Added compression level argument to Canvas::toBuffer

src/Canvas.cc

@@ -166,7 +166,7 @@ Canvas::EIO_ToBuffer(eio_req *req) {
 #endif
   closure_t *closure = (closure_t *) req->data;
 
-  closure->status = cairo_surface_write_to_png_stream(
+  closure->status = canvas_write_to_png_stream(
       closure->canvas->surface()
     , toBuffer
     , closure);
@@ -224,6 +224,7 @@ Canvas::EIO_AfterToBuffer(eio_req *req) {
 NAN_METHOD(Canvas::ToBuffer) {
   NanScope();
   cairo_status_t status;
+  uint32_t compression_level = 6;
   Canvas *canvas = ObjectWrap::Unwrap<Canvas>(args.This());
 
   // TODO: async / move this out
@@ -235,10 +236,21 @@ NAN_METHOD(Canvas::ToBuffer) {
     NanReturnValue(buf);
   }
 
+  if (args.Length() == 2) {
+    if(args[1]->IsUint32()) {
+      compression_level = args[1]->Uint32Value();
+      if (compression_level > 9) {
+        return NanThrowRangeError("Allowed compression levels lie in the range [0, 9].");
+      }
+    } else {
+      return NanThrowTypeError("Compression level has to be an unsigned integer.");
+    }
+  }
+
   // Async
   if (args[0]->IsFunction()) {
     closure_t *closure = (closure_t *) malloc(sizeof(closure_t));
-    status = closure_init(closure, canvas);
+    status = closure_init(closure, canvas, compression_level);
 
     // ensure closure is ok
     if (status) {
@@ -264,7 +276,7 @@ NAN_METHOD(Canvas::ToBuffer) {
   // Sync
   } else {
     closure_t closure;
-    status = closure_init(&closure, canvas);
+    status = closure_init(&closure, canvas, compression_level);
 
     // ensure closure is ok
     if (status) {
@@ -384,7 +396,7 @@ Canvas::Canvas(int w, int h, canvas_type_t t): ObjectWrap() {
   if (CANVAS_TYPE_PDF == t) {
     _closure = malloc(sizeof(closure_t));
     assert(_closure);
-    cairo_status_t status = closure_init((closure_t *) _closure, this);
+    cairo_status_t status = closure_init((closure_t *) _closure, this, 0);
     assert(status == CAIRO_STATUS_SUCCESS);
     _surface = cairo_pdf_surface_create_for_stream(toBuffer, _closure, w, h);
   } else {

src/PNG.h

@@ -4,8 +4,7 @@
 #include <pngconf.h>
 #include <cairo.h>
 #include <stdlib.h>
-
-#pragma once
+#include "closure.h"
 
 #if defined(__GNUC__) && (__GNUC__ > 2) && defined(__OPTIMIZE__)
 #define likely(expr) (__builtin_expect (!!(expr), 1))
@@ -16,7 +15,139 @@
 #endif
 
 
+
+typedef png_size_t png_alloc_size_t;
+
+/* Allocate memory.  For reasonable files, size should never exceed
+ * 64K.  However, zlib may allocate more then 64K if you don't tell
+ * it not to.  See zconf.h and png.h for more information.  zlib does
+ * need to allocate exactly 64K, so whatever you call here must
+ * have the ability to do that.
+ *
+ * This piece of code can be compiled to validate max 64K allocations
+ * by setting MAXSEG_64K in zlib zconf.h *or* PNG_MAX_MALLOC_64K.
+ */
+typedef struct memory_information
+{
+   png_alloc_size_t                size;
+   png_voidp                 pointer;
+   struct memory_information *next;
+} memory_information;
+typedef memory_information *memory_infop;
+
+static memory_infop pinformation = NULL;
+static int current_allocation = 0;
+static int maximum_allocation = 0;
+static int total_allocation = 0;
+static int num_allocations = 0;
+
+png_voidp png_debug_malloc PNGARG((png_structp png_ptr,png_alloc_size_t size));
+static void png_debug_free PNGARG((png_structp png_ptr, png_voidp ptr));
+
+png_voidp png_debug_malloc(png_structp png_ptr, png_alloc_size_t size) {
+   /* png_malloc has already tested for NULL; png_create_struct calls
+    * png_debug_malloc directly, with png_ptr == NULL which is OK
+    */
+
+   if (size == 0)
+      return (NULL);
+
+   /* This calls the library allocator twice, once to get the requested
+      buffer and once to get a new free list entry. */
+   {
+      /* Disable malloc_fn and free_fn */
+      memory_infop pinfo;
+      png_set_mem_fn(png_ptr, NULL, NULL, NULL);
+      pinfo = (memory_infop)png_malloc(png_ptr,
+         (sizeof *pinfo));
+      pinfo->size = size;
+      current_allocation += size;
+      total_allocation += size;
+      num_allocations ++;
+
+      if (current_allocation > maximum_allocation) {
+         maximum_allocation = current_allocation;
+      }
+
+      pinfo->pointer = png_malloc(png_ptr, size);
+      /* Restore malloc_fn and free_fn */
+
+      png_set_mem_fn(png_ptr,
+          NULL, png_debug_malloc, png_debug_free);
+
+      if (size != 0 && pinfo->pointer == NULL) {
+         current_allocation -= size;
+         total_allocation -= size;
+         png_error(png_ptr,
+           "out of memory in pngtest->png_debug_malloc");
+      }
+
+      pinfo->next = pinformation;
+      pinformation = pinfo;
+      /* Make sure the caller isn't assuming zeroed memory. */
+      memset(pinfo->pointer, 0xdd, pinfo->size);
+
+      printf("png_malloc %lu bytes at %p\n", (unsigned long)size,
+         pinfo->pointer);
+
+      return (png_voidp)(pinfo->pointer);
+   }
+}
+
+/* Free a pointer.  It is removed from the list at the same time. */
+static void png_debug_free(png_structp png_ptr, png_voidp ptr) {
+   if (png_ptr == NULL)
+      fprintf(stderr, "NULL pointer to png_debug_free.\n");
+
+   if (ptr == 0)
+   {
+#if 0 /* This happens all the time. */
+      fprintf(stderr, "WARNING: freeing NULL pointer\n");
+#endif
+      return;
+   }
+
+   /* Unlink the element from the list. */
+   {
+      memory_infop *ppinfo = &pinformation;
+
+      for (;;)
+      {
+         memory_infop pinfo = *ppinfo;
+
+         if (pinfo->pointer == ptr)
+         {
+            *ppinfo = pinfo->next;
+            current_allocation -= pinfo->size;
+            if (current_allocation < 0)
+               fprintf(stderr, "Duplicate free of memory\n");
+            /* We must free the list element too, but first kill
+               the memory that is to be freed. */
+            memset(ptr, 0x55, pinfo->size);
+            png_free_default(png_ptr, pinfo);
+            pinfo = NULL;
+            break;
+         }
+
+         if (pinfo->next == NULL)
+         {
+            fprintf(stderr, "Pointer %p not found\n", ptr);
+            break;
+         }
+
+         ppinfo = &pinfo->next;
+      }
+   }
+
+   /* Finally free the data. */
+   printf("Freeing %p\n", ptr);
+
+   png_free_default(png_ptr, ptr);
+   ptr = NULL;
+}
+
 static void pngtest_flush(png_structp png_ptr) {
+//    fprintf(stderr, "Pngtest_flush called");
     /* Do nothing; fflush() is said to be just a waste of energy. */
     (void) png_ptr;   /* Stifle compiler warning */
 }
@@ -60,6 +191,11 @@ static void unpremultiply_data(png_structp png, png_row_infop row_info, png_byte
     }
 }
 
