package tview import ( "image" "github.com/gdamore/tcell/v2" ) var ( // DefaultFormFieldWidth is the default field screen width of form elements // whose field width is flexible (0). This is used in the Form class for // horizontal layouts. DefaultFormFieldWidth = 10 // DefaultFormFieldHeight is the default field height of multi-line form // elements whose field height is flexible (0). DefaultFormFieldHeight = 5 ) // FormItem is the interface all form items must implement to be able to be // included in a form. type FormItem interface { Primitive // GetLabel returns the item's label text. GetLabel() string // SetFormAttributes sets a number of item attributes at once. SetFormAttributes(labelWidth int, labelColor, bgColor, fieldTextColor, fieldBgColor tcell.Color) FormItem // GetFieldWidth returns the width of the form item's field (the area which // is manipulated by the user) in number of screen cells. A value of 0 // indicates the the field width is flexible and may use as much space as // required. GetFieldWidth() int // GetFieldHeight returns the height of the form item's field (the area which // is manipulated by the user). This value must be greater than 0. GetFieldHeight() int // SetFinishedFunc sets the handler function for when the user finished // entering data into the item. The handler may receive events for the // Enter key (we're done), the Escape key (cancel input), the Tab key (move // to next field), the Backtab key (move to previous field), or a negative // value, indicating that the action for the last known key should be // repeated. SetFinishedFunc(handler func(key tcell.Key)) FormItem // SetDisabled sets whether or not the item is disabled / read-only. A form // must have at least one item that is not disabled. SetDisabled(disabled bool) FormItem } // Form allows you to combine multiple one-line form elements into a vertical // or horizontal layout. Form elements include types such as InputField or // Checkbox. These elements can be optionally followed by one or more buttons // for which you can define form-wide actions (e.g. Save, Clear, Cancel). // // See https://github.com/rivo/tview/wiki/Form for an example. type Form struct { *Box // The items of the form (one row per item). items []FormItem // The buttons of the form. buttons []*Button // If set to true, instead of position items and buttons from top to bottom, // they are positioned from left to right. horizontal bool // The alignment of the buttons. buttonsAlign int // The number of empty cells between items. itemPadding int // The index of the item or button which has focus. (Items are counted first, // buttons are counted last.) This is only used when the form itself receives // focus so that the last element that had focus keeps it. focusedElement int // The label color. labelColor tcell.Color // The background color of the input area. fieldBackgroundColor tcell.Color // The text color of the input area. fieldTextColor tcell.Color // The style of the buttons when they are not focused. buttonStyle tcell.Style // The style of the buttons when they are focused. buttonActivatedStyle tcell.Style // The style of the buttons when they are disabled. buttonDisabledStyle tcell.Style // The last (valid) key that wsa sent to a "finished" handler or -1 if no // such key is known yet. lastFinishedKey tcell.Key // An optional function which is called when the user hits Escape. cancel func() } // NewForm returns a new form. func NewForm() *Form { box := NewBox().SetBorderPadding(1, 1, 1, 1) f := &Form{ Box: box, itemPadding: 1, labelColor: Styles.SecondaryTextColor, fieldBackgroundColor: Styles.ContrastBackgroundColor, fieldTextColor: Styles.PrimaryTextColor, buttonStyle: tcell.StyleDefault.Background(Styles.ContrastBackgroundColor).Foreground(Styles.PrimaryTextColor), buttonActivatedStyle: tcell.StyleDefault.Background(Styles.PrimaryTextColor).Foreground(Styles.ContrastBackgroundColor), buttonDisabledStyle: tcell.StyleDefault.Background(Styles.ContrastBackgroundColor).Foreground(Styles.ContrastSecondaryTextColor), lastFinishedKey: tcell.KeyTab, // To skip over inactive elements at the beginning of the form. } return f } // SetItemPadding sets the number of empty rows between form items for vertical // layouts and the number of empty cells between form items for horizontal // layouts. func (f *Form) SetItemPadding(padding int) *Form { f.itemPadding = padding return f } // SetHorizontal sets the direction the form elements are laid out. If set to // true, instead of positioning them from top to bottom (the default), they are // positioned from left to right, moving into the next row if there is not // enough space. func (f *Form) SetHorizontal(horizontal bool) *Form { f.horizontal = horizontal return f } // SetLabelColor sets the color of the labels. func (f *Form) SetLabelColor(color tcell.Color) *Form { f.labelColor = color return f } // SetFieldBackgroundColor sets the background color of the input areas. func (f *Form) SetFieldBackgroundColor(color tcell.Color) *Form { f.fieldBackgroundColor = color return f } // SetFieldTextColor sets the text color of the input areas. func (f *Form) SetFieldTextColor(color tcell.Color) *Form { f.fieldTextColor = color return f } // SetButtonsAlign sets how the buttons align horizontally, one of AlignLeft // (the default), AlignCenter, and AlignRight. This is only func (f *Form) SetButtonsAlign(align int) *Form { f.buttonsAlign = align return f } // SetButtonBackgroundColor sets the background color of the buttons. This is // also the text color of the buttons when they are focused. func (f *Form) SetButtonBackgroundColor(color tcell.Color) *Form { f.buttonStyle = f.buttonStyle.Background(color) f.buttonActivatedStyle = f.buttonActivatedStyle.Foreground(color) return f } // SetButtonTextColor sets the color of the button texts. This is also the // background of the buttons when they are focused. func (f *Form) SetButtonTextColor(color tcell.Color) *Form { f.buttonStyle = f.buttonStyle.Foreground(color) f.buttonActivatedStyle = f.buttonActivatedStyle.Background(color) return f } // SetButtonStyle sets the style of the buttons when they are not focused. func (f *Form) SetButtonStyle(style tcell.Style) *Form { f.buttonStyle = style return f } // SetButtonActivatedStyle sets the style of the buttons when they are focused. func (f *Form) SetButtonActivatedStyle(style tcell.Style) *Form { f.buttonActivatedStyle = style return f } // SetButtonDisabledStyle sets the style of the buttons when they are disabled. func (f *Form) SetButtonDisabledStyle(style tcell.Style) *Form { f.buttonDisabledStyle = style return f } // SetFocus shifts the focus to the form element with the given index, counting // non-button items first and buttons last. Note that this index is only used // when the form itself receives focus. func (f *Form) SetFocus(index int) *Form { if index < 0 { f.focusedElement = 0 } else if index >= len(f.items)+len(f.buttons) { f.focusedElement = len(f.items) + len(f.buttons) } else { f.focusedElement = index } return f } // AddTextArea adds a text area to the form. It has a label, an optional initial // text, a size (width and height) referring to the actual input area (a // fieldWidth of 0 extends it as far right as possible, a fieldHeight of 0 will // cause it to be [DefaultFormFieldHeight]), and a maximum number of bytes of // text allowed (0 means no limit). // // The optional callback function is invoked when the content of the text area // has changed. Note that especially for larger texts, this is an expensive // operation due to technical constraints of the [TextArea] primitive (every key // stroke leads to a new reallocation of the entire text). func (f *Form) AddTextArea(label, text string, fieldWidth, fieldHeight, maxLength int, changed func(text string)) *Form { if fieldHeight == 0 { fieldHeight = DefaultFormFieldHeight } textArea := NewTextArea(). SetLabel(label). SetSize(fieldHeight, fieldWidth). SetMaxLength(maxLength) if text != "" { textArea.SetText(text, true) } if changed != nil { textArea.SetChangedFunc(func() { changed(textArea.GetText()) }) } f.items = append(f.items, textArea) return f } // AddTextView adds a text view to the form. It has a label and text, a size // (width and height) referring to the actual text element (a fieldWidth of 0 // extends it as far right as possible, a fieldHeight of 0 will cause it to be // [DefaultFormFieldHeight]), a flag to turn on/off dynamic colors, and a flag // to turn on/off scrolling. If scrolling is turned off, the text view will not // receive focus. func (f *Form) AddTextView(label, text string, fieldWidth, fieldHeight int, dynamicColors, scrollable bool) *Form { if fieldHeight == 0 { fieldHeight = DefaultFormFieldHeight } textArea := NewTextView(). SetLabel(label). SetSize(fieldHeight, fieldWidth). SetDynamicColors(dynamicColors). SetScrollable(scrollable). SetText(text) f.items = append(f.items, textArea) return f } // AddInputField adds an input field to the form. It has a label, an optional // initial value, a field width (a value of 0 extends it as far as possible), // an optional accept function to validate the item's value (set to nil to // accept any text), and an (optional) callback function which is invoked when // the input field's text has changed. func (f *Form) AddInputField(label, value string, fieldWidth int, accept func(textToCheck string, lastChar rune) bool, changed func(text string)) *Form { f.items = append(f.items, NewInputField(). SetLabel(label). SetText(value). SetFieldWidth(fieldWidth). SetAcceptanceFunc(accept). SetChangedFunc(changed)) return f } // AddPasswordField adds a password field to the form. This is similar to an // input field except that the user's input not shown. Instead, a "mask" // character is displayed. The password field has a label, an optional initial // value, a field width (a value of 0 extends it as far as possible), and an // (optional) callback function which is invoked when the input field's text has // changed. func (f *Form) AddPasswordField(label, value string, fieldWidth int, mask rune, changed func(text string)) *Form { if mask == 0 { mask = '*' } f.items = append(f.items, NewInputField(). SetLabel(label). SetText(value). SetFieldWidth(fieldWidth). SetMaskCharacter(mask). SetChangedFunc(changed)) return f } // AddDropDown adds a drop-down element to the form. It has a label, options, // and an (optional) callback function which is invoked when an option was // selected. The initial option may be a negative value to indicate that no // option is currently selected. func (f *Form) AddDropDown(label string, options []string, initialOption int, selected func(option string, optionIndex int)) *Form { f.items = append(f.items, NewDropDown(). SetLabel(label). SetOptions(options, selected). SetCurrentOption(initialOption)) return f } // AddCheckbox adds a checkbox to the form. It has a label, an initial state, // and an (optional) callback function which is invoked when the state of the // checkbox was changed by the user. func (f *Form) AddCheckbox(label string, checked bool, changed func(checked bool)) *Form { f.items = append(f.items, NewCheckbox(). SetLabel(label). SetChecked(checked). SetChangedFunc(changed)) return f } // AddImage adds an image to the form. It has a label and the image will fit in // the specified width and height (its aspect ratio is preserved). See // [Image.SetColors] for a description of the "colors" parameter. Images are not // interactive and are skipped over in a form. The "width" value may be 0 // (adjust dynamically) but "height" should generally be a positive value. func (f *Form) AddImage(label string, image image.Image, width, height, colors int) *Form { f.items = append(f.items, NewImage(). SetLabel(label). SetImage(image). SetSize(height, width). SetAlign(AlignTop, AlignLeft). SetColors(colors)) return f } // AddButton adds a new button to the form. The "selected" function is called // when the user selects this button. It may be nil. func (f *Form) AddButton(label string, selected func()) *Form { f.buttons = append(f.buttons, NewButton(label).SetSelectedFunc(selected)) return f } // GetButton returns the button at the specified 0-based index. Note that // buttons have been specially prepared for this form and modifying some of // their attributes may have unintended side effects. func (f *Form) GetButton(index int) *Button { return f.buttons[index] } // RemoveButton removes the button at the specified position, starting with 0 // for the button that was added first. func (f *Form) RemoveButton(index int) *Form { f.buttons = append(f.buttons[:index], f.buttons[index+1:]...) return f } // GetButtonCount returns the number of buttons in this form. func (f *Form) GetButtonCount() int { return len(f.buttons) } // GetButtonIndex returns the index of the button with the given label, starting // with 0 for the button that was added first. If no such label was found, -1 // is returned. func (f *Form) GetButtonIndex(label string) int { for index, button := range f.buttons { if button.GetLabel() == label { return index } } return -1 } // Clear removes all input elements from the form, including the buttons if // specified. func (f *Form) Clear(includeButtons bool) *Form { f.items = nil if includeButtons { f.ClearButtons() } f.focusedElement = 0 return f } // ClearButtons removes all buttons from the form. func (f *Form) ClearButtons() *Form { f.buttons = nil return f } // AddFormItem adds a new item to the form. This can be used to add your own // objects to the form. Note, however, that the Form class will override some // of its attributes to make it work in the form context. Specifically, these // are: // // - The label width // - The label color // - The background color // - The field text color // - The field background color func (f *Form) AddFormItem(item FormItem) *Form { f.items = append(f.items, item) return f } // GetFormItemCount returns the number of items in the form (not including the // buttons). func (f *Form) GetFormItemCount() int { return len(f.items) } // GetFormItem returns the form item at the given position, starting with index // 0. Elements are referenced in the order they were added. Buttons are not // included. func (f *Form) GetFormItem(index int) FormItem { return f.items[index] } // RemoveFormItem removes the form element at the given position, starting with // index 0. Elements are referenced