[PATCH 8/8] windowscodecs: Add a general wrapper around the decoder interface.

Esme Povirk esme at codeweavers.com
Fri Oct 9 14:56:23 CDT 2020


Signed-off-by: Esme Povirk <esme at codeweavers.com>
---
 dlls/windowscodecs/Makefile.in         |   1 +
 dlls/windowscodecs/decoder.c           | 746 +++++++++++++++++++++++
 dlls/windowscodecs/pngformat.c         | 810 +------------------------
 dlls/windowscodecs/wincodecs_private.h |   3 +
 4 files changed, 765 insertions(+), 795 deletions(-)
 create mode 100644 dlls/windowscodecs/decoder.c

diff --git a/dlls/windowscodecs/Makefile.in b/dlls/windowscodecs/Makefile.in
index fde28aea778..2472ef57d63 100644
--- a/dlls/windowscodecs/Makefile.in
+++ b/dlls/windowscodecs/Makefile.in
@@ -14,6 +14,7 @@ C_SRCS = \
 	colortransform.c \
 	converter.c \
 	ddsformat.c \
+	decoder.c \
 	fliprotate.c \
 	gifformat.c \
 	icnsformat.c \
diff --git a/dlls/windowscodecs/decoder.c b/dlls/windowscodecs/decoder.c
new file mode 100644
index 00000000000..599b5780e8f
--- /dev/null
+++ b/dlls/windowscodecs/decoder.c
@@ -0,0 +1,746 @@
+/*
+ * Copyright 2020 Esme Povirk
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+#include "config.h"
+#include "wine/port.h"
+
+#include <stdarg.h>
+
+#define NONAMELESSUNION
+#define COBJMACROS
+
+#include "windef.h"
+#include "winbase.h"
+#include "objbase.h"
+
+#include "wincodecs_private.h"
+
+#include "wine/debug.h"
+
+WINE_DEFAULT_DEBUG_CHANNEL(wincodecs);
+
+typedef struct {
+    IWICBitmapDecoder IWICBitmapDecoder_iface;
+    LONG ref;
+    CRITICAL_SECTION lock; /* must be held when stream or decoder is accessed */
+    IStream *stream;
+    struct decoder *decoder;
+    struct decoder_info decoder_info;
+    struct decoder_stat file_info;
+    WICDecodeOptions cache_options;
+} CommonDecoder;
+
+static inline CommonDecoder *impl_from_IWICBitmapDecoder(IWICBitmapDecoder *iface)
+{
+    return CONTAINING_RECORD(iface, CommonDecoder, IWICBitmapDecoder_iface);
+}
+
+static HRESULT WINAPI CommonDecoder_QueryInterface(IWICBitmapDecoder *iface, REFIID iid,
+    void **ppv)
+{
+    CommonDecoder *This = impl_from_IWICBitmapDecoder(iface);
+    TRACE("(%p,%s,%p)\n", iface, debugstr_guid(iid), ppv);
+
+    if (!ppv) return E_INVALIDARG;
+
+    if (IsEqualIID(&IID_IUnknown, iid) || IsEqualIID(&IID_IWICBitmapDecoder, iid))
+    {
+        *ppv = &This->IWICBitmapDecoder_iface;
+    }
+    else
+    {
+        *ppv = NULL;
+        return E_NOINTERFACE;
+    }
+
+    IUnknown_AddRef((IUnknown*)*ppv);
+    return S_OK;
+}
+
+static ULONG WINAPI CommonDecoder_AddRef(IWICBitmapDecoder *iface)
+{
+    CommonDecoder *This = impl_from_IWICBitmapDecoder(iface);
+    ULONG ref = InterlockedIncrement(&This->ref);
+
+    TRACE("(%p) refcount=%u\n", iface, ref);
+
+    return ref;
+}
+
+static ULONG WINAPI CommonDecoder_Release(IWICBitmapDecoder *iface)
+{
+    CommonDecoder *This = impl_from_IWICBitmapDecoder(iface);
+    ULONG ref = InterlockedDecrement(&This->ref);
+
+    TRACE("(%p) refcount=%u\n", iface, ref);
+
+    if (ref == 0)
+    {
+        if (This->stream)
+            IStream_Release(This->stream);
+        This->lock.DebugInfo->Spare[0] = 0;
+        DeleteCriticalSection(&This->lock);
+        HeapFree(GetProcessHeap(), 0, This);
+    }
+
+    return ref;
+}
+
+static HRESULT WINAPI CommonDecoder_QueryCapability(IWICBitmapDecoder *iface, IStream *stream,
+    DWORD *capability)
+{
+    CommonDecoder *This = impl_from_IWICBitmapDecoder(iface);
+    HRESULT hr;
+
+    TRACE("(%p,%p,%p)\n", iface, stream, capability);
+
+    if (!stream || !capability) return E_INVALIDARG;
+
+    hr = IWICBitmapDecoder_Initialize(iface, stream, WICDecodeMetadataCacheOnDemand);
+    if (hr != S_OK) return hr;
+
+    *capability = (This->file_info.flags & DECODER_FLAGS_CAPABILITY_MASK);
+    return S_OK;
+}
+
+static HRESULT WINAPI CommonDecoder_Initialize(IWICBitmapDecoder *iface, IStream *pIStream,
+    WICDecodeOptions cacheOptions)
+{
+    CommonDecoder *This = impl_from_IWICBitmapDecoder(iface);
+    HRESULT hr=S_OK;
+
+    TRACE("(%p,%p,%x)\n", iface, pIStream, cacheOptions);
+
+    EnterCriticalSection(&This->lock);
+
+    if (This->stream)
+        hr = WINCODEC_ERR_WRONGSTATE;
+
+    if (SUCCEEDED(hr))
+        hr = decoder_initialize(This->decoder, pIStream, &This->file_info);
+
+    if (SUCCEEDED(hr))
+    {
+        This->cache_options = cacheOptions;
+        This->stream = pIStream;
+        IStream_AddRef(This->stream);
+    }
+
+    LeaveCriticalSection(&This->lock);
+
+    return hr;
+}
+
+static HRESULT WINAPI CommonDecoder_GetContainerFormat(IWICBitmapDecoder *iface,
+    GUID *pguidContainerFormat)
+{
+    CommonDecoder *This = impl_from_IWICBitmapDecoder(iface);
+    memcpy(pguidContainerFormat, &This->decoder_info.container_format, sizeof(GUID));
+    return S_OK;
+}
+
+static HRESULT WINAPI CommonDecoder_GetDecoderInfo(IWICBitmapDecoder *iface,
+    IWICBitmapDecoderInfo **ppIDecoderInfo)
+{
+    CommonDecoder *This = impl_from_IWICBitmapDecoder(iface);
+    TRACE("(%p,%p)\n", iface, ppIDecoderInfo);
+
+    return get_decoder_info(&This->decoder_info.clsid, ppIDecoderInfo);
+}
+
+static HRESULT WINAPI CommonDecoder_CopyPalette(IWICBitmapDecoder *iface,
+    IWICPalette *palette)
+{
+    TRACE("(%p,%p)\n", iface, palette);
+    return WINCODEC_ERR_PALETTEUNAVAILABLE;
+}
+
+static HRESULT WINAPI CommonDecoder_GetMetadataQueryReader(IWICBitmapDecoder *iface,
+    IWICMetadataQueryReader **reader)
+{
+    TRACE("(%p,%p)\n", iface, reader);
+
+    if (!reader) return E_INVALIDARG;
+
+    *reader = NULL;
+    return WINCODEC_ERR_UNSUPPORTEDOPERATION;
+}
+
+static HRESULT WINAPI CommonDecoder_GetPreview(IWICBitmapDecoder *iface,
+    IWICBitmapSource **ppIBitmapSource)
+{
+    TRACE("(%p,%p)\n", iface, ppIBitmapSource);
+
+    if (!ppIBitmapSource) return E_INVALIDARG;
+
+    *ppIBitmapSource = NULL;
+    return WINCODEC_ERR_UNSUPPORTEDOPERATION;
+}
+
+static HRESULT WINAPI CommonDecoder_GetColorContexts(IWICBitmapDecoder *iface,
+    UINT cCount, IWICColorContext **ppIColorContexts, UINT *pcActualCount)
+{
+    TRACE("(%p,%u,%p,%p)\n", iface, cCount, ppIColorContexts, pcActualCount);
