screenshot

If you need to capture a widget that is not currently being rendered in the application's widget tree, use the static methods provided by ScreenshotController. This is useful for generating images of specific components in isolation.

Methods:

• ScreenshotController.widgetToUiImage(widget, {delay, pixelRatio, context, targetSize}): Renders the widget in an off-screen view and returns a ui.Image.
• ScreenshotController.captureFromWidget(widget, {delay, pixelRatio, context, targetSize}): Returns the captured widget as a Uint8List (PNG).
• ScreenshotController.captureFromLongWidget(widget, {delay, pixelRatio, context, constraints}): Specifically designed for large widgets. It calculates the required size of the widget before capturing.

Usage Constraints for captureFromLongWidget:

1. Do not use scrolling widgets like ListView or GridView. Instead, use Column or Row.
2. Do not use layout widgets like Flexible, Expanded, or Spacer without passing explicit constraints, as they require a parent with defined constraints to function.

// Capturing a widget that isn't in the tree
Uint8List bytes = await ScreenshotController.captureFromWidget(
  MyStandaloneWidget(),
  delay: Duration(seconds: 1),
  context: context, // Recommended to inherit Theme and MediaQuery
);

// Capturing a long widget (e.g., a large form or list-like structure)
Uint8List longBytes = await ScreenshotController.captureFromLongWidget(
  MyLongWidget(),
  constraints: BoxConstraints(maxWidth: 500),
  delay: Duration(seconds: 1),
);

The ScreenshotController can be used to capture images of widgets that are currently part of the active widget tree. To do this, you must wrap the target widget in a Screenshot widget, which provides the necessary RepaintBoundary and links it to the controller via a GlobalKey.

Key Methods:

• capture(): Returns the captured widget as a Uint8List (PNG format).
• captureAsUiImage(): Returns the captured widget as a ui.Image.
• captureAndSave(directory, {fileName, pixelRatio, delay}): Captures the widget and saves it directly to the specified directory as a file.

Important Note: A delay is required to ensure the widget has finished rendering. For larger widget trees, increase the delay (e.g., 1 second).

final ScreenshotController controller = ScreenshotController();

// In your build method:
Screenshot(
  controller: controller,
  child: MyWidgetToCapture(),
);

// To capture:
Uint8List? bytes = await controller.capture();

// To capture and save to a path:
String? filePath = await controller.captureAndSave(
  '/path/to/directory', 
  fileName: 'my_image.png'
);

To capture long widgets (like a long list) that are not currently visible, use captureFromLongWidget.

Important Implementation Rules:

• Use a Column to hold children instead of a scrolling widget.
• Do not use Expanded, Flexible, or Spacer inside the long widget.
• You can provide constraints (e.g., BoxConstraints) to define the maximum size of the output image.
• It is recommended to wrap the widget in InheritedTheme.captureAll and a Material widget to ensure correct rendering.

screenshotController
      .captureFromLongWidget(
          InheritedTheme.captureAll(
            context, 
            Material(
              child: myLongWidget,
            ),
          ),
          delay: Duration(milliseconds: 100),
          context: context,
          // constraints: BoxConstraints(maxHeight: 1000, maxWidth: 1000),
      )
      .then((capturedImage) {
    // Handle captured image
  });