Merge pull request #2415 from dreampiggy/feature_minimum_progress_interval

Feature minimum progress interval

SDWebImage/SDWebImageDownloader.m

@@ -250,10 +250,18 @@ static void * SDWebImageDownloaderContext = &SDWebImageDownloaderContext;
     }
     NSOperation<SDWebImageDownloaderOperation> *operation = [[operationClass alloc] initWithRequest:request inSession:self.session options:options context:context];
     
-    if (self.config.urlCredential) {
-        operation.credential = self.config.urlCredential;
-    } else if (self.config.username && self.config.password) {
-        operation.credential = [NSURLCredential credentialWithUser:self.config.username password:self.config.password persistence:NSURLCredentialPersistenceForSession];
+    if ([operation respondsToSelector:@selector(setCredential:)]) {
+        if (self.config.urlCredential) {
+            operation.credential = self.config.urlCredential;
+        } else if (self.config.username && self.config.password) {
+            operation.credential = [NSURLCredential credentialWithUser:self.config.username password:self.config.password persistence:NSURLCredentialPersistenceForSession];
+        }
+    }
+        
+    if ([operation respondsToSelector:@selector(setMinimumProgressInterval:)]) {
+        NSTimeInterval minimumProgressInterval = self.config.minimumProgressInterval;
+        minimumProgressInterval = MIN(MAX(minimumProgressInterval, 0), 1);
+        operation.minimumProgressInterval = minimumProgressInterval;
     }
     
     if (options & SDWebImageDownloaderHighPriority) {

SDWebImage/SDWebImageDownloaderConfig.h

@@ -41,6 +41,15 @@ typedef NS_ENUM(NSInteger, SDWebImageDownloaderExecutionOrder) {
  */
 @property (nonatomic, assign) NSTimeInterval downloadTimeout;
 
+/**
+ * The minimum interval about progress percent during network downloading. Which means the next progress callback and current progress callback's progress percent difference should be larger or equal to this value.
+ * The value should be 0.0-1.0.
+ * @note If you're using progressive decoding feature, this will also effect the image refresh rate.
+ * @note This value may enhance the performance if you don't want progress callback too frequently.
+ * Defaults to 0, which means each time we receive the new data from URLSession, we callback the progressBlock immediately.
+ */
+@property (nonatomic, assign) NSTimeInterval minimumProgressInterval;
+
 /**
  * The custom session configuration in use by NSURLSession. If you don't provide one, we will use `defaultSessionConfiguration` instead.
  * Defatuls to nil.

SDWebImage/SDWebImageDownloaderConfig.m

@@ -34,6 +34,7 @@ static SDWebImageDownloaderConfig * _defaultDownloaderConfig;
     SDWebImageDownloaderConfig *config = [[[self class] allocWithZone:zone] init];
     config.maxConcurrentDownloads = self.maxConcurrentDownloads;
     config.downloadTimeout = self.downloadTimeout;
+    config.minimumProgressInterval = self.minimumProgressInterval;
     config.sessionConfiguration = [self.sessionConfiguration copyWithZone:zone];
     config.operationClass = self.operationClass;
     config.executionOrder = self.executionOrder;

SDWebImage/SDWebImageDownloaderOperation.h

@@ -36,9 +36,6 @@ FOUNDATION_EXPORT NSString * _Nonnull const SDWebImageDownloadFinishNotification
 - (nullable id)addHandlersForProgress:(nullable SDWebImageDownloaderProgressBlock)progressBlock
                             completed:(nullable SDWebImageDownloaderCompletedBlock)completedBlock;
 
-- (nullable NSURLCredential *)credential;
-- (void)setCredential:(nullable NSURLCredential *)value;
-
 - (BOOL)cancel:(nullable id)token;
 
 - (nullable NSURLRequest *)request;
@@ -46,6 +43,10 @@ FOUNDATION_EXPORT NSString * _Nonnull const SDWebImageDownloadFinishNotification
 
 @optional
 - (nullable NSURLSessionTask *)dataTask;
+- (nullable NSURLCredential *)credential;
+- (void)setCredential:(nullable NSURLCredential *)credential;
+- (NSTimeInterval)minimumProgressInterval;
+- (void)setMinimumProgressInterval:(NSTimeInterval)minimumProgressInterval;
 
 @end
 
@@ -74,6 +75,15 @@ FOUNDATION_EXPORT NSString * _Nonnull const SDWebImageDownloadFinishNotification
  */
 @property (nonatomic, strong, nullable) NSURLCredential *credential;
 
+/**
+ * The minimum interval about progress percent during network downloading. Which means the next progress callback and current progress callback's progress percent difference should be larger or equal to this value.
+ * The value should be 0.0-1.0.
+ * @note If you're using progressive decoding feature, this will also effect the image refresh rate.
+ * @note This value may enhance the performance if you don't want progress callback too frequently.
+ * Defaults to 0, which means each time we receive the new data from URLSession, we callback the progressBlock immediately.
+ */
+@property (assign, nonatomic) NSTimeInterval minimumProgressInterval;
+
 /**
  * The options for the receiver.
  */

SDWebImage/SDWebImageDownloaderOperation.m

@@ -37,9 +37,11 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
 @property (assign, nonatomic, getter = isFinished) BOOL finished;
 @property (strong, nonatomic, nullable) NSMutableData *imageData;
 @property (copy, nonatomic, nullable) NSData *cachedData; // for `SDWebImageDownloaderIgnoreCachedResponse`
-@property (assign, nonatomic, readwrite) NSUInteger expectedSize;
+@property (assign, nonatomic) NSUInteger expectedSize; // may be 0
+@property (assign, nonatomic) NSUInteger receivedSize;
 @property (strong, nonatomic, nullable, readwrite) NSURLResponse *response;
 @property (strong, nonatomic, nullable) NSError *responseError;
+@property (assign, nonatomic) double previousProgress; // previous progress percent
 
