Use managed buffers in Agg backend

This means we don't have to free them ourselves.

Author: QuLogic

src/_backend_agg.cpp

@@ -41,30 +41,23 @@ RendererAgg::RendererAgg(unsigned int width, unsigned int height, double dpi)
 
     unsigned stride(width * 4);
 
-    pixBuffer = new agg::int8u[NUMBYTES];
-    renderingBuffer.attach(pixBuffer, width, height, stride);
+    pixBuffer = std::make_unique<agg::int8u[]>(NUMBYTES);
+    renderingBuffer.attach(pixBuffer.get(), width, height, stride);
     pixFmt.attach(renderingBuffer);
     rendererBase.attach(pixFmt);
     rendererBase.clear(_fill_color);
     rendererAA.attach(rendererBase);
     rendererBin.attach(rendererBase);
     hatch_size = int(dpi);
-    hatchBuffer = new agg::int8u[hatch_size * hatch_size * 4];
-    hatchRenderingBuffer.attach(hatchBuffer, hatch_size, hatch_size, hatch_size * 4);
-}
-
-RendererAgg::~RendererAgg()
-{
-    delete[] hatchBuffer;
-    delete[] alphaBuffer;
-    delete[] pixBuffer;
+    hatchBuffer = std::make_unique<agg::int8u[]>(hatch_size * hatch_size * 4);
+    hatchRenderingBuffer.attach(hatchBuffer.get(), hatch_size, hatch_size, hatch_size * 4);
 }
 
 void RendererAgg::create_alpha_buffers()
 {
     if (!alphaBuffer) {
-        alphaBuffer = new agg::int8u[width * height];
-        alphaMaskRenderingBuffer.attach(alphaBuffer, width, height, width);
+        alphaBuffer = std::make_unique<agg::int8u[]>(width * height);
+        alphaMaskRenderingBuffer.attach(alphaBuffer.get(), width, height, width);
         rendererBaseAlphaMask.attach(pixfmtAlphaMask);
         rendererAlphaMask.attach(rendererBaseAlphaMask);
     }

src/_backend_agg.h

@@ -11,6 +11,7 @@
 #include <cmath>
 #include <algorithm>
 #include <functional>
+#include <memory>
 #include <optional>
 #include <vector>
 
@@ -126,8 +127,6 @@ class RendererAgg
 
     RendererAgg(unsigned int width, unsigned int height, double dpi);
 
-    virtual ~RendererAgg();
-
     unsigned int get_width()
     {
         return width;
@@ -206,10 +205,10 @@ class RendererAgg
     double dpi;
     size_t NUMBYTES; // the number of bytes in buffer
 
-    agg::int8u *pixBuffer;
+    std::unique_ptr<agg::int8u[]> pixBuffer;
     agg::rendering_buffer renderingBuffer;
 
-    agg::int8u *alphaBuffer;
+    std::unique_ptr<agg::int8u[]> alphaBuffer;
     agg::rendering_buffer alphaMaskRenderingBuffer;
     alpha_mask_type alphaMask;
     agg::pixfmt_gray8 pixfmtAlphaMask;
@@ -229,7 +228,7 @@ class RendererAgg
     agg::trans_affine lastclippath_transform;
 
     size_t hatch_size;
-    agg::int8u *hatchBuffer;
+    std::unique_ptr<agg::int8u[]> hatchBuffer;
     agg::rendering_buffer hatchRenderingBuffer;
 
     agg::rgba _fill_color;

src/_backend_agg_wrapper.cpp

@@ -263,7 +263,7 @@ PYBIND11_MODULE(_backend_agg, m, py::mod_gil_not_used())
                 4,
                 1
             };
-            return py::buffer_info(renderer->pixBuffer, shape, strides);
+            return py::buffer_info(renderer->pixBuffer.get(), shape, strides);
         });
 
     py::class_<BufferRegion>(m, "BufferRegion", py::buffer_protocol())