in the order they were added. Buttons are // not included. func (f *Form) RemoveFormItem(index int) *Form { f.items = append(f.items[:index], f.items[index+1:]...) return f } // GetFormItemByLabel returns the first form element with the given label. If // no such element is found, nil is returned. Buttons are not searched and will // therefore not be returned. func (f *Form) GetFormItemByLabel(label string) FormItem { for _, item := range f.items { if item.GetLabel() == label { return item } } return nil } // GetFormItemIndex returns the index of the first form element with the given // label. If no such element is found, -1 is returned. Buttons are not searched // and will therefore not be returned. func (f *Form) GetFormItemIndex(label string) int { for index, item := range f.items { if item.GetLabel() == label { return index } } return -1 } // GetFocusedItemIndex returns the indices of the form element or button which // currently has focus. If they don't, -1 is returned resepectively. func (f *Form) GetFocusedItemIndex() (formItem, button int) { index := f.focusIndex() if index < 0 { return -1, -1 } if index < len(f.items) { return index, -1 } return -1, index - len(f.items) } // SetCancelFunc sets a handler which is called when the user hits the Escape // key. func (f *Form) SetCancelFunc(callback func()) *Form { f.cancel = callback return f } // Draw draws this primitive onto the screen. func (f *Form) Draw(screen tcell.Screen) { f.Box.DrawForSubclass(screen, f) // Determine the actual item that has focus. if index := f.focusIndex(); index >= 0 { f.focusedElement = index } // Determine the dimensions. x, y, width, height := f.GetInnerRect() topLimit := y bottomLimit := y + height rightLimit := x + width startX := x // Find the longest label. var maxLabelWidth int for _, item := range f.items { labelWidth := TaggedStringWidth(item.GetLabel()) if labelWidth > maxLabelWidth { maxLabelWidth = labelWidth } } maxLabelWidth++ // Add one space. // Calculate positions of form items. type position struct{ x, y, width, height int } positions := make([]position, len(f.items)+len(f.buttons)) var ( focusedPosition position lineHeight = 1 ) for index, item := range f.items { // Calculate the space needed. labelWidth := TaggedStringWidth(item.GetLabel()) var itemWidth int if f.horizontal { fieldWidth := item.GetFieldWidth() if fieldWidth <= 0 { fieldWidth = DefaultFormFieldWidth } labelWidth++ itemWidth = labelWidth + fieldWidth } else { // We want all fields to align vertically. labelWidth = maxLabelWidth itemWidth = width } itemHeight := item.GetFieldHeight() if itemHeight <= 0 { itemHeight = DefaultFormFieldHeight } // Advance to next line if there is no space. if f.horizontal && x+labelWidth+1 >= rightLimit { x = startX y += lineHeight + 1 lineHeight = itemHeight } // Update line height. if itemHeight > lineHeight { lineHeight = itemHeight } // Adjust the item's attributes. if x+itemWidth >= rightLimit { itemWidth = rightLimit - x } item.SetFormAttributes( labelWidth, f.labelColor, f.backgroundColor, f.fieldTextColor, f.fieldBackgroundColor, ) // Save position. positions[index].x = x positions[index].y = y positions[index].width = itemWidth positions[index].height = itemHeight if item.HasFocus() { focusedPosition = positions[index] } // Advance to next item. if f.horizontal { x += itemWidth + f.itemPadding } else { y += itemHeight + f.itemPadding } } // How wide are the buttons? buttonWidths := make([]int, len(f.buttons)) buttonsWidth := 0 for index, button := range f.buttons { w := TaggedStringWidth(button.GetLabel()) + 4 buttonWidths[index] = w buttonsWidth += w + 1 } buttonsWidth-- // Where do we place them? if !f.horizontal && x+buttonsWidth < rightLimit { if f.buttonsAlign == AlignRight { x = rightLimit - buttonsWidth } else if f.buttonsAlign == AlignCenter { x = (x + rightLimit - buttonsWidth) / 2 } // In vertical layouts, buttons always appear after an empty line. if f.itemPadding == 0 { y++ } } // Calculate positions of buttons. for index, button := range f.buttons { space := rightLimit - x buttonWidth := buttonWidths[index] if f.horizontal { if space < buttonWidth-4 { x = startX y += lineHeight + 1 space = width lineHeight = 1 } } else { if space < 1 { break // No space for this button anymore. } } if buttonWidth > space { buttonWidth = space } button.SetStyle(f.buttonStyle). SetActivatedStyle(f.buttonActivatedStyle). SetDisabledStyle(f.buttonDisabledStyle) buttonIndex := index + len(f.items) positions[buttonIndex].x = x positions[buttonIndex].y = y positions[buttonIndex].width = buttonWidth positions[buttonIndex].height = 1 if button.HasFocus() { focusedPosition = positions[buttonIndex] } x += buttonWidth + 1 } // Determine vertical offset based on the position of the focused item. var offset int if