I am learning flutter and currently switched from android to flutter.In flutter i mostly get an error something like
bottom overflowed by 234 pixels or renderbox overflowed by 340 pixels.And i fixes that problem by increase the height of the widget.If so then how to know that what much size giving to widget.I mean in android we can declare the height of the layout to be wrap content and its works perfectly.Please explain me that how can i avoid this situation because if i fixes the issue by changing the height of widget in one device then in devices of other screen sizes if throws same error ?Here is a image which throws an error.Ignore the red error , see the error in below screen.Thanks in advance.
!https://imgur.com/a/PsZzeMp
If you want to give fixed width and height to your widgets wrap it with SizedBox.
You can specify fixed width and height and you child widget will be the exact dimension.
If you want one of the dimension fixed and the other as big as the parent widget, you can try something like this:
SizedBox(
width: double.inifinity,
height: 50.0
child: Conttainer()
)
If you are worried about giving fixed dimensions. You can give the height or width according to the ratio of the screen size. You can get the height and width of the screen like this:
double width = MediaQuery.of(context).size.width;
Use the above value to give the width to your widgets like below:
Container(
width: MediaQuery.of(context).size.width * 0.8,
height: 100,
)
To answer question in the comment. You can do the following to wrap the text with dynamic content.
ConstrainedBox(
constraints: BoxConstraints(
maxWidth: 100
),
child: Text(
'ADASFASF ssss'
),
)
The above code will wrap the text to next line if the text widget is more than 100 pixels wide. As we don't have any constraints on the height.
Overflow happens when the minimum size of a child widget is bigger than the parent's constraints (width and/or height).
Which means you can:
make the parent widget bigger (eg: SizedBox(height:, width:,))
make the child smaller (eg: using a FittedBox(fit: BoxFit.scaleDown) widget)
Though the first method will not allow you a size bigger than the parent's parent widget. It should be enough to build the children relatively to their parents and not the other way.
In your case, it seems like you text + image widget is taking a little too much space. I recommend wrapping it in a FittedBox that will scale down the child widget until it fits in you bottom bar.
FittedBox(
fit: BoxFit.scaleDown,
child: _buildChildWidget(),
)
You can then wrap it in other widgets to build the layout you want (Row, Expanded, Flexible, LayoutBuilder, ...).
As the overflow issue usually happens because text or images are too big. A good exercise is trying to make your app work while setting text size to the maximum value allowed by the accessibility options of your device. You can do the same with images by setting an image size relative to your text size for example.
Paddings and margins can also cause problems because they leave less space for the child widget.
Related
Is there a way to make a widget, for instance a Container, always expand to a screen border, not dependent of a specific widget tree structure?
Containers impose constraints on their children so you can't make a child's width bigger than its parent when it is a container
some tips :
you can use the Expanded widget to take all the remaining space
to take all the size of the screen you can use width: double.infinity
As they said already, in Container() you can use width: double.infinity or width: MediaQuery.of(context).size.width. But for this, the parent of Container can't have a size smaller than the screen.
While I debug my flutter app, at certain points I see warnings like this:
Bottom overflow by 1234 pixel
BoxConstraints have a negative value
I suppose, my concept of Flutter viewport / layout isn't correct:
Currently, I image an infinite drawing area, where I declaratively
define widgets.
Widgets, which are too large, get drawn outside the
viewport [or clipped].
Could you please refine my probably wrong concept?
This happens when the size [height, width] exceeds the the total size of the screen.
For example : the aspect ratio height of mobile screen is 500 and the size.height of button is 600, then the Bottom overflow by 100 pixel.
Generally overflow means, that the widget you want to paint on the screen crosses the border of the screen and therefore isn't visible anymore... This can also happen if you implement non scrollable columns in containers of a certain height... Usually, you can wrap your widget in a SingleChildScrollView widget and as a child choose a column/row (depending on the direction you want it to be aligned...) or make a list view and set the scrolldirection property to Axis.vertical or Axis.horizontal...
Container(
height: min(
widget.order.products.length * 20.0 + 10,
100,
),)
widget.order.products.length => will return me the list of dynamic products.
While viewing the list of these products, I want the set the height of the container dynamic which I'm not able to do with the "min" function.
Can anyone help me.
Thanks in advance.
This can be done by using an IntrinsicHeight:
https://api.flutter.dev/flutter/widgets/IntrinsicHeight-class.html
A widget that sizes its child to the child's intrinsic height.
This class is useful, for example, when unlimited height is available and you would like a child that would otherwise attempt to expand infinitely to instead size itself to a more reasonable height.
The constraints that this widget passes to its child will adhere to the parent's constraints, so if the constraints are not large enough to satisfy the child's maximum intrinsic height, then the child will get less height than it otherwise would. Likewise, if the minimum height constraint is larger than the child's maximum intrinsic height, the child will be given more height than it otherwise would.
This van be put Around things like a listView, Column etc.
I am coming to Flutter from a web background, where I am used to defining screen elements in terms of percentages of the height and width of the screen, or of elements that contain them.
I just completed a course.
Now that I am enthused and want to start building an app, I am a little confused, as the course only spoke of heights & widths in absolute pixel values. I can see this being problematic with different aspect rations, and especially with different orientations.
Is there a canonical approach to this? The official docs also seem to use absolute pixel values, so maybe I am missing a fundamental point.
A search suggests that I might use MediaQuery and then scale everything according to that. But, I don't see widespread use of that in code samples.
Is there a non-opinionated standard approach?
