The Independent JPEG Group's JPEG software v1

1991-10-07 00:00:00 +00:00
commit 2cbeb8abd9
53 changed files with 13965 additions and 0 deletions
--- a/jrdppm.c
+++ b/jrdppm.c
@@ -0,0 +1,124 @@
+/*
+ * jrdppm.c
+ *
+ * Copyright (C) 1991, Thomas G. Lane.
+ * This file is part of the Independent JPEG Group's software.
+ * For conditions of distribution and use, see the accompanying README file.
+ *
+ * This file contains routines to read input images in PPM format.
+ * The PBMPLUS library is required (well, it will be in the real version).
+ *
+ * These routines may need modification for non-Unix environments or
+ * specialized applications.  As they stand, they assume input from
+ * an ordinary stdio stream.  They further assume that reading begins
+ * at the start of the file; input_init may need work if the
+ * user interface has already read some data (e.g., to determine that
+ * the file is indeed PPM format).
+ *
+ * These routines are invoked via the methods get_input_row
+ * and input_init/term.
+ */
+
+#include "jinclude.h"
+
+#ifdef PPM_SUPPORTED
+
+
+/*
+ * Read the file header; return image size and component count.
+ */
+
+METHODDEF void
+input_init (compress_info_ptr cinfo)
+{
+  int c, w, h, prec;
+
+  if (getc(cinfo->input_file) != 'P')
+    ERREXIT(cinfo->emethods, "Not a PPM file");
+
+  c = getc(cinfo->input_file);
+  switch (c) {
+  case '5':			/* it's a PGM file */
+    cinfo->input_components = 1;
+    cinfo->in_color_space = CS_GRAYSCALE;
+    break;
+
+  case '6':			/* it's a PPM file */
+    cinfo->input_components = 3;
+    cinfo->in_color_space = CS_RGB;
+    break;
+
+  default:
+    ERREXIT(cinfo->emethods, "Not a PPM file");
+    break;
+  }
+
+  if (fscanf(cinfo->input_file, " %d %d %d", &w, &h, &prec) != 3)
+    ERREXIT(cinfo->emethods, "Not a PPM file");
+
+  if (getc(cinfo->input_file) != '\n' || w <= 0 || h <= 0 || prec != 255)
+    ERREXIT(cinfo->emethods, "Not a PPM file");
+
+  cinfo->image_width = w;
+  cinfo->image_height = h;
+  cinfo->data_precision = 8;
+}
+
+
+/*
+ * Read one row of pixels.
+ */
+
+METHODDEF void
+get_input_row (compress_info_ptr cinfo, JSAMPARRAY pixel_row)
+{
+  register FILE * infile = cinfo->input_file;
+  register JSAMPROW ptr0, ptr1, ptr2;
+  register long col;
+  
+  if (cinfo->input_components == 1) {
+    ptr0 = pixel_row[0];
+    for (col = cinfo->image_width; col > 0; col--) {
+      *ptr0++ = getc(infile);
+    }
+  } else {
+    ptr0 = pixel_row[0];
+    ptr1 = pixel_row[1];
+    ptr2 = pixel_row[2];
+    for (col = cinfo->image_width; col > 0; col--) {
+      *ptr0++ = getc(infile);
+      *ptr1++ = getc(infile);
+      *ptr2++ = getc(infile);
+    }
+  }
+}
+
+
+/*
+ * Finish up at the end of the file.
+ */
+
+METHODDEF void
+input_term (compress_info_ptr cinfo)
+{
+  /* no work required */
+}
+
+
+/*
+ * The method selection routine for PPM format input.
+ * Note that this must be called by the user interface before calling
+ * jpeg_compress.  If multiple input formats are supported, the
+ * user interface is responsible for discovering the file format and
+ * calling the appropriate method selection routine.
+ */
+
+GLOBAL void
+jselrppm (compress_info_ptr cinfo)
+{
+  cinfo->methods->input_init = input_init;
+  cinfo->methods->get_input_row = get_input_row;
+  cinfo->methods->input_term = input_term;
+}
+
+#endif /* PPM_SUPPORTED */