Dart 56 🎯 Typed Data and Native Buffers (Uint8List, ByteData, Memory Efficiency)
Dart’s List<int> is a list of boxed objects. Every element is a pointer to a small object on the heap, and every read or write involves a pointer dereference. For an application that manipulates a few hundred numbers, the overhead is invisible. For an application that processes a megabyte of binary data, the overhead is enormous: the boxed representation takes several times the memory of the raw bytes, and the indirection slows every access. Dart’s typed data library solves this by providing lists and views that store their elements unboxed, in a contiguous block of memory. The Uint8List is a list of bytes, and the ByteData is a view over the same bytes that reads and writes them as larger integers or floating-point values. Together they are the foundation of binary I/O, image processing, network protocols, and every other task that works with raw bytes.
Key point: A Uint8List is a contiguous block of bytes. A ByteData is a view over the same block that interprets the bytes as Uint16, Int32, Float64, or any other fixed-width type. The two share the same memory, so writing through one is immediately visible through the other.
Why typed data exists
The boxed-list problem. A List<int> in Dart stores each element as a reference to an object. On a 64-bit VM, each boxed integer costs 8 bytes for the pointer plus the object’s own header and payload, which is typically 16 bytes total. A list of one million integers consumes at least 24 megabytes, plus the list’s own backing store. A Uint8List of one million bytes consumes exactly one megabyte. The difference is a factor of more than twenty.
The performance problem. Reading a boxed integer requires following the pointer to the heap object, reading the payload, and unboxing the value. Reading a byte from a Uint8List is a single memory access. On a tight loop over a large buffer, the difference is measured in seconds.
The interop problem. The operating system, the network stack, and the file system work with bytes. A List<int> cannot be passed to a native function that expects a pointer to a buffer. A Uint8List can, because its backing store is a contiguous block of memory that the VM can pin and pass to native code.
The view problem. The same bytes can be interpreted in different ways depending on the context. A four-byte sequence is a Uint32 in one protocol, a Float32 in another, and four Uint8 values in a third. The ByteData view provides the interpretation without copying the bytes.
The endianness problem. Binary formats specify whether multi-byte integers are stored in big-endian or little-endian order. The ByteData view provides both interpretations through the Endian parameter, so the same bytes can be read correctly regardless of the host machine’s byte order.
The allocation problem. A Uint8List can be allocated with a fixed size, and its memory is a single block. A List<int> grows by reallocating and copying its backing store, which is expensive for large buffers. The typed data lists are the right tool for fixed-size buffers.
a. The typed data types
Dart’s dart:typed_data library provides several list types, each with a fixed element width. The types are Int8List, Uint8List, Uint8ClampedList, Int16List, Uint16List, Int32List, Uint32List, Int64List, Uint64List, Float32List, Float64List, and Float16List.
The element widths
Each type has a fixed element width in bytes.
| Type | Element | Width | Range |
|---|---|---|---|
Int8List | Signed 8-bit | 1 byte | -128 to 127 |
Uint8List | Unsigned 8-bit | 1 byte | 0 to 255 |
Uint8ClampedList | Clamped 8-bit | 1 byte | 0 to 255 (clamped) |
Int16List | Signed 16-bit | 2 bytes | -32768 to 32767 |
Uint16List | Unsigned 16-bit | 2 bytes | 0 to 65535 |
Int32List | Signed 32-bit | 4 bytes | -2³¹ to 2³¹-1 |
Uint32List | Unsigned 32-bit | 4 bytes | 0 to 2³²-1 |
Int64List | Signed 64-bit | 8 bytes | -2⁶³ to 2⁶³-1 |
Uint64List | Unsigned 64-bit | 8 bytes | 0 to 2⁶⁴-1 |
Float32List | 32-bit float | 4 bytes | IEEE 754 single |
Float64List | 64-bit float | 8 bytes | IEEE 754 double |
The Uint8List
Uint8List is the most common type. It stores one byte per element, and it is the type that the file system, the network stack, and the image codecs use.
import 'dart:typed_data';
void main() {
final bytes = Uint8List(4);
bytes[0] = 0xDE;
bytes[1] = 0xAD;
bytes[2] = 0xBE;
bytes[3] = 0xEF;
print(bytes); // [222, 173, 190, 239]
}The list has a fixed length of four, and each element is a byte between 0 and 255.
The Uint8List.fromList constructor
A Uint8List can be created from an existing List<int>.
final bytes = Uint8List.fromList([0xDE, 0xAD, 0xBE, 0xEF]);The constructor copies the values into a new contiguous buffer.
