77 lines
2.2 KiB
Go
77 lines
2.2 KiB
Go
// Canvas defines a standard interface for images that support drawing
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// primitives.
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package canvas
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import "image"
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import "image/draw"
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import "image/color"
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// Cap represents a stroke cap type.
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type Cap int; const (
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CapButt Cap = iota // Square cap that ends at the point
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CapRound // Round cap that surrounds the point
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CapSquare // square cap that surrounds the point
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)
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// Joint represents a stroke joint type.
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type Joint int; const (
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JointRount Joint = iota // Rounded joint
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JointSharp // Sharp joint
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JointMiter // Clipped/beveled joint
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)
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// StrokeAlign determines whether a stroke is drawn inside, outside, or on a
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// path.
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type StrokeAlign int; const (
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StrokeAlignCenter StrokeAlign = iota // Centered on the path
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StrokeAlignInner // Inset into the path
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StrokeAlignOuter // Outset around the path
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)
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// Pen represents a drawing context that is linked to a canvas. Each canvas can
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// have multiple pens associated with it, each maintaining their own drawing
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// context.
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type Pen interface {
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// Rectangle draws a rectangle
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Rectangle (image.Rectangle)
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// Path draws a path
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Path (points ...image.Point)
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Closed (bool) // if the path is closed
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Cap (Cap) // line cap stype
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Joint (Joint) // line joint style
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StrokeWeight (int) // how thick the stroke is
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StrokeAlign (StrokeAlign) // where the stroke is drawn
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Stroke (color.Color) // Sets the stroke to a solid color
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Fill (color.Color) // Sets the fill to a solid color
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Texture (Texture) // Overlaps a texture onto the fill color
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}
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// Canvas is an image that supports drawing paths.
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type Canvas interface {
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draw.Image
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// Pen returns a new pen for this canvas.
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Pen () Pen
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// Clip returns a new canvas that points to a specific area of this one.
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Clip (image.Rectangle) Canvas
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}
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// Drawer is an object that can draw to a canvas.
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type Drawer interface {
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// Draw draws to the given canvas.
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Draw (Canvas)
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}
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// PushCanvas is a canvas that can push a region of itself to the screen (or
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// some other destination).
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type PushCanvas interface {
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Canvas
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// Push pushes a specified region to the screen.
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Push (image.Rectangle)
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}
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