rotation interview questions
Top rotation frequently asked interview questions
I am using -webkit-transform (and -moz-transform / -o-transform) to rotate a div. Also have position fixed added so the div scrols down with the user.
In Firefox it works fine, but in webkit based browsers it's broken. After using the -webkit-transform, the position fixed doesn't work anymore! How is that possible?
Source: (StackOverflow)
When I load an image frome the media gallery into a Bitmap, everything works fine, except that pictures that were shot with the camera while holding the phone vertically, are rotated so that I always get a horizontal picture even though it appears vertical in the gallery.
Why is that and how can I load it correctly?
Source: (StackOverflow)
I have been trying to figure out how to rotate videos with FFmpeg. I am working with iPhone videos taken in portrait mode. I know how to determine the current degrees of rotation using MediaInfo (excellent library, btw) but I'm stuck on FFmpeg now.
From what I've read, what you need to use is a vfilter option. According to what I see, it should look like this:
ffmpeg -vfilters "rotate=90" -i input.mp4 output.mp4
However, I can't get this to work. First, -vfilters doesn't exist anymore, it's now just -vf. Second, I get this error:
No such filter: 'rotate'
Error opening filters!
As far as I know, I have an all-options-on build of FFmpeg. Running ffmpeg -filters shows this:
Filters:
anull Pass the source unchanged to the output.
aspect Set the frame aspect ratio.
crop Crop the input video to x:y:width:height.
fifo Buffer input images and send them when they are requested.
format Convert the input video to one of the specified pixel formats.
hflip Horizontally flip the input video.
noformat Force libavfilter not to use any of the specified pixel formats
for the input to the next filter.
null Pass the source unchanged to the output.
pad Pad input image to width:height[:x:y[:color]] (default x and y:
0, default color: black).
pixdesctest Test pixel format definitions.
pixelaspect Set the pixel aspect ratio.
scale Scale the input video to width:height size and/or convert the i
mage format.
slicify Pass the images of input video on to next video filter as multi
ple slices.
unsharp Sharpen or blur the input video.
vflip Flip the input video vertically.
buffer Buffer video frames, and make them accessible to the filterchai
n.
color Provide an uniformly colored input, syntax is: [color[:size[:ra
te]]]
nullsrc Null video source, never return images.
nullsink Do absolutely nothing with the input video.
Having the options for vflip and hflip are great and all, but they just won't get me where I need to go. I need to the ability to rotate videos 90 degrees at the very least. 270 degrees would be an excellent option to have as well. Where have the rotate options gone?
Source: (StackOverflow)
I'm capturing image and setting it to image view.
public void captureImage() {
Intent intentCamera = new Intent("android.media.action.IMAGE_CAPTURE");
File filePhoto = new File(Environment.getExternalStorageDirectory(), "Pic.jpg");
imageUri = Uri.fromFile(filePhoto);
MyApplicationGlobal.imageUri = imageUri.getPath();
intentCamera.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
startActivityForResult(intentCamera, TAKE_PICTURE);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent intentFromCamera) {
super.onActivityResult(requestCode, resultCode, intentFromCamera);
if (resultCode == RESULT_OK && requestCode == TAKE_PICTURE) {
if (intentFromCamera != null) {
Bundle extras = intentFromCamera.getExtras();
if (extras.containsKey("data")) {
bitmap = (Bitmap) extras.get("data");
} else {
bitmap = getBitmapFromUri();
}
} else {
bitmap = getBitmapFromUri();
}
// imageView.setImageBitmap(bitmap);
imageView.setImageURI(imageUri);
} else {
}
}
public Bitmap getBitmapFromUri() {
getContentResolver().notifyChange(imageUri, null);
ContentResolver cr = getContentResolver();
Bitmap bitmap;
try {
bitmap = android.provider.MediaStore.Images.Media.getBitmap(cr, imageUri);
return bitmap;
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
But problem is, the image on some devices everytime it gets rotated. e.g. on Samsung device it works good, on Sony Experia image gets rotated by 90 degree and on Toshiba thrive(tab) by 180 degree
Source: (StackOverflow)
Auto Layout is making my life difficult. In theory, it was going to be really useful when I switched, but I seem to fight it all of the time.