focusedPosition.y+focusedPosition.height > bottomLimit { offset = focusedPosition.y + focusedPosition.height - bottomLimit if focusedPosition.y-offset < topLimit { offset = focusedPosition.y - topLimit } } // Draw items. for index, item := range f.items { // Set position. y := positions[index].y - offset height := positions[index].height item.SetRect(positions[index].x, y, positions[index].width, height) // Is this item visible? if y+height <= topLimit || y >= bottomLimit { continue } // Draw items with focus last (in case of overlaps). if item.HasFocus() { defer item.Draw(screen) } else { item.Draw(screen) } } // Draw buttons. for index, button := range f.buttons { // Set position. buttonIndex := index + len(f.items) y := positions[buttonIndex].y - offset height := positions[buttonIndex].height button.SetRect(positions[buttonIndex].x, y, positions[buttonIndex].width, height) // Is this button visible? if y+height <= topLimit || y >= bottomLimit { continue } // Draw button. button.Draw(screen) } } // Focus is called by the application when the primitive receives focus. func (f *Form) Focus(delegate func(p Primitive)) { // Hand on the focus to one of our child elements. if f.focusedElement < 0 || f.focusedElement >= len(f.items)+len(f.buttons) { f.focusedElement = 0 } var handler func(key tcell.Key) handler = func(key tcell.Key) { if key >= 0 { f.lastFinishedKey = key } switch key { case tcell.KeyTab, tcell.KeyEnter: f.focusedElement++ f.Focus(delegate) case tcell.KeyBacktab: f.focusedElement-- if f.focusedElement < 0 { f.focusedElement = len(f.items) + len(f.buttons) - 1 } f.Focus(delegate) case tcell.KeyEscape: if f.cancel != nil { f.cancel() } else { f.focusedElement = 0 f.Focus(delegate) } default: if key < 0 && f.lastFinishedKey >= 0 { // Repeat the last action. handler(f.lastFinishedKey) } } } // Track whether a form item has focus. var itemFocused bool f.hasFocus = false // Set the handler and focus for all items and buttons. for index, button := range f.buttons { button.SetExitFunc(handler) if f.focusedElement == index+len(f.items) { if button.IsDisabled() { f.focusedElement++ if f.focusedElement >= len(f.items)+len(f.buttons) { f.focusedElement = 0 } continue } itemFocused = true func(b *Button) { // Wrapping might not be necessary anymore in future Go versions. defer delegate(b) }(button) } } for index, item := range f.items { item.SetFinishedFunc(handler) if f.focusedElement == index { itemFocused = true func(i FormItem) { // Wrapping might not be necessary anymore in future Go versions. defer delegate(i) }(item) } } // If no item was focused, focus the form itself. if !itemFocused { f.Box.Focus(delegate) } } // HasFocus returns whether or not this primitive has focus. func (f *Form) HasFocus() bool { if f.focusIndex() >= 0 { return true } return f.Box.HasFocus() } // focusIndex returns the index of the currently focused item, counting form // items first, then buttons. A negative value indicates that no containeed item // has focus. func (f *Form) focusIndex() int { for index, item := range f.items { if item.HasFocus() { return index } } for index, button := range f.buttons { if button.HasFocus() { return len(f.items) + index } } return -1 } // MouseHandler returns the mouse handler for this primitive. func (f *Form) MouseHandler() func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) { return f.WrapMouseHandler(func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) { // At the end, update f.focusedElement and prepare current item/button. defer func() { if consumed { index := f.focusIndex() if index >= 0 { f.focusedElement = index } } }() // Determine items to pass mouse events to. for _, item := range f.items { // Exclude TextView items from mouse-down events as they are // read-only items and thus should not be focused. if _, ok := item.(*TextView); ok && action == MouseLeftDown { continue } consumed, capture = item.MouseHandler()(action, event, setFocus) if consumed { return } } for _, button := range f.buttons { consumed, capture = button.MouseHandler()(action, event, setFocus) if consumed { return } } // A mouse down anywhere else will return the focus to the last selected // element. if action == MouseLeftDown && f.InRect(event.Position()) { f.Focus(setFocus) consumed = true } return }) } // InputHandler returns the handler for this primitive. func (f *Form) InputHandler() func(event *tcell.EventKey, setFocus func(p Primitive)) { return f.WrapInputHandler(func(event *tcell.EventKey, setFocus func(p Primitive)) { for _, item := range f.items { if item != nil && item.HasFocus() { if handler := item.InputHandler(); handler != nil { handler(event, setFocus) return } } } for _, button := range f.buttons { if button.HasFocus() { if handler := button.InputHandler(); handler != nil { handler(event, setFocus) return } } } }) }