kmpdfkit_demo/lib/widgets/common/slider/cpdf_slider_theme.dart

import 'package:flutter/material.dart';

import 'package:flutter/services.dart';
import 'dart:ui' as ui;
import 'dart:math' as math;

///  Copyright © 2014-2023 PDF Technologies, Inc. All Rights Reserved.
///
///  THIS SOURCE CODE AND ANY ACCOMPANYING DOCUMENTATION ARE PROTECTED BY INTERNATIONAL COPYRIGHT LAW
///  AND MAY NOT BE RESOLD OR REDISTRIBUTED. USAGE IS BOUND TO THE ComPDFKit LICENSE AGREEMENT.
///  UNAUTHORIZED REPRODUCTION OR DISTRIBUTION IS SUBJECT TO CIVIL AND CRIMINAL PENALTIES.
///  This notice may not be removed from this file.

class CPDFImageSliderThumbShape extends SliderComponentShape {
  final double imageWidth;
  final double imageHeight;
  final ui.Image image;

  CPDFImageSliderThumbShape({
    this.imageWidth = 20,
    this.imageHeight = 20,
    required this.image,
  });

  @override
  Size getPreferredSize(bool isEnabled, bool isDiscrete) {
    return Size(imageWidth, imageHeight);
  }

  @override
  void paint(
    PaintingContext context,
    Offset center, {
    Animation<double>? activationAnimation,
    Animation<double>? enableAnimation,
    bool? isDiscrete,
    TextPainter? labelPainter,
    RenderBox? parentBox,
    SliderThemeData? sliderTheme,
    TextDirection? textDirection,
    double? value,
    double? textScaleFactor,
    Size? sizeWithOverflow,
  }) {
    final canvas = context.canvas;
    final imageOffset =
        Offset(center.dx - imageWidth / 2, center.dy - imageHeight / 2);

    final double targetWidth = imageWidth;
    final double targetHeight = imageHeight;
    final double scaleX = targetWidth / image.width.toDouble();
    final double scaleY = targetHeight / image.height.toDouble();
    final double scale = scaleX < scaleY ? scaleX : scaleY;

    final double destWidth = image.width.toDouble() * scale;
    final double destHeight = image.height.toDouble() * scale;

    final paint = Paint();
    final srcRect =
        Rect.fromLTWH(0, 0, image.width.toDouble(), image.height.toDouble());
    final dstRect =
        Rect.fromLTWH(imageOffset.dx, imageOffset.dy, destWidth, destHeight);
    canvas.drawImageRect(image, srcRect, dstRect, paint);
  }
}

enum CPDFSliderIndicatorPosition { top, left, right, bottom }

class CPDFPageSliderValueIndicatorShape extends SliderComponentShape {
  CPDFSliderIndicatorPosition position;

  late _RectangularSliderValueIndicatorPathPainter _pathPainter;

  CPDFPageSliderValueIndicatorShape({required this.position}) {
    _pathPainter =
        _RectangularSliderValueIndicatorPathPainter(position: position);
  }

  @override
  Size getPreferredSize(
    bool isEnabled,
    bool isDiscrete, {
    TextPainter? labelPainter,
    double? textScaleFactor,
  }) {
    assert(labelPainter != null);
    assert(textScaleFactor != null && textScaleFactor >= 0);
    return _pathPainter.getPreferredSize(labelPainter!, textScaleFactor!);
  }

  @override
  void paint(
    PaintingContext context,
    Offset center, {
    required Animation<double> activationAnimation,
    required Animation<double> enableAnimation,
    required bool isDiscrete,
    required TextPainter labelPainter,
    required RenderBox parentBox,
    required SliderThemeData sliderTheme,
    required TextDirection textDirection,
    required double value,
    required double textScaleFactor,
    required Size sizeWithOverflow,
  }) {
    final Canvas canvas = context.canvas;
    final double scale = activationAnimation.value;
    _pathPainter.paint(
      parentBox: parentBox,
      canvas: canvas,
      center: center,
      scale: scale,
      labelPainter: labelPainter,
      textScaleFactor: textScaleFactor,
      sizeWithOverflow: sizeWithOverflow,
      backgroundPaintColor: sliderTheme.valueIndicatorColor!,
    );
  }
}

class _RectangularSliderValueIndicatorPathPainter {
  CPDFSliderIndicatorPosition position;

  _RectangularSliderValueIndicatorPathPainter({required this.position});

  static const double _labelPadding = 8.0;
  static const double _minLabelWidth = 32.0;
  static const double _bottomTipYOffset = 24.0;
  static const double _upperRectRadius = 4;

  Size getPreferredSize(
    TextPainter labelPainter,
    double textScaleFactor,
  ) {
    return Size(
      _upperRectangleWidth(labelPainter, 1, textScaleFactor),
      labelPainter.height + _labelPadding,
    );
  }

  double getHorizontalShift({
    required RenderBox parentBox,
    required Offset center,
    required TextPainter labelPainter,
    required double textScaleFactor,
    required Size sizeWithOverflow,
    required double scale,
  }) {
    assert(!sizeWithOverflow.isEmpty);

    const double edgePadding = 16.0;
    final double rectangleWidth =
        _upperRectangleWidth(labelPainter, scale, textScaleFactor);