I am a little confused, as the course only spoke of heights & widths in absolute pixel values.
Actually, flutter uses density independent pixels (dp) for width/height arguments. dp actually scale with resolution, meaning 1 dp is displayed as the same PHYSICAL distance on every device. You don't have to worry about your elements being displayed at different sizes, just because the resolution of the screen they're on changes.
To be precise, flutter calls them logical pixel and:
By definition, there are roughly 38 logical pixels per centimeter, or about 96 logical pixels per inch, of the physical display.
So think about them as you would think about cm.
I am used to defining screen elements in terms of percentages of the height and width of the screen
Nonetheless, you might want to layout your widgets in a relative fashion (relative to the screen or the parent). For that purpose, flutter has different solutions:
Flexible
Expanded
Wrap
MediaQuery
LayoutBuilder
GridView
other layout options
Is there a non-opinionated standard approach?
It is a very opinionated question to begin with, but for example, Material design is a common standard for mobile-design. Flutters layout widgets are based around this approach.
But in the end, it is your design choice. For example, to achieve a responsive layout grid you could use Wrap, or you could use LayoutBuilder and determine yourself how you would like to layout rows and columns.
I would recommend you to scale widgets based on the size of the screen. This allows your application to be more flexible and adjust to various platforms and sizes such as large tablets or small phones. In order to do this, I recommend you to use the widget FractionallySizedBox which allows you to size widgets using a percentage of the screen size. For example, if you want a button widget to fill up 50 percent of a screen's width you can use the following code:
Container(
alignment: Alignment.center,
child: FractionallySizedBox(
widthFactor: 0.5,
child: FlatButton(
onTap: () {},
child: Text("PRESS HERE")
)
)
)
This code creates a button positioned in the center of the screen with a width of 50 percent of the screen size's width. You can also change the height of the button with the heightFactor field. By using this code the button widget will scale up and scale down for different screen sizes while still maintaining a size of half of the screen's width. For more resources, you should check out this video by the Flutter Team: https://youtu.be/PEsY654EGZ0 and their website on the FractionallySizedBox here: https://api.flutter.dev/flutter/widgets/FractionallySizedBox-class.html.
The FractionallySizedBox however is only one of many different approaches to making your flutter app fit to different screen sizes. Another approach is to use the AspectRatio Widget. Below is an example of this:
Container(
alignment: Alignment.center,
child: AspectRatio(
aspectRatio: 3/2
child: FlatButton(
onTap: () {},
child: Text("PRESS ME")
)
)
)
This code will create a button with a 3 to 2 ratio between its width and height. If the screen size changes the button will increase or decrease in size accordingly while again maintaining the 3 to 2 ratio. If you want more information the Flutter team also has a video on it (https://youtu.be/XcnP3_mO_Ms) along with some documentation here:(https://api.flutter.dev/flutter/widgets/AspectRatio-class.html).
Both widgets are perfectly fine and are considered standard practice to use but I personally use FractionallySizedBox more.
I hope my answer was helpful.
I get a strange margin under my GridView:
This image is from an IOS simulator, here's how it looks on a smaller screen on Android where the margin appears to be gone or a lot smaller:
Here's the code:
Column(
children: [
GridView.count(
shrinkWrap: true,
crossAxisCount: 8,
children: tiles
),
Text('mamma')
]
)
Each element in the grid (tiles) is an EmptyTile widget:
class EmptyTile extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Container(
decoration: BoxDecoration(
color: bgColor,
border: Border.all(color: borderColor)
)
);
}
}
I really can't figure out what this margin is or where it comes from, whether it has something to do with shrinkWrap or something else.
How can I remove this margin?
EDIT:
As requested here's the fullscreen images without the simplified example.
IOS:
Android:
Try this. by default it has padding and you should set padding to zero.
GridView.builder(
padding: EdgeInsets.all(0),
The difference in layout you experience comes from a combination of things:
How GridView manages its size.
How widgets are placed in a Column.
GridView tiles and size
When you build a GridView, its width and height are implicitly deduced from the crossAxisCount parameter and the constraints given by its parent.
The constraints are the limits in size in which the widget is allowed to draw.
The crossAxisCount defines how many tiles should fit in one line (row or column). Depending on its scrollDirection, it will either try to fill all the available width or height. By default this direction is set to Axis.vertical, which means that the width will be filled.
So when we come back to your example, this means that the size of each tile will depend on the width of the Column containing your grid, divided by the number of tiles you set in crossAxisCount. This size will be both the width and the height of every tile in your GridView.
Once Flutter knows the size of each of your tiles, it sets them on each row, until all tiles are placed or there isn't any available space.
Column layout
Now that we know more about GridView, we need to understand how Column builds its layout.
Columns allocates space to each widget in its children, following an algorithm best describes in the docs.
tl;dr:
Your GridView will only fill its own height in the Column, leaving the rest as free space. This is why you get empty space in your Column.
Possible fix
I actually don't really see how this is a problem. GridViews are supposed to only extend to display their children, so it totally makes sense for it to stop when it completed.
The thing is, most of the times this ind of grids are not used with a finite list of children, and more likely with a growing list.
If you only want to have one line of tiles, that will extend using the available space, you could use a simple Row.
If you want multiple lines of tiles, with non-square tiles, you need to dive a little deeper into GridView.custom.
Edit after question was updated with more screenshots:
It is possible that you need to rethink your layout so that the player panels are in the same Column than the game board. You will have a much better control over the layout this way.