diff options
Diffstat (limited to 'area.go')
| -rw-r--r-- | area.go | 13 |
1 files changed, 12 insertions, 1 deletions
@@ -3,6 +3,7 @@ package ui import ( + "fmt" "sync" "image" ) @@ -10,6 +11,7 @@ import ( // 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; Areas have horizontal and vertical scrollbars that are hidden when not needed. // The coordinate system of an Area always has an origin of (0,0) which maps to the top-left corner; all image.Points and image.Rectangles sent across Area's channels conform to this. +// The size of an Area must be at least 1x1 (that is, neither its width nor its height may be zero or negative). // // To handle events to the Area, an Area must be paired with an AreaHandler. // See AreaHandler for details. @@ -260,9 +262,16 @@ const ( // TODO add Super ) +func checkAreaSize(width int, height int, which string) { + if width <= 0 || height <= 0 { + panic(fmt.Errorf("invalid size %dx%d in %s", width, height, which)) + } +} + // NewArea creates a new Area with the given size and handler. -// It panics if handler is nil. +// It panics if handler is nil or if width or height is zero or negative. func NewArea(width int, height int, handler AreaHandler) *Area { + checkAreaSize(width, height, "NewArea()") if handler == nil { panic("handler passed to NewArea() must not be nil") } @@ -276,10 +285,12 @@ func NewArea(width int, height int, handler AreaHandler) *Area { // SetSize sets the Area's internal drawing size. // It has no effect on the actual control size. +// It panics if width or height is zero or negative. func (a *Area) SetSize(width int, height int) { a.lock.Lock() defer a.lock.Unlock() + checkAreaSize(width, height, "Area.SetSize()") if a.created { a.sysData.setAreaSize(width, height) return |