added another example and (untested) jpg support

ImageStreams.xcodeproj/project.pbxproj

@@ -33,6 +33,7 @@
 		4263431915FA67D500977AF9 /* png.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = png.hpp; sourceTree = "<group>"; };
 		4263431A15FA686300977AF9 /* basics.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = basics.hpp; sourceTree = "<group>"; };
 		4263431B15FA6A3200977AF9 /* libpng.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = libpng.framework; path = Library/Frameworks/libpng.framework; sourceTree = SDKROOT; };
+		4263431D1604A79F00977AF9 /* jpg.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = jpg.hpp; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -72,6 +73,7 @@
 				4263431A15FA686300977AF9 /* basics.hpp */,
 				4263431815FA679600977AF9 /* bmp.hpp */,
 				4263431915FA67D500977AF9 /* png.hpp */,
+				4263431D1604A79F00977AF9 /* jpg.hpp */,
 			);
 			path = ImageStreams;
 			sourceTree = "<group>";

ImageStreams/jpg.hpp

@@ -0,0 +1,89 @@
+//
+//  jpg.hpp
+//  ImageStreams
+//
+//  Created by Joshua Moerman on 9/15/12.
+//  Copyright (c) 2012 Vadovas. All rights reserved.
+//
+
+#ifndef ImageStreams_jpg_hpp
+#define ImageStreams_jpg_hpp
+
+#include <stdio.h>
+#include <stdexcept>
+#include <vector>
+#include <jpeglib.h>
+#include "basics.hpp"
+
+/*
+ JPEG only supports 8bits or 24bits per pixel (eg grayscale or full color).
+ Top to bottom
+ */
+
+namespace jpg{
+	
+	template <typename P = pixel_formats::rgb>
+	struct ostream{
+		typedef P pixel;
+		
+		ostream() = delete;
+		ostream(ostream const &) = delete;
+		ostream & operator=(ostream const &) = delete;
+		
+		ostream(uint32_t width, uint32_t height, std::string filename)
+		: fp(0)
+		, cinfo()
+		, jerr()
+		, row(width)
+		, x(0)
+		{
+			fp = fopen(filename.c_str(), "wb");
+			if(!fp) throw std::runtime_error("Could not open file");
+			
+			cinfo.err = jpeg_std_error(&jerr);
+			jpeg_create_compress(&cinfo);
+			jpeg_stdio_dest(&cinfo, fp);
+			
+			cinfo.image_width      = width;
+			cinfo.image_height     = height;
+			cinfo.input_components = pixel_formats::traits<pixel>::num_colors;
+			//cinfo.in_color_space   = JCS_RGB;	// or JCS_GRAYSCALE, will be set in jpeg_set_defaults()
+			
+			jpeg_set_defaults(&cinfo);
+			//jpeg_set_quality(&cinfo, 75, true);	// quality in [0, 100], boolean indicates "force_baseline" (only matters when quality < 25)
+			jpeg_start_compress(&cinfo, true);	// true means we will write completely
+		}
+		
+		~ostream(){
+			jpeg_finish_compress(&cinfo);
+			fclose(fp);
+			jpeg_destroy_compress(&cinfo);
+		}
+		
+		ostream& operator<<(pixel const & p){
+			row[x] = p;
+			++x;
+			if(x >= row.size()){
+				// this will return the number of scanlines written
+				jpeg_write_scanlines(&cinfo, reinterpret_cast<unsigned char const*>(row.data()), 1);
+				x = 0;
+			}
+			
+			return *this;
+		}
+		
+	private:
+		FILE* fp;
+		jpeg_compress_struct cinfo;
+		jpeg_error_mgr jerr;
+		
+		std::vector<pixel> row;
+		uint32_t x;
+	};
+	
+	typedef ostream<> colored_ostream;
+	typedef ostream<pixel_formats::gray> gray_ostream;
+	
+}
+
+#endif

ImageStreams/main.cpp

@@ -91,12 +91,29 @@ void logistic(std::string filename) {
 	
 	ImageType image(size, size, filename);
 	for(int i = 0; i < size*size; ++i){
-		double c = start + i * (end - start) / (size*size);
+		double c = start + i * (end - start) / double(size*size - 1);
 		// I know; the order of evaluation is implementation defined
 		image << typename ImageType::pixel(x = logistic_step(x, c), x = logistic_step(x, c), x = logistic_step(x, c));
 	}
 }
 
+template <typename ImageType>
+void logistic2(std::string filename) {
+	size_t width = 1280;
+	size_t height = 800;
+	double start = 3.847;
+	double end = 3.9;
+	
+	ImageType image(width, height, filename);
+	for(int y = 0; y < height; ++y){
+		double z = 0.5 * y / double(height - 1);
+		for(int x = 0; x < width; ++x){
+			double c = start + x * (end - start) / double(width - 1);
+			image << typename ImageType::pixel(z = logistic_step(z, c), z = logistic_step(z, c), z = logistic_step(z, c));
+		}
+	}
+}
+
 int main(int argc, const char * argv[]){
 	xor_color<png::colored_ostream>("xor_color.png");
 	xor_color<bmp::colored_ostream>("xor_color.bmp");
@@ -112,5 +129,8 @@ int main(int argc, const char * argv[]){
 	
 	logistic<png::colored_ostream>("logistic.png");
 	logistic<bmp::colored_ostream>("logistic.bmp");
+	
+	logistic2<png::colored_ostream>("logistic2.png");
+	logistic2<bmp::colored_ostream>("logistic2.bmp");
 }