The Uint8ClampedList
Uint8ClampedList clamps values to the 0–255 range instead of wrapping them. It is used in image processing, where a value below 0 or above 255 should be saturated rather than wrapped.
final clamped = Uint8ClampedList(4);
clamped[0] = 300; // Clamped to 255.
clamped[1] = -10; // Clamped to 0.The clamping behavior is what makes the type useful for pixel manipulation.
The typed data views
The asUint8List, asUint16List, asInt32List, and similar methods create a view of the same buffer with a different element type.
final bytes = Uint8List(8);
final view = bytes.asUint16List();
view[0] = 0x1234;
print(bytes); // [52, 18, 0, 0, 0, 0, 0, 0]The view shares the same memory. Writing through the view is visible in the original list.
The buffer property
Every typed data list has a buffer property that returns the underlying ByteBuffer.
final bytes = Uint8List(4);
final buffer = bytes.buffer;
print(buffer.lengthInBytes); // 4The ByteBuffer is the raw memory block. Multiple views can be created over the same buffer.
b. The ByteData view
The ByteData class is a view over a ByteBuffer that reads and writes multi-byte values at any offset. It is the tool for parsing and serializing binary formats.
The basic usage
import 'dart:typed_data';
void main() {
final bytes = Uint8List(8);
final data = ByteData.view(bytes.buffer);
data.setUint32(0, 0xDEADBEEF);
data.setUint32(4, 0xCAFEBABE);
print(data.getUint32(0).toRadixString(16)); // deadbeef
print(data.getUint32(4).toRadixString(16)); // cafebabe
}The ByteData.view constructor creates a view over the buffer. The setUint32 and getUint32 methods read and write 32-bit integers at the specified byte offsets.
The getter and setter methods
ByteData provides getters and setters for every fixed-width type.
| Method | Type | Width |
|---|---|---|
getInt8 / setInt8 | Signed 8-bit | 1 |
getUint8 / setUint8 | Unsigned 8-bit | 1 |
getInt16 / setInt16 | Signed 16-bit | 2 |
getUint16 / setUint16 | Unsigned 16-bit | 2 |
getInt32 / setInt32 | Signed 32-bit | 4 |
getUint32 / setUint32 | Unsigned 32-bit | 4 |
getInt64 / setInt64 | Signed 64-bit | 8 |
getUint64 / setUint64 | Unsigned 64-bit | 8 |
getFloat32 / setFloat32 | 32-bit float | 4 |
getFloat64 / setFloat64 | 64-bit float | 8 |
The endianness parameter
Every multi-byte getter and setter accepts an Endian parameter.
data.setUint32(0, 0x12345678, Endian.big);
data.setUint32(4, 0x12345678, Endian.little);
print(data.getUint32(0, Endian.big).toRadixString(16)); // 12345678
print(data.getUint32(4, Endian.little).toRadixString(16)); // 12345678The Endian.big and Endian.little constants specify the byte order. The default is Endian.big for the VM, but the correct value depends on the format being parsed.
The offset and length
The ByteData.view constructor accepts an optional offset and length.
final bytes = Uint8List(16);
final data = ByteData.view(bytes.buffer, 4, 8);The view starts at byte 4 of the buffer and spans 8 bytes. The view’s own offsets are relative to its start.
The ByteData.sublistView
The ByteData.sublistView constructor creates a view over a portion of an existing typed data list.
final bytes = Uint8List(16);
final data = ByteData.sublistView(bytes, 4, 12);The view starts at index 4 and ends at index 12 (exclusive). The view shares the same memory as the original list.
The buffer sharing
Multiple ByteData views can be created over the same buffer, each with a different offset and length.
final buffer = Uint8List(16).buffer;
final header = ByteData.view(buffer, 0, 4);
final body = ByteData.view(buffer, 4, 12);The two views share the same memory, so writing through the header is visible through the body.
c. Memory efficiency and patterns
Typed data is about memory and performance. The patterns below are the ones that matter.
The allocation
A Uint8List is allocated with a fixed size. The memory is a single contiguous block.
final bytes = Uint8List(1024 * 1024); // 1 MBThe allocation is fast, and the memory is exactly the size requested.
The copy
The setRange method copies bytes from one list to another.
final source = Uint8List.fromList([1, 2, 3, 4]);
final dest = Uint8List(4);
dest.setRange(0, 4, source);The copy is a single memcpy-like operation, much faster than an element-by-element loop.
