fix

include/tgfx/core/WriteStream.h

@@ -41,7 +41,7 @@ class WriteStream {
    * Writes bytes to the stream. Returns true if the write was successful. The actual write
    * operation is implemented in the subclasses.
    */
-  virtual bool write(const char* data, size_t size) = 0;
+  virtual bool write(const void* data, size_t size) = 0;
 
   /**
    * Writes text to the stream. Returns true if the write was successful.
@@ -87,7 +87,7 @@ class FileWriteStream : public WriteStream {
   /**
    * Writes bytes to the file stream. Returns true if the write was successful.
    */
-  bool write(const char* data, size_t size) override;
+  bool write(const void* data, size_t size) override;
 
   /**
    * Returns the current size of the written bytes.
@@ -135,7 +135,7 @@ class MemoryWriteStream : public WriteStream {
   /**
    * Writes bytes to the memory stream. Returns true if the write was successful.
    */
-  bool write(const char* data, size_t size) override;
+  bool write(const void* data, size_t size) override;
 
   /**
    * Returns the current size of the written bytes.
@@ -148,24 +148,24 @@ class MemoryWriteStream : public WriteStream {
   void flush() override{};
 
   /**
-   * Reads data from the stream at the specified offset and size. Returns true if the read was
-   * successful.
+   * Copies a range of the buffer bytes into a Data object. If offset or length is out of range,
+   * they are clamped to the beginning and end of the buffer. Returns nullptr if the clamped length
+   * is 0.
    */
-  bool read(char* data, size_t size, size_t offset);
+  std::shared_ptr<Data> copyRange(size_t offset, size_t length);
 
   /**
-   * Dumps all the written data as a Data object. The Data object is a copy of the current buffer
-   * and its lifecycle is independent of the MemoryWriteStream.
+   * Copies all the buffer bytes into a Data object.
    */
-  std::shared_ptr<Data> dumpAsData();
+  std::shared_ptr<Data> copy();
 
  private:
   /**
    * Creates a new MemoryWriteStream object.
    */
   MemoryWriteStream() = default;
 
-  std::vector<char> buffer;
+  std::vector<uint8_t> buffer;
 };
 
 }  // namespace tgfx

src/core/utils/WriteStream.cpp

@@ -46,7 +46,7 @@ size_t FileWriteStream::size() const {
   return static_cast<size_t>(ftell(file));
 }
 
-bool FileWriteStream::write(const char* data, size_t size) {
+bool FileWriteStream::write(const void* data, size_t size) {
   if (file == nullptr) {
     return false;
   }
@@ -78,25 +78,28 @@ std::unique_ptr<MemoryWriteStream> MemoryWriteStream::Make() {
   return std::unique_ptr<MemoryWriteStream>(new MemoryWriteStream());
 }
 
-bool MemoryWriteStream::write(const char* data, size_t size) {
-  buffer.insert(buffer.end(), data, data + size);
+bool MemoryWriteStream::write(const void* data, size_t size) {
+  const auto* bytes = static_cast<const uint8_t*>(data);
+  buffer.insert(buffer.end(), bytes, bytes + size);
   return true;
 }
 
 size_t MemoryWriteStream::size() const {
   return buffer.size();
 }
 
-bool MemoryWriteStream::read(char* data, size_t size, size_t offset) {
-  if (offset + size > buffer.size()) {
-    return false;
+std::shared_ptr<Data> MemoryWriteStream::copyRange(size_t offset, size_t length) {
+  if (offset >= buffer.size()) {
+    return nullptr;
   }
-  std::copy(buffer.begin() + static_cast<std::ptrdiff_t>(offset),
-            buffer.begin() + static_cast<std::ptrdiff_t>(offset + size), data);
-  return true;
+  length = std::min(length, buffer.size() - offset);
+  if (length == 0) {
+    return nullptr;
+  }
+  return Data::MakeWithCopy(buffer.data() + offset, length);
 }
 
-std::shared_ptr<Data> MemoryWriteStream::dumpAsData() {
+std::shared_ptr<Data> MemoryWriteStream::copy() {
   return Data::MakeWithCopy(buffer.data(), buffer.size());
 }
 

test/src/DataViewTest.cpp

@@ -98,10 +98,18 @@ TGFX_TEST(DataViewTest, MemoryWriteStream) {
   const char* text = "TGFX";
   stream->write(text, std::strlen(text));
 
-  auto data = stream->dumpAsData();
+  auto data = stream->copy();
   ASSERT_TRUE(data != nullptr);
   EXPECT_EQ(data->size(), 10U);
   EXPECT_EQ(std::string((char*)data->bytes(), data->size()), "Hello\nTGFX");
+
+  data = stream->copyRange(6, 4);
+  ASSERT_TRUE(data != nullptr);
+  EXPECT_EQ(data->size(), 4U);
+  EXPECT_EQ(std::string((char*)data->bytes(), data->size()), "TGFX");
+
+  data = stream->copyRange(10, 10);
+  ASSERT_TRUE(data == nullptr);
 }
 
 TGFX_TEST(DataViewTest, FileWriteStream) {