+    return WINCODEC_ERR_UNSUPPORTEDOPERATION;
+}
+
+static HRESULT WINAPI CommonDecoder_GetThumbnail(IWICBitmapDecoder *iface,
+    IWICBitmapSource **ppIThumbnail)
+{
+    TRACE("(%p,%p)\n", iface, ppIThumbnail);
+
+    if (!ppIThumbnail) return E_INVALIDARG;
+
+    *ppIThumbnail = NULL;
+    return WINCODEC_ERR_CODECNOTHUMBNAIL;
+}
+
+static HRESULT WINAPI CommonDecoder_GetFrameCount(IWICBitmapDecoder *iface,
+    UINT *pCount)
+{
+    CommonDecoder *This = impl_from_IWICBitmapDecoder(iface);
+    if (!pCount) return E_INVALIDARG;
+
+    if (!This->stream) return WINCODEC_ERR_WRONGSTATE;
+
+    *pCount = This->file_info.frame_count;
+    return S_OK;
+}
+
+static HRESULT WINAPI CommonDecoder_GetFrame(IWICBitmapDecoder *iface,
+    UINT index, IWICBitmapFrameDecode **ppIBitmapFrame);
+
+static const IWICBitmapDecoderVtbl CommonDecoder_Vtbl = {
+    CommonDecoder_QueryInterface,
+    CommonDecoder_AddRef,
+    CommonDecoder_Release,
+    CommonDecoder_QueryCapability,
+    CommonDecoder_Initialize,
+    CommonDecoder_GetContainerFormat,
+    CommonDecoder_GetDecoderInfo,
+    CommonDecoder_CopyPalette,
+    CommonDecoder_GetMetadataQueryReader,
+    CommonDecoder_GetPreview,
+    CommonDecoder_GetColorContexts,
+    CommonDecoder_GetThumbnail,
+    CommonDecoder_GetFrameCount,
+    CommonDecoder_GetFrame
+};
+
+typedef struct {
+    IWICBitmapFrameDecode IWICBitmapFrameDecode_iface;
+    IWICMetadataBlockReader IWICMetadataBlockReader_iface;
+    LONG ref;
+    CommonDecoder *parent;
+    DWORD frame;
+    struct decoder_frame decoder_frame;
+    BOOL metadata_initialized;
+    ULONG metadata_count;
+    struct decoder_block* metadata_blocks;
+} CommonDecoderFrame;
+
+static inline CommonDecoderFrame *impl_from_IWICBitmapFrameDecode(IWICBitmapFrameDecode *iface)
+{
+    return CONTAINING_RECORD(iface, CommonDecoderFrame, IWICBitmapFrameDecode_iface);
+}
+
+static inline CommonDecoderFrame *impl_from_IWICMetadataBlockReader(IWICMetadataBlockReader *iface)
+{
+    return CONTAINING_RECORD(iface, CommonDecoderFrame, IWICMetadataBlockReader_iface);
+}
+
+static HRESULT WINAPI CommonDecoderFrame_QueryInterface(IWICBitmapFrameDecode *iface, REFIID iid,
+    void **ppv)
+{
+    CommonDecoderFrame *This = impl_from_IWICBitmapFrameDecode(iface);
+    if (!ppv) return E_INVALIDARG;
+
+    if (IsEqualIID(&IID_IUnknown, iid) ||
+        IsEqualIID(&IID_IWICBitmapSource, iid) ||
+        IsEqualIID(&IID_IWICBitmapFrameDecode, iid))
+    {
+        *ppv = &This->IWICBitmapFrameDecode_iface;
+    }
+    else if (IsEqualIID(&IID_IWICMetadataBlockReader, iid) &&
+             (This->parent->file_info.flags & WICBitmapDecoderCapabilityCanEnumerateMetadata))
+    {
+        *ppv = &This->IWICMetadataBlockReader_iface;
+    }
+    else
+    {
+        *ppv = NULL;
+        return E_NOINTERFACE;
+    }
+
+    IUnknown_AddRef((IUnknown*)*ppv);
+    return S_OK;
+}
+
+static ULONG WINAPI CommonDecoderFrame_AddRef(IWICBitmapFrameDecode *iface)
+{
+    CommonDecoderFrame *This = impl_from_IWICBitmapFrameDecode(iface);
+    ULONG ref = InterlockedIncrement(&This->ref);
+
+    TRACE("(%p) refcount=%u\n", iface, ref);
+
+    return ref;
+}
+
+static ULONG WINAPI CommonDecoderFrame_Release(IWICBitmapFrameDecode *iface)
+{
+    CommonDecoderFrame *This = impl_from_IWICBitmapFrameDecode(iface);
+    ULONG ref = InterlockedDecrement(&This->ref);
+
+    TRACE("(%p) refcount=%u\n", iface, ref);
+
+    if (ref == 0)
+    {
+        IWICBitmapDecoder_Release(&This->parent->IWICBitmapDecoder_iface);
+        HeapFree(GetProcessHeap(), 0, This->metadata_blocks);
+        HeapFree(GetProcessHeap(), 0, This);
+    }
+
+    return ref;
+}
+
+static HRESULT WINAPI CommonDecoderFrame_GetSize(IWICBitmapFrameDecode *iface,
+    UINT *puiWidth, UINT *puiHeight)
+{
+    CommonDecoderFrame *This = impl_from_IWICBitmapFrameDecode(iface);
+
+    TRACE("(%p,%p,%p)\n", This, puiWidth, puiHeight);
+
+    if (!puiWidth || !puiHeight)
+        return E_POINTER;
+
+    *puiWidth = This->decoder_frame.width;
+    *puiHeight = This->decoder_frame.height;
+    return S_OK;
+}
+
+static HRESULT WINAPI CommonDecoderFrame_GetPixelFormat(IWICBitmapFrameDecode *iface,
+    WICPixelFormatGUID *pPixelFormat)
+{
+    CommonDecoderFrame *This = impl_from_IWICBitmapFrameDecode(iface);
+
+    TRACE("(%p,%p)\n", This, pPixelFormat);
+
+    if (!pPixelFormat)
+        return E_POINTER;
+
+    *pPixelFormat = This->decoder_frame.pixel_format;
+    return S_OK;
+}
+
+static HRESULT WINAPI CommonDecoderFrame_GetResolution(IWICBitmapFrameDecode *iface,
+    double *pDpiX, double *pDpiY)
+{
+    CommonDecoderFrame *This = impl_from_IWICBitmapFrameDecode(iface);
+
+    TRACE("(%p,%p,%p)\n", This, pDpiX, pDpiY);
+
+    if (!pDpiX || !pDpiY)
+        return E_POINTER;
+
+    *pDpiX = This->decoder_frame.dpix;
+    *pDpiY = This->decoder_frame.dpiy;
+    return S_OK;
+}
+
+static HRESULT WINAPI CommonDecoderFrame_CopyPalette(IWICBitmapFrameDecode *iface,
+    IWICPalette *pIPalette)
+{
+    CommonDecoderFrame *This = impl_from_IWICBitmapFrameDecode(iface);
+    HRESULT hr=S_OK;
+
+    TRACE("(%p,%p)\n", iface, pIPalette);
+
+    if (This->decoder_frame.num_colors)
+    {
+        hr = IWICPalette_InitializeCustom(pIPalette, This->decoder_frame.palette, This->decoder_frame.num_colors);
+    }
+    else
+    {
+        hr = WINCODEC_ERR_PALETTEUNAVAILABLE;
+    }
+
+    return hr;
+}
+
+static HRESULT WINAPI CommonDecoderFrame_CopyPixels(IWICBitmapFrameDecode *iface,
+    const WICRect *prc, UINT cbStride, UINT cbBufferSize, BYTE *pbBuffer)
+{
+    CommonDecoderFrame *This = impl_from_IWICBitmapFrameDecode(iface);
+    HRESULT hr;
+    UINT bytesperrow;
+    WICRect rect;
+
+    TRACE("(%p,%s,%u,%u,%p)\n", iface, debug_wic_rect(prc), cbStride, cbBufferSize, pbBuffer);
+
+    if (!pbBuffer)
+        return E_POINTER;
+
+    if (!prc)
+    {
+        rect.X = 0;
+        rect.Y = 0;
+        rect.Width = This->decoder_frame.width;
+        rect.Height = This->decoder_frame.height;
+        prc = ▭
+    }
+    else
+    {
+        if (prc->X < 0 || prc->Y < 0 ||
+            prc->X+prc->Width > This->decoder_frame.width ||
