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Diffstat (limited to 'area.go')
| -rw-r--r-- | area.go | 111 |
1 files changed, 111 insertions, 0 deletions
@@ -0,0 +1,111 @@ +// 16 december 2015 + +package ui + +import ( + "unsafe" +) + +// #include "pkgui.h" +import "C" + +// Area is a Control that represents a blank canvas that a program +// can draw on as it wishes. Areas also receive keyboard and mouse +// events, and programs can react to those as they see fit. Drawing +// and event handling are handled through an instance of a type +// that implements AreaHandler that every Area has; see AreaHandler +// for details. +// +// There are two types of areas. Non-scrolling areas are rectangular +// and have no scrollbars. Programs can draw on and get mouse +// events from any point in the Area, and the size of the Area is +// decided by package ui itself, according to the layout of controls +// in the Window the Area is located in and the size of said Window. +// There is no way to query the Area's size or be notified when its +// size changes; instead, you are given the area size as part of the +// draw and mouse event handlers, for use solely within those +// handlers. +// +// Scrolling areas have horziontal and vertical scrollbars. The amount +// that can be scrolled is determined by the area's size, which is +// decided by the programmer (both when creating the Area and by +// a call to SetSize). Only a portion of the Area is visible at any time; +// drawing and mouse events are automatically adjusted to match +// what portion is visible, so you do not have to worry about scrolling +// in your event handlers. AreaHandler has more information. +// +// The internal coordinate system of an Area is points, which are +// floating-point and device-independent. For more details, see +// AreaHandler. The size of a scrolling Area must be an exact integer +// number of points (that is, you cannot have an Area that is 32.5 +// points tall) and thus the parameters to NewScrollingArea and +// SetSize are ints. All other instances of points in parameters and +// structures (including sizes of drawn objects) are float64s. +type Area struct { + ControlBase + a *C.uiArea + ah *C.uiAreaHandler + scrolling bool +} + +// NewArea creates a new non-scrolling Area. +func NewArea(handler AreaHandler) *Area { + a := new(Area) + a.scrolling = false + a.ah = registerAreaHandler(handler) + + a.a = C.uiNewArea(a.ah) + + a.ControlBase = NewControlBase(a, uintptr(unsafe.Pointer(a.a))) + return a +} + +// NewScrollingArea creates a new scrolling Area of the given size, +// in points. +func NewScrollingArea(handler AreaHandler, width int, height int) *Area { + a := new(Area) + a.scrolling = true + a.ah = registerAreaHandler(handler) + + a.a = C.uiNewScrollingArea(a.ah, C.int(width), C.int(height)) + + a.ControlBase = NewControlBase(a, uintptr(unsafe.Pointer(a.a))) + return a +} + +// Destroy destroys the Area. +func (a *Area) Destroy() { + unregisterAreaHandler(a.ah) + a.ControlBase.Destroy() +} + +// SetSize sets the size of a scrolling Area to the given size, in points. +// SetSize panics if called on a non-scrolling Area. +func (a *Area) SetSize(width int, height int) { + if !a.scrolling { + panic("attempt to call SetSize on non-scrolling Area") + } + C.uiAreaSetSize(a.a, C.int(width), C.int(height)) +} + +// QueueRedrawAll queues the entire Area for redraw. +// The Area is not redrawn before this function returns; it is +// redrawn when next possible. +func (a *Area) QueueRedrawAll() { + C.uiAreaQueueRedrawAll(a.a) +} + +// ScrollTo scrolls the Area to show the given rectangle; what this +// means is implementation-defined, but you can safely assume +// that as much of the given rectangle as possible will be visible +// after this call. (TODO verify this on OS X) ScrollTo panics if called +// on a non-scrolling Area. +func (a *Area) ScrollTo(x float64, y float64, width float64, height float64) { + if !a.scrolling { + panic("attempt to call ScrollTo on non-scrolling Area") + } + C.uiAreaScrollTo(a.a, C.double(x), C.double(y), C.double(width), C.double(height)) +} + +// TODO BeginUserWindowMove +// TODO BeginUserWindowResize |