I've made a demo project to try to find help. Does anyone know how to make the spaces between views increase or decrease evenly whenever the view is resized?
Here are three labels (manually spaced vertically even):
What I want is for them to resize their spacing (not the view size) evenly when I rotate. By default, the top and bottom views squish towards the center:
Source: (StackOverflow)
I have an element that needs to be vertical in a design I have done. I have got the css for this to work in all browsers except IE9. I used the filter for IE7 & IE8:
progid:DXImageTransform.Microsoft.BasicImage(rotation=3);
This however seems to render my element transparent in IE9 and the CSS3 'tranform' porperty doesn't seem to do anything!
Does anyone know anyway of rotating elements in IE9?
Really appreciate the help!
W.
Source: (StackOverflow)
At the heart of an application (written in Python and using NumPy) I need to rotate a 4th order tensor. Actually, I need to rotate a lot of tensors many times and this is my bottleneck. My naive implementation (below) involving eight nested loops seems to be quite slow, but I cannot see a way to leverage NumPy's matrix operations and, hopefully, speed things up. I've a feeling I should be using np.tensordot, but I don't see how.
Mathematically, elements of the rotated tensor, T', are given by: T'ijkl = Σ gia gjb gkc gld Tabcd with the sum being over the repeated indices on the right hand side. T and Tprime are 3*3*3*3 NumPy arrays and the rotation matrix g is a 3*3 NumPy array. My slow implementation (taking ~0.04 seconds per call) is below.
#!/usr/bin/env python
import numpy as np
def rotT(T, g):
Tprime = np.zeros((3,3,3,3))
for i in range(3):
for j in range(3):
for k in range(3):
for l in range(3):
for ii in range(3):
for jj in range(3):
for kk in range(3):
for ll in range(3):
gg = g[ii,i]*g[jj,j]*g[kk,k]*g[ll,l]
Tprime[i,j,k,l] = Tprime[i,j,k,l] + \
gg*T[ii,jj,kk,ll]
return Tprime
if __name__ == "__main__":
T = np.array([[[[ 4.66533067e+01, 5.84985000e-02, -5.37671310e-01],
[ 5.84985000e-02, 1.56722231e+01, 2.32831900e-02],
[ -5.37671310e-01, 2.32831900e-02, 1.33399259e+01]],
[[ 4.60051700e-02, 1.54658176e+01, 2.19568200e-02],
[ 1.54658176e+01, -5.18223500e-02, -1.52814920e-01],
[ 2.19568200e-02, -1.52814920e-01, -2.43874100e-02]],
[[ -5.35577630e-01, 1.95558600e-02, 1.31108757e+01],
[ 1.95558600e-02, -1.51342210e-01, -6.67615000e-03],
[ 1.31108757e+01, -6.67615000e-03, 6.90486240e-01]]],
[[[ 4.60051700e-02, 1.54658176e+01, 2.19568200e-02],
[ 1.54658176e+01, -5.18223500e-02, -1.52814920e-01],
[ 2.19568200e-02, -1.52814920e-01, -2.43874100e-02]],
[[ 1.57414726e+01, -3.86167500e-02, -1.55971950e-01],
[ -3.86167500e-02, 4.65601977e+01, -3.57741000e-02],
[ -1.55971950e-01, -3.57741000e-02, 1.34215636e+01]],
[[ 2.58256300e-02, -1.49072770e-01, -7.38843000e-03],
[ -1.49072770e-01, -3.63410500e-02, 1.32039847e+01],
[ -7.38843000e-03, 1.32039847e+01, 1.38172700e-02]]],
[[[ -5.35577630e-01, 1.95558600e-02, 1.31108757e+01],
[ 1.95558600e-02, -1.51342210e-01, -6.67615000e-03],
[ 1.31108757e+01, -6.67615000e-03, 6.90486240e-01]],
[[ 2.58256300e-02, -1.49072770e-01, -7.38843000e-03],
[ -1.49072770e-01, -3.63410500e-02, 1.32039847e+01],
[ -7.38843000e-03, 1.32039847e+01, 1.38172700e-02]],
[[ 1.33639532e+01, -1.26331100e-02, 6.84650400e-01],
[ -1.26331100e-02, 1.34222177e+01, 1.67851800e-02],
[ 6.84650400e-01, 1.67851800e-02, 4.89151396e+01]]]])
g = np.array([[ 0.79389393, 0.54184237, 0.27593346],
[-0.59925749, 0.62028664, 0.50609776],
[ 0.10306737, -0.56714313, 0.8171449 ]])
for i in range(100):
Tprime = rotT(T,g)
Is there a way to make this go faster? Making the code generalise to other ranks of tensor would be useful, but is less important.