+            prc->Y+prc->Height > This->decoder_frame.height)
+            return E_INVALIDARG;
+    }
+
+    bytesperrow = ((This->decoder_frame.bpp * prc->Width)+7)/8;
+
+    if (cbStride < bytesperrow)
+        return E_INVALIDARG;
+
+    if ((cbStride * (prc->Height-1)) + bytesperrow > cbBufferSize)
+        return E_INVALIDARG;
+
+    EnterCriticalSection(&This->parent->lock);
+
+    hr = decoder_copy_pixels(This->parent->decoder, This->frame,
+        prc, cbStride, cbBufferSize, pbBuffer);
+
+    LeaveCriticalSection(&This->parent->lock);
+
+    return hr;
+}
+
+static HRESULT WINAPI CommonDecoderFrame_GetMetadataQueryReader(IWICBitmapFrameDecode *iface,
+    IWICMetadataQueryReader **ppIMetadataQueryReader)
+{
+    CommonDecoderFrame *This = impl_from_IWICBitmapFrameDecode(iface);
+
+    TRACE("(%p,%p)\n", iface, ppIMetadataQueryReader);
+
+    if (!ppIMetadataQueryReader)
+        return E_INVALIDARG;
+
+    if (!(This->parent->file_info.flags & WICBitmapDecoderCapabilityCanEnumerateMetadata))
+        return WINCODEC_ERR_UNSUPPORTEDOPERATION;
+
+    return MetadataQueryReader_CreateInstance(&This->IWICMetadataBlockReader_iface, NULL, ppIMetadataQueryReader);
+}
+
+static HRESULT WINAPI CommonDecoderFrame_GetColorContexts(IWICBitmapFrameDecode *iface,
+    UINT cCount, IWICColorContext **ppIColorContexts, UINT *pcActualCount)
+{
+    CommonDecoderFrame *This = impl_from_IWICBitmapFrameDecode(iface);
+    HRESULT hr=S_OK;
+    UINT i;
+    BYTE *profile;
+    DWORD profile_len;
+
+    TRACE("(%p,%u,%p,%p)\n", iface, cCount, ppIColorContexts, pcActualCount);
+
+    if (!pcActualCount) return E_INVALIDARG;
+
+    *pcActualCount = This->decoder_frame.num_color_contexts;
+
+    if (This->decoder_frame.num_color_contexts && cCount && ppIColorContexts)
+    {
+        if (cCount >= This->decoder_frame.num_color_contexts)
+        {
+            EnterCriticalSection(&This->parent->lock);
+
+            for (i=0; i<This->decoder_frame.num_color_contexts; i++)
+            {
+                hr = decoder_get_color_context(This->parent->decoder, This->frame, i,
+                    &profile, &profile_len);
+                if (SUCCEEDED(hr))
+                {
+                    hr = IWICColorContext_InitializeFromMemory(ppIColorContexts[i], profile, profile_len);
+
+                    HeapFree(GetProcessHeap(), 0, profile);
+                }
+                
+                if (FAILED(hr))
+                    break;
+            }
+
+            LeaveCriticalSection(&This->parent->lock);
+        }
+        else
+        {
+            hr = E_INVALIDARG;
+        }
+    }
+
+    return hr;
+}
+
+static HRESULT WINAPI CommonDecoderFrame_GetThumbnail(IWICBitmapFrameDecode *iface,
+    IWICBitmapSource **ppIThumbnail)
+{
+    TRACE("(%p,%p)\n", iface, ppIThumbnail);
+
+    if (!ppIThumbnail) return E_INVALIDARG;
+
+    *ppIThumbnail = NULL;
+    return WINCODEC_ERR_CODECNOTHUMBNAIL;
+}
+
+static const IWICBitmapFrameDecodeVtbl CommonDecoderFrameVtbl = {
+    CommonDecoderFrame_QueryInterface,
+    CommonDecoderFrame_AddRef,
+    CommonDecoderFrame_Release,
+    CommonDecoderFrame_GetSize,
+    CommonDecoderFrame_GetPixelFormat,
+    CommonDecoderFrame_GetResolution,
+    CommonDecoderFrame_CopyPalette,
+    CommonDecoderFrame_CopyPixels,
+    CommonDecoderFrame_GetMetadataQueryReader,
+    CommonDecoderFrame_GetColorContexts,
+    CommonDecoderFrame_GetThumbnail
+};
+
+static HRESULT WINAPI CommonDecoderFrame_Block_QueryInterface(IWICMetadataBlockReader *iface, REFIID iid,
+    void **ppv)
+{
+    CommonDecoderFrame *This = impl_from_IWICMetadataBlockReader(iface);
+    return IWICBitmapFrameDecode_QueryInterface(&This->IWICBitmapFrameDecode_iface, iid, ppv);
+}
+
+static ULONG WINAPI CommonDecoderFrame_Block_AddRef(IWICMetadataBlockReader *iface)
+{
+    CommonDecoderFrame *This = impl_from_IWICMetadataBlockReader(iface);
+    return IWICBitmapFrameDecode_AddRef(&This->IWICBitmapFrameDecode_iface);
+}
+
+static ULONG WINAPI CommonDecoderFrame_Block_Release(IWICMetadataBlockReader *iface)
+{
+    CommonDecoderFrame *This = impl_from_IWICMetadataBlockReader(iface);
+    return IWICBitmapFrameDecode_Release(&This->IWICBitmapFrameDecode_iface);
+}
+
+static HRESULT WINAPI CommonDecoderFrame_Block_GetContainerFormat(IWICMetadataBlockReader *iface,
+    GUID *pguidContainerFormat)
+{
+    CommonDecoderFrame *This = impl_from_IWICMetadataBlockReader(iface);
+    if (!pguidContainerFormat) return E_INVALIDARG;
+    *pguidContainerFormat = This->parent->decoder_info.block_format;
+    return S_OK;
+}
+
+static HRESULT WINAPI CommonDecoderFrame_InitializeMetadata(CommonDecoderFrame *This)
+{
+    HRESULT hr=S_OK;
+
+    if (This->metadata_initialized)
+        return S_OK;
+
+    EnterCriticalSection(&This->parent->lock);
+
+    if (!This->metadata_initialized)
+    {
+        hr = decoder_get_metadata_blocks(This->parent->decoder, This->frame, &This->metadata_count, &This->metadata_blocks);
+        if (SUCCEEDED(hr))
+            This->metadata_initialized = TRUE;
+    }
+
+    LeaveCriticalSection(&This->parent->lock);
+
+    return hr;
+}
+
+static HRESULT WINAPI CommonDecoderFrame_Block_GetCount(IWICMetadataBlockReader *iface,
+    UINT *pcCount)
+{
+    CommonDecoderFrame *This = impl_from_IWICMetadataBlockReader(iface);
+    HRESULT hr;
+
+    TRACE("%p,%p\n", iface, pcCount);
+
+    if (!pcCount) return E_INVALIDARG;
+
+    hr = CommonDecoderFrame_InitializeMetadata(This);
+    if (SUCCEEDED(hr))
+        *pcCount = This->metadata_count;
+
+    return hr;
+}
+
+static HRESULT WINAPI CommonDecoderFrame_Block_GetReaderByIndex(IWICMetadataBlockReader *iface,
+    UINT nIndex, IWICMetadataReader **ppIMetadataReader)
+{
+    CommonDecoderFrame *This = impl_from_IWICMetadataBlockReader(iface);
+    HRESULT hr;
+    IWICComponentFactory* factory;
+    IWICStream* stream;
+
+    TRACE("%p,%d,%p\n", iface, nIndex, ppIMetadataReader);
+
+    if (!ppIMetadataReader)
+        return E_INVALIDARG;
+
+    hr = CommonDecoderFrame_InitializeMetadata(This);
+
+    if (SUCCEEDED(hr) && nIndex >= This->metadata_count)
+        hr = E_INVALIDARG;
+
+    if (SUCCEEDED(hr))
