449 lines
11 KiB
Go
449 lines
11 KiB
Go
// 13 december 2015
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package ui
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// #include "pkgui.h"
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import "C"
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// Path represents a geometric path in a drawing context.
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// This is the basic unit of drawing: all drawing operations consist of
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// forming a path, then stroking, filling, or clipping to that path.
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// A path is an OS resource; you must explicitly free it when finished.
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// Paths consist of multiple figures. Once you have added all the
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// figures to a path, you must "end" the path to make it ready to draw
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// with.
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// TODO rewrite all that
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//
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// Or more visually, the lifecycle of a Path is
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// p := NewPath()
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// for every figure {
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// p.NewFigure(...) // or NewFigureWithArc
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// p.LineTo(...) // any number of these in any order
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// p.ArcTo(...)
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// p.BezierTo(...)
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// if figure should be closed {
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// p.CloseFigure()
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// }
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// }
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// p.End()
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// // ...
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// dp.Context.Stroke(p, ...) // any number of these in any order
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// dp.Context.Fill(p, ...)
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// dp.Context.Clip(p)
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// // ...
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// p.Free() // when done with the path
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//
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// A Path also defines its fill mode. (This should ideally be a fill
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// parameter, but some implementations prevent it.)
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// TODO talk about fill modes
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type Path struct {
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p *C.uiDrawPath
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}
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// TODO
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//
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// TODO disclaimer
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type FillMode uint
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const (
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Winding FillMode = iota
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Alternate
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)
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// NewPath creates a new Path with the given fill mode.
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func NewPath(fillMode FillMode) *Path {
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var fm C.uiDrawFillMode
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switch fillMode {
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case Winding:
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fm = C.uiDrawFillModeWinding
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case Alternate:
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fm = C.uiDrawFillModeAlternate
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default:
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panic("invalid fill mode passed to ui.NewPath()")
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}
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return &Path{
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p: C.uiDrawNewPath(fm),
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}
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}
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// Free destroys a Path. After calling Free the Path cannot be used.
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func (p *Path) Free() {
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C.uiDrawFreePath(p.p)
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}
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// NewFigure starts a new figure in the Path. The current point
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// is set to the given point.
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func (p *Path) NewFigure(x float64, y float64) {
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C.uiDrawPathNewFigure(p.p, C.double(x), C.double(y))
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}
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// NewFigureWithArc starts a new figure in the Path and adds an arc
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// as the first element of the figure. Unlike ArcTo, NewFigureWithArc
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// does not draw an initial line segment. Otherwise, see ArcTo.
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func (p *Path) NewFigureWithArc(xCenter float64, yCenter float64, radius float64, startAngle float64, sweep float64, isNegative bool) {
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C.uiDrawPathNewFigureWithArc(p.p,
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C.double(xCenter), C.double(yCenter),
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C.double(radius),
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C.double(startAngle), C.double(sweep),
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frombool(isNegative))
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}
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// LineTo adds a line to the current figure of the Path starting from
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// the current point and ending at the given point. The current point
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// is set to the ending point.
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func (p *Path) LineTo(x float64, y float64) {
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C.uiDrawPathLineTo(p.p, C.double(x), C.double(y))
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}
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// ArcTo adds a circular arc to the current figure of the Path.
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// You pass it the center of the arc, its radius in radians, the starting
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// angle (couterclockwise) in radians, and the number of radians the
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// arc should sweep (counterclockwise). A line segment is drawn from
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// the current point to the start of the arc. The current point is set to
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// the end of the arc.
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func (p *Path) ArcTo(xCenter float64, yCenter float64, radius float64, startAngle float64, sweep float64, isNegative bool) {
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C.uiDrawPathArcTo(p.p,
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C.double(xCenter), C.double(yCenter),
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C.double(radius),
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C.double(startAngle), C.double(sweep),
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frombool(isNegative))
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}
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// BezierTo adds a cubic Bezier curve to the current figure of the Path.
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// Its start point is the current point. c1x and c1y are the first control
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// point. c2x and c2y are the second control point. endX and endY
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// are the end point. The current point is set to the end point.
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func (p *Path) BezierTo(c1x float64, c1y float64, c2x float64, c2y float64, endX float64, endY float64) {
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C.uiDrawPathBezierTo(p.p,
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C.double(c1x), C.double(c1y),
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C.double(c2x), C.double(c2y),
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C.double(endX), C.double(endY))
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}
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// CloseFigure draws a line segment from the current point of the
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// current figure of the Path back to its initial point. After calling this,
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// the current figure is over and you must either start a new figure
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// or end the Path. If this is not called and you start a new figure or
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// end the Path, then the current figure will not have this closing line
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// segment added to it (but the figure will still be over).
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func (p *Path) CloseFigure() {
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C.uiDrawPathCloseFigure(p.p)
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}
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// AddRectangle creates a new figure in the Path that consists entirely
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// of a rectangle whose top-left corner is at the given point and whose
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// size is the given size. The rectangle is a closed figure; you must
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// either start a new figure or end the Path after calling this method.
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func (p *Path) AddRectangle(x float64, y float64, width float64, height float64) {
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C.uiDrawPathAddRectangle(p.p, C.double(x), C.double(y), C.double(width), C.double(height))
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}
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// End ends the current Path. You cannot add figures to a Path that has
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// been ended. You cannot draw with a Path that has not been ended.
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func (p *Path) End() {
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C.uiDrawPathEnd(p.p)
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}
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// DrawContext represents a drawing surface that you can draw to.
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// At present the only DrawContexts are surfaces associated with
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// Areas and are provided by package ui; see AreaDrawParams.
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type DrawContext struct {
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c *C.uiDrawContext
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}
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// BrushType defines the various types of brushes.
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//
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// TODO disclaimer
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type BrushType int
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const (
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BrushTypeSolid BrushType = iota
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BrushTypeLinearGradient
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BrushTypeRadialGradient
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BrushTypeImage // presently unimplemented
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)
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// TODO
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//
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// TODO disclaimer
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// TODO rename these to put LineCap at the beginning? or just Cap?
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type LineCap int
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const (
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FlatCap LineCap = iota
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RoundCap
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SquareCap
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)
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// TODO
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//
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// TODO disclaimer
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type LineJoin int
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const (
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MiterJoin LineJoin = iota
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RoundJoin
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BevelJoin
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)
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// TODO document
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const DefaultMiterLimit = 10.0
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// TODO
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type Brush struct {
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Type BrushType
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// If Type is Solid.
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// TODO
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R float64
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G float64
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B float64
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A float64
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// If Type is LinearGradient or RadialGradient.
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// TODO
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X0 float64 // start point for both
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Y0 float64
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X1 float64 // linear: end point; radial: circle center
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Y1 float64
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OuterRadius float64 // for radial gradients only
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Stops []GradientStop
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}
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// TODO
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type GradientStop struct {
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Pos float64 // between 0 and 1 inclusive
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R float64
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G float64
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B float64
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A float64
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}
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func (b *Brush) toC() *C.uiDrawBrush {
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cb := C.pkguiAllocBrush()
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cb.Type = C.uiDrawBrushType(b.Type)
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switch b.Type {
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case BrushTypeSolid:
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cb.R = C.double(b.R)
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cb.G = C.double(b.G)
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cb.B = C.double(b.B)
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cb.A = C.double(b.A)
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case BrushTypeLinearGradient, BrushTypeRadialGradient:
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cb.X0 = C.double(b.X0)
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cb.Y0 = C.double(b.Y0)
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cb.X1 = C.double(b.X1)
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cb.Y1 = C.double(b.Y1)
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cb.OuterRadius = C.double(b.OuterRadius)
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cb.NumStops = C.size_t(len(b.Stops))
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cb.Stops = C.pkguiAllocGradientStops(cb.NumStops)
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for i, s := range b.Stops {
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C.pkguiSetGradientStop(cb.Stops, C.size_t(i),
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C.double(s.Pos),
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C.double(s.R),
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C.double(s.G),
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C.double(s.B),
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C.double(s.A))
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}
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case BrushTypeImage:
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panic("unimplemented")
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default:
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panic("invalid brush type in Brush.toC()")
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}
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return cb
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}
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func freeBrush(cb *C.uiDrawBrush) {
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if cb.Type == C.uiDrawBrushTypeLinearGradient || cb.Type == C.uiDrawBrushTypeRadialGradient {
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C.pkguiFreeGradientStops(cb.Stops)
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}
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C.pkguiFreeBrush(cb)
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}
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// TODO
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type StrokeParams struct {
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Cap LineCap
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Join LineJoin
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Thickness float64
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MiterLimit float64
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Dashes []float64
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DashPhase float64
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}
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func (sp *StrokeParams) toC() *C.uiDrawStrokeParams {
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csp := C.pkguiAllocStrokeParams()
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csp.Cap = C.uiDrawLineCap(sp.Cap)
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csp.Join = C.uiDrawLineJoin(sp.Join)
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csp.Thickness = C.double(sp.Thickness)
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csp.MiterLimit = C.double(sp.MiterLimit)
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csp.Dashes = nil
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csp.NumDashes = C.size_t(len(sp.Dashes))
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if csp.NumDashes != 0 {
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csp.Dashes = C.pkguiAllocDashes(csp.NumDashes)
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for i, d := range sp.Dashes {
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C.pkguiSetDash(csp.Dashes, C.size_t(i), C.double(d))
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}
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}
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csp.DashPhase = C.double(sp.DashPhase)
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return csp
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}
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func freeStrokeParams(csp *C.uiDrawStrokeParams) {
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if csp.Dashes != nil {
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C.pkguiFreeDashes(csp.Dashes)
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}
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C.pkguiFreeStrokeParams(csp)
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}
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// TODO
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func (c *DrawContext) Stroke(p *Path, b *Brush, sp *StrokeParams) {
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cb := b.toC()
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defer freeBrush(cb)
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csp := sp.toC()
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defer freeStrokeParams(csp)
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C.uiDrawStroke(c.c, p.p, cb, csp)
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}
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// TODO
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func (c *DrawContext) Fill(p *Path, b *Brush) {
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cb := b.toC()
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defer freeBrush(cb)
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C.uiDrawFill(c.c, p.p, cb)
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}
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// TODO
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// TODO should the methods of these return self for chaining?