    /// Value indicator draws on the Overlay and by using the global Offset
    /// we are making sure we use the bounds of the Overlay instead of the Slider.
    final Offset globalCenter = parentBox.localToGlobal(center);

    // The rectangle must be shifted towards the center so that it minimizes the
    // chance of it rendering outside the bounds of the render box. If the shift
    // is negative, then the lobe is shifted from right to left, and if it is
    // positive, then the lobe is shifted from left to right.
    final double overflowLeft =
        math.max(0, rectangleWidth / 2 - globalCenter.dx + edgePadding);
    final double overflowRight = math.max(
        0,
        rectangleWidth / 2 -
            (sizeWithOverflow.width - globalCenter.dx - edgePadding));

    if (rectangleWidth < sizeWithOverflow.width) {
      return overflowLeft - overflowRight;
    } else if (overflowLeft - overflowRight > 0) {
      return overflowLeft - (edgePadding * textScaleFactor);
    } else {
      return -overflowRight + (edgePadding * textScaleFactor);
    }
  }

  double _upperRectangleWidth(
      TextPainter labelPainter, double scale, double textScaleFactor) {
    final double unscaledWidth =
        math.max(_minLabelWidth * textScaleFactor, labelPainter.width) +
            _labelPadding * 2;
    return unscaledWidth * scale;
  }

  void paint({
    required RenderBox parentBox,
    required Canvas canvas,
    required Offset center,
    required double scale,
    required TextPainter labelPainter,
    required double textScaleFactor,
    required Size sizeWithOverflow,
    required Color backgroundPaintColor,
    Color? strokePaintColor,
  }) {
    if (scale == 0.0) {
      // Zero scale essentially means "do not draw anything", so it's safe to just return.
      return;
    }
    assert(!sizeWithOverflow.isEmpty);

    final double rectangleWidth =
        _upperRectangleWidth(labelPainter, scale, textScaleFactor);
    final double horizontalShift = getHorizontalShift(
      parentBox: parentBox,
      center: center,
      labelPainter: labelPainter,
      textScaleFactor: textScaleFactor,
      sizeWithOverflow: sizeWithOverflow,
      scale: scale,
    );

    final double rectHeight = labelPainter.height + _labelPadding;
    final Rect upperRect = Rect.fromLTWH(
      -rectangleWidth / 2 + horizontalShift,
      -rectHeight,
      rectangleWidth,
      rectHeight,
    );

    final Path trianglePath = Path()..close();
    final Paint fillPaint = Paint()..color = backgroundPaintColor;
    final RRect upperRRect = RRect.fromRectAndRadius(
        upperRect, const Radius.circular(_upperRectRadius));
    trianglePath.addRRect(upperRRect);
    canvas.save();
    // Prepare the canvas for the base of the tooltip, which is relative to the
    // center of the thumb.

    switch (position) {
      case CPDFSliderIndicatorPosition.top:
        canvas.translate(center.dx, center.dy + _bottomTipYOffset * 2);
        canvas.scale(scale, scale);
        break;
      case CPDFSliderIndicatorPosition.bottom:
        canvas.translate(center.dx, center.dy - _bottomTipYOffset);
        canvas.scale(scale, scale);
        break;
      case CPDFSliderIndicatorPosition.left:
        final double bottomPadding =
            parentBox.size.height / 2 + _bottomTipYOffset;
        canvas.translate(
            center.dx + horizontalShift / 2, center.dy - bottomPadding / 2);
        canvas.scale(scale, scale);
        canvas.rotate(-(math.pi / 2));
        break;
      case CPDFSliderIndicatorPosition.right:
        final double bottomPadding =
            parentBox.size.height / 2 + _bottomTipYOffset;
        canvas.translate(
            center.dx - horizontalShift / 2, center.dy + bottomPadding / 2);
        canvas.scale(scale, scale);
        canvas.rotate(-(math.pi / 2));
        break;
    }
    canvas.save();
    if (strokePaintColor != null) {
      final Paint strokePaint = Paint()
        ..color = strokePaintColor
        ..strokeWidth = 1.0
        ..style = PaintingStyle.stroke;
      canvas.drawPath(trianglePath, strokePaint);
    }
    canvas.drawPath(trianglePath, fillPaint);

    // The label text is centered within the value indicator.
    final double bottomTipToUpperRectTranslateY = -upperRect.height;
    canvas.translate(0, bottomTipToUpperRectTranslateY);
    final Offset boxCenter = Offset(horizontalShift, upperRect.height / 2);
    final Offset halfLabelPainterOffset =
        Offset(labelPainter.width / 2, labelPainter.height / 2);
    final Offset labelOffset = boxCenter - halfLabelPainterOffset;
    labelPainter.paint(canvas, labelOffset);
    canvas.restore();
  }
}