+        hr = StreamImpl_Create(&stream);
+
+    if (SUCCEEDED(hr))
+    {
+        ULARGE_INTEGER offset, length;
+
+        offset.QuadPart = This->metadata_blocks[nIndex].offset;
+        length.QuadPart = This->metadata_blocks[nIndex].length;
+        hr = IWICStream_InitializeFromIStreamRegion(stream, This->parent->stream,
+            offset, length);
+
+        if (SUCCEEDED(hr))
+            hr = ImagingFactory_CreateInstance(&IID_IWICComponentFactory, (void**)&factory);
+
+        if (SUCCEEDED(hr))
+        {
+            hr = IWICComponentFactory_CreateMetadataReaderFromContainer(factory,
+                &This->parent->decoder_info.block_format, NULL, This->metadata_blocks[nIndex].options,
+                (IStream*)stream, ppIMetadataReader);
+
+            IWICComponentFactory_Release(factory);
+        }
+
+        IWICStream_Release(stream);
+    }
+
+    if (FAILED(hr))
+        *ppIMetadataReader = NULL;
+
+    return S_OK;
+}
+
+static HRESULT WINAPI CommonDecoderFrame_Block_GetEnumerator(IWICMetadataBlockReader *iface,
+    IEnumUnknown **ppIEnumMetadata)
+{
+    FIXME("%p,%p\n", iface, ppIEnumMetadata);
+    return E_NOTIMPL;
+}
+
+static const IWICMetadataBlockReaderVtbl CommonDecoderFrame_BlockVtbl = {
+    CommonDecoderFrame_Block_QueryInterface,
+    CommonDecoderFrame_Block_AddRef,
+    CommonDecoderFrame_Block_Release,
+    CommonDecoderFrame_Block_GetContainerFormat,
+    CommonDecoderFrame_Block_GetCount,
+    CommonDecoderFrame_Block_GetReaderByIndex,
+    CommonDecoderFrame_Block_GetEnumerator,
+};
+
+static HRESULT WINAPI CommonDecoder_GetFrame(IWICBitmapDecoder *iface,
+    UINT index, IWICBitmapFrameDecode **ppIBitmapFrame)
+{
+    CommonDecoder *This = impl_from_IWICBitmapDecoder(iface);
+    HRESULT hr=S_OK;
+    CommonDecoderFrame *result;
+
+    TRACE("(%p,%u,%p)\n", iface, index, ppIBitmapFrame);
+
+    if (!ppIBitmapFrame)
+        return E_POINTER;
+
+    EnterCriticalSection(&This->lock);
+
+    if (!This->stream || index >= This->file_info.frame_count)
+        hr = WINCODEC_ERR_FRAMEMISSING;
+
+    if (SUCCEEDED(hr))
+    {
+        result = HeapAlloc(GetProcessHeap(), 0, sizeof(*result));
+        if (!result)
+            hr = E_OUTOFMEMORY;
+    }
+
+    if (SUCCEEDED(hr))
+    {
+        result->IWICBitmapFrameDecode_iface.lpVtbl = &CommonDecoderFrameVtbl;
+        result->IWICMetadataBlockReader_iface.lpVtbl = &CommonDecoderFrame_BlockVtbl;
+        result->ref = 1;
+        result->parent = This;
+        result->frame = index;
+        result->metadata_initialized = FALSE;
+        result->metadata_count = 0;
+        result->metadata_blocks = NULL;
+
+        hr = decoder_get_frame_info(This->decoder, index, &result->decoder_frame);
+
+        if (SUCCEEDED(hr) && This->cache_options == WICDecodeMetadataCacheOnLoad)
+            hr = CommonDecoderFrame_InitializeMetadata(result);
+
+        if (FAILED(hr))
+            HeapFree(GetProcessHeap(), 0, result);
+    }
+
+    LeaveCriticalSection(&This->lock);
+
+    if (SUCCEEDED(hr))
+    {
+        TRACE("-> %ux%u, %u-bit pixelformat=%s res=%f,%f colors=%u contexts=%u\n",
+            result->decoder_frame.width, result->decoder_frame.height,
+            result->decoder_frame.bpp, wine_dbgstr_guid(&result->decoder_frame.pixel_format),
+            result->decoder_frame.dpix, result->decoder_frame.dpiy,
+            result->decoder_frame.num_colors, result->decoder_frame.num_color_contexts);
+        IWICBitmapDecoder_AddRef(&This->IWICBitmapDecoder_iface);
+        *ppIBitmapFrame = &result->IWICBitmapFrameDecode_iface;
+    }
+    else
+    {
+        *ppIBitmapFrame = NULL;
+    }
+
+    return hr;
+}
+
+HRESULT CommonDecoder_CreateInstance(struct decoder *decoder,
+    const struct decoder_info *decoder_info, REFIID iid, void** ppv)
+{
+    CommonDecoder *This;
+    HRESULT hr;
+
+    TRACE("(%s,%s,%p)\n", debugstr_guid(&decoder_info->clsid), debugstr_guid(iid), ppv);
+
+    This = HeapAlloc(GetProcessHeap(), 0, sizeof(*This));
+    if (!This)
+    {
+        decoder_destroy(decoder);
+        return E_OUTOFMEMORY;
+    }
+
+    This->IWICBitmapDecoder_iface.lpVtbl = &CommonDecoder_Vtbl;
+    This->ref = 1;
+    This->stream = NULL;
+    This->decoder = decoder;
+    This->decoder_info = *decoder_info;
+    InitializeCriticalSection(&This->lock);
+    This->lock.DebugInfo->Spare[0] = (DWORD_PTR)(__FILE__ ": CommonDecoder.lock");
+
+    hr = IWICBitmapDecoder_QueryInterface(&This->IWICBitmapDecoder_iface, iid, ppv);
+    IWICBitmapDecoder_Release(&This->IWICBitmapDecoder_iface);
+
+    return hr;
+}
+
diff --git a/dlls/windowscodecs/pngformat.c b/dlls/windowscodecs/pngformat.c
index efd5f6ab2c1..b36512447b2 100644
--- a/dlls/windowscodecs/pngformat.c
+++ b/dlls/windowscodecs/pngformat.c
@@ -392,795 +392,6 @@ static void user_warning_fn(png_structp png_ptr, png_const_charp warning_message
     WARN("PNG warning: %s\n", debugstr_a(warning_message));
 }
 
-typedef struct {
-    ULARGE_INTEGER ofs, len;
-    IWICMetadataReader* reader;
-} metadata_block_info;
-
-typedef struct {
-    IWICBitmapDecoder IWICBitmapDecoder_iface;
-    IWICBitmapFrameDecode IWICBitmapFrameDecode_iface;
-    IWICMetadataBlockReader IWICMetadataBlockReader_iface;
-    LONG ref;
-    IStream *stream;
-    struct decoder *png_decoder;
-    struct decoder_info decoder_info;
-    struct decoder_stat file_info;
-    struct decoder_frame decoder_frame;
-    png_structp png_ptr;
-    png_infop info_ptr;
-    png_infop end_info;
-    BOOL initialized;
-    int bpp;
-    int width, height;
-    UINT stride;
-    const WICPixelFormatGUID *format;
-    BYTE *image_bits;
-    CRITICAL_SECTION lock; /* must be held when png structures are accessed or initialized is set */
-    ULONG metadata_count;
-    struct decoder_block* metadata_blocks;
-} PngDecoder;
-
-static inline PngDecoder *impl_from_IWICBitmapDecoder(IWICBitmapDecoder *iface)
-{
-    return CONTAINING_RECORD(iface, PngDecoder, IWICBitmapDecoder_iface);
-}
-
-static inline PngDecoder *impl_from_IWICBitmapFrameDecode(IWICBitmapFrameDecode *iface)
-{
-    return CONTAINING_RECORD(iface, PngDecoder, IWICBitmapFrameDecode_iface);
