button.go

Documentation: github.com/rivo/tview

     1  package tview
     2  
     3  import (
     4  	"github.com/gdamore/tcell/v2"
     5  )
     6  
     7  // Button is labeled box that triggers an action when selected.
     8  //
     9  // See https://github.com/rivo/tview/wiki/Button for an example.
    10  type Button struct {
    11  	*Box
    12  
    13  	// If set to true, the button cannot be activated.
    14  	disabled bool
    15  
    16  	// The text to be displayed inside the button.
    17  	text string
    18  
    19  	// The button's style (when deactivated).
    20  	style tcell.Style
    21  
    22  	// The button's style (when activated).
    23  	activatedStyle tcell.Style
    24  
    25  	// The button's style (when disabled).
    26  	disabledStyle tcell.Style
    27  
    28  	// An optional function which is called when the button was selected.
    29  	selected func()
    30  
    31  	// An optional function which is called when the user leaves the button. A
    32  	// key is provided indicating which key was pressed to leave (tab or
    33  	// backtab).
    34  	exit func(tcell.Key)
    35  }
    36  
    37  // NewButton returns a new input field.
    38  func NewButton(label string) *Button {
    39  	box := NewBox()
    40  	box.SetRect(0, 0, TaggedStringWidth(label)+4, 1)
    41  	return &Button{
    42  		Box:            box,
    43  		text:           label,
    44  		style:          tcell.StyleDefault.Background(Styles.ContrastBackgroundColor).Foreground(Styles.PrimaryTextColor),
    45  		activatedStyle: tcell.StyleDefault.Background(Styles.PrimaryTextColor).Foreground(Styles.InverseTextColor),
    46  		disabledStyle:  tcell.StyleDefault.Background(Styles.ContrastBackgroundColor).Foreground(Styles.ContrastSecondaryTextColor),
    47  	}
    48  }
    49  
    50  // SetLabel sets the button text.
    51  func (b *Button) SetLabel(label string) *Button {
    52  	b.text = label
    53  	return b
    54  }
    55  
    56  // GetLabel returns the button text.
    57  func (b *Button) GetLabel() string {
    58  	return b.text
    59  }
    60  
    61  // SetLabelColor sets the color of the button text.
    62  func (b *Button) SetLabelColor(color tcell.Color) *Button {
    63  	b.style = b.style.Foreground(color)
    64  	return b
    65  }
    66  
    67  // SetStyle sets the style of the button used when it is not focused.
    68  func (b *Button) SetStyle(style tcell.Style) *Button {
    69  	b.style = style
    70  	return b
    71  }
    72  
    73  // SetLabelColorActivated sets the color of the button text when the button is
    74  // in focus.
    75  func (b *Button) SetLabelColorActivated(color tcell.Color) *Button {
    76  	b.activatedStyle = b.activatedStyle.Foreground(color)
    77  	return b
    78  }
    79  
    80  // SetBackgroundColorActivated sets the background color of the button text when
    81  // the button is in focus.
    82  func (b *Button) SetBackgroundColorActivated(color tcell.Color) *Button {
    83  	b.activatedStyle = b.activatedStyle.Background(color)
    84  	return b
    85  }
    86  
    87  // SetActivatedStyle sets the style of the button used when it is focused.
    88  func (b *Button) SetActivatedStyle(style tcell.Style) *Button {
    89  	b.activatedStyle = style
    90  	return b
    91  }
    92  
    93  // SetDisabledStyle sets the style of the button used when it is disabled.
    94  func (b *Button) SetDisabledStyle(style tcell.Style) *Button {
    95  	b.disabledStyle = style
    96  	return b
    97  }
    98  
    99  // SetDisabled sets whether or not the button is disabled. Disabled buttons
   100  // cannot be activated.
   101  //
   102  // If the button is part of a form, you should set focus to the form itself
   103  // after calling this function to set focus to the next non-disabled form item.
   104  func (b *Button) SetDisabled(disabled bool) *Button {
   105  	b.disabled = disabled
   106  	return b
   107  }
   108  
   109  // IsDisabled returns whether or not the button is disabled.
   110  func (b *Button) IsDisabled() bool {
   111  	return b.disabled
   112  }
   113  
   114  // SetSelectedFunc sets a handler which is called when the button was selected.
   115  func (b *Button) SetSelectedFunc(handler func()) *Button {
   116  	b.selected = handler
   117  	return b
   118  }
   119  
   120  // SetExitFunc sets a handler which is called when the user leaves the button.
   121  // The callback function is provided with the key that was pressed, which is one
   122  // of the following:
   123  //
   124  //   - KeyEscape: Leaving the button with no specific direction.
   125  //   - KeyTab: Move to the next field.
   126  //   - KeyBacktab: Move to the previous field.
   127  func (b *Button) SetExitFunc(handler func(key tcell.Key)) *Button {
   128  	b.exit = handler
   129  	return b
   130  }
   131  
   132  // Draw draws this primitive onto the screen.
   133  func (b *Button) Draw(screen tcell.Screen) {
   134  	// Draw the box.
   135  	style := b.style
   136  	if b.disabled {
   137  		style = b.disabledStyle
   138  	}
   139  	_, backgroundColor, _ := style.Decompose()
   140  	if b.HasFocus() && !b.disabled {
   141  		style = b.activatedStyle
   142  		_, backgroundColor, _ = style.Decompose()
   143  
   144  		// Highlight button for one drawing cycle.
   145  		borderColor := b.GetBorderColor()
   146  		b.SetBorderColor(backgroundColor)
   147  		defer func() {
   148  			b.SetBorderColor(borderColor)
   149  		}()
   150  	}
   151  	b.SetBackgroundColor(backgroundColor)
   152  	b.Box.DrawForSubclass(screen, b)
   153  
   154  	// Draw label.
   155  	x, y, width, height := b.GetInnerRect()
   156  	if width > 0 && height > 0 {
   157  		y = y + height/2
   158  		printWithStyle(screen, b.text, x, y, 0, width, AlignCenter, style, true)
   159  	}
   160  }
   161  
   162  // InputHandler returns the handler for this primitive.
   163  func (b *Button) InputHandler() func(event *tcell.EventKey, setFocus func(p Primitive)) {
   164  	return b.WrapInputHandler(func(event *tcell.EventKey, setFocus func(p Primitive)) {
   165  		if b.disabled {
   166  			return
   167  		}
   168  
   169  		// Process key event.
   170  		switch key := event.Key(); key {
   171  		case tcell.KeyEnter: // Selected.
   172  			if b.selected != nil {
   173  				b.selected()
   174  			}
   175  		case tcell.KeyBacktab, tcell.KeyTab, tcell.KeyEscape: // Leave. No action.
   176  			if b.exit != nil {
   177  				b.exit(key)
   178  			}
   179  		}
   180  	})
   181  }
   182  
   183  // MouseHandler returns the mouse handler for this primitive.
   184  func (b *Button) MouseHandler() func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
   185  	return b.WrapMouseHandler(func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
   186  		if b.disabled {
   187  			return false, nil
   188  		}
   189  
   190  		if !b.InRect(event.Position()) {
   191  			return false, nil
   192  		}
   193  
   194  		// Process mouse event.
   195  		if action == MouseLeftDown {
   196  			setFocus(b)
   197  			consumed = true
   198  		} else if action == MouseLeftClick {
   199  			if b.selected != nil {
   200  				b.selected()
   201  			}
   202  			consumed = true
   203  		}
   204  
   205  		return
   206  	})
   207  }
   208
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