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Diffstat (limited to 'draw.go')
| -rw-r--r-- | draw.go | 129 |
1 files changed, 129 insertions, 0 deletions
@@ -0,0 +1,129 @@ +// 13 december 2015 + +package main + +// #include "ui.h" +import "C" + +// Path represents a geometric path in a drawing context. +// This is the basic unit of drawing: all drawing operations consist of +// forming a path, then stroking, filling, or clipping to that path. +// A path is an OS resource; you must explicitly free it when finished. +// Paths consist of multiple figures. Once you have added all the +// figures to a path, you must "end" the path to make it ready to draw +// with. +// TODO rewrite all that +// +// Or more visually, the lifecycle of a Path is +// p := NewPath() +// for every figure { +// p.NewFigure(...) // or NewFigureWithArc +// p.LineTo(...) // any number of these in any order +// p.ArcTo(...) +// p.BezierTo(...) +// if figure should be closed { +// p.CloseFigure() +// } +// } +// p.End() +// // ... +// dp.Context.Stroke(p, ...) // any number of these in any order +// dp.Context.Fill(p, ...) +// dp.Context.Clip(p) +// // ... +// p.Free() // when done with the path +type Path struct { + p *C.uiDrawPath +} + +// NewPath creates a new Path. +func NewPath() *Path { + return &Path{ + p: C.uiDrawNewPath(), + } +} + +// Free destroys a Path. After calling Free the Path cannot be used. +func (p *Path) Free() { + C.uiDrawFreePath(p.p) +} + +// NewFigure starts a new figure in the Path. The current point +// is set to the given point. +func (p *Path) NewFigure(x float64, y float64) { + C.uiDrawPathNewFigure(p.p, C.double(x), C.double(y)) +} + +// NewFigureWithArc starts a new figure in the Path and adds an arc +// as the first element of the figure. Unlike ArcTo, NewFigureWithArc +// does not draw an initial line segment. Otherwise, see ArcTo. +func (p *Path) NewFigureWithArc(xCenter float64, yCenter float64, radius float64, startAngle float64, sweep float64, isNegative bool) { + C.uiDrawPathNewFigureWithArc(p.p, + C.double(xCenter), C.double(yCenter), + C.double(radius), + C.double(startAngle), C.double(sweep), + frombool(isNegative)) +} + +// LineTo adds a line to the current figure of the Path starting from +// the current point and ending at the given point. The current point +// is set to the ending point. +func (p *Path) LineTo(x float64, y float64) { + C.uiDrawPathLineTo(p.p, C.double(x), C.double(y)) +} + +// ArcTo adds a circular arc to the current figure of the Path. +// You pass it the center of the arc, its radius in radians, the starting +// angle (couterclockwise) in radians, and the number of radians the +// arc should sweep (counterclockwise). A line segment is drawn from +// the current point to the start of the arc. The current point is set to +// the end of the arc. +func (p *Path) ArcTo(xCenter float64, yCenter float64, radius float64, startAngle float64, sweep float64, isNegative bool) { + C.uiDrawPathArcTo(p.p, + C.double(xCenter), C.double(yCenter), + C.double(radius), + C.double(startAngle), C.double(sweep), + frombool(isNegative)) +} + +// BezierTo adds a cubic Bezier curve to the current figure of the Path. +// Its start point is the current point. c1x and c1y are the first control +// point. c2x and c2y are the second control point. endX and endY +// are the end point. The current point is set to the end point. +func (p *Path) BezierTo(c1x float64, c1y float64, c2x float64, c2y float64, endX float64, endY float64) { + C.uiDrawPathBezierTo(p.p, + C.double(c1x), C.double(c1y), + C.double(c2x), C.double(c2y), + C.double(endX), C.double(endY)) +} + +// CloseFigure draws a line segment from the current point of the +// current figure of the Path back to its initial point. After calling this, +// the current figure is over and you must either start a new figure +// or end the Path. If this is not called and you start a new figure or +// end the Path, then the current figure will not have this closing line +// segment added to it (but the figure will still be over). +func (p *Path) CloseFigure() { + C.uiDrawPathCloseFigure(p.p) +} + +// AddRectangle creates a new figure in the Path that consists entirely +// of a rectangle whose top-left corner is at the given point and whose +// size is the given size. The rectangle is a closed figure; you must +// either start a new figure or end the Path after calling this method. +func (p *Path) AddRectangle(x float64, y float64, width float64, height float64) { + C.uiDrawPathAddRectangle(p.p, C.double(x), C.double(y), C.double(width), C.double(height)) +} + +// End ends the current Path. You cannot add figures to a Path that has +// been ended. You cannot draw with a Path that has not been ended. +func (p *Path) End() { + C.uiDrawPathEnd(p.p) +} + +// DrawContext represents a drawing surface that you can draw to. +// At present the only DrawContexts are surfaces associated with +// Areas and are provided by package ui; see AreaDrawParams. +type DrawContext struct { + c *C.uiDrawContext +} |