cameraViewTransform = CGAffineTransformIdentity;
preview_picker.cameraViewTransform = CGAffineTransformScale(preview_picker.cameraViewTransform, 1.0, 1.2499);
preview_picker.cameraViewTransform = CGAffineTransformScale(preview_picker.cameraViewTransform, 1.0, 1.2499);
cameraTransformX -= 1.0;
}
I know its not a proper way to go back to previous transform, but it will do the tricks. :)
My solution was to save initial cameraViewTransform and use that for both zoom in/zoom out. For zoom out you reduce scale, set initially for example at 3. Here is my code:
// initial cameraViewTransform
self.initialTransform = self.videoRecorderController.cameraViewTransform;
// for zoom in
if(self.zoomIn) {
// increment scale
self.scale += 0.5;
self.videoRecorderController.cameraViewTransform = CGAffineTransformScale(self.initialTransform, self.scale, self.scale);
}
// for zoom out
else {
self.scale -= 0.5;
self.videoRecorderController.cameraViewTransform = CGAffineTransformScale(self.initialTransform, self.scale , self.scale);
}
Related
My app is simple: I want to move a small uiimageview around a view of an iPad with the accelerometer (now Core Motion). So, I can move the uiimageview around with the accelerometer, but I am having trouble establishing working borders in landscape mode. So, here is my code. The problem is that the uiimageview tends to stick to the borders and some of the borders are not perfectly on the edge of the view. Here is my code, any help is greatly appreciated:
- (void)startMyMotionDetect
{
__block float stepMoveFactor = 15;
[self.motionManager
startAccelerometerUpdatesToQueue:[[NSOperationQueue alloc] init]
withHandler:^(CMAccelerometerData *data, NSError *error)
{
dispatch_async(dispatch_get_main_queue(),
^{
CGRect rect = self.sumbarine.frame;
float movetoY = rect.origin.x + (data.acceleration.x * stepMoveFactor);
float maxY = self.view.frame.size.width-rect.size.width;
float movetoX = (rect.origin.y + rect.size.height)
- (data.acceleration.y * stepMoveFactor);
float maxX = self.view.frame.size.height;
if ( movetoX >0 && movetoX < maxX ) {
rect.origin.x += (data.acceleration.y * stepMoveFactor);
};
if ( movetoY > 0 && movetoY < maxY ) {
rect.origin.y += (data.acceleration.x * stepMoveFactor);
};
[UIView animateWithDuration:0 delay:0
options:UIViewAnimationOptionCurveEaseIn
animations:
^{
self.sumbarine.frame = rect;
}
completion:nil
];
}
);
}
];
}
The sticking issue comes from your conditions for moving. Right now, you say, if "moveToX/Y" is > 0, and less than the width/height, then add Acceleration X/Y.
What happens if origin is == or >greater than "maxX/Y"? Answer: Nothing. And thus, the submarine image acts like it's stuck to a board. Probably it can move on the alternate axis, until it's finally stuck at a condition where it no longer can move.
You'll want to play around with your conditional rules. I do not know what type of actions/input you're trying to implement for gameplay, so I can't tell you what to do next. I'm assuming the sub is supposed to go up/down depending on some user gesture/action.
One last piece of advice. Accelerometers are based on G-Force... What this means for you is even though acceleration on some axis is positive when you move say left... There's also an inverse curve when you need apply the force needed to stop. Try looking at the motiongraphs app (available in documentation) to help you get a better feel/sense of this stuff.
And remember, have fun!
is there anyway we can do rotation of image in a pendulum effect in iphone using UIView Animation or CoreAnimation
Use CGAffineTransformRotate to rotate your UIImageView e.g.
yourImage.transform = CGAffineTransformRotate(CGAffineTransformIdentity, M_PI * (_angle/ 180.0));
Also, you'll need to set up the anchor point on your image, prior to rotating it, so that you can make it swing from the correct position. e.g.
yourImage.layer.anchorPoint = CGPointMake(0.5,0); // Set anchor to top middle.
Obviously, you'll need to set up a timer to adjust move the image and control the angle. You could do something like the following in a timer. (untested)
_angle = 45; // Set starting angle.
_direction = 1; // Set starting direction.
