✍️ Flutter TextField widget that automatically resizes text field to fit perfectly within its bounds.
Note: Kudos to @leisim! This work is inspired by his awesome lib Auto Size Text. Please check it out if you want to auto size the Flutter Text widget content.
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- Update README.md to show examples of more use cases
- Add more unit tests
AutoSizeTextField behaves exactly like a TextField. The only difference is that it resizes text to fit within its bounds.
AutoSizeTextField(
controller: _textEditingController,
style: TextStyle(fontSize: 20),
maxLines: 2,
)Note: AutoSizeTextField needs bounded constraints to resize the text. More info here.
The fullwidth parameter extends the width of TextField to its parent's BoxContraints to occupy full width.
Set to false to let the width TextField determined by the width of the text.
The maxLines parameter works like you are used to with the Text widget. If there is no maxLines parameter specified, the AutoSizeTextField only fits the text according to the available width and height.
AutoSizeTextField(
controller: _textEditingController,
style: TextStyle(fontSize: 30),
maxLines: null,
decoration: InputDecoration(
border: InputBorder.none,
isDense: true,
contentPadding: const EdgeInsets.all(20)
),
)
The AutoSizeTextField starts with TextStyle.fontSize. It measures the resulting text and rescales it to fit within its bonds. You can however set the allowed range of the resulting font size.
With minFontSize you can specify the smallest possible font size. If the text still doesn't fit, it will be handled according to overflow. The default minFontSize is 12.
maxFontSize sets the largest possible font size. This is useful if the TextStyle inherits the font size and you want to constrain it.
AutoSizeTextField(
controller: _textEditingController,
style: TextStyle(fontSize: 30),
minFontSize: 18,
maxLines: 4,
overflow: TextOverflow.ellipsis,
)The AutoSizeTextField will try each font size, starting with TextStyle.fontSize until the text fits within its bounds.
stepGranularity specifies how much the font size is decreased each step. Usually, this value should not be below 1 for best performance.
AutoSizeTextField(
controller: _textEditingController,
style: TextStyle(fontSize: 40),
minFontSize: 10,
stepGranularity: 10,
maxLines: 4,
overflow: TextOverflow.ellipsis,
)If you want to allow only specific font sizes, you can set them with presetFontSizes.
If presetFontSizes is set, minFontSize, maxFontSize and stepGranularity will be ignored.
AutoSizeTextField(
controller: _textEditingController,
presetFontSizes: [40, 20, 14],
maxLines: 4,
)If the text is overflowing and does not fit its bounds, this widget is displayed instead. This can be useful to prevent text being too small to read.
AutoSizeTextField(
maxLines: 1,
controller: _textEditingController
)| Parameter | Description |
|---|---|
key* |
Controls how one widget replaces another widget in the tree. |
textKey |
Sets the key for the resulting Text widget |
style* |
If non-null, the style to use for this text |
fullwidth |
Default: true, It extends the width of TextField to its parent's BoxContraints to occupy full width. Set to false to let the width TextField determined by the width of the text. |
minFontSize |
The minimum text size constraint to be used when auto-sizing text. Is being ignored if presetFontSizes is set. |
maxFontSize |
The maximum text size constraint to be used when auto-sizing text. Is being ignored if presetFontSizes is set. |
stepGranularity |
The step size in which the font size is being adapted to constraints. |
presetFontSizes |
Predefines all the possible font sizes. Important: presetFontSizes have to be in descending order. |
locale* |
Used to select a font when the same Unicode character can be rendered differently, depending on the locale. |
wrapWords |
Whether words which don't fit in one line should be wrapped. Defaults to true to behave like Text. |
overflowReplacement |
If the text is overflowing and does not fit its bounds, this widget is displayed instead. |
maxLines |
An optional maximum number of lines for the text to span. |
minWidth |
An optional min width for input field. Only set it when fullwidth = false |
- Parameters marked with * behave exactly the same as in
TextField. - The unlisted parameters behave exactly the same as
TextField.
AutoSizeTextField is really fast. In fact, you can replace all your TextField widgets with AutoSizeTextField.
Nevertheless you should not use an unreasonable high fontSize in your TextStyle. E.g. don't set the fontSize to 1000 if you know, that the text will never be larger than 30.
If your font size has a very large range, consider increasing stepGranularity.
If AutoSizeTextField overflows or does not resize the text, you should check if it has constrained width and height.
Wrong code:
Row(
children: <Widget>[
AutoSizeTextField(
controller: _textEditingController,
maxLines: 1,
),
],
)Because Row and other widgets like Container, Column or ListView do not constrain their children, the text will overflow.
You can fix this by constraining the AutoSizeTextField. Wrap it with Expanded in case of Row and Column or use a SizedBox or another widget with fixed width (and height).
Correct code:
Row(
children: <Widget>[
Expanded( // Constrains AutoSizeTextField to the width of the Row
child: AutoSizeTextField(
controller: _textEditingController,
maxLines: 1,
)
),
],
)
}AutoSizeTextField does not resize text below the minFontSize which defaults to 12.:
Copyright (c) 2020 Zhuoran LI
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