77 lines
2.8 KiB
Dart
77 lines
2.8 KiB
Dart
import 'package:flutter/material.dart';
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import './render.dart';
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/// Abstract definition for a [LazyCanvas] background.
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abstract class CanvasBackground {
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/// the fill color of background
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final Color bgColor;
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const CanvasBackground({this.bgColor = Colors.white});
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/// draw the backround on this context. Implement this to have
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/// different kinds of backgrounds
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/// [screenOffset] is the screen space offset for clipping
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/// [canvasOffset] is the grid space offset from the controller
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void paint(Canvas canvas, Offset screenOffset, Offset canvasOffset, double scale, Size canvasSize);
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}
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class NoBackground extends CanvasBackground {
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const NoBackground();
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@override
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void paint(Canvas canvas, Offset screenOffset, Offset canvasOffset, double scale, Size canvasSize) {}
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}
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class SingleColorBackround extends CanvasBackground {
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const SingleColorBackround(Color backgroundColor) : super(bgColor: backgroundColor);
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@override
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void paint(Canvas canvas, Offset screenOffset, Offset canvasOffset, double scale, Size canvasSize) {
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final paint = Paint()
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..color = bgColor
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..style = PaintingStyle.fill;
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canvas.drawRect(Rect.fromLTWH(screenOffset.dx, screenOffset.dy, canvasSize.width, canvasSize.height), paint);
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}
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}
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class DotGridBackround extends CanvasBackground {
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final double size;
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final double spacing;
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final Color color;
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const DotGridBackround({this.size = 2.0, this.spacing = 50.0, this.color = Colors.black12}) : super();
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@override
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void paint(Canvas canvas, Offset screenOffset, Offset canvasOffset, double scale, Size canvasSize) {
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final paint = Paint()
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..color = color
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..strokeWidth = 1.0 * scale;
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double scaledSpacing = spacing * scale;
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double scaledSize = size * scale;
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// Use canvasOffset to determine the grid position in grid space
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// Calculate the grid origin in canvas space (0,0 should be at a grid point)
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// Find the first grid point that aligns with the coordinate system
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double firstGridX = (canvasOffset.dx / spacing).floor() * spacing;
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double firstGridY = (canvasOffset.dy / spacing).floor() * spacing;
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// Convert grid space coordinates to screen space
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double screenStartX = (firstGridX - canvasOffset.dx) * scale + screenOffset.dx;
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double screenStartY = (firstGridY - canvasOffset.dy) * scale + screenOffset.dy;
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// Ensure we start drawing before the visible area to avoid gaps
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while (screenStartX > screenOffset.dx) {
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screenStartX -= scaledSpacing;
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}
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while (screenStartY > screenOffset.dy) {
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screenStartY -= scaledSpacing;
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}
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for (double x = screenStartX; x < screenOffset.dx + canvasSize.width + scaledSpacing; x += scaledSpacing) {
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for (double y = screenStartY; y < screenOffset.dy + canvasSize.height + scaledSpacing; y += scaledSpacing) {
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canvas.drawCircle(Offset(x, y), scaledSize, paint);
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}
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}
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}
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}
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