-}
-
-static inline PngDecoder *impl_from_IWICMetadataBlockReader(IWICMetadataBlockReader *iface)
-{
-    return CONTAINING_RECORD(iface, PngDecoder, IWICMetadataBlockReader_iface);
-}
-
-static const IWICBitmapFrameDecodeVtbl PngDecoder_FrameVtbl;
-
-static HRESULT WINAPI PngDecoder_QueryInterface(IWICBitmapDecoder *iface, REFIID iid,
-    void **ppv)
-{
-    PngDecoder *This = impl_from_IWICBitmapDecoder(iface);
-    TRACE("(%p,%s,%p)\n", iface, debugstr_guid(iid), ppv);
-
-    if (!ppv) return E_INVALIDARG;
-
-    if (IsEqualIID(&IID_IUnknown, iid) || IsEqualIID(&IID_IWICBitmapDecoder, iid))
-    {
-        *ppv = &This->IWICBitmapDecoder_iface;
-    }
-    else
-    {
-        *ppv = NULL;
-        return E_NOINTERFACE;
-    }
-
-    IUnknown_AddRef((IUnknown*)*ppv);
-    return S_OK;
-}
-
-static ULONG WINAPI PngDecoder_AddRef(IWICBitmapDecoder *iface)
-{
-    PngDecoder *This = impl_from_IWICBitmapDecoder(iface);
-    ULONG ref = InterlockedIncrement(&This->ref);
-
-    TRACE("(%p) refcount=%u\n", iface, ref);
-
-    return ref;
-}
-
-static ULONG WINAPI PngDecoder_Release(IWICBitmapDecoder *iface)
-{
-    PngDecoder *This = impl_from_IWICBitmapDecoder(iface);
-    ULONG ref = InterlockedDecrement(&This->ref);
-
-    TRACE("(%p) refcount=%u\n", iface, ref);
-
-    if (ref == 0)
-    {
-        if (This->stream)
-            IStream_Release(This->stream);
-        if (This->png_ptr)
-            ppng_destroy_read_struct(&This->png_ptr, &This->info_ptr, &This->end_info);
-        if (This->png_decoder)
-            decoder_destroy(This->png_decoder);
-        This->lock.DebugInfo->Spare[0] = 0;
-        DeleteCriticalSection(&This->lock);
-        HeapFree(GetProcessHeap(), 0, This->image_bits);
-        HeapFree(GetProcessHeap(), 0, This->metadata_blocks);
-        HeapFree(GetProcessHeap(), 0, This);
-    }
-
-    return ref;
-}
-
-static HRESULT WINAPI PngDecoder_QueryCapability(IWICBitmapDecoder *iface, IStream *stream,
-    DWORD *capability)
-{
-    PngDecoder *This = impl_from_IWICBitmapDecoder(iface);
-    HRESULT hr;
-
-    TRACE("(%p,%p,%p)\n", iface, stream, capability);
-
-    if (!stream || !capability) return E_INVALIDARG;
-
-    hr = IWICBitmapDecoder_Initialize(iface, stream, WICDecodeMetadataCacheOnDemand);
-    if (hr != S_OK) return hr;
-
-    *capability = (This->file_info.flags & DECODER_FLAGS_CAPABILITY_MASK);
-    return S_OK;
-}
-
-static void user_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
-{
-    IStream *stream = ppng_get_io_ptr(png_ptr);
-    HRESULT hr;
-    ULONG bytesread;
-
-    hr = IStream_Read(stream, data, length, &bytesread);
-    if (FAILED(hr) || bytesread != length)
-    {
-        ppng_error(png_ptr, "failed reading data");
-    }
-}
-
-static HRESULT WINAPI PngDecoder_Initialize(IWICBitmapDecoder *iface, IStream *pIStream,
-    WICDecodeOptions cacheOptions)
-{
-    PngDecoder *This = impl_from_IWICBitmapDecoder(iface);
-    LARGE_INTEGER seek;
-    HRESULT hr=S_OK;
-    png_bytep *row_pointers=NULL;
-    UINT image_size;
-    UINT i;
-    int color_type, bit_depth;
-    png_bytep trans;
-    int num_trans;
-    png_uint_32 transparency;
-    png_color_16p trans_values;
-    jmp_buf jmpbuf;
-
-    TRACE("(%p,%p,%x)\n", iface, pIStream, cacheOptions);
-
-    EnterCriticalSection(&This->lock);
-
-    if (This->initialized)
-    {
-        hr = WINCODEC_ERR_WRONGSTATE;
-        goto end;
-    }
-
-    hr = decoder_initialize(This->png_decoder, pIStream, &This->file_info);
-    if (FAILED(hr))
-        goto end;
-
-    /* this function cannot fail in PNG decoder */
-    decoder_get_frame_info(This->png_decoder, 0, &This->decoder_frame);
-
-    /* initialize libpng */
-    This->png_ptr = ppng_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
-    if (!This->png_ptr)
-    {
-        hr = E_FAIL;
-        goto end;
-    }
-
-    This->info_ptr = ppng_create_info_struct(This->png_ptr);
-    if (!This->info_ptr)
-    {
-        ppng_destroy_read_struct(&This->png_ptr, NULL, NULL);
-        This->png_ptr = NULL;
-        hr = E_FAIL;
-        goto end;
-    }
-
-    This->end_info = ppng_create_info_struct(This->png_ptr);
-    if (!This->end_info)
-    {
-        ppng_destroy_read_struct(&This->png_ptr, &This->info_ptr, NULL);
-        This->png_ptr = NULL;
-        hr = E_FAIL;
-        goto end;
-    }
-
-    /* set up setjmp/longjmp error handling */
-    if (setjmp(jmpbuf))
-    {
-        ppng_destroy_read_struct(&This->png_ptr, &This->info_ptr, &This->end_info);
-        This->png_ptr = NULL;
-        hr = WINCODEC_ERR_UNKNOWNIMAGEFORMAT;
-        goto end;
-    }
-    ppng_set_error_fn(This->png_ptr, jmpbuf, user_error_fn, user_warning_fn);
-    ppng_set_crc_action(This->png_ptr, PNG_CRC_QUIET_USE, PNG_CRC_QUIET_USE);
-
-    /* seek to the start of the stream */
-    seek.QuadPart = 0;
-    hr = IStream_Seek(pIStream, seek, STREAM_SEEK_SET, NULL);
-    if (FAILED(hr)) goto end;
-
-    /* set up custom i/o handling */
-    ppng_set_read_fn(This->png_ptr, pIStream, user_read_data);
-
-    /* read the header */
-    ppng_read_info(This->png_ptr, This->info_ptr);
-
-    /* choose a pixel format */
-    color_type = ppng_get_color_type(This->png_ptr, This->info_ptr);
-    bit_depth = ppng_get_bit_depth(This->png_ptr, This->info_ptr);
-
-    /* PNGs with bit-depth greater than 8 are network byte order. Windows does not expect this. */
-    if (bit_depth > 8)
-        ppng_set_swap(This->png_ptr);
-
-    /* check for color-keyed alpha */
-    transparency = ppng_get_tRNS(This->png_ptr, This->info_ptr, &trans, &num_trans, &trans_values);
-
-    if (transparency && (color_type == PNG_COLOR_TYPE_RGB ||
-        (color_type == PNG_COLOR_TYPE_GRAY && bit_depth == 16)))
-    {
-        /* expand to RGBA */
-        if (color_type == PNG_COLOR_TYPE_GRAY)
-            ppng_set_gray_to_rgb(This->png_ptr);
-        ppng_set_tRNS_to_alpha(This->png_ptr);
-        color_type = PNG_COLOR_TYPE_RGB_ALPHA;
-    }
-
-    switch (color_type)
-    {
-    case PNG_COLOR_TYPE_GRAY_ALPHA:
-        /* WIC does not support grayscale alpha formats so use RGBA */
-        ppng_set_gray_to_rgb(This->png_ptr);
