flutter-canvas

来源： https://stackoverflow.com/questions/59626727/how-to-erase-clip-from-canvas-custompaint

来源： https://stackoverflow.com/questions/59626727/how-to-erase-clip-from-canvas-custompaint

来源： https://stackoverflow.com/questions/59626727/how-to-erase-clip-from-canvas-custompaint

问题 For some reason, the Stack widget does not show the Container with the CustomPaint . However if removed from Stack , it works fine. What am I missing here? class _DemoNavBar extends State<DemoNavBar> { @override Widget build(BuildContext context) { // TODO: implement build return MaterialApp( home: Stack( children: <Widget>[ Container(child: CustomPaint(painter: CurvePainter())) ], ) ); } } class CurvePainter extends CustomPainter { @override void paint(Canvas canvas, Size size) { var paint =

问题 For some reason, the Stack widget does not show the Container with the CustomPaint . However if removed from Stack , it works fine. What am I missing here? class _DemoNavBar extends State<DemoNavBar> { @override Widget build(BuildContext context) { // TODO: implement build return MaterialApp( home: Stack( children: <Widget>[ Container(child: CustomPaint(painter: CurvePainter())) ], ) ); } } class CurvePainter extends CustomPainter { @override void paint(Canvas canvas, Size size) { var paint =

问题 For some reason, the Stack widget does not show the Container with the CustomPaint . However if removed from Stack , it works fine. What am I missing here? class _DemoNavBar extends State<DemoNavBar> { @override Widget build(BuildContext context) { // TODO: implement build return MaterialApp( home: Stack( children: <Widget>[ Container(child: CustomPaint(painter: CurvePainter())) ], ) ); } } class CurvePainter extends CustomPainter { @override void paint(Canvas canvas, Size size) { var paint =

问题 For some reason, the Stack widget does not show the Container with the CustomPaint . However if removed from Stack , it works fine. What am I missing here? class _DemoNavBar extends State<DemoNavBar> { @override Widget build(BuildContext context) { // TODO: implement build return MaterialApp( home: Stack( children: <Widget>[ Container(child: CustomPaint(painter: CurvePainter())) ], ) ); } } class CurvePainter extends CustomPainter { @override void paint(Canvas canvas, Size size) { var paint =

问题 How do I "cut a hole" in a shape with flutter canvas? I have this rather complex set of shapes that is made to look like a real world object. This object has a hole in it shaped like a rounded rectangle. I would really like to subtract a RRect from a shape, but I cannot find any information on how to do this. canvas.clipRRect(myRRect) just removes everything that is not covered by myRRect . I want the opposite of that. i.e. to make a myRRect shape hole in the current canvas shape or shapes.

问题 This attachment is from the rendered canvas image which is saved locally via canvas. In image I have drawn the square box which I want to render in canvas and save locally without left and right extra spaces . I just want to save the square box and remove that unnecessary space of PNG-image. So, how to do this? widget-source-code: return CustomPaint( painter: PngImageCropper(image: image), ); PngImageCropper-code class PngImageCropper extends CustomPainter { PngImageCropper({ this.image, });

问题 Hello can anyone tell me why the background to this masking attempt is black. This must be close but I just can't kill the background. I've seen others reference that saveLayer(rect, paint) is the key here as that shoves the whole canvas rect in to the masking operation. This question (no masking operation) and this one (no actual answer) are similar but were no use to me. main.dart import 'dart:typed_data'; import 'dart:ui' as ui; import 'package:flutter/cupertino.dart'; import 'package