Widgets 02 | Text

This time I will tell you more about the Text.It fits from beginners to experts.

What is the Text?

This problem is very fooling but needs to know, The text show our string and it also is a widget in the flutter, we can use it as a common widget, so be careful about their parameters.

Facebook Page	Twitter	GitHub	​
​Flutter Open ​	​NieBin​	​NieBin​	​

Before start

In the widgets 01, we create a page to show our container, also we create a page show our Text. The way of creating a page is the same as before, you do not care about this, you just focus on the Text widget now. We will put them all in the children as follows.

class TextPage extends StatefulWidget {
  @override
  _TextState createState() => _TextState();
}

class _TextState extends State<TextPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Text"),
      ),
      body: SingleChildScrollView(
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            Text("Hello World"),
          ],
        ),
      ),
    );
  }
}

Then, we can put our Text into the children to continue our tutorial.

Constructor

You must make a custom to look at the constructor of the widgets before using it.

 Text(this.data, {
    Key key,
    this.style,
    this.textAlign,
    this.textDirection,
    this.locale,
    this.softWrap,
    this.overflow,
    this.textScaleFactor,
    this.maxLines,
    this.semanticsLabel,
  })

The this.data is where we put the String, this is easy to understand, we do not talk about this. the style is most common to use. this.locale control its language,this time I don't plan to talk about it, I will write another article to explain it. So let's talk about the parameters one by one.

style

Let's look at its definition.

 final TextStyle style;

It is a TextStyle class, look at its definition,so many important parameters are here,such as the fontSize, color, height.

TextStyle({
    this.inherit = true,
    this.color,
    this.fontSize,
    this.fontWeight,
    this.fontStyle,
    this.letterSpacing,
    this.wordSpacing,
    this.textBaseline,
    this.height,
    this.locale,
    this.foreground,
    this.background,
    this.shadows,
    this.decoration,
    this.decorationColor,
    this.decorationStyle,
    this.debugLabel,
    String fontFamily,
    String package,
  }

The function of these parameters is a definition with its name. The color parameter control the color of Text.The fontSize controls its font size. We just show an example for simple param.

 Text(
              "TextStyle with easy parameters",
              style: TextStyle(
                color: Colors.black,
                fontSize: 22.0,
                background: Paint()
                  ..color = Color(0xffc7e5b4)
                  ..style = PaintingStyle.fill,
              ),
            )

We just change the parameters，they will show as follows.

Text(
              "TextStyle with easy parameters",
              style: TextStyle(
                color: Colors.white,
                fontSize: 14.0,
                background: Paint()
                  ..color = Color(0xffF2A7B3)
                  ..style = PaintingStyle.fill,
              ),
            )

Above code, we can learn how to use color ,fontSize and backgroundt,the background is a Paint that controls the color or other things, I don't want to expand this for more detail.

1. foreground

  final Paint foreground;

We can see that the foreground is also as the background above, so just use the Paint,the ..is a special operator in the flutter.

var p= Paint()
..color = Color(0xffA8CBFD)
..style = PaintingStyle.fill);

Is same as below.

var p= Paint();
p.color = Color(0xffA8CBFD);
p.style = PaintingStyle.fill);

We just code as follows.

 Text(
              "TextStyle with foreground",
              style: TextStyle(
                  fontSize: 40,
                  foreground: Paint()
                    ..color = Color(0xffA8CBFD)
                    ..strokeWidth = 1
                    ..style = PaintingStyle.stroke),
            )

The paint draw the Text with the foreground, be careful that we can't use the color parameter with this, so you can only choose one parameter.

2. fontWeight

  final FontWeight fontWeight;

You can see the definition, the class is FontWeight, you can use its constant with a fore definition. We will use the FontWeight.w700 , it represents bold text. The other constants you can find in the class FontWeight,remain to you.

Text(
              "TextStyle with fontWeight",
              style: TextStyle(
                fontSize: 20,
                color: RED,
                fontWeight: FontWeight.w700,
              ),
            )

3. fontStyle

We know the type is FontStyle, we use its only two constants.As follows, this example will show an italic text.

 Text(
              "TextStyle with fontStyle",
              style: TextStyle(
                fontSize: 20,
                color: BLUE_LIGHT,
                fontStyle: FontStyle.italic,
              ),
            )

4. letterSpacing

The parameter will control the distance between the letter inside a word. For example, the word Helloif set this param, the distance between H,e,l,l,o will depend on this param.

  Text(
              "TextStyle with letterSpacing 4",
              style: TextStyle(
                fontSize: 16,
                color: Colors.black,
                background: Paint()..color = GREEN,
                letterSpacing: 4,
              ),
            ),
            SizedBox(
              height: 10,
            ),
            Text(
              "TextStyle with letterSpacing 20",
              style: TextStyle(
                fontSize: 16,
                color: Colors.black,
                background: Paint()..color = GREEN,
                letterSpacing: 10,
              ),
            )

5. wordSpacing

The parameter controls the distance between the two words, I will set two different wordSpacing to compare.

Text(
              "TextStyle with wordSpacing 1",
              style: TextStyle(
                  fontSize: 16,
                  color: Colors.black,
                  background: Paint()..color = RED,
                  wordSpacing: 1),
            ),
            Text(
              "TextStyle with wordSpacing 20",
              style: TextStyle(
                  fontSize: 16,
                  color: Colors.black,
                  background: Paint()..color = RED,
                  wordSpacing: 20),
            )

6. shadows

When we see the definition of the shadows, we can see this.

  final List<ui.Shadow> shadows;

The Shadow constructor is below.

const Shadow({
    this.color = const Color(_kColorDefault),
    this.offset = Offset.zero,
    this.blurRadius = 0.0,
  }

The offset is the direction from the origin point of the widget, the blurRadius is the distance of the blurred space.

