Rewrite selection erase to not allocate internal string buffer twice

widget/entry.go

@@ -901,16 +901,13 @@ func (e *Entry) TypedRune(r rune) {
 	// if we've typed a character and we're selecting then replace the selection with the character
 	cb := e.OnChanged
 	if e.selecting {
-		e.OnChanged = nil // don't propagate this change to binding etc
 		e.eraseSelection()
-		e.OnChanged = cb // the change later will then trigger callback
 	}
 
-	provider := e.textProvider()
-	e.selecting = false
-
 	runes := []rune{r}
 	pos := e.cursorTextPos()
+
+	provider := e.textProvider()
 	provider.insertAt(pos, string(runes))
 
 	content := provider.String()
@@ -985,7 +982,7 @@ func (e *Entry) cutToClipboard(clipboard fyne.Clipboard) {
 
 	e.copyToClipboard(clipboard)
 	e.propertyLock.Lock()
-	e.eraseSelection()
+	e.eraseSelectionAndUpdate()
 	content := e.Text
 	cb := e.OnChanged
 	e.propertyLock.Unlock()
@@ -997,17 +994,17 @@ func (e *Entry) cutToClipboard(clipboard fyne.Clipboard) {
 	e.Refresh()
 }
 
-// eraseSelection removes the current selected region and moves the cursor
-func (e *Entry) eraseSelection() {
+// eraseSelection deletes the selected text and moves the cursor but does not update the text field.
+func (e *Entry) eraseSelection() bool {
 	if e.Disabled() {
-		return
+		return false
 	}
 
 	provider := e.textProvider()
 	posA, posB := e.selection()
 
 	if posA == posB {
-		return
+		return false
 	}
 
 	erasedText := e.Text[posA:posB]
@@ -1016,13 +1013,22 @@ func (e *Entry) eraseSelection() {
 	e.CursorRow, e.CursorColumn = e.rowColFromTextPos(posA)
 	e.selectRow, e.selectColumn = e.CursorRow, e.CursorColumn
 	e.selecting = false
-	e.updateText(provider.String(), false)
 
 	e.undoStack.MergeOrAdd(&entryModifyAction{
 		Delete:   true,
 		Position: posA,
 		Text:     erasedText,
 	})
+
+	return true
+}
+
+// eraseSelectionAndUpdate removes the current selected region and moves the cursor.
+// It also updates the text if something has been erased.
+func (e *Entry) eraseSelectionAndUpdate() {
+	if e.eraseSelection() {
+		e.updateText(e.textProvider().String(), false)
+	}
 }
 
 func (e *Entry) getRowCol(p fyne.Position) (int, int) {
@@ -1049,33 +1055,48 @@ func (e *Entry) getRowCol(p fyne.Position) (int, int) {
 // pasteFromClipboard inserts text from the clipboard content,
 // starting from the cursor position.
 func (e *Entry) pasteFromClipboard(clipboard fyne.Clipboard) {
-	if e.selecting {
-		e.SetFieldsAndRefresh(e.eraseSelection)
-	}
-
 	text := clipboard.Content()
 	if text == "" {
+		e.propertyLock.Lock()
+		changed := e.selecting && e.eraseSelection()
+		e.propertyLock.Unlock()
+
+		if changed {
+			e.Refresh()
+		}
+
 		return // Nothing to paste into the text content.
 	}
 
 	if !e.MultiLine {
 		// format clipboard content to be compatible with single line entry
 		text = strings.Replace(text, "\n", " ", -1)
 	}
-	provider := e.textProvider()
+
+	e.propertyLock.Lock()
+	if e.selecting {
+		e.eraseSelection()
+	}
+
 	runes := []rune(text)
 	pos := e.cursorTextPos()
+	provider := e.textProvider()
 	provider.insertAt(pos, text)
 
-	e.propertyLock.Lock()
 	e.undoStack.Add(&entryModifyAction{
 		Position: pos,
 		Text:     text,
 	})
-	e.updateText(provider.String(), false)
+	content := provider.String()
+	e.updateText(content, false)
 	e.CursorRow, e.CursorColumn = e.rowColFromTextPos(pos + len(runes))
+	cb := e.OnChanged
 	e.propertyLock.Unlock()
 
+	if cb != nil {
+		cb(content) // We know that the text has changed.
+	}
+
 	e.Refresh() // placing the cursor (and refreshing) happens last
 }
 
@@ -1267,7 +1288,7 @@ func (e *Entry) selectingKeyHandler(key *fyne.KeyEvent) bool {
 	case fyne.KeyBackspace, fyne.KeyDelete:
 		// clears the selection -- return handled
 		e.propertyLock.Lock()
-		e.eraseSelection()
+		e.eraseSelectionAndUpdate()
 		content := e.Text
 		cb := e.OnChanged
 		e.propertyLock.Unlock()
@@ -1281,7 +1302,7 @@ func (e *Entry) selectingKeyHandler(key *fyne.KeyEvent) bool {
 	case fyne.KeyReturn, fyne.KeyEnter:
 		if e.MultiLine {
 			// clear the selection -- return unhandled to add the newline
-			e.SetFieldsAndRefresh(e.eraseSelection)
+			e.SetFieldsAndRefresh(e.eraseSelectionAndUpdate)
 		}
 		return false
 	}

widget/entry_internal_test.go

@@ -280,7 +280,7 @@ func TestEntry_EraseSelection(t *testing.T) {
 	keyPress(&fyne.KeyEvent{Name: fyne.KeyRight})
 
 	_ = e.Theme()
-	e.eraseSelection()
+	e.eraseSelectionAndUpdate()
 	e.updateText(e.textProvider().String(), false)
 	assert.Equal(t, "Testing\nTeng\nTesting", e.Text)
 	a, b := e.selection()