extended_text

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Extended official text to build special text like inline image or @somebody quickly,it also support custom background,custom over flow and custom selection toolbar and handles.

Table of contents

• extended_text
  • Table of contents
  • Speical Text
    • Create Speical Text
    • SpecialTextSpanBuilder
  • Image
    • ImageSpan
  • Selection
    • TextSelectionControls
    • Control ToolBar Handle
      • Default Behavior
      • Custom Behavior
  • Custom Background
  • Custom Overflow
  • Join Zero-Width Space

Speical Text

Create Speical Text

extended text helps to convert your text to speical textSpan quickly.

for example, follwing code show how to create @xxxx speical textSpan.

class AtText extends SpecialText {
  AtText(TextStyle textStyle, SpecialTextGestureTapCallback onTap,
      {this.showAtBackground = false, this.start})
      : super(flag, ' ', textStyle, onTap: onTap);
  static const String flag = '@';
  final int start;

  /// whether show background for @somebody
  final bool showAtBackground;

  @override
  InlineSpan finishText() {
    final TextStyle textStyle =
        this.textStyle?.copyWith(color: Colors.blue, fontSize: 16.0);

    final String atText = toString();

    return showAtBackground
        ? BackgroundTextSpan(
            background: Paint()..color = Colors.blue.withOpacity(0.15),
            text: atText,
            actualText: atText,
            start: start,

            ///caret can move into special text
            deleteAll: true,
            style: textStyle,
            recognizer: (TapGestureRecognizer()
              ..onTap = () {
                if (onTap != null) {
                  onTap(atText);
                }
              }))
        : SpecialTextSpan(
            text: atText,
            actualText: atText,
            start: start,
            style: textStyle,
            recognizer: (TapGestureRecognizer()
              ..onTap = () {
                if (onTap != null) {
                  onTap(atText);
                }
              }));
  }
}

SpecialTextSpanBuilder

create your SpecialTextSpanBuilder

class MySpecialTextSpanBuilder extends SpecialTextSpanBuilder {
  MySpecialTextSpanBuilder({this.showAtBackground = false});

  /// whether show background for @somebody
  final bool showAtBackground;
  @override
  TextSpan build(String data,
      {TextStyle textStyle, SpecialTextGestureTapCallback onTap}) {
    if (kIsWeb) {
      return TextSpan(text: data, style: textStyle);
    }

    return super.build(data, textStyle: textStyle, onTap: onTap);
  }

  @override
  SpecialText createSpecialText(String flag,
      {TextStyle textStyle, SpecialTextGestureTapCallback onTap, int index}) {
    if (flag == null || flag == '') {
      return null;
    }

    ///index is end index of start flag, so text start index should be index-(flag.length-1)
    if (isStart(flag, AtText.flag)) {
      return AtText(
        textStyle,
        onTap,
        start: index - (AtText.flag.length - 1),
        showAtBackground: showAtBackground,
      );
    } else if (isStart(flag, EmojiText.flag)) {
      return EmojiText(textStyle, start: index - (EmojiText.flag.length - 1));
    } else if (isStart(flag, DollarText.flag)) {
      return DollarText(textStyle, onTap,
          start: index - (DollarText.flag.length - 1));
    }
    return null;
  }
}

Image

ImageSpan

show inline image by using ImageSpan.

class ImageSpan extends ExtendedWidgetSpan {
  ImageSpan(
    ImageProvider image, {
    Key key,
    @required double imageWidth,
    @required double imageHeight,
    EdgeInsets margin,
    int start = 0,
    ui.PlaceholderAlignment alignment = ui.PlaceholderAlignment.bottom,
    String actualText,
    TextBaseline baseline,
    BoxFit fit= BoxFit.scaleDown,
    ImageLoadingBuilder loadingBuilder,
    ImageFrameBuilder frameBuilder,
    String semanticLabel,
    bool excludeFromSemantics = false,
    Color color,
    BlendMode colorBlendMode,
    AlignmentGeometry imageAlignment = Alignment.center,
    ImageRepeat repeat = ImageRepeat.noRepeat,
    Rect centerSlice,
    bool matchTextDirection = false,
    bool gaplessPlayback = false,
    FilterQuality filterQuality = FilterQuality.low,
    GestureTapCallback onTap,
    HitTestBehavior behavior = HitTestBehavior.deferToChild,
  })

parameter	description	default
image	The image to display(ImageProvider).	-
imageWidth	The width of image(not include margin)	required
imageHeight	The height of image(not include margin)	required
margin	The margin of image	-
actualText	Actual text, take care of it when enable selection,something likes "[love]"	'\uFFFC'
start	Start index of text,take care of it when enable selection.	0

