exp/textinput: add HandleInputWithBounds

Closes #3233

examples/textinput/main.go

@@ -135,9 +135,11 @@ func (t *TextField) Update() error {
 	x, y := t.bounds.Min.X, t.bounds.Min.Y
 	cx, cy := t.cursorPos()
 	px, py := textFieldPadding()
-	x += cx + px
-	y += cy + py + int(fontFace.Metrics().HAscent)
-	handled, err := t.field.HandleInput(x, y)
+	x0 := x + cx + px
+	x1 := x + cx + px + 6 // To be exact, this should be the width of the current character.
+	y0 := y + cy + py
+	y1 := y0 + int(fontFace.Metrics().HLineGap+fontFace.Metrics().HAscent+fontFace.Metrics().HDescent)
+	handled, err := t.field.HandleInputWithBounds(image.Rect(x0, y0, x1, y1))
 	if err != nil {
 		return err
 	}

exp/textinput/field.go

@@ -15,6 +15,7 @@
 package textinput
 
 import (
+	"image"
 	"sync"
 )
 
@@ -99,7 +100,21 @@ type Field struct {
 // If HandleInput returns true, a Field user should not handle further input events.
 //
 // HandleInput returns an error when handling input causes an error.
+//
+// Deprecated: use HandleInputWithBounds instead.
 func (f *Field) HandleInput(x, y int) (handled bool, err error) {
+	return f.HandleInputWithBounds(image.Rect(x, y, x+1, y+1))
+}
+
+// HandleInputWithBounds updates the field state.
+// HandleInputWithBounds must be called every tick, i.e., every Update, when Field is focused.
+// HandleInputWithBounds takes a character bounds, which decides the position where an IME window is shown if needed.
+//
+// HandleInputWithBounds returns whether the text inputting is handled or not.
+// If HandleInputWithBounds returns true, a Field user should not handle further input events.
+//
+// HandleInputWithBounds returns an error when handling input causes an error.
+func (f *Field) HandleInputWithBounds(bounds image.Rectangle) (handled bool, err error) {
 	if f.err != nil {
 		return false, f.err
 	}
@@ -113,7 +128,7 @@ func (f *Field) HandleInput(x, y int) (handled bool, err error) {
 		if f.ch == nil {
 			// TODO: On iOS Safari, Start doesn't work as expected (#2898).
 			// Handle a click event and focus the textarea there.
-			f.ch, f.end = start(x, y)
+			f.ch, f.end = start(bounds)
 			// Start returns nil for non-supported envrionments, or when unable to start text inputting for some reasons.
 			if f.ch == nil {
 				return handled, nil

exp/textinput/textinput.go

@@ -19,6 +19,7 @@
 package textinput
 
 import (
+	"image"
 	"unicode/utf16"
 	"unicode/utf8"
 
@@ -26,8 +27,6 @@ import (
 )
 
 // textInputState represents the current state of text inputting.
-//
-// textInputState is the low-level API. For most use cases, Field is easier to use.
 type textInputState struct {
 	// Text represents the current inputting text.
 	Text string
@@ -58,12 +57,11 @@ type textInputState struct {
 // start starts text inputting.
 // start returns a channel to send the state repeatedly, and a function to end the text inputting.
 //
-// start is the low-level API. For most use cases, Field is easier to use.
-//
 // start returns nil and nil if the current environment doesn't support this package.
-func start(x, y int) (states <-chan textInputState, close func()) {
-	cx, cy := ui.Get().LogicalPositionToClientPositionInNativePixels(float64(x), float64(y))
-	return theTextInput.Start(int(cx), int(cy))
+func start(bounds image.Rectangle) (states <-chan textInputState, close func()) {
+	cMinX, cMinY := ui.Get().LogicalPositionToClientPositionInNativePixels(float64(bounds.Min.X), float64(bounds.Min.Y))
+	cMaxX, cMaxY := ui.Get().LogicalPositionToClientPositionInNativePixels(float64(bounds.Max.X), float64(bounds.Max.Y))
+	return theTextInput.Start(image.Rect(int(cMinX), int(cMinY), int(cMaxX), int(cMaxY)))
 }
 
 func convertUTF16CountToByteCount(text string, c int) int {

exp/textinput/textinput_darwin.go

@@ -23,6 +23,8 @@ package textinput
 import "C"
 
 import (
+	"image"
+
 	"github.com/ebitengine/purego/objc"
 
 	"github.com/hajimehoshi/ebiten/v2/internal/ui"
@@ -118,9 +120,9 @@ type textInput struct {
 
 var theTextInput textInput
 
-func (t *textInput) Start(x, y int) (<-chan textInputState, func()) {
+func (t *textInput) Start(bounds image.Rectangle) (<-chan textInputState, func()) {
 	ui.Get().RunOnMainThread(func() {
-		t.start(x, y)
+		t.start(bounds)
 	})
 	return t.session.ch, t.session.end
 }
@@ -193,7 +195,7 @@ type nsRect struct {
 	size   nsSize
 }
 
