James
scratcher
Scratch cards are one of the most popular things that you can find on various shopping apps and payment applications. In the most general way, a scratch card is a card designed for competitions, often made of thin cardstock or plastic to conceal PINs, where one or more areas contain concealed information that can be revealed by scratching off an opaque covering. So, sometimes we wonder how to create scratch cards that temporarily hide content from the users.
In this tutorial article, we will learn about the Scratch card widget, which temporarily hides content from the user.
Features
To begin with Scratch cards, here are some features of it:
- Android and iOS support
- Cover content with full color or custom image
- Track the scratch progress and threshold
- Fully configurable
Getting started
Let’s get Started
In this step, there are two things you have to do.
- First thing you need to do is adding the scratcher as a project dependency in
pubspec.yaml:
dependencies:
scratcher: "^2.1.0"
- Now you can install it by running
flutter pub getor through code editor.
Setting up
- Import the library:
import 'package:scratcher/scratcher.dart';
- Cover desired widget with the scratch card:
Scratcher(
brushSize: 30,
threshold: 50,
color: Colors.red,
onChange: (value) => print("Scratch progress: $value%"),
onThreshold: () => print("Threshold reached, you won!"),
child: Container(
height: 300,
width: 300,
color: Colors.blue,
),
)
Properties
| Property | Type | Description |
|---|---|---|
| child | Widget | Widget rendered under the scratch area. |
| enabled | bool | Whether new scratches can be applied. |
| threshold | double | Percentage level of scratch area which should be revealed to complete. |
| brushSize | double | Size of the brush. The bigger it is the faster user can scratch the card. |
| accuracy | ScratchAccuracy | Determines how accurate the progress should be reported. Lower accuracy means higher performance. |
| color | Color | Color used to cover the child widget. |
| image | Image | Image widget used to cover the child widget. |
| rebuildOnResize | bool | Determines if the scratcher should rebuild itself when space constraints change (resize). |
| onChange | Function | Callback called when new part of area is revealed (min 0.1% difference). |
| onThreshold | Function | Callback called when threshold is reached (only when defined). |
| onScratchStart | Function | Callback called when scratching starts. |
| onScratchUpdate | Function | Callback called during scratching. |
| onScratchEnd | Function | Callback called when scratching ends. |
Programmatic access
You can control the Scratcher programmatically by assigning the GlobalKey to the widget.
final scratchKey = GlobalKey<ScratcherState>();
Scratcher(
key: scratchKey,
// remaining properties
)
After assigning the key, you can call any exposed methods e.g.:
RaisedButton(
child: const Text('Reset'),
onPressed: () {
scratchKey.currentState.reset(duration: Duration(milliseconds: 2000));
},
);
| Method | Description |
|---|---|
| reset | Resets the scratcher state to the initial values. |
| reveal | Reveals the whole scratcher, so than only original child is displayed. |
Example Project
There is a crazy example project in the example folder. Check it out to see most of the available options.
GitHub
https://github.com/vintage/scratcher