Source: (StackOverflow)
I have one of my activities which I would like to prevent from rotating because I'm starting an AsyncTask, and screen rotation makes it restart. So is there any way to tell this activity "DO NOT ROTATE the screen even if the user is shaking his phone like mad"?
Source: (StackOverflow)
In my Android application, when I rotate the device (slide out the keyboard) then my Activity is restarted (onCreate is called). Now, this is probably how it's supposed to be, but I do a lot of initial setting up in the onCreate method, so I need either:
- Put all the initial setting up in another function so it's not all lost on device rotation or
- Make it so
onCreate is not called again and the layout just adjusts or
- Limit the app to just portrait so that
onCreate is not called.
Source: (StackOverflow)
With iPad with iOS6, we have this bug where a modal view controller will expand to full screen, even if it is told to
be using "form sheet" presentation style. But, this happens only if there are two modals, a parent one and its child.
So this is how the first modal is created and presented:
UINavigationController *navigationController = [[[UINavigationController alloc] initWithRootViewController:controller] autorelease];
navigationController.modalPresentationStyle = UIModalPresentationFormSheet;
[parentController presentModalViewController:navigationController animated:YES];
// parentController is my application's root controller
This is how the child modal is created and presented:
UINavigationController *navigationController = [[[UINavigationController alloc] initWithRootViewController:controller] autorelease];
navigationController.modalPresentationStyle = UIModalPresentationFormSheet;
[parentController presentModalViewController:navigationController animated:YES];
// parentController is the navigationController from above
So when rotating from landscape to portrait, the parent modal will expand to full screen and remain that way even if we rotate back to landscape.
When we have the parent modal all by itself (no child modal), then it works as expected, which is that it remains in form sheet style.
Note that this happens on iOS6 only (device and simulator) and doesn't happen on iOS 5 (simulator and reported to work by testers).
So far, I have tried the following without success:
- setting
wantsFullScreenLayout to NO
- forcing
wantsFullScreenLayout to always return NO by overriding it
- Making certain my controllers inside the navigation controller also specify
UIModalPresentationFormSheet
- implementing
preferredInterfaceOrientationForPresentation
- upgrade to iOS 6.0.1
Thanks!
UPDATE:
So, I adapted the response from the Apple Developer Forums (https://devforums.apple.com/message/748486#748486) so that it works with multiple nested modal.
- (BOOL) needNestedModalHack {
return [UIDevice currentDevice].systemVersion.floatValue >= 6;
}
- (void) willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation
duration:(NSTimeInterval)duration {
// We are the top modal, make to sure that parent modals use our size
if (self.needNestedModalHack && self.presentedViewController == nil && self.presentingViewController) {
for (UIViewController* parent = self.presentingViewController;
parent.presentingViewController;
parent = parent.presentingViewController) {
parent.view.superview.frame = parent.presentedViewController.view.superview.frame;
}
}
[super willAnimateRotationToInterfaceOrientation:toInterfaceOrientation duration:duration];
}
- (void) willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation
duration:(NSTimeInterval)duration {
// We are the top modal, make to sure that parent modals are hidden during transition
if (self.needNestedModalHack && self.presentedViewController == nil && self.presentingViewController) {
for (UIViewController* parent = self.presentingViewController;
parent.presentingViewController;
parent = parent.presentingViewController) {
parent.view.superview.hidden = YES;
}
}
[super willRotateToInterfaceOrientation:toInterfaceOrientation duration:duration];
}
- (void) didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation {
// We are the top modal, make to sure that parent modals are shown after animation
if (self.needNestedModalHack && self.presentedViewController == nil && self.presentingViewController) {
for (UIViewController* parent = self.presentingViewController;
parent.presentingViewController;
parent = parent.presentingViewController) {
parent.view.superview.hidden = NO;
}
}
[super didRotateFromInterfaceOrientation:fromInterfaceOrientation];
}
Source: (StackOverflow)
I have CSS style for a layer:
.element {
-webkit-transform: rotate(7.5deg);
-moz-transform: rotate(7.5deg);
-ms-transform: rotate(7.5deg);
-o-transform: rotate(7.5deg);
transform: rotate(7.5deg);
}
Is there a way to get curent rotation value through jQuery?