The sublist
The sublist method creates a new list with a copy of the specified range.
final bytes = Uint8List.fromList([1, 2, 3, 4, 5]);
final sub = bytes.sublist(1, 4); // [2, 3, 4]The sublist copies the data. The buffer.asUint8List(offset, length) view does not copy.
The view
The asUint8List method on the buffer creates a view without copying.
final bytes = Uint8List.fromList([1, 2, 3, 4, 5]);
final view = bytes.buffer.asUint8List(1, 3); // View of [2, 3, 4]Writing through the view modifies the original list. The view is a window into the same memory.
The bulk read
The File.readAsBytes method returns a Uint8List with the file’s contents.
final bytes = await File('data.bin').readAsBytes();The method reads the entire file into a single buffer. The result is a Uint8List, not a List<int>.
The bulk write
The File.writeAsBytes method writes a Uint8List to a file.
await File('data.bin').writeAsBytes(bytes);The write is a single system call with the buffer’s bytes.
The stream
The File.openRead method returns a stream of Uint8List chunks.
await for (final chunk in File('large.bin').openRead()) {
process(chunk);
}Each chunk is a Uint8List. The stream reads the file in blocks, which avoids loading the entire file into memory.
The network
The Socket and HttpClient classes work with Uint8List.
final socket = await Socket.connect('example.com', 80);
socket.add(Uint8List.fromList(utf8.encode('GET / HTTP/1.1\r\n\r\n')));
await for (final chunk in socket) {
process(chunk);
}The add method accepts a List<int>, and the stream yields Uint8List chunks.
The conversion to a string
The utf8.decode function converts a Uint8List to a string.
final bytes = Uint8List.fromList([72, 101, 108, 108, 111]);
final text = utf8.decode(bytes); // "Hello"The utf8.encode function does the reverse.
The base64 encoding
The base64Encode function encodes a Uint8List as a base64 string.
final encoded = base64Encode(bytes);
final decoded = base64Decode(encoded);The functions work with List<int>, and the Uint8List is a List<int>.
The hex encoding
A Uint8List can be converted to a hex string with a manual loop or a package.
final hex = bytes.map((b) => b.toRadixString(16).padLeft(2, '0')).join();The loop converts each byte to a two-digit hex string.
The memory comparison
The typed data types use far less memory than the boxed lists.
| Type | Elements | Approximate memory |
|---|---|---|
List<int> (boxed) | 1,000,000 | 24 MB+ |
Uint8List | 1,000,000 | 1 MB |
Int32List | 1,000,000 | 4 MB |
Float64List | 1,000,000 | 8 MB |
The difference is the boxed object overhead, which the typed data types avoid.
The performance comparison
A loop over a Uint8List is much faster than a loop over a List<int>.
// Slow: boxed list.
final boxed = List<int>.filled(1000000, 0);
for (var i = 0; i < boxed.length; i++) {
boxed[i] = boxed[i] + 1;
}
// Fast: typed data.
final typed = Uint8List(1000000);
for (var i = 0; i < typed.length; i++) {
typed[i] = typed[i] + 1;
}The typed loop is several times faster, because the elements are not boxed and unboxed.