Selection

parameter	description	default
selectionEnabled	Whether enable selection	false
selectionColor	Color of selection	Theme.of(context).textSelectionColor
dragStartBehavior	DragStartBehavior for text selection	DragStartBehavior.start
textSelectionControls	An interface for building the selection UI, to be provided by the implementor of the toolbar widget or handle widget	extendedMaterialTextSelectionControls/extendedCupertinoTextSelectionControls

TextSelectionControls

default value of textSelectionControls are MaterialExtendedTextSelectionControls/CupertinoExtendedTextSelectionControls

override buildToolbar or buildHandle to custom your toolbar widget or handle widget

class MyExtendedMaterialTextSelectionControls
    extends ExtendedMaterialTextSelectionControls {
  MyExtendedMaterialTextSelectionControls();
  @override
  Widget buildToolbar(
    BuildContext context,
    Rect globalEditableRegion,
    double textLineHeight,
    Offset selectionMidpoint,
    List<TextSelectionPoint> endpoints,
    TextSelectionDelegate delegate,
  ) {}

  @override
  Widget buildHandle(
      BuildContext context, TextSelectionHandleType type, double textHeight) {
  }
}

Control ToolBar Handle

contain your page into ExtendedTextSelectionPointerHandler, so you can control toolbar and handle.

Default Behavior

set your page as child of ExtendedTextSelectionPointerHandler

 return ExtendedTextSelectionPointerHandler(
      //default behavior
       child: result,
    );

• tap region outside of extended text, hide toolbar and handle
• scorll, hide toolbar and handle

Custom Behavior

get selectionStates(ExtendedTextSelectionState) by builder call back, and handle by your self.

 return ExtendedTextSelectionPointerHandler(
      //default behavior
      // child: result,
      //custom your behavior
      builder: (states) {
        return Listener(
          child: result,
          behavior: HitTestBehavior.translucent,
          onPointerDown: (value) {
            for (var state in states) {
              if (!state.containsPosition(value.position)) {
                //clear other selection
                state.clearSelection();
              }
            }
          },
          onPointerMove: (value) {
            //clear other selection
            for (var state in states) {
              state.clearSelection();
            }
          },
        );
      },
    );

Custom Background

refer to issues 24335/24337 about background

  BackgroundTextSpan(
      text:
          "This text has nice background with borderradius,no mattter how many line,it likes nice",
      background: Paint()..color = Colors.indigo,
      clipBorderRadius: BorderRadius.all(Radius.circular(3.0))),

parameter	description	default
background	Background painter	-
clipBorderRadius	Clip BorderRadius	-
paintBackground	Paint background call back, you can paint background by self	-

Custom Overflow

refer to issue 26748

parameter	description	default
child	The widget of TextOverflow.	@required
maxHeight	The maxHeight of [TextOverflowWidget], default is preferredLineHeight.	preferredLineHeight
align	The Align of [TextOverflowWidget], left/right.	right
position	The position which TextOverflowWidget should be shown.	TextOverflowPosition.end

  ExtendedText(
   overflowWidget: TextOverflowWidget(
     position: TextOverflowPosition.end,
     align: TextOverflowAlign.center,
     // just for debug
     debugOverflowRectColor: Colors.red.withOpacity(0.1),
     child: Container(
       child: Row(
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[
           const Text('\u2026 '),
           InkWell(
             child: const Text(
               'more',
             ),
             onTap: () {
               launch(
                   'https://github.com/fluttercandies/extended_text');
             },
           )
         ],
       ),
     ),
   ),
  )

Join Zero-Width Space

refer to issue 18761

if [ExtendedText.joinZeroWidthSpace] is true, it will join '\u{200B}' into text, make line breaking and overflow style better.

  ExtendedText(
      joinZeroWidthSpace: true,
    )

or you can convert by following method:

1. String

  String input='abc'.joinChar();

2. InlineSpan

     InlineSpan innerTextSpan;
     innerTextSpan = joinChar(
        innerTextSpan,
        Accumulator(),
        zeroWidthSpace,
    );

Take care of following things:

1. the word is not a word, it will not working when you want to double tap to select a word.

2. text is changed, if [ExtendedText.selectionEnabled] is true, you should override TextSelectionControls and remove zeroWidthSpace.

class MyTextSelectionControls extends TextSelectionControls {

  @override
  void handleCopy(TextSelectionDelegate delegate,
      ClipboardStatusNotifier? clipboardStatus) {
    final TextEditingValue value = delegate.textEditingValue;

    String data = value.selection.textInside(value.text);
    // remove zeroWidthSpace
    data = data.replaceAll(zeroWidthSpace, '');

    Clipboard.setData(ClipboardData(
      text: value.selection.textInside(value.text),
    ));
    clipboardStatus?.update();
    delegate.textEditingValue = TextEditingValue(
      text: value.text,
      selection: TextSelection.collapsed(offset: value.selection.end),
    );
    delegate.bringIntoView(delegate.textEditingValue.selection.extent);
    delegate.hideToolbar();
  }
}