shithub: choc

Download patch

ref: 787ab13a1e7fb5054a082cd0278c125f925e6664
parent: 628e1e152b0d683917e4c55c2f5300a2d252edfd
author: Jonathan Dowland <jon+github@alcopop.org>
date: Wed Jul 15 18:15:42 EDT 2015 

Write out aspect-corrected 1600x1200  PNGs

When writing out PNG screenshots, write out a 1600x1200 PNG with
aspect correction applied.

1600x1200 is the smallest size necessary to do this losslessly:
each pixel is repeated 5 times per row and each row is repeated
6 times.

The resulting shots are still smaller than their PCX equivalents.
For the Doom 1 titlepic, 320x200 PCX is 77K, 1600x1200 PNG 65k.

Thanks to Simon, Alex and Andrew for discussing the approach taken;
Fabian, Mike and Alexandre-Xavier for further discussion.


--- a/src/v_video.c
+++ b/src/v_video.c
@@ -719,7 +719,7 @@
 }
 
 void WritePNGfile(char *filename, byte *data,
-                  int width, int height,
+                  int inwidth, int inheight,
                   byte *palette)
 {
     png_structp ppng;
@@ -726,8 +726,14 @@
     png_infop pinfo;
     png_colorp pcolor;
     FILE *handle;
-    int i;
+    int i, j;
+    int width, height;
+    byte *rowbuf;
 
+    // scale up to accommodate aspect ratio correction
+    width = inwidth * 5;
+    height = inheight * 6;
+
     handle = fopen(filename, "wb");
     if (!handle)
     {
@@ -773,9 +779,26 @@
 
     png_write_info(ppng, pinfo);
 
-    for (i = 0; i < SCREENHEIGHT; i++)
+    rowbuf = malloc(width);
+
+    if (rowbuf)
     {
-        png_write_row(ppng, data + i*SCREENWIDTH);
+        for (i = 0; i < SCREENHEIGHT; i++)
+        {
+            // expand the row 5x
+            for (j = 0; j < SCREENWIDTH; j++)
+            {
+                memset(rowbuf + j * 5, *(data + i*SCREENWIDTH + j), 5);
+            }
+
+            // write the row 6 times
+            for (j = 0; j < 6; j++)
+            {
+                png_write_row(ppng, rowbuf);
+            }
+        }
+
+        free(rowbuf);
     }
 
     png_write_end(ppng, pinfo);