[gimp/pippin/linear-is-the-new-black: 7/19] app: gimp_composite_blend do fish computation before processing

[Øyvind Kolås <ok src gnome org>]

commit 4c9e69c8c53ab5fc2916470b180597fb9df01297
Author: Øyvind Kolås <pippin gimp org>
Date:   Tue Jan 17 14:28:05 2017 +0100

    app: gimp_composite_blend do fish computation before processing
    
    Thus making the code easier to read and more generic.

 .../layer-modes/gimpoperationpointlayermode.c      |    4 +
 .../layer-modes/gimpoperationpointlayermode.h      |  149 ++++++++++----------
 2 files changed, 78 insertions(+), 75 deletions(-)
---
diff --git a/app/operations/layer-modes/gimpoperationpointlayermode.c 
b/app/operations/layer-modes/gimpoperationpointlayermode.c
index aca474c..8e47edf 100644
--- a/app/operations/layer-modes/gimpoperationpointlayermode.c
+++ b/app/operations/layer-modes/gimpoperationpointlayermode.c
@@ -68,8 +68,10 @@ G_DEFINE_TYPE (GimpOperationPointLayerMode, gimp_operation_point_layer_mode,
 
 const Babl *_gimp_fish_rgba_to_perceptual = NULL;
 const Babl *_gimp_fish_perceptual_to_rgba = NULL;
+const Babl *_gimp_fish_perceptual_to_laba = NULL;
 const Babl *_gimp_fish_rgba_to_laba = NULL;
 const Babl *_gimp_fish_laba_to_rgba = NULL;
+const Babl *_gimp_fish_laba_to_perceptual = NULL;
 
 static void
 gimp_operation_point_layer_mode_class_init (GimpOperationPointLayerModeClass *klass)
@@ -126,8 +128,10 @@ gimp_operation_point_layer_mode_class_init (GimpOperationPointLayerModeClass *kl
   {
     _gimp_fish_rgba_to_perceptual = babl_fish ("RGBA float", "R'G'B'A float");
     _gimp_fish_perceptual_to_rgba = babl_fish ("R'G'B'A float", "RGBA float");
+    _gimp_fish_perceptual_to_laba = babl_fish ("R'G'B'A float", "CIE Lab alpha float");
     _gimp_fish_rgba_to_laba = babl_fish ("RGBA float", "CIE Lab alpha float");
     _gimp_fish_laba_to_rgba = babl_fish ("CIE Lab alpha float", "RGBA float");
+    _gimp_fish_laba_to_perceptual = babl_fish ("CIE Lab alpha float", "R'G'B'A float");
   }
 }
 
diff --git a/app/operations/layer-modes/gimpoperationpointlayermode.h 
b/app/operations/layer-modes/gimpoperationpointlayermode.h
index 66539cb..225784b 100644
--- a/app/operations/layer-modes/gimpoperationpointlayermode.h
+++ b/app/operations/layer-modes/gimpoperationpointlayermode.h
@@ -61,8 +61,10 @@ GType   gimp_operation_point_layer_mode_get_type (void) G_GNUC_CONST;
 
 extern const Babl *_gimp_fish_rgba_to_perceptual;
 extern const Babl *_gimp_fish_perceptual_to_rgba;
+extern const Babl *_gimp_fish_perceptual_to_laba;
 extern const Babl *_gimp_fish_rgba_to_laba;
 extern const Babl *_gimp_fish_laba_to_rgba;
+extern const Babl *_gimp_fish_laba_to_perceptual;
 
 static inline void
 gimp_operation_layer_composite (const gfloat *in,
@@ -116,95 +118,99 @@ gimp_composite_blend (gfloat              *in,
                                               float *out,
                                               int samples))
 {
+  int samples_backup = samples;
   gfloat *blend_in    = in;
   gfloat *blend_layer = layer;
   gfloat *blend_out   = out;
+  const Babl *fish_to_blend;
+  const Babl *fish_to_composite;
+  const Babl *fish_from_composite;
  
+  switch (blend_trc)
+  {
+    case GIMP_LAYER_BLEND_RGB_LINEAR:
+      fish_to_blend = NULL;
+      switch (composite_trc)
+      {
+        default:
+        case GIMP_LAYER_BLEND_RGB_LINEAR:
+          fish_to_composite  = NULL;
+          fish_from_composite = NULL;
+          break;
+        case GIMP_LAYER_BLEND_RGB_PERCEPTUAL:
+          fish_to_composite = _gimp_fish_rgba_to_perceptual;
+          fish_from_composite = _gimp_fish_perceptual_to_rgba;
+          break;
+      }
+      break;
+    case GIMP_LAYER_BLEND_LAB:
+      fish_to_blend   = _gimp_fish_rgba_to_laba;
+      switch (composite_trc)
+      {
+        default:
+        case GIMP_LAYER_BLEND_RGB_LINEAR:
+          fish_to_composite = _gimp_fish_laba_to_rgba;
+          fish_from_composite = NULL;
+          break;
+        case GIMP_LAYER_BLEND_RGB_PERCEPTUAL:
+          fish_to_composite = _gimp_fish_laba_to_perceptual;
+          fish_from_composite = _gimp_fish_perceptual_to_rgba;
+          break;
+      }
+      break;
+    case GIMP_LAYER_BLEND_RGB_PERCEPTUAL:
+      fish_to_blend   = _gimp_fish_rgba_to_perceptual;
+      switch (composite_trc)
+      {
+        default:
+        case GIMP_LAYER_BLEND_RGB_LINEAR:
+          fish_to_composite = _gimp_fish_perceptual_to_rgba;
+          fish_from_composite = NULL;
+          break;
+        case GIMP_LAYER_BLEND_RGB_PERCEPTUAL:
+          fish_to_composite = NULL;
+          fish_from_composite = _gimp_fish_perceptual_to_rgba;
+          break;
+      }
+      break;
+  }
+
   if (blendfun == NULL)
   {
-     switch (composite_trc)
-     {
-       case GIMP_LAYER_BLEND_RGB_LINEAR:
+     if (fish_to_blend == NULL)
+       {
          blend_out = layer;
-         break;
-       case GIMP_LAYER_BLEND_LAB:
+       }
+     else
+       {
          blend_out = alloca (sizeof (gfloat) * 4 * samples);
-         babl_process (_gimp_fish_rgba_to_laba, layer, blend_out, samples);
-         break;
-       case GIMP_LAYER_BLEND_RGB_PERCEPTUAL:
-         blend_out = alloca (sizeof (gfloat) * 4 * samples);
-         babl_process (_gimp_fish_rgba_to_perceptual, layer, blend_out, samples);
-         break;
-     }
+         babl_process (fish_to_blend, layer, blend_out, samples);
+       }
   }
-  else if (blend_trc == GIMP_LAYER_BLEND_RGB_LINEAR)
+  else if (fish_to_blend == NULL)
   {
     if (in == out)
       blend_out = alloca (sizeof (gfloat) * 4 * samples);
 
