Add a -[MLFile willDisplay] and -[MLFile willHide].

Call this when the data associated to that file are about to be displayed. This will increase the priority for any pending meta data fetching.

Headers/Public/MLFile.h

@@ -45,6 +45,22 @@ extern NSString *kMLFileTypeTVShowEpisode;
 @property (nonatomic, retain) NSSet* labels;
 @property (nonatomic, retain) NSNumber* isOnDisk;
 
+/**
+ * the data in this object are about to be put on screen
+ *
+ * If multiple MLFile object are processed, this
+ * increase the priority of the processing for this MLFile.
+ */
+- (void)willDisplay;
+
+/**
+ * We don't display the data of this object on screen.
+ *
+ * This put back the eventually increased priority for this MLFile,
+ * to a default one.
+ * \see willDisplay
+ */
+- (void)didHide;
 @end
 
 

Sources/MLFile.m

@@ -11,6 +11,7 @@
 #import "MLShow.h"
 #import "MLShowEpisode.h"
 #import "MLMediaLibrary.h"
+#import "MLThumbnailerQueue.h"
 
 NSString *kMLFileTypeMovie = @"movie";
 NSString *kMLFileTypeClip = @"clip";
@@ -94,4 +95,14 @@ NSString *kMLFileTypeTVShowEpisode = @"tvShowEpisode";
 @dynamic labels;
 @dynamic isOnDisk;
 
+- (void)willDisplay
+{
+    [[MLThumbnailerQueue sharedThumbnailerQueue] setHighPriorityForFile:self];
+}
+
+- (void)didHide
+{
+    [[MLThumbnailerQueue sharedThumbnailerQueue] setDefaultPriorityForFile:self];
+}
+
 @end

Sources/MLThumbnailerQueue.h

@@ -11,10 +11,12 @@
 @class MLFile;
 
 @interface MLThumbnailerQueue : NSOperationQueue {
-
+    NSDictionary *_fileDescriptionToOperation;
 }
 + (MLThumbnailerQueue *)sharedThumbnailerQueue;
 - (void)addFile:(MLFile *)file;
+- (void)setHighPriorityForFile:(MLFile *)file;
+- (void)setDefaultPriorityForFile:(MLFile *)file;
 
 - (void)stop;
 - (void)resume;

Sources/MLThumbnailerQueue.m

@@ -12,6 +12,7 @@
 #import "MLFile.h"
 #import <UIKit/UIKit.h>
 
+
 @interface ThumbnailOperation : NSOperation <VLCMediaThumbnailerDelegate>
 {
     MLFile *_file;
@@ -19,6 +20,10 @@
 @property (retain,readwrite) MLFile *file;
 @end
 
+@interface MLThumbnailerQueue ()
+- (void)didFinishOperation:(ThumbnailOperation *)op;
+@end
+
 @implementation ThumbnailOperation
 @synthesize file=_file;
 - (id)initWithFile:(MLFile *)file;
@@ -41,6 +46,7 @@
     VLCMediaThumbnailer *thumbnailer = [VLCMediaThumbnailer thumbnailerWithMedia:media andDelegate:self];
     [thumbnailer fetchThumbnail];
     [[MLThumbnailerQueue sharedThumbnailerQueue] setSuspended:YES]; // Balanced in -mediaThumbnailer:didFinishThumbnail
+    [[MLThumbnailerQueue sharedThumbnailerQueue] didFinishOperation:self];
     [self retain]; // Balanced in -mediaThumbnailer:didFinishThumbnail:
 }
 - (void)main
@@ -69,9 +75,37 @@
     return shared;
 }
 
+- (id)init
+{
+    self = [super init];
+    if (self != nil) {
+        _fileDescriptionToOperation = [[NSMutableDictionary alloc] init];
+    }
+    return self;
+}
+
+- (void)dealloc
+{
+    [_fileDescriptionToOperation release];
+    [super dealloc];
+}
+
+
+static inline NSString *hashFromFile(MLFile *file)
+{
+    return [NSString stringWithFormat:@"%p", [[file objectID] URIRepresentation]];
+}
+
+- (void)didFinishOperation:(ThumbnailOperation *)op
+{
+    [_fileDescriptionToOperation setValue:nil forKey:hashFromFile(op.file)];
+}
+
 - (void)addFile:(MLFile *)file
 {
-    [self addOperation:[[[ThumbnailOperation alloc] initWithFile:file] autorelease]];
+    ThumbnailOperation *op = [[ThumbnailOperation alloc] initWithFile:file];
+    [_fileDescriptionToOperation setValue:op forKey:hashFromFile(file)];
+    [self addOperation:op];
 }
 
 - (void)stop
@@ -83,4 +117,16 @@
 {
     [self setMaxConcurrentOperationCount:1];
 }
+
+- (void)setHighPriorityForFile:(MLFile *)file
+{
+    ThumbnailOperation *op = [_fileDescriptionToOperation objectForKey:hashFromFile(file)];
+    [op setQueuePriority:NSOperationQueuePriorityHigh];
+}
+
+- (void)setDefaultPriorityForFile:(MLFile *)file
+{
+    ThumbnailOperation *op = [_fileDescriptionToOperation objectForKey:hashFromFile(file)];
+    [op setQueuePriority:NSOperationQueuePriorityNormal];
+}
 @end