So let's see an example.

Text(
              "TextStyle with Shadow",
              style: TextStyle(fontSize: 30, color: BLUE_DEEP, shadows: [
                Shadow(color: RED, offset: Offset(1, 2), blurRadius: 2)
              ]),
            ),
            Text(
              "TextStyle with Shadow",
              style: TextStyle(fontSize: 30, color: RED, shadows: [
                Shadow(
                    color: Colors.black, offset: Offset(1, 4), blurRadius: 1),
                Shadow(color: BLUE_DEEP, offset: Offset(2, 1), blurRadius: 2)
              ]),
            ),

7. decoration

In this part, I will tell three params:decoration, decorationColor, decorationStyle. They draw the same line show in the Text, the decoration controls the location, decorationColor control the color, decorationStyle control the shape. The definition is below.

  final TextDecoration decoration;
  final Color decorationColor;
  final TextDecorationStyle decorationStyle;

Let's see an example.

Text(
              "TextStyle with decoration underline",
              style: TextStyle(
                  fontSize: 20,
                  background: Paint()..color = GREEN,
                  decoration: TextDecoration.underline,
                  decorationColor: Colors.red,
                  decorationStyle: TextDecorationStyle.wavy),
            ),
            Text(
              "TextStyle with decoration lineThrough",
              style: TextStyle(
                  fontSize: 20,
                  background: Paint()..color = BLUE_LIGHT,
                  decoration: TextDecoration.lineThrough,
                  decorationColor: Colors.black,
                  decorationStyle: TextDecorationStyle.double),
            ),

8. fontFamily

This parameter changes the typeface for the font. It is a bit difficult, but be patient.

First, we should download a typeface file on the web and in our project, I put into the assets/font. You should know the folders are created by myself, you can do that too.

Then, config the pubspec.yaml file in our project,as I note with the red rectangle and paste the config as well.

flutter:

  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true
  assets:
    - assets/images/
    - assets/font/
  fonts:
    - family: manigu
      fonts:
        - asset: assets/font/ManigueStaile.ttf

Finally, we can use the font name maniguas we set above.

Text(
              "Flutter open: TextStyle with fontFamily",
              style: TextStyle(fontFamily: "manigu", fontSize: 40, color: RED),
            )

It is easy for use, if you want more detail about the typeface to use, you can click this link. So far, we finish the using of TextStyle, let's look at the other using.

textAlign

This param controls the Text location in the parent widget, I will show you it in a Container. The TextAlign constants are below, I just use the end to show.

1	2	3
left	center	right
start	justify	end

 Container(
              constraints: BoxConstraints.expand(height: 40),
              color: BLUE,
              child: Text(
                "TextAlign end",
                style: TextStyle(background: Paint()..color = RED),
                textAlign: TextAlign.end,
              ),
            )

textDirection

Normally, we draw the Text from left from right, but we can change it with the textDirection parameter.

  Container(
              color: YELLOW,
              constraints: BoxConstraints.expand(height: 40, width: 160),
              child: Text(
                "textDirection draw from right to left",
                textDirection: TextDirection.rtl,
              ),
            )

softWrap

This param will control the whether or not the show all content when there is not enough space for the text to show. If true means that it will show the all content, otherwise not show.

Container(
              color: RED,
              constraints: BoxConstraints.expand(height: 40, width: 160),
              child: Text("softWrap true Text Text Text Text", softWrap: true),
            ),
Container(
              color: BLUE,
              constraints: BoxConstraints.expand(height: 40, width: 160),
              child: Text("softWrap false Text Text Text Text", softWrap: false),
            )

overflow

When there is not enough place to show, how we hand the end part, the overflow is a choice to handle this, above we end just cover the other part, but we can end with three points like follows, you also can use clip,fade.

 Container(
              color: YELLOW,
              constraints: BoxConstraints.expand(height: 40, width: 240),
              child: Text(
                "overflow TextOverflow.ellipsis: Text Text Text",
                softWrap: false,
                overflow: TextOverflow.ellipsis,
              ),
            ),

maxLines

Also, you can use the maxLines to limit the space, in above part we can see the Text show two lines when there is no space in the horizontal direction.

 Container(
              color: RED_LIGHT,
              constraints: BoxConstraints.expand(height: 40, width: 230),
              child: Text(
                "max lines = 1 content content content content content",
                maxLines: 1,
                overflow: TextOverflow.ellipsis,
              ),
            )

textScaleFactor

When we want to make the Text larger or more little, we can use the fontSize to change its size. But there is another choice to change its scale, the textScaleFactor. It depends on the fontSize, for example, when we set fontSize=10 ,textScaleFactor =2, the real scale of the Text will be equal to 20, means that the real-scale= fontSize*textScaleFactor for the Text.

 Text(
              "textScaleFactor = 1 fontSize = 16 ",
              style: TextStyle(fontSize: 16, color: BLUE),
              textScaleFactor: 1,
            ),
            Text(
              "textScaleFactor = 1.5 fontSize = 20 ",
              style: TextStyle(fontSize: 16, color: RED),
              textScaleFactor: 1.2,
            ),

Conclusion

Today we learn how to use the Text, the most common used param is the style, it mainly controls the Text itself, but some other parameters are controlled with its parent widget. But you needn't know all of them, it's just used with your requirement.

Thanks for your reading!

The end.

Whole code in GitHub,star to support.

Facebook Page	Twitter	QQ Group	GitHub	​
​Flutter Open ​	​NieBin​	963828159	​NieBin​	​