-func (t *textInput) start(x, y int) {
+func (t *textInput) start(bounds image.Rectangle) {
 	t.endIfNeeded()
 
 	tc := getTextInputClient()
@@ -203,10 +205,11 @@ func (t *textInput) start(x, y int) {
 	window.Send(selMakeFirstResponder, tc)
 
 	r := objc.Send[nsRect](contentView, selFrame)
-	y = int(r.size.height) - y - 4
+	// The Y dirction is upward in the Cocoa coordinate system.
+	y := int(r.size.height) - bounds.Max.Y
 	tc.Send(selSetFrame, nsRect{
-		origin: nsPoint{float64(x), float64(y)},
-		size:   nsSize{1, 1},
+		origin: nsPoint{float64(bounds.Min.X), float64(y)},
+		size:   nsSize{float64(bounds.Dx()), float64(bounds.Dy())},
 	})
 
 	session := newSession()

exp/textinput/textinput_js.go

@@ -16,6 +16,7 @@ package textinput
 
 import (
 	"fmt"
+	"image"
 	"syscall/js"
 
 	"github.com/hajimehoshi/ebiten/v2/internal/ui"
@@ -156,7 +157,7 @@ body.addEventListener("keyup", handler);`)
 	// TODO: What about other events like wheel?
 }
 
-func (t *textInput) Start(x, y int) (<-chan textInputState, func()) {
+func (t *textInput) Start(bounds image.Rectangle) (<-chan textInputState, func()) {
 	if !t.textareaElement.Truthy() {
 		return nil, nil
 	}
@@ -177,8 +178,12 @@ func (t *textInput) Start(x, y int) (<-chan textInputState, func()) {
 		t.textareaElement.Set("value", "")
 		t.textareaElement.Call("focus")
 		style := t.textareaElement.Get("style")
-		style.Set("left", fmt.Sprintf("%dpx", x))
-		style.Set("top", fmt.Sprintf("%dpx", y))
+		style.Set("left", fmt.Sprintf("%dpx", bounds.Min.X))
+		style.Set("top", fmt.Sprintf("%dpx", bounds.Min.Y))
+		style.Set("width", fmt.Sprintf("%dpx", bounds.Dx()))
+		style.Set("height", fmt.Sprintf("%dpx", bounds.Dy()))
+		style.Set("font-size", fmt.Sprintf("%dpx", bounds.Dy()))
+		style.Set("line-height", fmt.Sprintf("%dpx", bounds.Dy()))
 
 		if t.session == nil {
 			s := newSession()
@@ -200,8 +205,8 @@ func (t *textInput) Start(x, y int) (<-chan textInputState, func()) {
 
 	// On iOS Safari, `focus` works only in user-interaction events (#2898).
 	// Assuming Start is called every tick, defer the starting process to the next user-interaction event.
-	js.Global().Get("window").Set("_ebitengine_textinput_x", x)
-	js.Global().Get("window").Set("_ebitengine_textinput_y", y)
+	js.Global().Get("window").Set("_ebitengine_textinput_x", bounds.Min.X)
+	js.Global().Get("window").Set("_ebitengine_textinput_y", bounds.Max.Y)
 	return nil, nil
 }
 

exp/textinput/textinput_noime.go

@@ -17,6 +17,8 @@
 package textinput
 
 import (
+	"image"
+
 	"github.com/hajimehoshi/ebiten/v2"
 )
 
@@ -27,7 +29,7 @@ type textInput struct {
 
 var theTextInput textInput
 
-func (t *textInput) Start(x, y int) (<-chan textInputState, func()) {
+func (t *textInput) Start(bounds image.Rectangle) (<-chan textInputState, func()) {
 	// AppendInputChars is updated only when the tick is updated.
 	// If the tick is not updated, return nil immediately.
 	tick := ebiten.Tick()

exp/textinput/textinput_windows.go

@@ -15,6 +15,7 @@
 package textinput
 
 import (
+	"image"
 	"sync"
 	"unsafe"
 
@@ -41,7 +42,7 @@ type textInput struct {
 
 var theTextInput textInput
 
-func (t *textInput) Start(x, y int) (<-chan textInputState, func()) {
+func (t *textInput) Start(bounds image.Rectangle) (<-chan textInputState, func()) {
 	if microsoftgdk.IsXbox() {
 		return nil, nil
 	}
@@ -50,7 +51,7 @@ func (t *textInput) Start(x, y int) (<-chan textInputState, func()) {
 	var err error
 	ui.Get().RunOnMainThread(func() {
 		t.end()
-		err = t.start(x, y)
+		err = t.start(bounds)
 		session = newSession()
 		t.session = session
 	})
@@ -76,7 +77,7 @@ func (t *textInput) Start(x, y int) (<-chan textInputState, func()) {
 }
 
 // start must be called from the main thread.
-func (t *textInput) start(x, y int) error {
+func (t *textInput) start(bounds image.Rectangle) error {
 	if t.err != nil {
 		return t.err
 	}
@@ -117,8 +118,14 @@ func (t *textInput) start(x, y int) error {
 		dwIndex: 0,
 		dwStyle: _CFS_CANDIDATEPOS,
 		ptCurrentPos: _POINT{
-			x: int32(x),
-			y: int32(y),
+			x: int32(bounds.Min.X),
+			y: int32(bounds.Max.Y),
+		},
+		rcArea: _RECT{
+			left:   int32(bounds.Min.X),
+			top:    int32(bounds.Max.Y),
+			right:  int32(bounds.Max.X),
+			bottom: int32(bounds.Max.Y),
 		},
 	}); err != nil {
 		return err