Document: Add placeholder label

Add a "Your document contents here" label to the center of the
NSDocument window similar to the one that Xcode's document-based app
template.

Took inspiration from this Stack Overflow answer to get the center point
of the window's content view:
https://stackoverflow.com/questions/6560842/getting-the-center-point-of-an-nsview/14811056#14811056

2 files changed, 40 insertions, 0 deletions

diff --git a/src/Document.h b/src/Document.h
index e566ac0..e54c71a 100644
--- a/src/Document.h
+++ b/src/Document.h
@@ -1,4 +1,7 @@
 #import <Cocoa/Cocoa.h>
 
 @interface Document : NSDocument
+{
+	NSTextField *_label;
+}
 @end
diff --git a/src/Document.m b/src/Document.m
index 7b514eb..e50737d 100644
--- a/src/Document.m
+++ b/src/Document.m
@@ -6,10 +6,23 @@
 {
 	self = [super init];
 	if (self) {
+		_label = [[NSTextField alloc]
+			initWithFrame:NSMakeRect(0, 0, 180, 20)];
+		[_label setStringValue:@"Your document contents here"];
+		[_label setBezeled:NO];
+		[_label setDrawsBackground:NO];
+		[_label setEditable:NO];
+		[_label setFont:[NSFont systemFontOfSize:18]];
 	}
 	return self;
 }
 
+- (void)dealloc
+{
+	[_label release];
+	[super dealloc];
+}
+
 // TODO: Are window controllers deallocated automatically by the parent?
 // [[NSWindowController alloc] initWithWindow:]?
 
@@ -27,6 +40,30 @@
 		backing:NSBackingStoreBuffered
 		defer:NO];
 	// [window setFrameAutosaveName:@"document"]; // document name?
+	[[window contentView] addSubview:_label];
+
+	// Center the label.
+	NSRect content_view_frame = [[window contentView] frame];
+	// NSSize window_size = [[window contentView] bounds].size;
+	NSPoint content_view_center = NSMakePoint(
+		NSMidX(content_view_frame),
+		NSMidY(content_view_frame)
+	);
+	NSRect label_frame = NSMakeRect(
+		content_view_center.x - 125,
+		content_view_center.y,
+		250,
+		28
+	);
+	[_label setFrame:label_frame];
+	[_label setAutoresizingMask:
+		NSViewMinXMargin
+		| NSViewMaxXMargin
+		| NSViewMinYMargin
+		| NSViewMaxYMargin];
+
+	// TODO: Cascade, store previous top-left position.
+	// [window cascadeTopLeftFromPoint:NSMakePoint(100, 100)];
 
 	NSWindowController *window_controller = [[NSWindowController alloc]
 		initWithWindow:window];