The Flutter docs show an example of rotating a "div" by 15 degrees, both for HTML/CSS and Flutter code:
The Flutter code is:
var container = new Container( // gray box
child: new Center(
child: new Transform(
child: new Text(
"Lorem ipsum",
),
alignment: FractionalOffset.center,
transform: new Matrix4.identity()
..rotateZ(15 * 3.1415927 / 180),
),
),
);
And the relevant parts are new Transform and alignment: FractionalOffset.center and transform: new Matrix4.identity()..rotateZ(15 * 3.1415927 / 180)
I'm curious, is there a simpler way to rotate a Container in Flutter? Is there a short-hand for the case of "15 degrees" ?
Thanks!
In mobile apps, I think it's kind of rare to have things start out rotated 15 degrees and just stay there forever. So that may be why Flutter's support for rotation is better if you're planning to adjust the rotation over time.
It feels like overkill, but a RotationTransition with an AlwaysStoppedAnimation would accomplish exactly what you want.
new RotationTransition(
turns: new AlwaysStoppedAnimation(15 / 360),
child: new Text("Lorem ipsum"),
)
If you want to rotate something 90, 180, or 270 degrees, you can use a RotatedBox.
new RotatedBox(
quarterTurns: 1,
child: new Text("Lorem ipsum")
)
You can use Transform.rotate to rotate your widget. I used Text and rotated it with 45˚ (π/4)
Example:
import 'dart:math' as math;
Transform.rotate(
angle: -math.pi / 4,
child: Text('Text'),
)
If you are working with a canvas (as in a CustomPaint widget), you can rotate 15 degrees like this:
import 'dart:math' as math;
class MyPainter extends CustomPainter {
#override
void paint(Canvas canvas, Size size) {
canvas.save();
// rotate the canvas
final degrees = 15;
final radians = degrees * math.pi / 180;
canvas.rotate(radians);
// draw the text
final textStyle = TextStyle(color: Colors.black, fontSize: 30);
final textSpan = TextSpan(text: 'Hello, world.', style: textStyle);
TextPainter(text: textSpan, textDirection: TextDirection.ltr)
..layout(minWidth: 0, maxWidth: size.width)
..paint(canvas, Offset(0, 0));
canvas.restore();
}
#override
bool shouldRepaint(CustomPainter old) {
return false;
}
}
However, if you are doing something simple then I would use a RotatedBox or Transform.rotate as suggested by the other answers.
There is Two Main Flutter Widget available for this functionality, RotationTransition and Transform.rotate
another supported option is RotatedBox but this rotate widget only
supports quarter turns, which means they support vertical and only horizontal orientation.
and if you rotate already created widgets like Container so for the container by transformAlignmentyou can rotate widget.
RotationTransition: which animates the rotation of a widget, mainly we prefer when we need rotation with animation transition.https://api.flutter.dev/flutter/widgets/RotationTransition-class.html
Transform.rotate: which applies a rotation paint effect, they Create a widget that transforms its child using a rotation around the center.
RotationTransition Widget example:-
RotationTransition(
turns: AlwaysStoppedAnimation(15 / 360),
child: Text("flutter is awesome")
)
Transform.rotate Widget example :-
Transform.rotate(
angle: 15 * math.pi / 180,
child: Text("flutter is awesome")
)
Container(
decoration: BoxDecoration(borderRadius: BorderRadius.circular(50), color: Color(0xffF6F8FF),),
width: MediaQuery.of(context).size.width*0.6,
height: MediaQuery.of(context).size.height*0.4,
alignment:
new Alignment(0, 0),
transform:
new Matrix4.translationValues(MediaQuery.of(context).size.width * 0.55, -250.0, 0.0)
..rotateZ(28 * 3.1415927 / 180),
),
Related
on an android device I am able to use this code:
final size = MediaQuery.of(context).size;
var scale = size.aspectRatio *
Get.find<cameraservice>().camcontroller!.value.aspectRatio;
if (scale < 1) {
scale = 1 / scale;
}
return Transform.scale(
scale: scale,
child: Center(
child: CameraPreview(Get.find<cameraservice>().camcontroller!),
),
);
however, using the same code running on an IOS device, I see a white border on the sides.
any help would be appreciated.
using camera
camera 0.9.4+12 package.
Inside your Scaffold, you can do the following (and given that controller is your Camera controller instance (your Get.find().camcontroller!):
Scaffold(
body: Transform.scale(
scale: controller!.value.aspectRatio / MediaQuery.of(context).size.aspectRatio,
child: Center(
child: AspectRatio(
aspectRatio: controller!.value.aspectRatio,
child: CameraPreview(controller!)
)
)
)
)
I`m using width and height params of Container to determine widget size. but the widget is not adaptive if tested on other devices. I came from native android where i used to use density independent pixels(dp) that is adaptive to any screen size. what is the equivalent to dp in flutter ?
I dont want to use MediaQuery every time to calculate screen width and height.
