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

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,
  })

Selection

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))),

Custom Overflow

refer to issue 26748

  ExtendedText(...
            overFlowWidget:
                TextOverflowWidget(
                    //maxHeight: double.infinity,
                    //align: TextOverflowAlign.right,
                    //fixedOffset: Offset.zero,
                    child: Row(
                      mainAxisSize: MainAxisSize.min,
                      children: <Widget>[
                        const Text('\u2026 '),
                        RaisedButton(
                          child: const Text('more'),
                          onPressed: () {
                            launch(
                                'https://github.com/fluttercandies/extended_text');
                          },
                        )
                      ],
                    ),
                  ),
            ...
          )