re-enable zero allocation image interface - refs #3069

include/mapnik/image.hpp

@@ -34,6 +34,7 @@ namespace detail {
 struct MAPNIK_DECL buffer
 {
     explicit buffer(std::size_t size);
+    explicit buffer(unsigned char* data, std::size_t size);
     buffer(buffer && rhs) noexcept;
     buffer(buffer const& rhs);
     ~buffer();
@@ -51,6 +52,7 @@ struct MAPNIK_DECL buffer
 private:
     std::size_t size_;
     unsigned char* data_;
+    bool owns_;
 
 };
 
@@ -93,6 +95,11 @@ public:
           bool initialize = true,
           bool premultiplied = false,
           bool painted = false);
+    image(int width,
+          int height,
+          detail::buffer && buf,
+          bool premultiplied = false,
+          bool painted = false);
     image(image<T> const& rhs);
     image(image<T> && rhs) noexcept;
     image<T>& operator=(image<T> rhs);

include/mapnik/image_impl.hpp

@@ -77,6 +77,16 @@ image<T>::image()
       painted_(false)
 {}
 
+template <typename T>
+image<T>::image(int width, int height, detail::buffer && buf, bool premultiplied, bool painted)
+    : dimensions_(width, height),
+      buffer_(std::move(buf)),
+      pData_(reinterpret_cast<pixel_type*>(buffer_.data())),
+      offset_(0.0),
+      scaling_(1.0),
+      premultiplied_alpha_(premultiplied),
+      painted_(painted) {}
+
 template <typename T>
 image<T>::image(int width, int height, bool initialize, bool premultiplied, bool painted)
     : dimensions_(width, height),

src/image.cpp

@@ -36,27 +36,37 @@ namespace detail
 // BUFFER
 buffer::buffer(std::size_t size)
     : size_(size),
-      data_(static_cast<unsigned char*>(size_ != 0 ? ::operator new(size_) : nullptr))
+      data_(static_cast<unsigned char*>(size_ != 0 ? ::operator new(size_) : nullptr)),
+      owns_(true)
+{}
+
+buffer::buffer(unsigned char* data, std::size_t size)
+    : size_(size),
+      data_(data),
+      owns_(false)
 {}
 
 buffer::buffer(buffer && rhs) noexcept
 : size_(std::move(rhs.size_)),
-    data_(std::move(rhs.data_))
+    data_(std::move(rhs.data_)),
+    owns_(std::move(rhs.owns_))
 {
     rhs.size_ = 0;
     rhs.data_ = nullptr;
+    rhs.owns_ = true;
 }
 
 buffer::buffer(buffer const& rhs)
     : size_(rhs.size_),
-      data_(static_cast<unsigned char*>(size_ != 0 ? ::operator new(size_) : nullptr))
+      data_(static_cast<unsigned char*>(size_ != 0 ? ::operator new(size_) : nullptr)),
+      owns_(rhs.owns_)
 {
     if (data_) std::copy(rhs.data_, rhs.data_ + rhs.size_, data_);
 }
 
 buffer::~buffer()
 {
-    ::operator delete(data_);
+    if (owns_) ::operator delete(data_);
 }
 
 buffer& buffer::operator=(buffer rhs)
@@ -69,6 +79,7 @@ void buffer::swap(buffer & rhs)
 {
     std::swap(size_, rhs.size_);
     std::swap(data_, rhs.data_);
+    std::swap(owns_, rhs.owns_);
 }
 
 unsigned char* buffer::data()

test/unit/imaging/image_io_test.cpp

@@ -21,6 +21,11 @@ SECTION("readers") {
     boost::optional<std::string> type;
     try
     {
+        mapnik::image_rgba8 im_og;
+        auto im_size = mapnik::image_rgba8::pixel_size * im_og.width() * im_og.height();
+        mapnik::detail::buffer buf(im_og.bytes(),im_size);
+        mapnik::image_rgba8 im2(im_og.width(),im_og.height(),std::move(buf));
+        CHECK( im2.bytes() == im_og.bytes() );
 #if defined(HAVE_JPEG)
         should_throw = "./test/data/images/blank.jpg";
         REQUIRE( mapnik::util::exists( should_throw ) );