Complete Example Session
// ============================================
// PART 1: THE BASIC UINT8LIST
// ============================================
import 'dart:typed_data';
void main() {
final bytes = Uint8List(4);
bytes[0] = 0xDE;
bytes[1] = 0xAD;
bytes[2] = 0xBE;
bytes[3] = 0xEF;
print(bytes); // [222, 173, 190, 239]
}
// ============================================
// PART 2: THE BYTEDATA VIEW
// ============================================
void main() {
final bytes = Uint8List(8);
final data = ByteData.view(bytes.buffer);
data.setUint32(0, 0xDEADBEEF);
data.setUint32(4, 0xCAFEBABE);
print(data.getUint32(0).toRadixString(16)); // deadbeef
}
// ============================================
// PART 3: THE ENDIAN PARAMETER
// ============================================
void main() {
final bytes = Uint8List(4);
final data = ByteData.view(bytes.buffer);
data.setUint32(0, 0x12345678, Endian.big);
print(bytes); // [18, 52, 86, 120]
data.setUint32(0, 0x12345678, Endian.little);
print(bytes); // [120, 86, 52, 18]
}
// ============================================
// PART 4: THE TYPED VIEW
// ============================================
void main() {
final bytes = Uint8List(8);
final view = bytes.asUint16List();
view[0] = 0x1234;
view[1] = 0x5678;
print(bytes); // [52, 18, 120, 86, 0, 0, 0, 0]
}
// ============================================
// PART 5: THE SUBLIST VIEW
// ============================================
void main() {
final bytes = Uint8List.fromList([1, 2, 3, 4, 5, 6]);
final view = bytes.buffer.asUint8List(2, 3);
print(view); // [3, 4, 5]
view[0] = 99;
print(bytes); // [1, 2, 99, 4, 5, 6]
}
// ============================================
// PART 6: THE FILE READ
// ============================================
import 'dart:io';
Future<void> main() async {
final bytes = await File('data.bin').readAsBytes();
print(bytes.length);
}
// ============================================
// PART 7: THE FILE STREAM
// ============================================
Future<void> main() async {
final file = File('large.bin');
await for (final chunk in file.openRead()) {
print('Chunk: ${chunk.length} bytes');
}
}
// ============================================
// PART 8: THE NETWORK SOCKET
// ============================================
import 'dart:io';
Future<void> main() async {
final socket = await Socket.connect('example.com', 80);
socket.add(utf8.encode('GET / HTTP/1.1\r\nHost: example.com\r\n\r\n'));
await for (final chunk in socket) {
print(utf8.decode(chunk));
}
}
// ============================================
// PART 9: THE STRING CONVERSION
// ============================================
import 'dart:convert';
void main() {
final bytes = Uint8List.fromList([72, 101, 108, 108, 111]);
final text = utf8.decode(bytes);
print(text); // Hello
final encoded = utf8.encode('Hello');
print(encoded); // [72, 101, 108, 108, 111]
}
// ============================================
// PART 10: THE MEMORY AND PERFORMANCE
// ============================================
import 'dart:typed_data';
void main() {
// Allocate 1 MB.
final typed = Uint8List(1024 * 1024);
print(typed.length); // 1048576
// Fill it fast.
for (var i = 0; i < typed.length; i++) {
typed[i] = i & 0xFF;
}
// Read it as 32-bit integers.
final view = typed.buffer.asUint32List();
print(view[0].toRadixString(16));
}The ten parts showed the basic Uint8List, the ByteData view, the endian parameter, the typed view, the sublist view, the file read, the file stream, the network socket, the string conversion, and the memory and performance comparison.
Quick Reference
The Typed Data Types
| Type | Element | Width |
|---|---|---|
Int8List | Signed 8-bit | 1 |
Uint8List | Unsigned 8-bit | 1 |
Uint8ClampedList | Clamped 8-bit | 1 |
Int16List | Signed 16-bit | 2 |
Uint16List | Unsigned 16-bit | 2 |
Int32List | Signed 32-bit | 4 |
Uint32List | Unsigned 32-bit | 4 |
Int64List | Signed 64-bit | 8 |
Uint64List | Unsigned 64-bit | 8 |
Float32List | 32-bit float | 4 |
Float64List | 64-bit float | 8 |
The ByteData Methods
| Method | Width | Endian |
|---|---|---|
getInt8 / setInt8 | 1 | N/A |
getUint8 / setUint8 | 1 | N/A |
getInt16 / setInt16 | 2 | Yes |
getUint16 / setUint16 | 2 | Yes |
getInt32 / setInt32 | 4 | Yes |
getUint32 / setUint32 | 4 | Yes |
getInt64 / setInt64 | 8 | Yes |
getUint64 / setUint64 | 8 | Yes |
getFloat32 / setFloat32 | 4 | Yes |
getFloat64 / setFloat64 | 8 | Yes |
The Endian Constants
| Constant | Meaning |
|---|---|
Endian.big | Most significant byte first |
Endian.little | Least significant byte first |
The Conversion Functions
| Function | Direction |
|---|---|
utf8.encode | String → Uint8List |
utf8.decode | Uint8List → String |
base64Encode | Bytes → base64 String |
base64Decode | base64 String → Bytes |
The Memory Comparison
| Type | 1M Elements |
|---|---|
List<int> | ~24 MB |
Uint8List | 1 MB |
Int32List | 4 MB |
Float64List | 8 MB |
Best Practices
✅ Do This:
// Use Uint8List for binary data.
final bytes = Uint8List(1024); // ✅
// Use ByteData for multi-byte values.
final data = ByteData.view(bytes.buffer);
data.setUint32(0, value, Endian.big); // ✅
// Use views instead of copies.
