[4/4] gdiplus: Add support for reading png gAMA chunks.

[Vincent Povirk]

-------------- next part --------------
From 36978ee9548b8a3d8ff180418b62091484495e8f Mon Sep 17 00:00:00 2001
From: Vincent Povirk <vincent at codeweavers.com>
Date: Wed, 1 Apr 2015 15:26:00 -0500
Subject: [PATCH 4/6] gdiplus: Add support for reading png gAMA chunks.

---
 dlls/gdiplus/image.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/dlls/gdiplus/image.c b/dlls/gdiplus/image.c
index 643cf6c..4d58834 100644
--- a/dlls/gdiplus/image.c
+++ b/dlls/gdiplus/image.c
@@ -3456,6 +3456,7 @@ static void png_metadata_reader(GpBitmap *bitmap, IWICBitmapDecoder *decoder, UI
         { "Source", PropertyTagEquipModel },
         { "Comment", PropertyTagExifUserComment },
     };
+    BOOL seen_gamma=FALSE;
 
     hr = IWICBitmapDecoder_GetFrame(decoder, active_frame, &frame);
     if (hr != S_OK) return;
@@ -3502,6 +3503,35 @@ static void png_metadata_reader(GpBitmap *bitmap, IWICBitmapDecoder *decoder, UI
                             PropVariantClear(&value);
                         }
                     }
+                    else if (SUCCEEDED(hr) && IsEqualGUID(&GUID_MetadataFormatChunkgAMA, &format))
+                    {
+                        PROPVARIANT value;
+                        PropertyItem* item;
+
+                        hr = IWICMetadataReader_GetValueByIndex(reader, 0, NULL, NULL, &value);
+
+                        if (SUCCEEDED(hr))
+                        {
+                            if (!seen_gamma && value.vt == VT_UI4)
+                            {
+                                item = GdipAlloc(sizeof(PropertyItem) + sizeof(ULONG) * 2);
+                                if (item)
+                                {
+                                    ULONG *rational;
+                                    item->length = sizeof(ULONG) * 2;
+                                    item->type = PropertyTagTypeRational;
+                                    item->id = PropertyTagGamma;
+                                    rational = item->value = item + 1;
+                                    rational[0] = 100000;
+                                    rational[1] = value.u.ulVal;
+                                    add_property(bitmap, item);
+                                    seen_gamma = TRUE;
+                                    GdipFree(item);
+                                }
+                            }
+                            PropVariantClear(&value);
+                        }
+                    }
 
                     IWICMetadataReader_Release(reader);
                 }
-- 
2.1.0