-(void) movePend
{
if(_direction == 45){
_direction = 1;
} else if(_direction == 180) {
_direction = 0;
}
_angle = (_direction) ? _angle-- : _angle++; // Determine which way to rotate.
yourImage.transform = CGAffineTransformRotate(CGAffineTransformIdentity, M_PI * (_angle/ 180.0));
}
I have a UIView that I rotate with this code:
helpView.transform = CGAffineTransformMakeRotation(degreesToRadians( rotationAngle ));
Where degreeToRadians just is a macro to convert from degrees to radians.
This works fine as long as the view is visible, eg alpha = 1. When I hide it (alpha = 0, which I animate) it does not rotate any more. I guess this is a smart way for the devices to "save" on drawing time, but is there any way I can force it to be drawn even when alpha is 0? Otherwise I will have to rotate it before I show it again.
Any good ideas?
Thanks
Edit: This is the code I use to show/hide the view.
-(void)showHelp
{
bool helpAlpha = !helpView.alpha;
CGFloat newScale;
if (helpView.alpha) {
newScale = kHelpSmall;
helpView.transform = CGAffineTransformMakeScale(kHelpBig, kHelpBig);
} else {
newScale = kHelpBig;
helpView.transform = CGAffineTransformMakeScale(kHelpSmall, kHelpSmall);
}
[UIView animateWithDuration:(kAnimationTimeShort / 2) animations:^(void) {
[helpView setAlpha:helpAlpha];
helpView.transform = CGAffineTransformMakeScale(newScale, newScale);
}];
}
As you see I also scale it for a nicer effect. Works perfect when visible, does not rotate when alpha = 0. Rotation is done in another method, where I would prefer to keep it as I also rotate some other views there.
You are resetting the transform every time you use CGAffineTransformMake*. If you do this, you will get either a rotated transform or a scaled one. I am assuming the scaled one is after the rotated one and hence you aren't able to see the view rotated. If you need both the effects to remain, you will have to use CGAffineTransformRotate. So a scale and rotate will be
helpView.transform = CGAffineTransformMakeScale(kHelpSmall, kHelpSmall);
helpView.transform = CGAffineTransformRotate(helpView.transform, degreesToRadians(rotationAngle));
The order might vary.
I am struggling to get my custom drawing code to render at the proper scale for all iOS devices, i.e., older iPhones, those with retina displays and the iPad.
I have a subclass of UIView that has a custom class that displays a vector graphic. It has a scale property that I can set. I do the scaling in initWithCoder when the UIView loads and I first instantiate the vector graphic. This UIView is shown when the user taps a button on the home screen.
At first I tried this:
screenScaleFactor = 1.0;
if ([UIScreen instancesRespondToSelector:#selector(scale)]) {
screenScaleFactor = [[UIScreen mainScreen] scale];
}
// and then I multiply stuff by screenScale
... which worked for going between normal iPhones and retina iPhones, but chokes on the iPad. As I said, you can get to the UIView at issue by tapping a button on the home screen. When run on the iPad, if you display the UIView when at 1X, it works, but at 2X I get a vector graphic that twice as big as it should be.
So I tried this instead:
UPDATE: This block is the one that's right. (with the corrected spelling, of course!)
screenScaleFactor = 1.0;
if ([self respondsToSelector:#selector(contentScaleFactor)]) { //EDIT: corrected misspellng.
screenScaleFactor = (float)self.contentScaleFactor;
}
// again multiplying stuff by screenScale
Which works at both 1X and 2X on the iPad and on the older iPhones, but on a retina display, the vector graphic is half the size it should be.
In the first case, I query the UIScreen for its scale property and in the second case, I'm asking the parent view of the vector graphic for its contentsScaleFactor. Neither of these seem to get me where I want for all cases.
Any suggestions?
