NSOperationQueue OperationQueueForCell (DataItemCollectionViewCell cell)
{
NSOperationQueue queue;
if (operationQueues.TryGetValue (cell, out queue))
return queue;
queue = new NSOperationQueue ();
operationQueues.Add (cell, queue);
return queue;
}
NSOperationQueue OperationQueueForCell(DataItemCollectionViewCell cell)
{
NSOperationQueue queue;
if (operationQueues.TryGetValue(cell, out queue))
{
return(queue);
}
queue = new NSOperationQueue();
operationQueues.Add(cell, queue);
return(queue);
}
public void ComposeCell(DataItemCollectionViewCell cell, DataItem dataItem)
{
var operationQueue = OperationQueueForCell(cell);
operationQueue.CancelAllOperations();
cell.RepresentedDataItem = dataItem;
cell.Label.Text = dataItem.Title;
cell.ImageView.Alpha = 1f;
cell.ImageView.Image = (UIImage)processedImageCache.ObjectForKey((NSString)dataItem.Identifier);
if (cell.ImageView.Image != null)
{
return;
}
var processImageOperation = new NSBlockOperation();
processImageOperation.AddExecutionBlock(() => {
if (processImageOperation.IsCancelled)
{
return;
}
UIImage image = null;
DispatchQueue.MainQueue.DispatchSync(() => {
image = ProcessImageNamed(dataItem.ImageName);
});
if (image == null)
{
return;
}
processedImageCache.SetObjectforKey(image, (NSString)dataItem.Identifier);
NSOperationQueue.MainQueue.AddOperation(() => {
if (cell.RepresentedDataItem == null)
{
return;
}
cell.ImageView.Alpha = 0f;
cell.ImageView.Image = image;
UIView.Animate(0.25, () => cell.ImageView.Alpha = 1f);
});
});
operationQueue.AddOperation(processImageOperation);
}
public void ComposeCell (DataItemCollectionViewCell cell, DataItem dataItem)
{
var operationQueue = OperationQueueForCell (cell);
operationQueue.CancelAllOperations ();
cell.RepresentedDataItem = dataItem;
cell.Label.Text = dataItem.Title;
cell.ImageView.Alpha = 1f;
cell.ImageView.Image = (UIImage)processedImageCache.ObjectForKey ((NSString)dataItem.Identifier);
if (cell.ImageView.Image != null)
return;
var processImageOperation = new NSBlockOperation ();
processImageOperation.AddExecutionBlock (() => {
if (processImageOperation.IsCancelled)
return;
UIImage image = null;
DispatchQueue.MainQueue.DispatchSync (() => {
image = ProcessImageNamed (dataItem.ImageName);
});
if (image == null)
return;
processedImageCache.SetObjectforKey (image, (NSString)dataItem.Identifier);
NSOperationQueue.MainQueue.AddOperation (() => {
if (cell.RepresentedDataItem == null)
return;
cell.ImageView.Alpha = 0f;
cell.ImageView.Image = image;
UIView.Animate (0.25, () => cell.ImageView.Alpha = 1f);
});
});
operationQueue.AddOperation (processImageOperation);
}