+struct png_write_closure_t {
+    cairo_write_func_t write_func;
+    void *closure;
+};
+
 static cairo_status_t canvas_write_png(cairo_surface_t *surface, png_rw_ptr write_func, void *closure) {
     unsigned int i;
     cairo_status_t status = CAIRO_STATUS_SUCCESS;
@@ -97,7 +233,8 @@ static cairo_status_t canvas_write_png(cairo_surface_t *surface, png_rw_ptr writ
     }
 
 #ifdef PNG_USER_MEM_SUPPORTED
-    png = png_create_write_struct_2(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL, NULL, NULL, NULL);
+//    png = png_create_write_struct_2(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL, NULL, png_debug_malloc, png_debug_free);
+     png = png_create_write_struct_2(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL, NULL, NULL, NULL);
 #else
     png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
 #endif
@@ -126,6 +263,9 @@ static cairo_status_t canvas_write_png(cairo_surface_t *surface, png_rw_ptr writ
 #endif
 
     png_set_write_fn(png, closure, write_func, pngtest_flush);
+//    png_set_flush(png, 100);
+//    png_set_compression_buffer_size(png, 1024*1024);
+    png_set_compression_level(png, ((closure_t *) ((png_write_closure_t *) closure)->closure)->compression_level);
 
     switch (cairo_image_surface_get_format(surface)) {
     case CAIRO_FORMAT_ARGB32:
@@ -178,19 +318,14 @@ static cairo_status_t canvas_write_png(cairo_surface_t *surface, png_rw_ptr writ
         png_set_filler(png, 0, PNG_FILLER_AFTER);
     }
 
-    png_write_image (png, rows);
-    png_write_end (png, info);
+    png_write_image(png, rows);
+    png_write_end(png, info);
 
-    png_destroy_write_struct (&png, &info);
+    png_destroy_write_struct(&png, &info);
     free(rows);
     return status;
 }
 
-struct png_write_closure_t {
-    cairo_write_func_t write_func;
-    void *closure;
-};
-
 static void stream_write_func(png_structp png, png_bytep data, png_size_t size) {
     cairo_status_t status;
     struct png_write_closure_t *png_closure;
@@ -213,10 +348,6 @@ static cairo_status_t canvas_write_to_png_stream(cairo_surface_t *surface, cairo
         return cairo_surface_status(surface);
     }
 
-//    if (surface->finished) {
-//        return CAIRO_STATUS_SURFACE_FINISHED;
-//    }
-
     png_closure.write_func = write_func;
     png_closure.closure = closure;
 

src/closure.h

@@ -30,6 +30,7 @@ typedef struct {
   uint8_t *data;
   Canvas *canvas;
   cairo_status_t status;
+  unsigned int compression_level;
 } closure_t;
 
 /*
@@ -37,11 +38,12 @@ typedef struct {
  */
 
 cairo_status_t
-closure_init(closure_t *closure, Canvas *canvas) {
+closure_init(closure_t *closure, Canvas *canvas, unsigned int compression_level) {
   closure->len = 0;
   closure->canvas = canvas;
   closure->data = (uint8_t *) malloc(closure->max_len = PAGE_SIZE);
   if (!closure->data) return CAIRO_STATUS_NO_MEMORY;
+  closure->compression_level = compression_level;
   return CAIRO_STATUS_SUCCESS;
 }