widget.go

// Copyright 2010 The Walk Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package walk

import (
	"github.com/lxn/win"
)

// LayoutFlags specify how a Widget wants to be treated when used with a Layout.
//
// These flags are interpreted in respect to Widget.SizeHint.
type LayoutFlags byte

const (
	// ShrinkableHorz allows a Widget to be shrunk horizontally.
	ShrinkableHorz LayoutFlags = 1 << iota

	// ShrinkableVert allows a Widget to be shrunk vertically.
	ShrinkableVert

	// GrowableHorz allows a Widget to be enlarged horizontally.
	GrowableHorz

	// GrowableVert allows a Widget to be enlarged vertically.
	GrowableVert

	// GreedyHorz specifies that the widget prefers to take up as much space as
	// possible, horizontally.
	GreedyHorz

	// GreedyVert specifies that the widget prefers to take up as much space as
	// possible, vertically.
	GreedyVert
)

type Widget interface {
	Window

	// AsWidgetBase returns a *WidgetBase that implements Widget.
	AsWidgetBase() *WidgetBase

	// Form returns the root ancestor Form of the Widget.
	Form() Form

	// LayoutFlags returns a combination of LayoutFlags that specify how the
	// Widget wants to be treated by Layout implementations.
	LayoutFlags() LayoutFlags

	// MinSizeHint returns the minimum outer Size, including decorations, that
	// makes sense for the respective type of Widget.
	MinSizeHint() Size

	// Parent returns the Container of the Widget.
	Parent() Container

	// SetParent sets the parent of the Widget and adds the Widget to the
	// Children list of the Container.
	SetParent(value Container) error

	// SetToolTipText sets the tool tip text of the Widget.
	SetToolTipText(s string) error

	// SizeHint returns the preferred Size for the respective type of Widget.
	SizeHint() Size

	// ToolTipText returns the tool tip text of the Widget.
	ToolTipText() string
}

type WidgetBase struct {
	WindowBase
	parent                      Container
	toolTipTextProperty         Property
	toolTipTextChangedPublisher EventPublisher
}

// InitWidget initializes a Widget.
func InitWidget(widget Widget, parent Window, className string, style, exStyle uint32) error {
	if parent == nil {
		return newError("parent cannot be nil")
	}

	if err := InitWindow(widget, parent, className, style|win.WS_CHILD, exStyle); err != nil {
		return err
	}

	if container, ok := parent.(Container); ok {
		if container.Children() == nil {
			// Required by parents like MainWindow and GroupBox.
			if win.SetParent(widget.Handle(), container.Handle()) == 0 {
				return lastError("SetParent")
			}
		} else {
			if err := container.Children().Add(widget); err != nil {
				return err
			}
		}
	}

	return nil
}

func (wb *WidgetBase) init(widget Widget) error {
	if err := globalToolTip.AddTool(wb); err != nil {
		return err
	}

	wb.toolTipTextProperty = NewProperty(
		func() interface{} {
			return wb.window.(Widget).ToolTipText()
		},
		func(v interface{}) error {
			wb.window.(Widget).SetToolTipText(v.(string))
			return nil
		},
		wb.toolTipTextChangedPublisher.Event())

	wb.MustRegisterProperty("ToolTipText", wb.toolTipTextProperty)

	return nil
}

// AsWidgetBase just returns the receiver.
func (wb *WidgetBase) AsWidgetBase() *WidgetBase {
	return wb
}

// Bounds returns the outer bounding box Rectangle of the WidgetBase, including
// decorations.
//
// The coordinates are relative to the parent of the Widget.
func (wb *WidgetBase) Bounds() Rectangle {
	b := wb.WindowBase.Bounds()

	if wb.parent != nil {
		p := win.POINT{int32(b.X), int32(b.Y)}
		if !win.ScreenToClient(wb.parent.Handle(), &p) {
			newError("ScreenToClient failed")
			return Rectangle{}
		}
		b.X = int(p.X)
		b.Y = int(p.Y)
	}

	return b
}

// BringToTop moves the WidgetBase to the top of the keyboard focus order.
func (wb *WidgetBase) BringToTop() error {
	if wb.parent != nil {
		if err := wb.parent.BringToTop(); err != nil {
			return err
		}
	}

	return wb.WindowBase.BringToTop()
}

// Enabled returns if the WidgetBase is enabled for user interaction.
func (wb *WidgetBase) Enabled() bool {
	if wb.parent != nil {
		return wb.enabled && wb.parent.Enabled()
	}

	return wb.enabled
}

// Font returns the Font of the WidgetBase.
//
// By default this is a MS Shell Dlg 2, 8 point font.
func (wb *WidgetBase) Font() *Font {
	if wb.font != nil {
		return wb.font
	} else if wb.parent != nil {
		return wb.parent.Font()
	}

	return defaultFont
}

// Form returns the root ancestor Form of the Widget.
func (wb *WidgetBase) Form() Form {
	return ancestor(wb)
}