I tried this
$('.element').css("-moz-transform")
The result is matrix(0.991445, 0.130526, -0.130526, 0.991445, 0px, 0px) which doesn't tell me a lot. What I'm looking to get is 7.5.
Source: (StackOverflow)
This is not a question.
I just felt that after spending this much time figuring out how to do this I would hate myself if i didn't save it somewhere and I would be a lousy programer if I didnt share what I had found. (killing two birds with one stone here.)
So here is the code for rotating text in a table to act as a header.
<html>
<head>
<!--[if IE]>
<style>
.rotate_text
{
writing-mode: tb-rl;
filter: flipH() flipV();
}
</style>
<![endif]-->
<!--[if !IE]><!-->
<style>
.rotate_text
{
-moz-transform:rotate(-90deg);
-moz-transform-origin: top left;
-webkit-transform: rotate(-90deg);
-webkit-transform-origin: top left;
-o-transform: rotate(-90deg);
-o-transform-origin: top left;
position:relative;
top:20px;
}
</style>
<!--<![endif]-->
<style>
table
{
border: 1px solid black;
table-layout: fixed;
width: 69px; /*Table width must be set or it wont resize the cells*/
}
th, td
{
border: 1px solid black;
width: 23px;
}
.rotated_cell
{
height:300px;
vertical-align:bottom
}
</style>
</head>
<body>
<table border='1'>
<tr>
<td class='rotated_cell'>
<div class='rotate_text'>Test1</div>
</td>
<td class='rotated_cell'>
<div class='rotate_text'>TEST2</div>
</td>
<td class='rotated_cell'>
<div class='rotate_text'>WOOOOOOOOOOOOOOOOHOOOOOO</div>
</td>
</tr>
<tr><td>X</td><td>X</td><td>X</td></tr>
<tr><td>X</td><td>X</td><td>X</td></tr>
<tr><td>X</td><td>X</td><td>X</td></tr>
<tr><td>X</td><td>X</td><td>X</td></tr>
</table>
</body>
</html>
Source: (StackOverflow)
I´m having this issue with iOS 6 SDK: I´m having some views that should be allowed to rotate (e.g. a videoview), and some that don´t.
Now I understand I have to check all orientations in the app´s Info.plist and then sort out in each ViewController, what should happen. But it doesn´t work! The app always rotates to the orientations, that are given in the Info.plist.
Info.plist:
<key>UISupportedInterfaceOrientations</key>
<array>
<string>UIInterfaceOrientationPortrait</string>
<string>UIInterfaceOrientationLandscapeLeft</string>
<string>UIInterfaceOrientationLandscapeRight</string>
</array>
any ViewController that shouldn´t be allowed to rotate:
//deprecated
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
- (NSUInteger)supportedInterfaceOrientations{
return UIInterfaceOrientationMaskPortrait;
}
Observation: App rotates to landscape and portrait orientation. Any ideas why or what I´m doing wrong?
Cheers,
Marc
Edit: My latest findings also indicate, that if you want to have rotation at some point in your app, you have to activate all four rotation directions in your project settings or Info.plist. An alternative to this is to override
- (NSUInteger)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window
in your AppDelegate, which overrides the Info.plist. It isn´t possible anymore to set only Portrait in your Info.plist and then having rotation in some ViewController by overriding shouldAutorotateToInterfaceOrientation or supportedInterfaceOrientations.
Source: (StackOverflow)
Is it possible to rotate a view around its own centre?
In my present implementation the sub-views (buttons, etc) seem to move along a funny path before they end up in the desired positions (since the super view's coordinate system is rotated). I would like the views to spin 90 degrees around theire own centres as in the picture below.
Source: (StackOverflow)
I have a button that I want to put on a 45 degree angle. For some reason I can't get this to work.
Can someone please provide the code to accomplish this?
Source: (StackOverflow)