JP2: combine sRGB and Grayscale reading functions

Signed-off-by: mio <stigma@disroot.org>

kimgio/jp2.cpp

@@ -20,6 +20,7 @@
 #include <openjpeg.h>
 
 #include <kdebug.h>
+#include <tdeglobal.h>
 #include <tdetempfile.h>
 #include <tqcolor.h>
 #include <tqcstring.h>
@@ -36,10 +37,6 @@
  * - Doesn't support OPJ_CODEC_J2K.
  * - Doesn't support subsampling.
  * - Doesn't read ICC profiles.
- * - Doesn't write images.
- *
- * Improvements:
- * - kimgio_jp2_read_srgba/kimgio_jp2_read_grayscale could be merged.
  *
  * The API documentation is rather poor, so good references on how to use OpenJPEG
  * are the tools provided by OpenJPEG, such as 'opj_decompress':
@@ -91,48 +88,7 @@ static void kimgio_jp2_warn_handler(const char *message, void *data)
     kdWarning(kCategory) << "Warning decoding JP2 image: " << message;
 }
 
-static void kimgio_jp2_read_srgba(TQImage &image, const KIMGJP2Wrapper &jp2)
-{
-    const int height = image.height();
-    const int width = image.width();
-
-    unsigned char alphaMask = 0x0;
-
-    for (int row = 0; row < height; row++)
-    {
-        for (int col = 0; col < width; col++)
-        {
-            const int offset = row * width + col;
-            OPJ_INT32 r, g, b, a = 0xFF;
-
-            // Convert to unsigned
-            r = jp2.image->comps[0].data[offset];
-            r += (jp2.image->comps[0].sgnd ? 1 << (jp2.image->comps[0].prec - 1) : 0);
-
-            g = jp2.image->comps[1].data[offset];
-            g += (jp2.image->comps[0].sgnd ? 1 << (jp2.image->comps[1].prec - 1) : 0);
-
-            b = jp2.image->comps[2].data[offset];
-            b += (jp2.image->comps[2].sgnd ? 1 << (jp2.image->comps[2].prec - 1) : 0);
-
-            if (jp2.image->numcomps > 3 && jp2.image->comps[3].alpha)
-            {
-                a = jp2.image->comps[3].data[offset];
-                a += (jp2.image->comps[3].sgnd ? 1 << (jp2.image->comps[3].prec - 1) : 0);
-            }
-
-            image.setPixel(col, row, tqRgba(r, g, b, a));
-            alphaMask |= (255 - a);
-        }
-    }
-
-    if (alphaMask != 0x0)
-    {
-        image.setAlphaBuffer(true);
-    }
-}
-
-static void kimgio_jp2_read_grayscale(TQImage &image, const KIMGJP2Wrapper &jp2)
+static void kimgio_jp2_read_image(TQImage &image, const KIMGJP2Wrapper &jp2)
 {
     const int height = image.height();
     const int width = image.width();
@@ -144,20 +100,63 @@ static void kimgio_jp2_read_grayscale(TQImage &image, const KIMGJP2Wrapper &jp2)
         for (int col = 0; col < width; col++)
         {
             const int offset = row * width + col;
-            OPJ_INT32 g, a = 0xFF;
+            uint8_t rgba[4] = { 0x00, 0x00, 0x00, 0xFF };
 
-            // Convert to unsigned
-            g = jp2.image->comps[0].data[offset];
-            g += (jp2.image->comps[0].sgnd ? (1 << jp2.image->comps[0].prec - 1) : 0);
-
-            if (jp2.image->numcomps > 1 && jp2.image->comps[1].alpha)
+            for (int comp = 0; comp < jp2.image->numcomps; comp++)
             {
-                a = jp2.image->comps[1].data[offset];
-                a = (jp2.image->comps[1].sgnd ? (1 << jp2.image->comps[1].prec - 1) : 0);
+                OPJ_INT32 value = jp2.image->comps[comp].data[offset];
+                value += (jp2.image->comps[comp].sgnd ? (1 << jp2.image->comps[comp].prec - 1) : 0);
+                value = kClamp(value, 0, 255);
+
+                switch (comp)
+                {
+                    case 0:
+                    {
+                        // Red or Grayscale
+                        rgba[0] = value;
+                        rgba[1] = value;
+                        rgba[2] = value;
+                        break;
+                    }
+                    case 1:
+                    {
+                        if ((jp2.image->color_space == OPJ_CLRSPC_GRAY) &&
+                            (jp2.image->comps[comp].alpha != 0))
+                        {
+                            // Grayscale with Alpha
+                            rgba[3] = value;
+                        }
+                        else
+                        {
+                            // Green
+                            rgba[1] = value;
+                        }
+                        break;
+                    }
+                    case 2:
+                    {
+                        // Blue
+                        rgba[2] = value;
+                        break;
+                    }
+                    case 3:
+                    {
+                        // Alpha?
+                        if (jp2.image->comps[comp].alpha != 0)
+                        {
+                            rgba[3] = value;
+                        }
+                        break;
+                    }
+                    default:
+                    {
+                        break;
+                    }
+                }
             }
 
-            image.setPixel(col, row, tqRgba(g, g, g, a));
-            alphaMask |= (255 - a);
+            image.setPixel(col, row, tqRgba(rgba[0], rgba[1], rgba[2], rgba[3]));
+            alphaMask |= (255 - rgba[3]);
         }
     }
 
@@ -297,13 +296,9 @@ TDE_EXPORT void kimgio_jp2_read(TQImageIO* io)
     switch (jp2.image->color_space)
     {
         case OPJ_CLRSPC_SRGB:
-        {
-            kimgio_jp2_read_srgba(image, jp2);
-            break;
-        }
         case OPJ_CLRSPC_GRAY:
         {
-            kimgio_jp2_read_grayscale(image, jp2);
+            kimgio_jp2_read_image(image, jp2);
             break;
         }
         default: