diff options
| -rw-r--r-- | area.go | 79 |
1 files changed, 79 insertions, 0 deletions
@@ -0,0 +1,79 @@ +// 14 march 2014 + +package ui + +import ( + "sync" + "image" +) + +// Area represents a blank canvas upon which programs may draw anything and receive arbitrary events from the user. +// An Area has an explicit size, represented in pixels, that may be different from the size shown in its Window; scrollbars are placed automatically should they be needed. +// To facilitate development and debugging, for the time being, Areas have a fixed size of 320x240 and only work on GTK+. +type Area struct { + // Paint is signaled when the Area needs to be redrawn. + // You MUST handle Paint signals; failure to do so will result in the UI task hanging. + // See the documentation of PaintRequest for details. + Paint chan PaintRequest + + lock sync.Mutex + created bool + sysData *sysData +} + +// PaintRequest contains the information needed to redraw an Area. +// On each Paint event, an Area will receive a full request on its Paint channel. +// It must send something back on Out in order to complete the painting. +// Example: +// imgFromFile, _, err := image.Decode(file) +// if err != nil { panic(err) } +// img := image.NewNRGBA(imgFromFile.Rect) +// draw.Draw(img, img.Rect, imgFromFile, image.ZP, draw.Over) +// for req := range area.Paint { +// req.Out <- img.SubImage(req.Rect).(*image.NRGBA) +// } +type PaintRequest struct { + // Rect is the clip rectangle of the whole Area that needs to be redrawn. + // The image sent on Out must have the same size as Rect (but does not have to have the same Rect.Min/Rect.Max points). + Rect image.Rectangle + + // Out is where you send the image to draw. + // Only one image per PaintRequest may be sent; you must send an image. + // Do not close Out; the package will do this itself. + Out chan<- *image.NRGBA +} + +// NewArea creates a new Area. +func NewArea() *Area { + return &Area{ + sysData: mksysdata(c_area), + Paint: make(chan PaintRequest), + } +} + +func (a *Area) make(window *sysData) error { + a.lock.Lock() + defer a.lock.Unlock() + + a.sysData.paint = a.Paint + err := a.sysData.make("", window) + if err != nil { + return err + } + a.created = true + return nil +} + +func (a *Area) setRect(x int, y int, width int, height int, winheight int) error { + a.lock.Lock() + defer a.lock.Unlock() + + return a.sysData.setRect(x, y, width, height, winheight) +} + +func (a *Area) preferredSize() (width int, height int) { + a.lock.Lock() + defer a.lock.Unlock() + + return a.sysData.preferredSize() +} |