Custom Painting
CustomPaint, Canvas API, CustomPainter, drawing operations, performance, clipping
1Which widget should be used to draw custom graphics in Flutter?
Which widget should be used to draw custom graphics in Flutter?
답변
CustomPaint is the dedicated widget for custom drawing in Flutter. It takes a CustomPainter as a parameter containing the drawing logic via the paint() method. This widget creates a canvas where shapes, text, and images can be drawn with full control over every pixel.
2What are the two mandatory methods to implement in a CustomPainter?
What are the two mandatory methods to implement in a CustomPainter?
답변
A CustomPainter must implement paint() to define what is drawn on the Canvas, and shouldRepaint() to indicate whether the widget should be redrawn when the painter changes. shouldRepaint() returns a boolean and receives the old painter as a parameter to compare states.
3What is the role of the Paint object in Flutter custom drawing?
What is the role of the Paint object in Flutter custom drawing?
답변
The Paint object defines the drawing style: color, stroke width, fill style (fill or stroke), line join type, shader effects, and filters. It acts as a configurable brush that determines the appearance of everything drawn on the Canvas.
What is the difference between PaintingStyle.fill and PaintingStyle.stroke?
How to draw a circle on a Flutter Canvas?
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