You can use the SizeBox.expand widget to let your widget expand to take the available space regardless of size documentation
SizedBox.expand(
child:MyButton(),
),
And if you want to keep an aspect ratio regardless of screen size you can use the AspectRatio widget documentation
AspectRatio(
aspectRatio: 3/2,
child:MyButton(),
),
If your widgets are just in a row or column and you want to add weights among them to fill the spaces you can use the Expanded widget
Expanded(
flex: 1,//weight for the widget
child: Container(
color: Colors.amber,
height: 100,
),
)
,
You can set the size of your UI widgets this way:
width: 100.0 * MediaQuery.of(context).devicPixelRatio ,
the function MediaQuery.of(context).devicPixelRatio will return the actual number of pixel in each logical pixel, so you'll be sure that the same 100.0 pixel on your test device are typical to those of the user whatever screen density they have.
i applied this way :
class SizeConfig {
static MediaQueryData _mediaQueryData;
static double screenWidth;
static double screenHeight;
static double blockSizeHorizontal;
static double blockSizeVertical;
void init(BuildContext context) {
_mediaQueryData = MediaQuery.of(context);
screenWidth = _mediaQueryData.size.width;
screenHeight = _mediaQueryData.size.height;
blockSizeHorizontal = screenWidth / 100;
blockSizeVertical = screenHeight / 100;
}
}
class HomeScreen extends StatelessWidget { #override Widget
build(BuildContext context) { SizeConfig().init(context); … } }
#override
Widget build(BuildContext context) {
return Center(
child: Container(
height: SizeConfig.blockSizeVertical * 20,
width: SizeConfig.blockSizeHorizontal * 50,
color: Colors.orange,
),
);
}
https://medium.com/flutter-community/flutter-effectively-scale-ui-according-to-different-screen-sizes-2cb7c115ea0a
I am using CustomPainter where I need to draw line
class ShapesPainter extends CustomPainter {
#override
void paint(Canvas canvas, Size size) {
final Paint firstPaint = Paint();
firstPaint.color = const Color.fromARGB(255, 236, 0, 140);
final Path firstPath = Path();
firstPath.lineTo(size.width, 0);
firstPath.lineTo(0, size.height * 0.10);
firstPath.close();
canvas.drawShadow(firstPath, Colors.black87, 2.0, false);
canvas.drawPath(firstPath, firstPaint);
}
}
I need to leave margin around the screen so I am using margin in container:
........
Container(
color: Colors.white,
margin:
EdgeInsets.only(top: 60.0, bottom: 20.0, left: 15.0, right: 15.0),
child: Container(
child: CustomPaint(
painter: ShapesPainter(),
child: Container(
.......
I need to draw a shadow under my custom path which I used anvas.drawShadow method in my build Widget, But there is a little shadow also coming over the left side, Please see the image below I pointed an error, here is pointing arrow to small shadow:
As I couldn't find any solution for the canvas.drawShadow effect on Path, I just created another Path() on top of the shadowed path, which solved the issue, but its kind of a hack.
final Path firstPathb = Path();
firstPathHide.lineTo(size.width, 0);
firstPathHide.lineTo(-10.0, size.height * 0.10);
firstPathHide.close();
canvas.drawPath(firstPathHide, firstPaint);
I'm trying to create a bottom navigation bar like the Twitter app has, but I can't find how to customize the highlightShape size.
I can customize corners, colors but not size, I would like to make same size which exceed the bounds of the widget like splash in my builder.
Here is how look my bottom navigation button. Thank you! for help in advance.
Center(
child: Ink(
height: height,
width: width,
child: InkResponse(
splashFactory: InkRipple.splashFactory,
radius: radiusSize,
onTap: () {
const int itemIndex = 1;
_onTapped(itemIndex);
},
child: _pageIndex == 1
? Icon(OMIcons.favoriteBorder, color: Colors.black, size: 28.0)
: Icon(OMIcons.favoriteBorder, color: Colors.grey[600]),
),
),
),
This may be an old question but, the "max" radius should match the normal radius if no radius property is specified.
To change the normal radius you should create a custom splashfactory , https://stackoverflow.com/a/51116178/10205629 .
Or as a little hack you could copy the source code and create your own inkresponse modifying the values
Let's say I want to position a widget inside a Stack but with a percent of the Stack position instead of a fixed size. How to do that in flutter ?
I'd expect that the Positionned.fromRelativeRect constructor would be the thing, using floats between 0 and 1. But seems like no.
Align allows to position the widget in percent. But heightFactor and widthFactor changes the Align size instead of the child size. Which is not what I want.
You can combine a Positioned.fill and LayoutBuilder to achieve such result.
new Stack(
children: <Widget>[
new Positioned.fill(
child: new LayoutBuilder(
builder: (context, constraints) {
return new Padding(
padding: new EdgeInsets.only(top: constraints.biggest.height * .59, bottom: constraints.biggest.height * .31),
child: new Text("toto", textAlign: TextAlign.center,),
);
},
),
)
],
),
one thing that i figured out not long ago is that you can position a widget on the screen using a container its alignment parameter with the help of the Alignment.lerp(x,y,z) function
//the widget will be placed in the center of the container
alignment: Alignment.lerp(Alignment.topCenter, Alignment.bottomCenter, 0),
//the widget will be placed in the bottom of the container
alignment: Alignment.lerp(Alignment.topCenter, Alignment.bottomCenter, 1),
//the widget will be placed in the bottom quarter of the container
alignment: Alignment.lerp(Alignment.topCenter, Alignment.bottomCenter, 0.5),
//the widget will be placed in the top quarter of the container
alignment: Alignment.lerp(Alignment.topCenter, Alignment.bottomCenter, -0.5),
use FractionalOffset & FractionallySizedBox it's very simple in contrast
around no unnecessary code like Positioned.fill
no no extra calculations like Alignment
...
Container(
color: Colors.blue[200],
alignment: FractionalOffset(0.7, 0.6),
child: FractionallySizedBox(
widthFactor: 0.1,
heightFactor: 1/3,
child: Container(color: Colors.red[900])
),
),
...
If you want to use LayoutBuilder then do without Positioned.fill, like this:
you need one LayoutBuilder, no need to turn around every elements and use Transform.translate instead of Padding.
new LayoutBuilder(
builder: (context, constraints) {
return Stack(
children: <Widget>[
Transform.translate(
offset: Offset(
constraints.biggest.width * left,
constraints.biggest.height * top),
child: new Text("toto", textAlign: TextAlign.center,),
),
...
],
);
}
)