     blendfun (blend_in, blend_layer, blend_out, samples);
-
-    switch (composite_trc)
+    if (fish_to_composite)
     {
-      case GIMP_LAYER_BLEND_RGB_LINEAR:
-        break;
-      case GIMP_LAYER_BLEND_LAB:
-        babl_process (_gimp_fish_rgba_to_laba, blend_out, blend_out, samples);
-        break;
-      case GIMP_LAYER_BLEND_RGB_PERCEPTUAL:
-        babl_process (_gimp_fish_rgba_to_perceptual, blend_out, blend_out, samples);
-        break;
+      babl_process (fish_to_composite, blend_out, blend_out, samples);
     }
   }
-  else if (blend_trc == GIMP_LAYER_BLEND_RGB_PERCEPTUAL)
-  {
+  else {
     blend_in    = alloca (sizeof (gfloat) * 4 * samples);
     blend_layer = alloca (sizeof (gfloat) * 4 * samples);
 
     if (in == out)
       blend_out   = alloca (sizeof (gfloat) * 4 * samples);
-
-    babl_process (_gimp_fish_rgba_to_perceptual, in, blend_in, samples);
-    babl_process (_gimp_fish_rgba_to_perceptual, layer, blend_layer, samples);
- 
-    blendfun (blend_in, blend_layer, blend_out, samples);
- 
-    switch (composite_trc)
-    {
-      case GIMP_LAYER_BLEND_RGB_LINEAR:
-        babl_process (_gimp_fish_perceptual_to_rgba, blend_out, blend_out, samples);
-        break;
-      case GIMP_LAYER_BLEND_LAB:
-        babl_process (_gimp_fish_perceptual_to_rgba, blend_out, blend_out, samples);
-        // XXX : double conversion - could be avoided with custom fish
-        babl_process (_gimp_fish_rgba_to_laba, blend_out, blend_out, samples);
-        break;
-      case GIMP_LAYER_BLEND_RGB_PERCEPTUAL:
-        break;
-    }
-  }
-  else if (blend_trc == GIMP_LAYER_BLEND_LAB)
-  {
-    blend_in    = alloca (sizeof (gfloat) * 4 * samples);
-    blend_layer = alloca (sizeof (gfloat) * 4 * samples);
-    babl_process (_gimp_fish_rgba_to_laba, in, blend_in, samples);
-    babl_process (_gimp_fish_rgba_to_laba, layer, blend_layer, samples);
-    if (in == out)
-      blend_out   = alloca (sizeof (gfloat) * 4 * samples);
- 
+    babl_process (fish_to_blend, in, blend_in, samples);
+    babl_process (fish_to_blend, layer, blend_layer, samples);
     blendfun (blend_in, blend_layer, blend_out, samples);
 
-    switch (composite_trc)
+    if (fish_to_composite)
     {
-      case GIMP_LAYER_BLEND_RGB_LINEAR:
-        babl_process (_gimp_fish_laba_to_rgba, blend_out, blend_out, samples);
-        break;
-      case GIMP_LAYER_BLEND_LAB:
-        break;
-      case GIMP_LAYER_BLEND_RGB_PERCEPTUAL:
-        babl_process (_gimp_fish_laba_to_rgba, blend_out, blend_out, samples);
-        babl_process (_gimp_fish_perceptual_to_rgba, blend_out, blend_out, samples);
-        break;
+      babl_process (fish_to_composite, blend_out, blend_out, samples);
     }
   }
  
@@ -338,18 +344,11 @@ gimp_composite_blend (gfloat              *in,
       break;
   }
 
-  switch (composite_trc)
+  if (fish_from_composite)
   {
-    case GIMP_LAYER_BLEND_RGB_LINEAR:
-      break;
-    case GIMP_LAYER_BLEND_LAB:
-      out -= 4 * samples;
-      babl_process (_gimp_fish_laba_to_rgba, out, out, samples);
-      break;
-    case GIMP_LAYER_BLEND_RGB_PERCEPTUAL:
-      out -= 4 * samples;
-      babl_process (_gimp_fish_perceptual_to_rgba, out, out, samples);
-      break;
+    samples = samples_backup;
+    out -= 4 * samples;
+    babl_process (fish_from_composite, out, out, samples);
   }
 }