ASInternalHelpers.mm
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IMP ASReplaceMethodWithBlock(Class c, SEL origSEL, id block)
{
NSCParameterAssert(block);
// Get original method
Method origMethod = class_getInstanceMethod(c, origSEL);
NSCParameterAssert(origMethod);
// Convert block to IMP trampoline and replace method implementation
IMP newIMP = imp_implementationWithBlock(block);
// Try adding the method if not yet in the current class
if (!class_addMethod(c, origSEL, newIMP, method_getTypeEncoding(origMethod))) {
return method_setImplementation(origMethod, newIMP);
} else {
return method_getImplementation(origMethod);
}
}
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void ASPerformBlockOnMainThread(void (^block)(void))
{
if (block == nil){
return;
}
if (ASDisplayNodeThreadIsMain()) {
block();
} else {
dispatch_async(dispatch_get_main_queue(), block);
}
}
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void ASPerformBlockOnBackgroundThread(void (^block)(void))
{
if (block == nil){
return;
}
if (ASDisplayNodeThreadIsMain()) {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), block);
} else {
block();
}
}
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Class _Nullable ASGetClassFromType(const char * _Nullable type)
{
// Class types all start with @"
if (type == NULL || strncmp(type, "@\"", 2) != 0) {
return Nil;
}
// Ensure length >= 3
size_t typeLength = strlen(type);
if (typeLength < 3) {
ASDisplayNodeCFailAssert(@"Got invalid type-encoding: %s", type);
return Nil;
}
// Copy type[2..(end-1)]. So @"UIImage" -> UIImage
size_t resultLength = typeLength - 3;
char className[resultLength + 1];
strncpy(className, type + 2, resultLength);
className[resultLength] = '\0';
return objc_getClass(className);
}
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void ASInitializeFrameworkMainThread(void)
{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
ASDisplayNodeCAssertMainThread();
// Ensure these values are cached on the main thread before needed in the background.
if (ASActivateExperimentalFeature(ASExperimentalLayerDefaults)) {
// Nop. We will gather default values on-demand in ASDefaultAllowsGroupOpacity and ASDefaultAllowsEdgeAntialiasing
} else {
CALayer *layer = [[[UIView alloc] init] layer];
allowsGroupOpacityFromUIKitOrNil = @(layer.allowsGroupOpacity);
allowsEdgeAntialiasingFromUIKitOrNil = @(layer.allowsEdgeAntialiasing);
}
ASNotifyInitialized();
});
}
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BOOL ASSubclassOverridesSelector(Class superclass, Class subclass, SEL selector)
{
if (superclass == subclass) return NO; // Even if the class implements the selector, it doesn't override itself.
Method superclassMethod = class_getInstanceMethod(superclass, selector);
Method subclassMethod = class_getInstanceMethod(subclass, selector);
return (superclassMethod != subclassMethod);
}
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BOOL ASSubclassOverridesClassSelector(Class superclass, Class subclass, SEL selector)
{
if (superclass == subclass) return NO; // Even if the class implements the selector, it doesn't override itself.
Method superclassMethod = class_getClassMethod(superclass, selector);
Method subclassMethod = class_getClassMethod(subclass, selector);
return (superclassMethod != subclassMethod);
}
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IMP ASReplaceMethodWithBlock(Class c, SEL origSEL, id block)
{
NSCParameterAssert(block);
// Get original method
Method origMethod = class_getInstanceMethod(c, origSEL);
NSCParameterAssert(origMethod);
// Convert block to IMP trampoline and replace method implementation
IMP newIMP = imp_implementationWithBlock(block);
// Try adding the method if not yet in the current class
if (!class_addMethod(c, origSEL, newIMP, method_getTypeEncoding(origMethod))) {
return method_setImplementation(origMethod, newIMP);
} else {
return method_getImplementation(origMethod);
}
}