Code refactor: move OIIO image buffer writing outside session, into callback.

Original patch by Guillaume, modifications by Brecht.

Differential Revision: https://developer.blender.org/D3102

intern/cycles/app/cycles_standalone.cpp

@@ -51,6 +51,7 @@ struct Options {
 	SessionParams session_params;
 	bool quiet;
 	bool show_help, interactive, pause;
+	string output_path;
 } options;
 
 static void session_print(const string& str)
@@ -86,6 +87,34 @@ static void session_print_status()
 	session_print(status);
 }
 
+static bool write_render(const uchar *pixels, int w, int h, int channels)
+{
+	string msg = string_printf("Writing image %s", options.output_path.c_str());
+	session_print(msg);
+
+	ImageOutput *out = ImageOutput::create(options.output_path);
+	if(!out) {
+		return false;
+	}
+
+	ImageSpec spec(w, h, channels, TypeDesc::UINT8);
+	if(!out->open(options.output_path, spec)) {
+		return false;
+	}
+
+	/* conversion for different top/bottom convention */
+	out->write_image(TypeDesc::UINT8,
+		pixels + (h - 1) * w * channels,
+		AutoStride,
+		-w * channels,
+		AutoStride);
+
+	out->close();
+	delete out;
+
+	return true;
+}
+
 static BufferParams& session_buffer_params()
 {
 	static BufferParams buffer_params;
@@ -120,6 +149,7 @@ static void scene_init()
 
 static void session_init()
 {
+	options.session_params.write_render_cb = write_render;
 	options.session = new Session(options.session_params);
 
 	if(options.session_params.background && !options.quiet)
@@ -364,7 +394,7 @@ static void options_parse(int argc, const char **argv)
 		"--background", &options.session_params.background, "Render in background, without user interface",
 		"--quiet", &options.quiet, "In background mode, don't print progress messages",
 		"--samples %d", &options.session_params.samples, "Number of samples to render",
-		"--output %s", &options.session_params.output_path, "File path to write output image",
+		"--output %s", &options.output_path, "File path to write output image",
 		"--threads %d", &options.session_params.threads, "CPU Rendering Threads",
 		"--width  %d", &options.width, "Window width in pixel",
 		"--height %d", &options.height, "Window height in pixel",

intern/cycles/render/buffers.cpp

@@ -21,7 +21,6 @@
 
 #include "util/util_foreach.h"
 #include "util/util_hash.h"
-#include "util/util_image.h"
 #include "util/util_math.h"
 #include "util/util_opengl.h"
 #include "util/util_time.h"
@@ -448,37 +447,5 @@ bool DisplayBuffer::draw_ready()
 	return (draw_width != 0 && draw_height != 0);
 }
 
-void DisplayBuffer::write(const string& filename)
-{
-	int w = draw_width;
-	int h = draw_height;
-
-	if(w == 0 || h == 0)
-		return;
-	
-	if(half_float)
-		return;
-
-	/* read buffer from device */
-	uchar4 *pixels = rgba_byte.copy_from_device(0, w, h);
-
-	/* write image */
-	ImageOutput *out = ImageOutput::create(filename);
-	ImageSpec spec(w, h, 4, TypeDesc::UINT8);
-
-	out->open(filename, spec);
-
-	/* conversion for different top/bottom convention */
-	out->write_image(TypeDesc::UINT8,
-		(uchar*)(pixels + (h-1)*w),
-		AutoStride,
-		-w*sizeof(uchar4),
-		AutoStride);
-
-	out->close();
-
-	delete out;
-}
-
 CCL_NAMESPACE_END
 

intern/cycles/render/buffers.h

@@ -113,7 +113,6 @@ public:
 	~DisplayBuffer();
 
 	void reset(BufferParams& params);
-	void write(const string& filename);
 
 	void draw_set(int width, int height);
 	void draw(Device *device, const DeviceDrawParams& draw_params);

intern/cycles/render/session.cpp

@@ -55,7 +55,7 @@ Session::Session(const SessionParams& params_)
 
 	device = Device::create(params.device, stats, params.background);
 
-	if(params.background && params.output_path.empty()) {
+	if(params.background && !params.write_render_cb) {
 		buffers = NULL;
 		display = NULL;
 	}
@@ -101,7 +101,7 @@ Session::~Session()
 		wait();
 	}
 
-	if(!params.output_path.empty()) {
+	if(params.write_render_cb) {
 		/* tonemap and write out image if requested */
 		delete display;
 
@@ -109,8 +109,10 @@ Session::~Session()
 		display->reset(buffers->params);
 		tonemap(params.samples);
 
-		progress.set_status("Writing Image", params.output_path);
-		display->write(params.output_path);
+		int w = display->draw_width;
+		int h = display->draw_height;
+		uchar4 *pixels = display->rgba_byte.copy_from_device(0, w, h);
+		params.write_render_cb((uchar*)pixels, w, h, 4);
 	}
 
 	/* clean up */

intern/cycles/render/session.h

@@ -45,7 +45,6 @@ public:
 	DeviceInfo device;
 	bool background;
 	bool progressive_refine;
-	string output_path;
 
 	bool progressive;
 	bool experimental;
@@ -71,11 +70,15 @@ public:
 
 	ShadingSystem shadingsystem;
 
+	function<bool(const uchar *pixels,
+	              int width,
+	              int height,
+	              int channels)> write_render_cb;
+
 	SessionParams()
 	{
 		background = false;
 		progressive_refine = false;
-		output_path = "";
 
 		progressive = false;
 		experimental = false;
@@ -106,7 +109,6 @@ public:
 	{ return !(device == params.device
 		&& background == params.background
 		&& progressive_refine == params.progressive_refine
-		&& output_path == params.output_path
 		/* && samples == params.samples */
 		&& progressive == params.progressive
 		&& experimental == params.experimental