-        /* fall through */
-    case PNG_COLOR_TYPE_RGB_ALPHA:
-        This->bpp = bit_depth * 4;
-        switch (bit_depth)
-        {
-        case 8:
-            ppng_set_bgr(This->png_ptr);
-            This->format = &GUID_WICPixelFormat32bppBGRA;
-            break;
-        case 16: This->format = &GUID_WICPixelFormat64bppRGBA; break;
-        default:
-            ERR("invalid RGBA bit depth: %i\n", bit_depth);
-            hr = E_FAIL;
-            goto end;
-        }
-        break;
-    case PNG_COLOR_TYPE_GRAY:
-        This->bpp = bit_depth;
-        if (!transparency)
-        {
-            switch (bit_depth)
-            {
-            case 1: This->format = &GUID_WICPixelFormatBlackWhite; break;
-            case 2: This->format = &GUID_WICPixelFormat2bppGray; break;
-            case 4: This->format = &GUID_WICPixelFormat4bppGray; break;
-            case 8: This->format = &GUID_WICPixelFormat8bppGray; break;
-            case 16: This->format = &GUID_WICPixelFormat16bppGray; break;
-            default:
-                ERR("invalid grayscale bit depth: %i\n", bit_depth);
-                hr = E_FAIL;
-                goto end;
-            }
-            break;
-        }
-        /* else fall through */
-    case PNG_COLOR_TYPE_PALETTE:
-        This->bpp = bit_depth;
-        switch (bit_depth)
-        {
-        case 1: This->format = &GUID_WICPixelFormat1bppIndexed; break;
-        case 2: This->format = &GUID_WICPixelFormat2bppIndexed; break;
-        case 4: This->format = &GUID_WICPixelFormat4bppIndexed; break;
-        case 8: This->format = &GUID_WICPixelFormat8bppIndexed; break;
-        default:
-            ERR("invalid indexed color bit depth: %i\n", bit_depth);
-            hr = E_FAIL;
-            goto end;
-        }
-        break;
-    case PNG_COLOR_TYPE_RGB:
-        This->bpp = bit_depth * 3;
-        switch (bit_depth)
-        {
-        case 8:
-            ppng_set_bgr(This->png_ptr);
-            This->format = &GUID_WICPixelFormat24bppBGR;
-            break;
-        case 16: This->format = &GUID_WICPixelFormat48bppRGB; break;
-        default:
-            ERR("invalid RGB color bit depth: %i\n", bit_depth);
-            hr = E_FAIL;
-            goto end;
-        }
-        break;
-    default:
-        ERR("invalid color type %i\n", color_type);
-        hr = E_FAIL;
-        goto end;
-    }
-
-    /* read the image data */
-    This->width = ppng_get_image_width(This->png_ptr, This->info_ptr);
-    This->height = ppng_get_image_height(This->png_ptr, This->info_ptr);
-    This->stride = (This->width * This->bpp + 7) / 8;
-    image_size = This->stride * This->height;
-
-    This->image_bits = HeapAlloc(GetProcessHeap(), 0, image_size);
-    if (!This->image_bits)
-    {
-        hr = E_OUTOFMEMORY;
-        goto end;
-    }
-
-    row_pointers = HeapAlloc(GetProcessHeap(), 0, sizeof(png_bytep)*This->height);
-    if (!row_pointers)
-    {
-        hr = E_OUTOFMEMORY;
-        goto end;
-    }
-
-    for (i=0; i<This->height; i++)
-        row_pointers[i] = This->image_bits + i * This->stride;
-
-    ppng_read_image(This->png_ptr, row_pointers);
-
-    HeapFree(GetProcessHeap(), 0, row_pointers);
-    row_pointers = NULL;
-
-    ppng_read_end(This->png_ptr, This->end_info);
-
-    decoder_get_metadata_blocks(This->png_decoder, 0, &This->metadata_count, &This->metadata_blocks);
-
-    This->stream = pIStream;
-    IStream_AddRef(This->stream);
-
-    This->initialized = TRUE;
-
-end:
-    LeaveCriticalSection(&This->lock);
-
-    HeapFree(GetProcessHeap(), 0, row_pointers);
-
-    return hr;
-}
-
-static HRESULT WINAPI PngDecoder_GetContainerFormat(IWICBitmapDecoder *iface,
-    GUID *pguidContainerFormat)
-{
-    PngDecoder *This = impl_from_IWICBitmapDecoder(iface);
-    memcpy(pguidContainerFormat, &This->decoder_info.container_format, sizeof(GUID));
-    return S_OK;
-}
-
-static HRESULT WINAPI PngDecoder_GetDecoderInfo(IWICBitmapDecoder *iface,
-    IWICBitmapDecoderInfo **ppIDecoderInfo)
-{
-    PngDecoder *This = impl_from_IWICBitmapDecoder(iface);
-    TRACE("(%p,%p)\n", iface, ppIDecoderInfo);
-
-    return get_decoder_info(&This->decoder_info.clsid, ppIDecoderInfo);
-}
-
-static HRESULT WINAPI PngDecoder_CopyPalette(IWICBitmapDecoder *iface,
-    IWICPalette *palette)
-{
-    TRACE("(%p,%p)\n", iface, palette);
-    return WINCODEC_ERR_PALETTEUNAVAILABLE;
-}
-
-static HRESULT WINAPI PngDecoder_GetMetadataQueryReader(IWICBitmapDecoder *iface,
-    IWICMetadataQueryReader **reader)
-{
-    TRACE("(%p,%p)\n", iface, reader);
-
-    if (!reader) return E_INVALIDARG;
-
-    *reader = NULL;
-    return WINCODEC_ERR_UNSUPPORTEDOPERATION;
-}
-
-static HRESULT WINAPI PngDecoder_GetPreview(IWICBitmapDecoder *iface,
-    IWICBitmapSource **ppIBitmapSource)
-{
-    TRACE("(%p,%p)\n", iface, ppIBitmapSource);
-
-    if (!ppIBitmapSource) return E_INVALIDARG;
-
-    *ppIBitmapSource = NULL;
-    return WINCODEC_ERR_UNSUPPORTEDOPERATION;
-}
-
-static HRESULT WINAPI PngDecoder_GetColorContexts(IWICBitmapDecoder *iface,
-    UINT cCount, IWICColorContext **ppIColorContexts, UINT *pcActualCount)
-{
-    TRACE("(%p,%u,%p,%p)\n", iface, cCount, ppIColorContexts, pcActualCount);
-    return WINCODEC_ERR_UNSUPPORTEDOPERATION;
-}
-
-static HRESULT WINAPI PngDecoder_GetThumbnail(IWICBitmapDecoder *iface,
-    IWICBitmapSource **ppIThumbnail)
-{
-    TRACE("(%p,%p)\n", iface, ppIThumbnail);
-
-    if (!ppIThumbnail) return E_INVALIDARG;
-
-    *ppIThumbnail = NULL;
-    return WINCODEC_ERR_CODECNOTHUMBNAIL;
-}
-
-static HRESULT WINAPI PngDecoder_GetFrameCount(IWICBitmapDecoder *iface,
-    UINT *pCount)
-{
-    PngDecoder *This = impl_from_IWICBitmapDecoder(iface);
-    if (!pCount) return E_INVALIDARG;
-
-    if (!This->initialized) return WINCODEC_ERR_WRONGSTATE;
-
-    *pCount = This->file_info.frame_count;
-    return S_OK;
-}
-
-static HRESULT WINAPI PngDecoder_GetFrame(IWICBitmapDecoder *iface,
-    UINT index, IWICBitmapFrameDecode **ppIBitmapFrame)
-{
-    PngDecoder *This = impl_from_IWICBitmapDecoder(iface);
-    TRACE("(%p,%u,%p)\n", iface, index, ppIBitmapFrame);
-
-    if (!This->initialized) return WINCODEC_ERR_FRAMEMISSING;
