Provide support for storing PNG files on the clipboard (wxMSW)

PNG is a custom clipboard format but images stored in this format are supported by e.g. MS Excel, MS PowerPoint, GIMP (including image transparency).

See #17631.

include/wx/defs.h

@@ -2153,6 +2153,7 @@ enum wxDataFormatId
     wxDF_LOCALE =           16,
     wxDF_PRIVATE =          20,
     wxDF_HTML =             30, /* Note: does not correspond to CF_ constant */
+    wxDF_PNG =              31, /* Note: does not correspond to CF_ constant */
     wxDF_MAX
 };
 

interface/wx/dataobj.h

@@ -34,6 +34,8 @@
              A list of filenames.}
     @itemdef{wxDF_HTML,
              An HTML string. This is currently only valid on Mac and MSW.}
+    @itemdef{wxDF_PNG,
+             A PNG file. This is valid only on MSW.}
     @endDefList
 
     As mentioned above, these standard formats may be passed to any function

src/msw/clipbrd.cpp

@@ -73,6 +73,7 @@
 
 static bool gs_wxClipboardIsOpen = false;
 static int gs_htmlcfid = 0;
+static int gs_pngcfid = 0;
 
 bool wxOpenClipboard()
 {
@@ -136,6 +137,8 @@ bool wxIsClipboardFormatAvailable(wxDataFormat dataFormat)
     wxDataFormat::NativeFormat cf = dataFormat.GetFormatId();
     if (cf == wxDF_HTML)
         cf = gs_htmlcfid;
+    else if ( cf == wxDF_PNG )
+        cf = gs_pngcfid;
 
     if ( ::IsClipboardFormatAvailable(cf) )
     {
@@ -162,6 +165,15 @@ bool wxIsClipboardFormatAvailable(wxDataFormat dataFormat)
 
 
 #if !wxUSE_OLE_CLIPBOARD
+namespace
+{
+struct wxRawImageData
+{
+    size_t m_size;
+    void* m_data;
+};
+}
+
 bool wxSetClipboardData(wxDataFormat dataFormat,
                         const void *data,
                         int width, int height)
@@ -414,6 +426,16 @@ bool wxSetClipboardData(wxDataFormat dataFormat,
                 delete [] buf;
                 break;
             }
+
+            case wxDF_PNG:
+            {
+                const wxRawImageData* imgData = reinterpret_cast<const wxRawImageData*>(data);
+
+                GlobalPtr hImage(imgData->m_size, GMEM_MOVEABLE | GMEM_DDESHARE);
+                memcpy(GlobalPtrLock(hImage).Get(), imgData->m_data, imgData->m_size);
+                handle = ::SetClipboardData(gs_pngcfid, hImage);
+                break;
+            }
     }
 
     if ( handle == 0 )
@@ -515,9 +537,11 @@ bool wxClipboard::Flush()
 
 bool wxClipboard::Open()
 {
-    // Get clipboard id for HTML format...
+    // Get clipboard id for HTML and PNG formats...
     if(!gs_htmlcfid)
         gs_htmlcfid = RegisterClipboardFormat(wxT("HTML Format"));
+    if ( !gs_pngcfid )
+        gs_pngcfid = ::RegisterClipboardFormat(wxT("PNG"));
 
     // OLE opens clipboard for us
     m_isOpened = true;
@@ -636,6 +660,16 @@ bool wxClipboard::AddData( wxDataObject *data )
         }
         break;
 
+        case wxDF_PNG:
+        {
+            wxCustomDataObject* imageDataObject = reinterpret_cast<wxCustomDataObject*>(data);
+            wxRawImageData imgData;
+            imgData.m_size = imageDataObject->GetDataSize();
+            imgData.m_data = imageDataObject->GetData();
+            bRet = wxSetClipboardData(format, &imgData);
+        }
+        break;
+
 #if wxUSE_METAFILE
         case wxDF_METAFILE:
         {
@@ -768,6 +802,8 @@ bool wxClipboard::GetData( wxDataObject& data )
 
         if (cf == wxDF_HTML)
             cf = gs_htmlcfid;
+        else if ( cf == wxDF_PNG )
+            cf = gs_pngcfid;
         // if the format is not available, try the next one
         // this test includes implicit / sythetic formats
         if ( !::IsClipboardFormatAvailable(cf) )

