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89 lines
2.6 KiB
Plaintext
89 lines
2.6 KiB
Plaintext
//
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// ASCGImageBuffer.mm
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// Texture
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//
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// Copyright (c) Pinterest, Inc. All rights reserved.
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// Licensed under Apache 2.0: http://www.apache.org/licenses/LICENSE-2.0
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//
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#import <AsyncDisplayKit/ASCGImageBuffer.h>
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#import <sys/mman.h>
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#import <mach/mach_init.h>
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#import <mach/vm_map.h>
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#import <mach/vm_statistics.h>
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/**
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* The behavior of this class is modeled on the private function
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* _CGDataProviderCreateWithCopyOfData, which is the function used
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* by CGBitmapContextCreateImage.
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*
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* If the buffer is larger than a page, we use mmap and mark it as
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* read-only when they are finished drawing. Then we wrap the VM
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* in an NSData
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*/
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@implementation ASCGImageBuffer {
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BOOL _createdData;
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BOOL _isVM;
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NSUInteger _length;
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}
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- (instancetype)initWithLength:(NSUInteger)length
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{
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if (self = [super init]) {
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_length = length;
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_isVM = false;//(length >= vm_page_size);
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if (_isVM) {
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_mutableBytes = mmap(NULL, length, PROT_WRITE | PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, VM_MAKE_TAG(VM_MEMORY_COREGRAPHICS_DATA), 0);
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if (_mutableBytes == MAP_FAILED) {
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NSAssert(NO, @"Failed to map for CG image data.");
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_isVM = NO;
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}
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}
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// Check the VM flag again because we may have failed above.
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if (!_isVM) {
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_mutableBytes = malloc(length);
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}
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}
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return self;
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}
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- (void)dealloc
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{
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if (!_createdData) {
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[ASCGImageBuffer deallocateBuffer:_mutableBytes length:_length isVM:_isVM];
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}
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}
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- (CGDataProviderRef)createDataProviderAndInvalidate
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{
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NSAssert(!_createdData, @"Should not create data provider from buffer multiple times.");
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_createdData = YES;
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// Mark the pages as read-only.
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if (_isVM) {
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__unused kern_return_t result = vm_protect(mach_task_self(), (vm_address_t)_mutableBytes, _length, true, VM_PROT_READ);
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NSAssert(result == noErr, @"Error marking buffer as read-only: %@", [NSError errorWithDomain:NSMachErrorDomain code:result userInfo:nil]);
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}
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// Wrap in an NSData
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BOOL isVM = _isVM;
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NSData *d = [[NSData alloc] initWithBytesNoCopy:_mutableBytes length:_length deallocator:^(void * _Nonnull bytes, NSUInteger length) {
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[ASCGImageBuffer deallocateBuffer:bytes length:length isVM:isVM];
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}];
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return CGDataProviderCreateWithCFData((__bridge CFDataRef)d);
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}
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+ (void)deallocateBuffer:(void *)buf length:(NSUInteger)length isVM:(BOOL)isVM
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{
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if (isVM) {
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__unused kern_return_t result = vm_deallocate(mach_task_self(), (vm_address_t)buf, length);
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NSAssert(result == noErr, @"Failed to unmap cg image buffer: %@", [NSError errorWithDomain:NSMachErrorDomain code:result userInfo:nil]);
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} else {
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free(buf);
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}
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}
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@end
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