[ASDisplayNode] Add automatic measurement before layout (#1725)

* Add automatic measurement before layout

* Remove code not needed or addressed in a different PR

* Adjust comments and rename __layoutSublayouts to __layoutSubnodes

* Check before setting up a placeholder layer if the node should have a placeholder

AsyncDisplayKit/ASDisplayNode.h

@@ -17,6 +17,8 @@
 #import <AsyncDisplayKit/ASAsciiArtBoxCreator.h>
 #import <AsyncDisplayKit/ASLayoutable.h>
 
+#define ASDisplayNodeLoggingEnabled 0
+
 @class ASDisplayNode;
 
 /**

AsyncDisplayKit/ASDisplayNode.mm

@@ -53,8 +53,11 @@ NSString * const ASRenderingEngineDidDisplayNodesScheduledBeforeTimestamp = @"AS
 
 @end
 
-//#define LOG(...) NSLog(__VA_ARGS__)
-#define LOG(...)
+#if ASDisplayNodeLoggingEnabled
+  #define LOG(...) NSLog(__VA_ARGS__)
+#else
+  #define LOG(...)
+#endif
 
 // Conditionally time these scopes to our debug ivars (only exist in debug/profile builds)
 #if TIME_DISPLAYNODE_OPS
@@ -880,7 +883,7 @@ static ASDisplayNodeMethodOverrides GetASDisplayNodeMethodOverrides(Class c)
 
 - (void)animateLayoutTransition:(id<ASContextTransitioning>)context
 {
-  [self __layoutSublayouts];
+  [self __layoutSubnodes];
   [context completeTransition:YES];
 }
 
@@ -1114,26 +1117,61 @@ static ASDisplayNodeMethodOverrides GetASDisplayNodeMethodOverrides(Class c)
   ASDisplayNodeAssertMainThread();
   ASDN::MutexLocker l(_propertyLock);
   CGRect bounds = self.bounds;
+
+  [self measureNodeWithBoundsIfNecessary:bounds];
+
   if (CGRectEqualToRect(bounds, CGRectZero)) {
     // Performing layout on a zero-bounds view often results in frame calculations
     // with negative sizes after applying margins, which will cause
     // measureWithSizeRange: on subnodes to assert.
     return;
   }
-
+  
   // Handle placeholder layer creation in case the size of the node changed after the initial placeholder layer
   // was created
   if ([self _shouldHavePlaceholderLayer]) {
     [self _setupPlaceholderLayerIfNeeded];
   }
   _placeholderLayer.frame = bounds;
-
+  
   [self layout];
   [self layoutDidFinish];
 }
 
+- (void)measureNodeWithBoundsIfNecessary:(CGRect)bounds
+{
+  // Normally measure will be called before layout occurs. If this doesn't happen, nothing is going to call it at all.
+  // We simply call measureWithSizeRange: using a size range equal to whatever bounds were provided to that element
+  if (self.supernode == nil && !self.supportsRangeManagedInterfaceState && [self _hasDirtyLayout]) {
+    if (CGRectEqualToRect(bounds, CGRectZero)) {
+      LOG(@"Warning: No size given for node before node was trying to layout itself: %@. Please provide a frame for the node.", self);
+    } else {
+      [self measureWithSizeRange:ASSizeRangeMake(bounds.size, bounds.size)];
+    }
+  }
+}
+
+- (void)layout
+{
+  ASDisplayNodeAssertMainThread();
+  
+  if ([self _hasDirtyLayout]) {
+    return;
+  }
+  
+  [self __layoutSubnodes];
+}
+
+- (void)__layoutSubnodes
+{
+  for (ASLayout *subnodeLayout in _layout.sublayouts) {
+    ((ASDisplayNode *)subnodeLayout.layoutableObject).frame = [subnodeLayout frame];
+  }
+}
+
 - (void)layoutDidFinish
 {
+  // Hook for subclasses
 }
 
 - (CATransform3D)_transformToAncestor:(ASDisplayNode *)ancestor
@@ -2463,24 +2501,6 @@ void recursivelyTriggerDisplayForLayer(CALayer *layer, BOOL shouldBlock)
   [layoutTransition startTransition];
 }
 
-- (void)layout
-{
-  ASDisplayNodeAssertMainThread();
-
-  if ([self _hasDirtyLayout]) {
-    return;
-  }
-  
-  [self __layoutSublayouts];
-}
-
-- (void)__layoutSublayouts
-{
-  for (ASLayout *subnodeLayout in _layout.sublayouts) {
-    ((ASDisplayNode *)subnodeLayout.layoutableObject).frame = [subnodeLayout frame];
-  }
-}
-
 - (void)displayWillStart
 {
   ASDisplayNodeAssertMainThread();

examples/Videos/Sample/ViewController.h

@@ -14,8 +14,7 @@
 //  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 //  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 //
-#import <AsyncDisplayKit/AsyncDisplayKit.h>
-#import <AsyncDisplayKit/ASVideoNode.h>
+#import <UIKit/UIKit.h>
 
 @interface ViewController : UIViewController
 

examples/Videos/Sample/ViewController.m

@@ -16,8 +16,7 @@
 //
 
 #import "ViewController.h"
-#import "ASLayoutSpec.h"
-#import "ASStaticLayoutSpec.h"
+#import <AsyncDisplayKit/AsyncDisplayKit.h>
 
 @interface ViewController()<ASVideoNodeDelegate>
 @property (nonatomic, strong) ASDisplayNode *rootNode;
@@ -28,12 +27,13 @@
 
 #pragma mark - UIViewController
 
-- (void)viewWillAppear:(BOOL)animated
+- (void)viewDidLoad
 {
-  [super viewWillAppear:animated];
-
+  [super viewDidLoad];
+  
   // Root node for the view controller
   _rootNode = [ASDisplayNode new];
+  _rootNode.frame = self.view.bounds;
   _rootNode.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
   
   ASVideoNode *guitarVideoNode = self.guitarVideoNode;
@@ -68,16 +68,6 @@
   [self.view addSubnode:_rootNode];
 }
 
-- (void)viewDidLayoutSubviews
-{
-  [super viewDidLayoutSubviews];
-  
-  // After all subviews are layed out we have to measure it and move the root node to the right place
-  CGSize viewSize = self.view.bounds.size;
-  [self.rootNode measureWithSizeRange:ASSizeRangeMake(viewSize, viewSize)];
-  [self.rootNode setNeedsLayout];
-}
-
 #pragma mark - Getter / Setter
 
 - (ASVideoNode *)guitarVideoNode;