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Fix null pointer reference on MacOS #174

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Fix null pointer reference on MacOS #174

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a23a356
Fix null pointer reference on MacOS
keathmilligan Aug 24, 2025
1a8e669
Return scaled dimensions, robustness
keathmilligan Aug 25, 2025
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68 changes: 55 additions & 13 deletions src/targets/mac/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -86,13 +86,44 @@ pub fn get_main_display() -> Display {

pub fn get_scale_factor(target: &Target) -> f64 {
match target {
Target::Window(window) => unsafe {
let cg_win_id = window.raw_handle;
let ns_app: id = NSApp();
let ns_window: id = msg_send![ns_app, windowWithWindowNumber: cg_win_id as NSUInteger];
let scale_factor: f64 = msg_send![ns_window, backingScaleFactor];
scale_factor
},
Target::Window(window) => {
// Get the window's frame to determine which display it's on
let content = match block_on(sc::ShareableContent::current()) {
Ok(c) => c,
Err(_) => return 1.0, // fallback on SC failures to avoid panic
};

// Find the window in ScreenCaptureKit
if let Some(sc_window) = content
.windows()
.iter()
.find(|w| w.id() == window.raw_handle)
{
let window_frame = sc_window.frame();
let window_center_x = window_frame.origin.x + window_frame.size.width / 2.0;
let window_center_y = window_frame.origin.y + window_frame.size.height / 2.0;

// Find which display contains the center of the window
for display in content.displays().iter() {
let display_id = display.display_id();
let bounds = display_id.bounds();

if window_center_x >= bounds.origin.x
&& window_center_x < bounds.origin.x + bounds.size.width
&& window_center_y >= bounds.origin.y
&& window_center_y < bounds.origin.y + bounds.size.height
{
// Found the display containing the window's center
if let Some(mode) = display_id.display_mode() {
return (mode.pixel_width() as f64) / mode.width() as f64;
}
}
}
}

// Fallback: if we can't determine the display or get scale factor, use 1.0
1.0
}
Target::Display(display) => {
let mode = display.raw_handle.display_mode().unwrap();
(mode.pixel_width() / mode.width()) as f64
Expand All @@ -102,13 +133,24 @@ pub fn get_scale_factor(target: &Target) -> f64 {

pub fn get_target_dimensions(target: &Target) -> (u64, u64) {
match target {
Target::Window(window) => unsafe {
Target::Window(window) => {
let cg_win_id = window.raw_handle;
let ns_app: id = NSApp();
let ns_window: id = msg_send![ns_app, windowWithWindowNumber: cg_win_id as NSUInteger];
let frame: NSRect = msg_send![ns_window, frame];
(frame.size.width as u64, frame.size.height as u64)
},

// Use ScreenCaptureKit directly to get window dimensions
let content = match block_on(sc::ShareableContent::current()) {
Ok(c) => c,
Err(_) => return (800, 600), // conservative fallback on SC failures
};
if let Some(sc_window) = content.windows().iter().find(|w| w.id() == cg_win_id) {
let frame = sc_window.frame(); // points
let scale = get_scale_factor(target); // uses SC as well; safe to reuse
let w_px = (frame.size.width * scale).round() as u64;
let h_px = (frame.size.height * scale).round() as u64;
return (w_px, h_px);
}
// Fallback to default dimensions if window not found
(800, 600)
}
Target::Display(display) => {
let mode = display.raw_handle.display_mode().unwrap();
(mode.width(), mode.height())
Expand Down