--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/render_png.c	Fri Jun 06 18:35:46 2008 +0300
@@ -0,0 +1,136 @@
+#include <stdlib.h>
+
+#include <png.h>
+
+#include "common.h"
+#include "render_internal.h"
+#include "render_png.h"
+
+struct render_png {
+    // libpng handles
+    png_structp png_ptr;
+    png_infop info_ptr;
+
+    // our render op, containing the I/O callbacks
+    struct render *render;
+};
+
+void _render_png_write(png_structp png_ptr, png_bytep data, png_size_t length) {
+    struct render_png *ctx = png_get_io_ptr(png_ptr);
+
+    if (ctx->render->io_write_fn)
+        if (ctx->render->io_write_fn(data, length, ctx->render->cb_arg)) {
+            // error, doesn't return
+            png_error(png_ptr, "_render_png_write: io_write_fn");
+        }
+}
+
+void _render_png_flush(png_structp png_ptr) {
+    struct render_png *ctx = png_get_io_ptr(png_ptr);
+    
+    if (ctx->render->io_flush_fn)
+        if (ctx->render->io_flush_fn(ctx->render->cb_arg)) {
+            // error, doesn't return
+            png_error(png_ptr, "_render_png_flush: io_flush_fn");
+        }
+}
+
+void _render_png_free (struct render_png *ctx) {
+    if (ctx)
+        png_destroy_write_struct(&ctx->png_ptr, &ctx->info_ptr);
+
+    free(ctx);
+}
+
+
+struct render_png *render_png_init (struct render *render) {
+
+    struct render_png *ctx = NULL;
+
+    // calloc the render_png
+    if (!(ctx = calloc(1, sizeof(struct render_png))))
+        ERROR("calloc");
+
+    // store the struct render
+    ctx->render = render;
+
+    // libpng initialization
+    if (!(ctx->png_ptr = png_create_write_struct (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL)))
+        ERROR("png_create_write_struct");
+
+    if (!(ctx->info_ptr = png_create_info_struct(ctx->png_ptr)))
+        ERROR("png_create_info_struct");
+
+    // libpng error handling
+    if (setjmp(png_jmpbuf(ctx->png_ptr)))
+        ERROR("libpng");
+    
+    if (render->io_stream) {
+        // use normal libpng I/O
+        // XXX: who fcloses this?
+        png_init_io(ctx->png_ptr, render->io_stream);
+    } else {
+        // setup our custom I/O callbacks
+        png_set_write_fn(ctx->png_ptr, ctx, &_render_png_write, &_render_png_flush);
+    }
+
+    // some PNG metadata
+    png_set_IHDR(ctx->png_ptr, ctx->info_ptr, render->img_w, render->img_h, 8, PNG_COLOR_TYPE_GRAY, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+
+    // write out the PNG header
+    png_write_info(ctx->png_ptr, ctx->info_ptr);
+
+    // success
+    return ctx;
+
+error:
+    _render_png_free(ctx);
+    return NULL;
+}
+
+int render_png_row (struct render_png *ctx, unsigned char *rowbuf) {
+    // libpng error handling
+    if (setjmp(png_jmpbuf(ctx->png_ptr)))
+        ERROR("libpng");
+
+    // write it in
+    png_write_row(ctx->png_ptr, rowbuf);
+
+    // success
+    return 0;
+
+error:
+    _render_png_free(ctx);
+    return -1;
+}
+
+int render_png_done (struct render_png *ctx) {
+    // libpng error handling
+    if (setjmp(png_jmpbuf(ctx->png_ptr)))
+        ERROR("libpng");
+
+    // write end
+    png_write_end(ctx->png_ptr, ctx->info_ptr);
+
+    // success
+    return 0;
+
+error:
+    _render_png_free(ctx);
+    return -1;
+}
+
+int render_png_abort (struct render_png *ctx) {
+    // libpng error handling
+    if (setjmp(png_jmpbuf(ctx->png_ptr)))
+        ERROR("libpng");
+
+    _render_png_free(ctx);
+
+    // success
+    return 0;
+
+error:
+    return -1;
+}
+