final view = bytes.buffer.asUint8List(offset, length); // ✅
// Use the Endian parameter for binary formats.
data.getUint32(0, Endian.little); // ✅
// Use readAsBytes for file reading.
final bytes = await File('data.bin').readAsBytes(); // ✅
// Use openRead for large files.
await for (final chunk in File('large.bin').openRead()) { } // ✅
// Use utf8.decode for string conversion.
final text = utf8.decode(bytes); // ✅❌ Don’t Do This:
// Don't use List<int> for binary data.
final bytes = List<int>.filled(1024, 0); // ❌ Boxed
// Don't copy when a view suffices.
final sub = bytes.sublist(0, 100); // ❌ Copies. Use a view.
// Don't assume the endianness.
data.getUint32(0); // ⚠️ Default may not match the format
// Don't read a large file into memory.
final bytes = await File('huge.bin').readAsBytes(); // ❌ Use a stream
// Don't convert bytes to a string without an encoding.
String.fromCharCodes(bytes); // ⚠️ Ignores UTF-8
// Don't use element-by-element copy for large buffers.
for (var i = 0; i < src.length; i++) dest[i] = src[i]; // ❌ Use setRangeCommon Pitfalls
| Pitfall | Why It Happens | Fix |
|---|---|---|
| Wrong values read | Wrong endianness | Specify Endian |
| View does not share | Used sublist | Use buffer.asUint8List |
| Out of range | Offset beyond the buffer | Check the length |
| Memory blowup | Used List<int> | Use Uint8List |
| Slow copy | Element-by-element | Use setRange |
| Encoding error | Used String.fromCharCodes | Use utf8.decode |
| Alignment error | Unaligned view | Align to the element width |
Real-World Examples
1. Basic Uint8List
final bytes = Uint8List(4);2. ByteData View
final data = ByteData.view(bytes.buffer);3. Set and Get
data.setUint32(0, 0xDEADBEEF, Endian.big);
final value = data.getUint32(0, Endian.big);4. Typed View
final view = bytes.asUint16List();5. Sublist View
final view = bytes.buffer.asUint8List(4, 8);6. File Read
final bytes = await File('data.bin').readAsBytes();7. File Stream
await for (final chunk in File('large.bin').openRead()) { }8. String Conversion
final text = utf8.decode(bytes);9. Set Range
dest.setRange(0, src.length, src);10. Performance
final typed = Uint8List(1024 * 1024);Visual
The Boxed List vs the Typed List
┌────────────────────────────────────────────────────────────┐
│ List<int> (BOXED) │
│ │
│ ┌─────────┐ │
│ │ List │ │
│ │ ┌─────┐ │ HEAP │
│ │ │ ptr │─┼────▶┌─────────┐ │
│ │ ├─────┤ │ │ Object │ │
│ │ │ ptr │─┼────▶│ header │ │
│ │ ├─────┤ │ │ value:1 │ │
│ │ │ ptr │─┼────▶├─────────┤ │
│ │ ├─────┤ │ │ Object │ │
│ │ │ ptr │─┼────▶│ header │ │
│ │ └─────┘ │ │ value:2 │ │
│ └─────────┘ └─────────┘ │
│ │
│ Each element is a separate heap object. │
│ Memory: 8 bytes pointer + 16 bytes object per element. │
│ │
│ ────────────────────────────────────────────────────── │
│ │
│ Uint8List (TYPED) │
│ │
│ ┌─────────────────────────────────────┐ │
│ │ [1][2][3][4][5][6][7][8] │ │
│ │ Contiguous bytes in one block. │ │
│ └─────────────────────────────────────┘ │
│ │
│ One byte per element. │
│ Memory: 1 byte per element. │
└────────────────────────────────────────────────────────────┘The ByteData View
┌────────────────────────────────────────────────────────────┐
│ ByteData VIEW │
│ │
│ Uint8List buffer: │
│ ┌────┬────┬────┬────┬────┬────┬────┬────┐ │
│ │ DE │ AD │ BE │ EF │ CA │ FE │ BA │ BE │ │
│ └────┴────┴────┴────┴────┴────┴────┴────┘ │
│ 0 1 2 3 4 5 6 7 │
│ │
│ ByteData.view(buffer): │
│ ┌───────────────┐ ┌───────────────┐ │
│ │ getUint32(0) │ │ getUint32(4) │ │
│ │ = 0xDEADBEEF │ │ = 0xCAFEBABE │ │
│ └───────────────┘ └───────────────┘ │
│ │
│ The same bytes are read as 32-bit integers. │
│ The view shares the buffer's memory. │
└────────────────────────────────────────────────────────────┘The Endianness
┌────────────────────────────────────────────────────────────┐
│ ENDIANNESS │
│ │
│ Value: 0x12345678 │
│ │
│ Big-endian: │
│ ┌────┬────┬────┬────┐ │
│ │ 12 │ 34 │ 56 │ 78 │ Most significant byte first. │
│ └────┴────┴────┴────┘ │
│ │
│ Little-endian: │
│ ┌────┬────┬────┬────┐ │
│ │ 78 │ 56 │ 34 │ 12 │ Least significant byte first. │
│ └────┴────┴────┴────┘ │
│ │
│ ByteData reads and writes with the specified endianness. │
│ The same bytes are interpreted differently. │
└────────────────────────────────────────────────────────────┘The View Sharing
┌────────────────────────────────────────────────────────────┐
│ VIEW SHARING │
│ │
│ ByteBuffer (shared memory): │
│ ┌────┬────┬────┬────┬────┬────┬────┬────┐ │
│ │ 0 │ 1 │ 2 │ 3 │ 4 │ 5 │ 6 │ 7 │ │
│ └────┴────┴────┴────┴────┴────┴────┴────┘ │
│ ▲ ▲ │
│ │ │ │
│ ┌─┴───────────┐ ┌─┴───────────┐ │
│ │ Header view │ │ Body view │ │
│ │ offset 0 │ │ offset 4 │ │
│ │ length 4 │ │ length 4 │ │
│ └─────────────┘ └─────────────┘ │
│ │
│ Both views share the same memory. │
│ Writing through one is visible through the other. │
└────────────────────────────────────────────────────────────┘Summary
| Item | Value |
|---|---|
Uint8List | A list of unsigned 8-bit integers |
ByteData | A view that reads multi-byte values |
ByteBuffer | The raw memory block |
asUint16List | A view with a different element type |
Endian.big | Most significant byte first |
Endian.little | Least significant byte first |
setRange | Bulk copy between lists |
buffer.asUint8List | A view without copying |
readAsBytes | Read a file as Uint8List |
openRead | Stream a file as Uint8List chunks |
utf8.decode | Convert bytes to a string |
Key takeaways:
- Typed data lists store unboxed elements in a contiguous block. A
Uint8Listuses one byte per element, and aList<int>uses roughly 24 bytes per element. The difference is the boxed object overhead that the typed data types avoid. - The
ByteDataview interprets the same bytes as different types. The view reads and writesUint16,Int32,Float64, and any other fixed-width value at any byte offset. The view shares the buffer’s memory. - The
Endianparameter controls the byte order. Binary formats specify whether multi-byte integers are big-endian or little-endian. ThegetUint32(offset, Endian.little)call reads the bytes in the specified order. - Views do not copy,
sublistdoes. Thebuffer.asUint8List(offset, length)method creates a view that shares the memory. Thesublist(start, end)method creates a new list with a copy of the data. - The typed data types are the foundation of binary I/O. The
File.readAsBytesmethod returns aUint8List, theSocketstream yieldsUint8Listchunks, and the image codecs work withUint8Listbuffers. - The conversion functions bridge between bytes and text. The
utf8.encodeandutf8.decodefunctions convert between strings and bytes. Thebase64Encodeandbase64Decodefunctions convert between bytes and base64 strings. setRangeis the bulk copy. The method copies a range of bytes in a single operation, which is much faster than an element-by-element loop.Uint8ClampedListclamps instead of wrapping. The type is used in image processing, where a value below 0 or above 255 should be saturated rather than wrapped.- The memory savings are dramatic. A million-element
List<int>consumes over 24 megabytes, while aUint8Listconsumes exactly one. The typed data types are the right choice for any buffer over a few hundred elements.
Remember: Dart’s typed data library provides lists and views that store their elements unboxed, in a contiguous block of memory. The Uint8List is the list of bytes, and the ByteData is the view that reads and writes multi-byte values at any offset. The Endian parameter controls the byte order, and the ByteBuffer is the raw memory that multiple views can share. The typed data types are the foundation of binary I/O, image processing, network protocols, and any other task that works with raw bytes. They use far less memory than the boxed lists, and they are much faster for large buffers. The result is code that handles megabytes of data with a fraction of the memory and time that a List<int> would require.
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