// LayoutFlags returns a combination of LayoutFlags that specify how the
// WidgetBase wants to be treated by Layout implementations.
func (wb *WidgetBase) LayoutFlags() LayoutFlags {
	return 0
}

// MinSizeHint returns the minimum outer Size, including decorations, that
// makes sense for the respective type of Widget.
func (wb *WidgetBase) MinSizeHint() Size {
	return Size{10, 10}
}

// Parent returns the Container of the WidgetBase.
func (wb *WidgetBase) Parent() Container {
	return wb.parent
}

// SetParent sets the parent of the WidgetBase and adds the WidgetBase to the
// Children list of the Container.
func (wb *WidgetBase) SetParent(parent Container) (err error) {
	if parent == wb.parent {
		return nil
	}

	style := uint32(win.GetWindowLong(wb.hWnd, win.GWL_STYLE))
	if style == 0 {
		return lastError("GetWindowLong")
	}

	if parent == nil {
		style &^= win.WS_CHILD
		style |= win.WS_POPUP

		if win.SetParent(wb.hWnd, 0) == 0 {
			return lastError("SetParent")
		}
		win.SetLastError(0)
		if win.SetWindowLong(wb.hWnd, win.GWL_STYLE, int32(style)) == 0 {
			return lastError("SetWindowLong")
		}
	} else {
		style |= win.WS_CHILD
		style &^= win.WS_POPUP

		win.SetLastError(0)
		if win.SetWindowLong(wb.hWnd, win.GWL_STYLE, int32(style)) == 0 {
			return lastError("SetWindowLong")
		}
		if win.SetParent(wb.hWnd, parent.Handle()) == 0 {
			return lastError("SetParent")
		}
	}

	b := wb.Bounds()

	if !win.SetWindowPos(
		wb.hWnd,
		win.HWND_BOTTOM,
		int32(b.X),
		int32(b.Y),
		int32(b.Width),
		int32(b.Height),
		win.SWP_FRAMECHANGED) {

		return lastError("SetWindowPos")
	}

	oldParent := wb.parent

	wb.parent = parent

	var oldChildren, newChildren *WidgetList
	if oldParent != nil {
		oldChildren = oldParent.Children()
	}
	if parent != nil {
		newChildren = parent.Children()
	}

	if newChildren == oldChildren {
		return nil
	}

	widget := wb.window.(Widget)

	if oldChildren != nil {
		oldChildren.Remove(widget)
	}

	if newChildren != nil && !newChildren.containsHandle(wb.hWnd) {
		newChildren.Add(widget)
	}

	return nil
}

// SizeHint returns a default Size that should be "overidden" by a concrete
// Widget type.
func (wb *WidgetBase) SizeHint() Size {
	return wb.window.(Widget).MinSizeHint()
}

// ToolTipText returns the tool tip text of the WidgetBase.
func (wb *WidgetBase) ToolTipText() string {
	return globalToolTip.Text(wb.window.(Widget))
}

// SetToolTipText sets the tool tip text of the WidgetBase.
func (wb *WidgetBase) SetToolTipText(s string) error {
	if err := globalToolTip.SetText(wb.window.(Widget), s); err != nil {
		return err
	}

	wb.toolTipTextChangedPublisher.Publish()

	return nil
}

func (wb *WidgetBase) updateParentLayout() error {
	if wb.parent == nil || wb.parent.Layout() == nil || wb.parent.Suspended() {
		return nil
	}

	return wb.parent.Layout().Update(false)
}

func ancestor(w Widget) Form {
	if w == nil {
		return nil
	}

	hWndRoot := win.GetAncestor(w.Handle(), win.GA_ROOT)

	rw, _ := windowFromHandle(hWndRoot).(Form)
	return rw
}

func minSizeEffective(w Widget) Size {
	return maxSize(w.MinSize(), w.MinSizeHint())
}