UPDATE:
Here's the method in my subclassed UIView (it's called a GaugeView):
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState(context);
CGAffineTransform t0 = CGContextGetCTM(context);
t0 = CGAffineTransformInvert(t0);
CGContextConcatCTM(context, t0);
[needle updateBox];
[needle draw: context];
}
needle is of class VectorSprite which is a subclass of Sprite which is subclassed from NSObject. These are from a programming book I'm working through. needle has the scale property that I set.
updateBox comes from Sprite and looks like this:
- (void) updateBox {
CGFloat w = width*scale;
CGFloat h = height*scale;
CGFloat w2 = w*0.5;
CGFloat h2 = h*0.5;
CGPoint origin = box.origin;
CGSize bsize = box.size;
CGFloat left = -kScreenHeight*0.5;
CGFloat right = -left;
CGFloat top = kScreenWidth*0.5;
CGFloat bottom = -top;
offScreen = NO;
if (wrap) {
if ((x+w2) < left) x = right + w2;
else if ((x-w2) > right) x = left - w2;
else if ((y+h2) < bottom) y = top + h2;
else if ((y-h2) > top) y = bottom - h2;
}
else {
offScreen =
((x+w2) < left) ||
((x-w2) > right) ||
((y+h2) < bottom) ||
((y-h2) > top);
}
origin.x = x-w2*scale;
origin.y = y-h2*scale;
bsize.width = w;
bsize.height = h;
box.origin = origin;
box.size = bsize;
}
Sprite also has the draw and drawBody methods which are:
- (void) draw: (CGContextRef) context {
CGContextSaveGState(context);
// Position the sprite
CGAffineTransform t = CGAffineTransformIdentity;
t = CGAffineTransformTranslate(t,x,y);
t = CGAffineTransformRotate(t,rotation);
t = CGAffineTransformScale(t,scale,scale);
CGContextConcatCTM(context, t);
// draw sprite body
[self drawBody: context];
CGContextRestoreGState(context);
}
- (void) drawBody: (CGContextRef) context {
// Draw your sprite here, centered
// on (x,y)
// As an example, we draw a filled white circle
if (alpha < 0.05) return;
CGContextBeginPath(context);
CGContextSetRGBFillColor(context, r,g,b,alpha);
CGContextAddEllipseInRect(context, CGRectMake(-width/2,-height/2,width,height));
CGContextClosePath(context);
CGContextDrawPath(context,kCGPathFill);
}
How, exactly, are you rendering the graphic?
This should be handled automatically in drawRect: (the context you get should be already 2x). This should also be handled automatically with UIGraphicsBeginImageContextWithOptions(size,NO,0); if available (if you need to fall back to UIGraphicsBeginImageContext(), assume a scale of 1). You shouldn't need to worry about it unless you're drawing the bitmap yourself somehow.
You could try something like self.contentScaleFactor = [[UIScreen mainScreen] scale], with appropriate checks first (this might mean if you display it in an iPad at 2x, you'll get high-res graphics).
Fundamentally, there's not much difference between an iPad in 2x mode and a "retina display", except that the iPad can switch between 1x and 2x.
Finally, there's a typo: #selector(contentsScaleFactor) has an extra s.
I'm animating a shrinking object. At any point the user can hit a button to get the current scale factor of the object. (I start by scaling the object up using a CGAffineTransformMakeScale, so the scale factor should be 1 when it reaches its original size). I'm just not sure how to retrieve the current scale factor from the animation UIImageView... Here's my code:
- (void)startShrink {
CGAffineTransform scaleFactor = CGAffineTransformMakeScale(kScaleX, kScaleY);
imageOutline.transform = scaleFactor;
CABasicAnimation *shrink = [CABasicAnimation animationWithKeyPath:#"transform.scale"];
shrink.toValue = [NSNumber numberWithDouble:0.5];
shrink.duration = 2.0;
shrink.fillMode=kCAFillModeForwards;
shrink.removedOnCompletion=NO;
shrink.delegate = self;
[imageOutline.layer addAnimation:shrink forKey:#"shrink"];
}
I tried the following, but I'm not sure m12 is the value I should be retrieving from the transform. Or if in fact this is the right approach:
- (float)calculateScale {
CATransform3D scaleTransform = [(CALayer *)[imageOutline.layer presentationLayer] transform];
float scale = scaleTransform.m12;
NSLog(#"Scale: %g", scale);
return scale;
}
Any advice most appreciated :)
Thanks, Michael.
If you just scale your view uniformly on all axes then scale value should equal to m11 (and m22 as well).
I just ran a sample with your code copy-pasted - it seems that the following 2 lines are redundant:
CGAffineTransform scaleFactor = CGAffineTransformMakeScale(kScaleX, kScaleY);
imageOutline.transform = scaleFactor;
View immediately shrinks by half (I used 0.5 for scale values) and then shrinks twice more with animation