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//! Static text label widget.
//!
//! Wraps [`QLabel`](https://doc.qt.io/qt-6/qlabel.html) for displaying
//! read-only text in a window.
use cxx::let_cxx_string;
use crate::ffi;
use crate::widget::AsWidget;
/// A static text label.
///
/// `Label` uses a **builder pattern**: call [`Label::new`] to obtain a
/// [`Builder`], set the parent, then call `.build()`.
///
/// # Example
///
/// ```no_run
/// use qtrs::Label;
///
/// let label = Label::new("Hello, world!").build();
/// ```
pub struct Label {
ptr: *mut ffi::QLabel,
has_parent: bool,
#[allow(dead_code)]
text: String,
}
impl Label {
/// Start building a new `QLabel`.
///
/// Returns a [`Builder`]. Set an optional parent, then call `.build()`.
pub fn new(text: impl Into<String>) -> Builder {
Builder::new(text.into())
}
/// Get the current label text.
///
/// Returns the cached copy — this is updated automatically when you
/// call [`set_text`](Self::set_text).
pub fn text(&self) -> &str {
&self.text
}
/// Update the label text at runtime.
///
/// This calls
/// [`QLabel::setText`](https://doc.qt.io/qt-6/qlabel.html#text-prop).
pub fn set_text(&mut self, text: impl Into<String>) {
debug_assert!(!self.ptr.is_null(), "Label::set_text on null pointer");
self.text = text.into();
let_cxx_string!(c_text = &self.text);
unsafe {
ffi::QLabel_setText(self.ptr, &c_text);
}
}
#[doc(hidden)]
pub(crate) fn from_raw(ptr: *mut ffi::QLabel, text: &str) -> Self {
debug_assert!(!ptr.is_null());
Self { ptr, has_parent: true, text: text.to_string() }
}
}
impl AsWidget for Label {
fn widget_ptr(&self) -> *mut ffi::QWidget {
debug_assert!(!self.ptr.is_null(), "Label::widget_ptr on null pointer");
unsafe { ffi::toQWidget_QLabel(self.ptr) }
}
fn set_has_parent(&mut self) {
self.has_parent = true;
}
}
impl Drop for Label {
fn drop(&mut self) {
if self.ptr.is_null() {
return;
}
if !self.has_parent {
unsafe { ffi::QLabel_delete(self.ptr) };
}
self.ptr = std::ptr::null_mut();
}
}
// ============================================================
// Builder
// ============================================================
/// Builder for [`Label`].
pub struct Builder {
text: String,
parent: Option<*mut ffi::QWidget>,
}
impl Builder {
fn new(text: String) -> Self {
Self {
text,
parent: None,
}
}
/// Set the parent widget.
///
/// The parent manages the label's C++ lifetime.
pub fn parent(mut self, parent: &dyn AsWidget) -> Self {
self.parent = Some(parent.widget_ptr());
self
}
/// Create the C++ `QLabel` and return the Rust wrapper.
pub fn build(self) -> Label {
let_cxx_string!(c_text = &self.text);
let ptr = unsafe {
ffi::QLabel_new(
&c_text,
self.parent.unwrap_or(std::ptr::null_mut()),
)
};
assert!(!ptr.is_null(), "QLabel_new returned null");
Label {
ptr,
has_parent: self.parent.is_some(),
text: self.text,
}
}
}