forked from gdamore/tcell
/
widget.go
160 lines (136 loc) · 5.05 KB
/
widget.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
// Copyright 2015 The Tcell Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use file except in compliance with the License.
// You may obtain a copy of the license at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package views
import (
"github.com/gdamore/tcell"
)
// Widget is the base object that all onscreen elements implement.
type Widget interface {
// Draw is called to inform the widget to draw itself. A containing
// Widget will generally call this during the application draw loop.
Draw()
// Resize is called in response to a resize of the View. Unlike with
// other events, Resize performed by parents first, and they must
// then call their children. This is because the children need to
// see the updated sizes from the parents before they are called.
// In general this is done *after* the views have updated.
Resize()
// HandleEvent is called to ask the widget to handle any events.
// If the widget has consumed the event, it should return true.
// Generally, events are handled by the lower layers first, that
// is for example, a button may have a chance to handle an event
// before the enclosing window or panel.
//
// Its expected that Resize events are consumed by the outermost
// Widget, and the turned into a Resize() call.
HandleEvent(ev tcell.Event) bool
// SetView is used by callers to set the visual context of the
// Widget. The Widget should use the View as a context for
// drawing.
SetView(view View)
// Size returns the size of the widget (content size) as width, height
// in columns. Layout managers should attempt to ensure that at least
// this much space is made available to the View for this Widget. Extra
// space may be allocated on as an needed basis.
Size() (int, int)
// Watch is used to register an interest in this widget's events.
// The handler will receive EventWidget events for this widget.
// The order of event delivery when there are multiple watchers is
// not specified, and may change from one event to the next.
Watch(handler tcell.EventHandler)
// Unwatch is used to urnegister an interest in this widget's events.
Unwatch(handler tcell.EventHandler)
}
// EventWidget is an event delivered by a specific widget.
type EventWidget interface {
Widget() Widget
tcell.Event
}
type widgetEvent struct {
widget Widget
tcell.EventTime
}
func (wev *widgetEvent) Widget() Widget {
return wev.widget
}
func (wev *widgetEvent) SetWidget(widget Widget) {
wev.widget = widget
}
// WidgetWatchers provides a common implementation for base Widget
// Watch and Unwatch interfaces, suitable for embedding in more concrete
// widget implementations.
type WidgetWatchers struct {
watchers map[tcell.EventHandler]struct{}
}
// Watch monitors this WidgetWatcher, causing the handler to be fired
// with EventWidget as they are occur on the watched Widget.
func (ww *WidgetWatchers) Watch(handler tcell.EventHandler) {
if ww.watchers == nil {
ww.watchers = make(map[tcell.EventHandler]struct{})
}
ww.watchers[handler] = struct{}{}
}
// Unwatch stops monitoring this WidgetWatcher. The handler will no longer
// be fired for Widget events.
func (ww *WidgetWatchers) Unwatch(handler tcell.EventHandler) {
if ww.watchers != nil {
delete(ww.watchers, handler)
}
}
// PostEvent delivers the EventWidget to all registered watchers. It is
// to be called by the Widget implementation.
func (ww *WidgetWatchers) PostEvent(wev EventWidget) {
for watcher := range ww.watchers {
// Deliver events to all listeners, ignoring return value.
watcher.HandleEvent(wev)
}
}
// PostEventWidgetContent is called by the Widget when its content is
// changed, delivering EventWidgetContent to all watchers.
func (ww *WidgetWatchers) PostEventWidgetContent(w Widget) {
ev := &EventWidgetContent{}
ev.SetWidget(w)
ev.SetEventNow()
ww.PostEvent(ev)
}
// PostEventWidgetResize is called by the Widget when the underlying View
// has resized, delivering EventWidgetResize to all watchers.
func (ww *WidgetWatchers) PostEventWidgetResize(w Widget) {
ev := &EventWidgetResize{}
ev.SetWidget(w)
ev.SetEventNow()
ww.PostEvent(ev)
}
// PostEventWidgetMove is called by the Widget when it is moved to a new
// location, delivering EventWidgetMove to all watchers.
func (ww *WidgetWatchers) PostEventWidgetMove(w Widget) {
ev := &EventWidgetMove{}
ev.SetWidget(w)
ev.SetEventNow()
ww.PostEvent(ev)
}
// XXX: WidgetExposed, Hidden?
// XXX: WidgetExposed, Hidden?
// EventWidgetContent is fired whenever a widget's content changes.
type EventWidgetContent struct {
widgetEvent
}
// EventWidgetResize is fired whenever a widget is resized.
type EventWidgetResize struct {
widgetEvent
}
// EventWidgetMove is fired whenver a widget changes location.
type EventWidgetMove struct {
widgetEvent
}