 // This is weak because it is injected by whoever manages this session. If this gets nil-ed out, we won't be able to run
 // the task associated with this operation
@@ -331,17 +333,37 @@ didReceiveResponse:(NSURLResponse *)response
         self.imageData = [[NSMutableData alloc] initWithCapacity:self.expectedSize];
     }
     [self.imageData appendData:data];
+    
+    self.receivedSize = self.imageData.length;
+    if (self.expectedSize == 0) {
+        // Unknown expectedSize, immediately call progressBlock and return
+        for (SDWebImageDownloaderProgressBlock progressBlock in [self callbacksForKey:kProgressCallbackKey]) {
+            progressBlock(self.receivedSize, self.expectedSize, self.request.URL);
+        }
+        return;
+    }
+    
+    // Get the finish status
+    BOOL finished = (self.receivedSize >= self.expectedSize);
+    // Get the current progress
+    double currentProgress = (double)self.receivedSize / (double)self.expectedSize;
+    double previousProgress = self.previousProgress;
+    // Check if we need callback progress
+    if (currentProgress - previousProgress < self.minimumProgressInterval) {
+        return;
+    }
+    self.previousProgress = currentProgress;
 
-    if ((self.options & SDWebImageDownloaderProgressiveLoad) && self.expectedSize > 0) {
+    if (self.options & SDWebImageDownloaderProgressiveLoad) {
         // Get the image data
         NSData *imageData = [self.imageData copy];
-        // Get the total bytes downloaded
-        const NSUInteger totalSize = imageData.length;
-        // Get the finish status
-        BOOL finished = (totalSize >= self.expectedSize);
         
         // progressive decode the image in coder queue
         dispatch_async(self.coderQueue, ^{
+            // If all the data has already been downloaded, earily return to avoid further decoding
+            if (self.receivedSize >= self.expectedSize) {
+                return;
+            }
             UIImage *image = SDImageLoaderDecodeProgressiveImageData(imageData, self.request.URL, finished, self, [[self class] imageOptionsFromDownloaderOptions:self.options], self.context);
             if (image) {
                 // We do not keep the progressive decoding image even when `finished`=YES. Because they are for view rendering but not take full function from downloader options. And some coders implementation may not keep consistent between progressive decoding and normal decoding.
@@ -350,9 +372,9 @@ didReceiveResponse:(NSURLResponse *)response
             }
         });
     }
-
+    
     for (SDWebImageDownloaderProgressBlock progressBlock in [self callbacksForKey:kProgressCallbackKey]) {
-        progressBlock(self.imageData.length, self.expectedSize, self.request.URL);
+        progressBlock(self.receivedSize, self.expectedSize, self.request.URL);
     }
 }
 

Tests/Tests/SDWebImageDownloaderTests.m

@@ -259,6 +259,34 @@
     [self waitForExpectationsWithCommonTimeout];
 }
 
+- (void)test17ThatMinimumProgressIntervalWorks {
+    XCTestExpectation *expectation = [self expectationWithDescription:@"Minimum progress interval"];
+    SDWebImageDownloaderConfig *config = SDWebImageDownloaderConfig.defaultDownloaderConfig;
+    config.minimumProgressInterval = 0.51; // This will make the progress only callback once
+    SDWebImageDownloader *downloader = [[SDWebImageDownloader alloc] initWithConfig:config];
+    NSURL *imageURL = [NSURL URLWithString:@"http://www.ioncannon.net/wp-content/uploads/2011/06/test2.webp"];
+    __block NSUInteger allProgressCount = 0; // All progress (including operation start / first HTTP response, etc)
+    __block NSUInteger validProgressCount = 0; // Only progress from `URLSession:dataTask:didReceiveData:`
+    [downloader downloadImageWithURL:imageURL options:0 progress:^(NSInteger receivedSize, NSInteger expectedSize, NSURL * _Nullable targetURL) {
+        allProgressCount++;
+        if (expectedSize <= 0 || receivedSize <= 0) {
+            // ignore the progress callback until we receive data
+            return;
+        }
+        validProgressCount++;
+    } completed:^(UIImage * _Nullable image, NSData * _Nullable data, NSError * _Nullable error, BOOL finished) {
+        if (allProgressCount > 1 && validProgressCount == 1) {
+            [expectation fulfill];
+        } else {
+            XCTFail(@"Progress callback more than once");
+        }
+    }];
+     
+    [self waitForExpectationsWithCommonTimeoutUsingHandler:^(NSError * _Nullable error) {
+        [downloader invalidateSessionAndCancel:YES];
+    }];
+}
+
 /**
  *  Per #883 - Fix multiple requests for same image and then canceling one
  *  Old SDWebImage (3.x) could not handle correctly multiple requests for the same image + cancel

Tests/Tests/SDWebImageTestDownloadOperation.h

@@ -15,7 +15,6 @@
  */
 @interface SDWebImageTestDownloadOperation : NSOperation <SDWebImageDownloaderOperation>
 
-@property (nonatomic, strong, nullable) NSURLCredential *credential;
 @property (nonatomic, strong, nullable) NSURLRequest *request;
 @property (nonatomic, strong, nullable) NSURLResponse *response;