[gdk-pixbuf/wip/otte/tga: 10/24] tga: Add tga_read_pixel() function and use it.

[Benjamin Otte <otte src gnome org>]

commit 223f6ef9861f82e400a640277f0c18164889cc66
Author: Benjamin Otte <otte redhat com>
Date:   Sun Sep 20 18:54:30 2015 +0200

    tga: Add tga_read_pixel() function and use it.

 gdk-pixbuf/io-tga.c |   84 ++++++++++++++++++++++++++++++++++----------------
 1 files changed, 57 insertions(+), 27 deletions(-)
---
diff --git a/gdk-pixbuf/io-tga.c b/gdk-pixbuf/io-tga.c
index b4ab70b..0ee1a5b 100644
--- a/gdk-pixbuf/io-tga.c
+++ b/gdk-pixbuf/io-tga.c
@@ -261,6 +261,43 @@ tga_format_supported (guint type,
     }
 }
 
+static inline void
+tga_read_pixel (TGAContext   *ctx,
+                const guchar *data,
+                TGAColor     *color)
+{
+  switch (ctx->hdr->type)
+    {
+      case TGA_TYPE_PSEUDOCOLOR:
+      case TGA_TYPE_RLE_PSEUDOCOLOR:
+        *color = *colormap_get_color (ctx->cmap, data[0]);
+        break;
+
+      case TGA_TYPE_TRUECOLOR:
+      case TGA_TYPE_RLE_TRUECOLOR:
+        color->b = data[0];
+        color->g = data[1];
+        color->r = data[2];
+        if (ctx->hdr->bpp == 32)
+          color->a = data[3];
+        else
+          color->a = 255;
+        break;
+
+      case TGA_TYPE_GRAYSCALE:
+      case TGA_TYPE_RLE_GRAYSCALE:
+        color->r = color->g = color->b = data[0];
+        if (ctx->hdr->bpp == 16)
+          color->a = data[1];
+        else
+          color->a = 255;
+        break;
+
+      default:
+        g_assert_not_reached ();
+    }
+}
+
 static gboolean fill_in_context(TGAContext *ctx, GError **err)
 {
        gboolean alpha;
@@ -307,6 +344,7 @@ static gboolean fill_in_context(TGAContext *ctx, GError **err)
 static gboolean
 parse_data_pseudocolor (TGAContext *ctx)
 {
+  TGAColor color;
   GBytes *bytes;
   gsize i;
   const guchar *data;
@@ -319,7 +357,9 @@ parse_data_pseudocolor (TGAContext *ctx)
 
   for (i = 0; i < ctx->pbuf->width; i++)
     {
-      tga_write_pixel (ctx, colormap_get_color (ctx->cmap, data[i]));
+      tga_read_pixel (ctx, data, &color);
+      tga_write_pixel (ctx, &color);
+      data++;
     }
 
   g_bytes_unref (bytes);
@@ -338,17 +378,11 @@ parse_data_truecolor (TGAContext *ctx)
   if (bytes == NULL)
     return FALSE;
 
-  color.a = 255;
   data = g_bytes_get_data (bytes, NULL);
 
   for (i = 0; i < ctx->pbuf->width; i++)
     {
-      color.r = data[2];
-      color.g = data[1];
-      color.b = data[0];
-      if (ctx->pbuf->n_channels == 4)
-        color.a = data[3];
-
+      tga_read_pixel (ctx, data, &color);
       tga_write_pixel (ctx, &color);
       data += ctx->pbuf->n_channels;
     }
@@ -378,10 +412,9 @@ parse_data_grayscale (TGAContext *ctx)
 
   for (i = 0; i < ctx->pbuf->width; i++)
     {
-      color.r = color.g = color.b = *s++;
-      if (has_alpha)
-        color.a = *s++;
+      tga_read_pixel (ctx, s, &color);
       tga_write_pixel (ctx, &color);
+      s += has_alpha ? 2 : 1;
     }
 
   g_bytes_unref (bytes);
@@ -429,6 +462,7 @@ static void write_rle_data(TGAContext *ctx, const TGAColor *color, guint *rle_co
 static void
 parse_rle_data_pseudocolor (TGAContext *ctx)
 {
+        TGAColor color;
         GBytes *bytes;
        guint rle_num, raw_num;
        const guchar *s;
@@ -447,7 +481,8 @@ parse_rle_data_pseudocolor (TGAContext *ctx)
                                 break;
                        } else {
                                rle_num = (tag & 0x7f) + 1;
-                               write_rle_data(ctx, colormap_get_color (ctx->cmap, *s), &rle_num);
+                                tga_read_pixel (ctx, s, &color);
+                               write_rle_data(ctx, &color, &rle_num);
                                s++, n++;
                                if (tga_all_pixels_written (ctx))
                                        break;
@@ -459,7 +494,8 @@ parse_rle_data_pseudocolor (TGAContext *ctx)
                                 break;
                        } else {
                                for (; raw_num; raw_num--) {
-                                        tga_write_pixel (ctx, colormap_get_color (ctx->cmap, *s));
+                                        tga_read_pixel (ctx, s, &color);
+                                        tga_write_pixel (ctx, &color);
                                        s++, n++;
                                        if (tga_all_pixels_written (ctx))
                                                break;
@@ -498,11 +534,8 @@ parse_rle_data_truecolor (TGAContext *ctx)
                                 break;
                        } else {
                                rle_num = (tag & 0x7f) + 1;
-                               col.b = *s++;
-                               col.g = *s++;
-                               col.r = *s++;
-                               if (ctx->hdr->bpp == 32)
-                                       col.a = *s++;
+                                tga_read_pixel (ctx, s, &col);
+                               s += ctx->pbuf->n_channels;
                                n += ctx->pbuf->n_channels;
                                write_rle_data(ctx, &col, &rle_num);
                                if (tga_all_pixels_written (ctx))
@@ -515,11 +548,8 @@ parse_rle_data_truecolor (TGAContext *ctx)
                                 break;
                        } else {
                                for (; raw_num; raw_num--) {
-                                       col.b = *s++;
-                                       col.g = *s++;
-                                       col.r = *s++;
-                                       if (ctx->hdr->bpp == 32)
-                                               col.a = *s++;
+                                        tga_read_pixel (ctx, s, &col);
+                                       s += ctx->pbuf->n_channels;
                                        n += ctx->pbuf->n_channels;
                                         tga_write_pixel (ctx, &col);
                                        if (tga_all_pixels_written (ctx))
@@ -561,10 +591,10 @@ parse_rle_data_grayscale (TGAContext *ctx)
                                 break;
                        } else {
                                rle_num = (tag & 0x7f) + 1;
-                               tone.r = tone.g = tone.b = *s;
+                                tga_read_pixel (ctx, s, &tone);
                                s++, n++;
                                if (ctx->pbuf->n_channels == 4) {
-                                       tone.a = *s++;
+                                       s++;
                                        n++;
                                }
                                write_rle_data(ctx, &tone, &rle_num);
@@ -578,10 +608,10 @@ parse_rle_data_grayscale (TGAContext *ctx)
                                 break;
                        } else {
                                for (; raw_num; raw_num--) {
-                                       tone.r = tone.g = tone.b = *s;
+                                        tga_read_pixel (ctx, s, &tone);
                                        s++, n++;
                                        if (ctx->pbuf->n_channels == 4) {
-                                               tone.a = *s++;
+                                               s++;
                                                n++;
                                        }
                                         tga_write_pixel (ctx, &tone);