-
-    if (index != 0) return E_INVALIDARG;
-
-    IWICBitmapDecoder_AddRef(iface);
-
-    *ppIBitmapFrame = &This->IWICBitmapFrameDecode_iface;
-
-    return S_OK;
-}
-
-static const IWICBitmapDecoderVtbl PngDecoder_Vtbl = {
-    PngDecoder_QueryInterface,
-    PngDecoder_AddRef,
-    PngDecoder_Release,
-    PngDecoder_QueryCapability,
-    PngDecoder_Initialize,
-    PngDecoder_GetContainerFormat,
-    PngDecoder_GetDecoderInfo,
-    PngDecoder_CopyPalette,
-    PngDecoder_GetMetadataQueryReader,
-    PngDecoder_GetPreview,
-    PngDecoder_GetColorContexts,
-    PngDecoder_GetThumbnail,
-    PngDecoder_GetFrameCount,
-    PngDecoder_GetFrame
-};
-
-static HRESULT WINAPI PngDecoder_Frame_QueryInterface(IWICBitmapFrameDecode *iface, REFIID iid,
-    void **ppv)
-{
-    PngDecoder *This = impl_from_IWICBitmapFrameDecode(iface);
-    if (!ppv) return E_INVALIDARG;
-
-    if (IsEqualIID(&IID_IUnknown, iid) ||
-        IsEqualIID(&IID_IWICBitmapSource, iid) ||
-        IsEqualIID(&IID_IWICBitmapFrameDecode, iid))
-    {
-        *ppv = &This->IWICBitmapFrameDecode_iface;
-    }
-    else if (IsEqualIID(&IID_IWICMetadataBlockReader, iid))
-    {
-        *ppv = &This->IWICMetadataBlockReader_iface;
-    }
-    else
-    {
-        *ppv = NULL;
-        return E_NOINTERFACE;
-    }
-
-    IUnknown_AddRef((IUnknown*)*ppv);
-    return S_OK;
-}
-
-static ULONG WINAPI PngDecoder_Frame_AddRef(IWICBitmapFrameDecode *iface)
-{
-    PngDecoder *This = impl_from_IWICBitmapFrameDecode(iface);
-    return IWICBitmapDecoder_AddRef(&This->IWICBitmapDecoder_iface);
-}
-
-static ULONG WINAPI PngDecoder_Frame_Release(IWICBitmapFrameDecode *iface)
-{
-    PngDecoder *This = impl_from_IWICBitmapFrameDecode(iface);
-    return IWICBitmapDecoder_Release(&This->IWICBitmapDecoder_iface);
-}
-
-static HRESULT WINAPI PngDecoder_Frame_GetSize(IWICBitmapFrameDecode *iface,
-    UINT *puiWidth, UINT *puiHeight)
-{
-    PngDecoder *This = impl_from_IWICBitmapFrameDecode(iface);
-    *puiWidth = This->decoder_frame.width;
-    *puiHeight = This->decoder_frame.height;
-    TRACE("(%p)->(%u,%u)\n", iface, *puiWidth, *puiHeight);
-    return S_OK;
-}
-
-static HRESULT WINAPI PngDecoder_Frame_GetPixelFormat(IWICBitmapFrameDecode *iface,
-    WICPixelFormatGUID *pPixelFormat)
-{
-    PngDecoder *This = impl_from_IWICBitmapFrameDecode(iface);
-    TRACE("(%p,%p)\n", iface, pPixelFormat);
-
-    memcpy(pPixelFormat, &This->decoder_frame.pixel_format, sizeof(GUID));
-
-    return S_OK;
-}
-
-static HRESULT WINAPI PngDecoder_Frame_GetResolution(IWICBitmapFrameDecode *iface,
-    double *pDpiX, double *pDpiY)
-{
-    PngDecoder *This = impl_from_IWICBitmapFrameDecode(iface);
-
-    *pDpiX = This->decoder_frame.dpix;
-    *pDpiY = This->decoder_frame.dpiy;
-
-    TRACE("(%p)->(%0.2f,%0.2f)\n", iface, *pDpiX, *pDpiY);
-
-    return S_OK;
-}
-
-static HRESULT WINAPI PngDecoder_Frame_CopyPalette(IWICBitmapFrameDecode *iface,
-    IWICPalette *pIPalette)
-{
-    PngDecoder *This = impl_from_IWICBitmapFrameDecode(iface);
-    HRESULT hr=S_OK;
-
-    TRACE("(%p,%p)\n", iface, pIPalette);
-
-    if (This->decoder_frame.num_colors)
-    {
-        hr = IWICPalette_InitializeCustom(pIPalette, This->decoder_frame.palette, This->decoder_frame.num_colors);
-    }
-    else
-    {
-        hr = WINCODEC_ERR_PALETTEUNAVAILABLE;
-    }
-
-    return hr;
-}
-
-static HRESULT WINAPI PngDecoder_Frame_CopyPixels(IWICBitmapFrameDecode *iface,
-    const WICRect *prc, UINT cbStride, UINT cbBufferSize, BYTE *pbBuffer)
-{
-    PngDecoder *This = impl_from_IWICBitmapFrameDecode(iface);
-    TRACE("(%p,%s,%u,%u,%p)\n", iface, debug_wic_rect(prc), cbStride, cbBufferSize, pbBuffer);
-
-    return decoder_copy_pixels(This->png_decoder, 0,
-        prc, cbStride, cbBufferSize, pbBuffer);
-}
-
-static HRESULT WINAPI PngDecoder_Frame_GetMetadataQueryReader(IWICBitmapFrameDecode *iface,
-    IWICMetadataQueryReader **ppIMetadataQueryReader)
-{
-    PngDecoder *This = impl_from_IWICBitmapFrameDecode(iface);
-
-    TRACE("(%p,%p)\n", iface, ppIMetadataQueryReader);
-
-    if (!ppIMetadataQueryReader)
-        return E_INVALIDARG;
-
-    return MetadataQueryReader_CreateInstance(&This->IWICMetadataBlockReader_iface, NULL, ppIMetadataQueryReader);
-}
-
-static HRESULT WINAPI PngDecoder_Frame_GetColorContexts(IWICBitmapFrameDecode *iface,
-    UINT cCount, IWICColorContext **ppIColorContexts, UINT *pcActualCount)
-{
-    PngDecoder *This = impl_from_IWICBitmapFrameDecode(iface);
-    HRESULT hr=S_OK;
-    BYTE *profile;
-    DWORD profile_len;
-
-    TRACE("(%p,%u,%p,%p)\n", iface, cCount, ppIColorContexts, pcActualCount);
-
-    if (!pcActualCount) return E_INVALIDARG;
-
-    *pcActualCount = This->decoder_frame.num_color_contexts;
-
-    if (This->decoder_frame.num_color_contexts && cCount && ppIColorContexts)
-    {
-        EnterCriticalSection(&This->lock);
-
-        hr = decoder_get_color_context(This->png_decoder, 0, 0,
-            &profile, &profile_len);
-
-        LeaveCriticalSection(&This->lock);
-
-        if (SUCCEEDED(hr))
-        {
-            hr = IWICColorContext_InitializeFromMemory(*ppIColorContexts, profile, profile_len);
-
-            HeapFree(GetProcessHeap(), 0, profile);
-        }
-    }
-
-    return hr;
-}
-
-static HRESULT WINAPI PngDecoder_Frame_GetThumbnail(IWICBitmapFrameDecode *iface,
-    IWICBitmapSource **ppIThumbnail)
-{
-    TRACE("(%p,%p)\n", iface, ppIThumbnail);
-
-    if (!ppIThumbnail) return E_INVALIDARG;
-
-    *ppIThumbnail = NULL;
-    return WINCODEC_ERR_CODECNOTHUMBNAIL;
-}
-
-static const IWICBitmapFrameDecodeVtbl PngDecoder_FrameVtbl = {
-    PngDecoder_Frame_QueryInterface,
-    PngDecoder_Frame_AddRef,
-    PngDecoder_Frame_Release,
-    PngDecoder_Frame_GetSize,
-    PngDecoder_Frame_GetPixelFormat,
-    PngDecoder_Frame_GetResolution,
-    PngDecoder_Frame_CopyPalette,
-    PngDecoder_Frame_CopyPixels,
-    PngDecoder_Frame_GetMetadataQueryReader,
-    PngDecoder_Frame_GetColorContexts,
-    PngDecoder_Frame_GetThumbnail
-};
-
-static HRESULT WINAPI PngDecoder_Block_QueryInterface(IWICMetadataBlockReader *iface, REFIID iid,
-    void **ppv)