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type Matrix struct {
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M11 float64
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M12 float64
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M21 float64
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M22 float64
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M31 float64
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M32 float64
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}
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// TODO identity matrix
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func NewMatrix() *Matrix {
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m := new(Matrix)
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m.SetIdentity()
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return m
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}
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// TODO
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func (m *Matrix) SetIdentity() {
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m.M11 = 1
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m.M12 = 0
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m.M21 = 0
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m.M22 = 1
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m.M31 = 0
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m.M32 = 0
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}
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func (m *Matrix) toC() *C.uiDrawMatrix {
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cm := C.pkguiAllocMatrix()
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cm.M11 = C.double(m.M11)
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cm.M12 = C.double(m.M12)
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cm.M21 = C.double(m.M21)
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cm.M22 = C.double(m.M22)
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cm.M31 = C.double(m.M31)
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cm.M32 = C.double(m.M32)
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return cm
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}
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func (m *Matrix) fromC(cm *C.uiDrawMatrix) {
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m.M11 = float64(cm.M11)
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m.M12 = float64(cm.M12)
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m.M21 = float64(cm.M21)
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m.M22 = float64(cm.M22)
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m.M31 = float64(cm.M31)
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m.M32 = float64(cm.M32)
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C.pkguiFreeMatrix(cm)
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}
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// TODO
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func (m *Matrix) Translate(x float64, y float64) {
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cm := m.toC()
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C.uiDrawMatrixTranslate(cm, C.double(x), C.double(y))
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m.fromC(cm)
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}
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// TODO
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func (m *Matrix) Scale(xCenter float64, yCenter float64, x float64, y float64) {
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cm := m.toC()
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C.uiDrawMatrixScale(cm,
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C.double(xCenter), C.double(yCenter),
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C.double(x), C.double(y))
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m.fromC(cm)
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}
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// TODO
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func (m *Matrix) Rotate(x float64, y float64, amount float64) {
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cm := m.toC()
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C.uiDrawMatrixRotate(cm, C.double(x), C.double(y), C.double(amount))
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m.fromC(cm)
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}
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// TODO
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func (m *Matrix) Skew(x float64, y float64, xamount float64, yamount float64) {
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cm := m.toC()
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C.uiDrawMatrixSkew(cm,
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C.double(x), C.double(y),
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C.double(xamount), C.double(yamount))
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m.fromC(cm)
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}
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// TODO
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func (m *Matrix) Multiply(m2 *Matrix) {
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cm := m.toC()
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cm2 := m2.toC()
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C.uiDrawMatrixMultiply(cm, cm2)
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C.pkguiFreeMatrix(cm2)
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m.fromC(cm)
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}
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// TODO
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func (m *Matrix) Invertible() bool {
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cm := m.toC()
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res := C.uiDrawMatrixInvertible(cm)
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C.pkguiFreeMatrix(cm)
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return tobool(res)
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}
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// TODO
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//
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// If m is not invertible, false is returned and m is left unchanged.
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func (m *Matrix) Invert() bool {
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cm := m.toC()
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res := C.uiDrawMatrixInvert(cm)
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m.fromC(cm)
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return tobool(res)
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}
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// TODO unimplemented
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func (m *Matrix) TransformPoint(x float64, y float64) (xout float64, yout float64) {
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panic("TODO")
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}
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// TODO unimplemented
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func (m *Matrix) TransformSize(x float64, y float64) (xout float64, yout float64) {
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panic("TODO")
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}
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// TODO
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func (c *DrawContext) Transform(m *Matrix) {
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cm := m.toC()
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C.uiDrawTransform(c.c, cm)
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C.pkguiFreeMatrix(cm)
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}
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// TODO
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func (c *DrawContext) Clip(p *Path) {
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C.uiDrawClip(c.c, p.p)
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}
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// TODO
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func (c *DrawContext) Save() {
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C.uiDrawSave(c.c)
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}
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// TODO
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func (c *DrawContext) Restore() {
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C.uiDrawRestore(c.c)
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}
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