Initial source commit

minorGems/graphics/converters/libpngSample.cpp

@@ -0,0 +1,108 @@
+
+
+
+
+#include <png.h>
+#include <stdio.h>
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+
+
+void abort_(const char * s, ...)
+{
+	va_list args;
+	va_start(args, s);
+	vfprintf(stderr, s, args);
+	fprintf(stderr, "\n");
+	va_end(args);
+	abort();
+}
+
+int main() {
+    
+    int w = 100;
+    int h = 100;
+    
+    unsigned int *data = new unsigned int[ w * h ];
+        
+    // red fades toward bottom
+    // green fades toward right
+    
+    unsigned int **rows = new unsigned int *[ h ];
+
+    for( int y=0; y<h; y++ ) {
+        for( int x=0; x<w; x++ ) {
+            unsigned char red = 255 - ( 255 * y / h );
+            unsigned char green = 255 - ( 255 * x / h );
+            
+            data[ y * w + x ] = red | green << 8 | 255 << 24;
+            }
+
+        rows[y] = &( data[ y * w ] );
+        }
+
+    
+    
+    
+
+	/* create file */
+	FILE *fp = fopen( "test.png", "wb");
+	if (!fp)
+		abort_("[write_png_file] File %s could not be opened for writing",
+               "test.png" );
+    
+    png_structp png_ptr;
+    png_infop info_ptr;
+
+	/* initialize stuff */
+	png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+	
+	if (!png_ptr)
+		abort_("[write_png_file] png_create_write_struct failed");
+
+	info_ptr = png_create_info_struct(png_ptr);
+	if (!info_ptr)
+		abort_("[write_png_file] png_create_info_struct failed");
+
+	if (setjmp(png_jmpbuf(png_ptr)))
+		abort_("[write_png_file] Error during init_io");
+
+	png_init_io(png_ptr, fp);
+
+
+	/* write header */
+	if (setjmp(png_jmpbuf(png_ptr)))
+		abort_("[write_png_file] Error during writing header");
+
+	png_set_IHDR(png_ptr, info_ptr, w, h,
+		     8, PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
+		     PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+	png_write_info(png_ptr, info_ptr);
+
+
+	/* write bytes */
+	if (setjmp(png_jmpbuf(png_ptr)))
+
+		abort_("[write_png_file] Error during writing bytes");
+
+	png_write_image(png_ptr, (png_byte**)rows);
+
+
+	/* end write */
+	if (setjmp(png_jmpbuf(png_ptr)))
+		abort_("[write_png_file] Error during end of write");
+
+	png_write_end(png_ptr, NULL);
+
+    
+    /* cleanup heap allocation */
+	/*for (y=0; y<height; y++)
+		free(row_pointers[y]);
+	free(row_pointers);
+    */
+    fclose(fp);
+    }