-{
-    PngDecoder *This = impl_from_IWICMetadataBlockReader(iface);
-    return IWICBitmapFrameDecode_QueryInterface(&This->IWICBitmapFrameDecode_iface, iid, ppv);
-}
-
-static ULONG WINAPI PngDecoder_Block_AddRef(IWICMetadataBlockReader *iface)
-{
-    PngDecoder *This = impl_from_IWICMetadataBlockReader(iface);
-    return IWICBitmapDecoder_AddRef(&This->IWICBitmapDecoder_iface);
-}
-
-static ULONG WINAPI PngDecoder_Block_Release(IWICMetadataBlockReader *iface)
-{
-    PngDecoder *This = impl_from_IWICMetadataBlockReader(iface);
-    return IWICBitmapDecoder_Release(&This->IWICBitmapDecoder_iface);
-}
-
-static HRESULT WINAPI PngDecoder_Block_GetContainerFormat(IWICMetadataBlockReader *iface,
-    GUID *pguidContainerFormat)
-{
-    PngDecoder *This = impl_from_IWICMetadataBlockReader(iface);
-    if (!pguidContainerFormat) return E_INVALIDARG;
-    memcpy(pguidContainerFormat, &This->decoder_info.block_format, sizeof(GUID));
-    return S_OK;
-}
-
-static HRESULT WINAPI PngDecoder_Block_GetCount(IWICMetadataBlockReader *iface,
-    UINT *pcCount)
-{
-    PngDecoder *This = impl_from_IWICMetadataBlockReader(iface);
-
-    TRACE("%p,%p\n", iface, pcCount);
-
-    if (!pcCount) return E_INVALIDARG;
-
-    *pcCount = This->metadata_count;
-
-    return S_OK;
-}
-
-static HRESULT WINAPI PngDecoder_Block_GetReaderByIndex(IWICMetadataBlockReader *iface,
-    UINT nIndex, IWICMetadataReader **ppIMetadataReader)
-{
-    PngDecoder *This = impl_from_IWICMetadataBlockReader(iface);
-    HRESULT hr;
-    IWICComponentFactory* factory;
-    IWICStream* stream;
-
-    TRACE("%p,%d,%p\n", iface, nIndex, ppIMetadataReader);
-
-    if (nIndex >= This->metadata_count || !ppIMetadataReader)
-        return E_INVALIDARG;
-
-    hr = StreamImpl_Create(&stream);
-
-    if (SUCCEEDED(hr))
-    {
-        ULARGE_INTEGER offset, length;
-
-        offset.QuadPart = This->metadata_blocks[nIndex].offset;
-        length.QuadPart = This->metadata_blocks[nIndex].length;
-        hr = IWICStream_InitializeFromIStreamRegion(stream, This->stream,
-            offset, length);
-
-        if (SUCCEEDED(hr))
-            hr = ImagingFactory_CreateInstance(&IID_IWICComponentFactory, (void**)&factory);
-
-        if (SUCCEEDED(hr))
-        {
-            hr = IWICComponentFactory_CreateMetadataReaderFromContainer(factory,
-                &GUID_ContainerFormatPng, NULL, This->metadata_blocks[nIndex].options,
-                (IStream*)stream, ppIMetadataReader);
-
-            IWICComponentFactory_Release(factory);
-        }
-
-        IWICStream_Release(stream);
-    }
-
-    if (FAILED(hr))
-        *ppIMetadataReader = NULL;
-
-    return S_OK;
-}
-
-static HRESULT WINAPI PngDecoder_Block_GetEnumerator(IWICMetadataBlockReader *iface,
-    IEnumUnknown **ppIEnumMetadata)
-{
-    FIXME("%p,%p\n", iface, ppIEnumMetadata);
-    return E_NOTIMPL;
-}
-
-static const IWICMetadataBlockReaderVtbl PngDecoder_BlockVtbl = {
-    PngDecoder_Block_QueryInterface,
-    PngDecoder_Block_AddRef,
-    PngDecoder_Block_Release,
-    PngDecoder_Block_GetContainerFormat,
-    PngDecoder_Block_GetCount,
-    PngDecoder_Block_GetReaderByIndex,
-    PngDecoder_Block_GetEnumerator,
-};
-
-HRESULT PngDecoder_CreateInstance(REFIID iid, void** ppv)
-{
-    PngDecoder *This;
-    HRESULT ret;
-
-    TRACE("(%s,%p)\n", debugstr_guid(iid), ppv);
-
-    *ppv = NULL;
-
-    if (!load_libpng())
-    {
-        ERR("Failed reading PNG because unable to find %s\n",SONAME_LIBPNG);
-        return E_FAIL;
-    }
-
-    This = HeapAlloc(GetProcessHeap(), 0, sizeof(PngDecoder));
-    if (!This) return E_OUTOFMEMORY;
-
-    ret = get_unix_decoder(&CLSID_WICPngDecoder, &This->decoder_info, &This->png_decoder);
-    if (FAILED(ret))
-    {
-        HeapFree(GetProcessHeap(), 0, This);
-        return ret;
-    }
-
-    This->IWICBitmapDecoder_iface.lpVtbl = &PngDecoder_Vtbl;
-    This->IWICBitmapFrameDecode_iface.lpVtbl = &PngDecoder_FrameVtbl;
-    This->IWICMetadataBlockReader_iface.lpVtbl = &PngDecoder_BlockVtbl;
-    This->ref = 1;
-    This->png_ptr = NULL;
-    This->info_ptr = NULL;
-    This->end_info = NULL;
-    This->stream = NULL;
-    This->initialized = FALSE;
-    This->image_bits = NULL;
-    InitializeCriticalSection(&This->lock);
-    This->lock.DebugInfo->Spare[0] = (DWORD_PTR)(__FILE__ ": PngDecoder.lock");
-    This->metadata_count = 0;
-    This->metadata_blocks = NULL;
-
-    ret = IWICBitmapDecoder_QueryInterface(&This->IWICBitmapDecoder_iface, iid, ppv);
-    IWICBitmapDecoder_Release(&This->IWICBitmapDecoder_iface);
-
-    return ret;
-}
-
 struct png_pixelformat {
     const WICPixelFormatGUID *guid;
     UINT bpp;
@@ -2034,12 +1245,6 @@ HRESULT PngEncoder_CreateInstance(REFIID iid, void** ppv)
 
 #else /* !SONAME_LIBPNG */
 
-HRESULT PngDecoder_CreateInstance(REFIID iid, void** ppv)
-{
-    ERR("Trying to load PNG picture, but PNG support is not compiled in.\n");
-    return E_FAIL;
-}
-
 HRESULT PngEncoder_CreateInstance(REFIID iid, void** ppv)
 {
     ERR("Trying to save PNG picture, but PNG support is not compiled in.\n");
@@ -2047,3 +1252,18 @@ HRESULT PngEncoder_CreateInstance(REFIID iid, void** ppv)
 }
 
 #endif
+
+HRESULT PngDecoder_CreateInstance(REFIID iid, void** ppv)
+{
+    HRESULT hr;
+    struct decoder *decoder;
+    struct decoder_info decoder_info;
+
+    hr = get_unix_decoder(&CLSID_WICPngDecoder, &decoder_info, &decoder);
+
+    if (SUCCEEDED(hr))
+        hr = CommonDecoder_CreateInstance(decoder, &decoder_info, iid, ppv);
+
+    return hr;
+}
+
diff --git a/dlls/windowscodecs/wincodecs_private.h b/dlls/windowscodecs/wincodecs_private.h
index e5294b8cf1a..2cdd1066eb7 100644
--- a/dlls/windowscodecs/wincodecs_private.h
+++ b/dlls/windowscodecs/wincodecs_private.h
@@ -343,4 +343,7 @@ struct unix_funcs
 
 HRESULT get_unix_decoder(const CLSID *decoder_clsid, struct decoder_info *info, struct decoder **result);
 
+extern HRESULT CommonDecoder_CreateInstance(struct decoder *decoder,
+    const struct decoder_info *decoder_info, REFIID iid, void** ppv) DECLSPEC_HIDDEN;
+
 #endif /* WINCODECS_PRIVATE_H */
-- 
2.17.1




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