src/msw/ole/dataobj.cpp

@@ -64,15 +64,15 @@
 namespace
 {
 
-wxDataFormat HtmlFormatFixup(wxDataFormat format)
+wxDataFormat NonStandardFormatsFixup(wxDataFormat format)
 {
-    // Since the HTML format is dynamically registered, the wxDF_HTML
+    // Since the HTML and PNG formats are dynamically registered, the wxDF_HTML and wxDF_PNG
-    // format does not match the native constant in the way other formats do,
+    // formats do not match the native constants in the way other formats do,
     // so for the format checks below to work, we must change the native
-    // id to the wxDF_HTML constant.
+    // id to the wxDF_HTML or wxDF_PNG constant.
     //
     // But skip this for the standard constants which are never going to match
-    // wxDF_HTML anyhow.
+    // wxDF_HTML or wxDF_PNG anyhow.
     if ( !format.IsStandard() )
     {
         wxChar szBuf[256];
@@ -80,6 +80,8 @@ wxDataFormat HtmlFormatFixup(wxDataFormat format)
         {
             if ( wxStrcmp(szBuf, wxT("HTML Format")) == 0 )
                 format = wxDF_HTML;
+            else if ( wxStrcmp(szBuf, wxT("PNG")) == 0 )
+                format = wxDF_PNG;
         }
     }
 
@@ -347,7 +349,7 @@ wxIDataObject::SaveSystemData(FORMATETC *pformatetc,
 
 bool wxDataFormat::operator==(wxDataFormatId format) const
 {
-    return HtmlFormatFixup(*this).m_format == (NativeFormat)format;
+    return NonStandardFormatsFixup(*this).m_format == (NativeFormat)format;
 }
 
 bool wxDataFormat::operator!=(wxDataFormatId format) const
@@ -357,7 +359,7 @@ bool wxDataFormat::operator!=(wxDataFormatId format) const
 
 bool wxDataFormat::operator==(const wxDataFormat& format) const
 {
-    return HtmlFormatFixup(*this).m_format == HtmlFormatFixup(format).m_format;
+    return NonStandardFormatsFixup(*this).m_format == NonStandardFormatsFixup(format).m_format;
 }
 
 bool wxDataFormat::operator!=(const wxDataFormat& format) const
@@ -367,7 +369,7 @@ bool wxDataFormat::operator!=(const wxDataFormat& format) const
 
 bool wxDataFormat::operator==(NativeFormat format) const
 {
-    return HtmlFormatFixup(*this).m_format == format;
+    return NonStandardFormatsFixup(*this).m_format == format;
 }
 
 bool wxDataFormat::operator!=(NativeFormat format) const
@@ -422,10 +424,12 @@ wxIEnumFORMATETC::wxIEnumFORMATETC(const wxDataFormat *formats, ULONG nCount)
     m_nCount = nCount;
     m_formats = new CLIPFORMAT[nCount];
     for ( ULONG n = 0; n < nCount; n++ ) {
-        if (formats[n].GetFormatId() != wxDF_HTML)
+        if ( formats[n].GetFormatId() == wxDF_HTML )
-            m_formats[n] = formats[n].GetFormatId();
-        else
             m_formats[n] = ::RegisterClipboardFormat(wxT("HTML Format"));
+        else if ( formats[n].GetFormatId() == wxDF_PNG )
+            m_formats[n] = ::RegisterClipboardFormat(wxT("PNG"));
+        else
+            m_formats[n] = formats[n].GetFormatId();
     }
 }
 
@@ -540,7 +544,7 @@ STDMETHODIMP wxIDataObject::GetData(FORMATETC *pformatetcIn, STGMEDIUM *pmedium)
     // for the bitmaps and metafiles we use the handles instead of global memory
     // to pass the data
     wxDataFormat format = (wxDataFormat::NativeFormat)pformatetcIn->cfFormat;
-    format = HtmlFormatFixup(format);
+    format = NonStandardFormatsFixup(format);
 
     // is this system data?
     if ( GetSystemData(format, pmedium) )
@@ -690,7 +694,7 @@ STDMETHODIMP wxIDataObject::SetData(FORMATETC *pformatetc,
             {
                 wxDataFormat format = pformatetc->cfFormat;
 
-                format = HtmlFormatFixup(format);
+                format = NonStandardFormatsFixup(format);
 
                 // check if this format is supported
                 if ( !m_pDataObject->IsSupported(format, wxDataObject::Set) ) {
@@ -737,6 +741,9 @@ STDMETHODIMP wxIDataObject::SetData(FORMATETC *pformatetc,
                         size = sizeof(METAFILEPICT);
                         break;
 
+                    case wxDF_PNG:
+                        wxFALLTHROUGH;
+
                     default:
                         size = ptr.GetSize();
 
@@ -816,7 +823,7 @@ STDMETHODIMP wxIDataObject::QueryGetData(FORMATETC *pformatetc)
 
     // and now check the type of data requested
     wxDataFormat format = pformatetc->cfFormat;
-    format = HtmlFormatFixup(format);
+    format = NonStandardFormatsFixup(format);
 
     if ( m_pDataObject->IsSupportedFormat(format) ) {
         wxLogTrace(wxTRACE_OleCalls, wxT("wxIDataObject::QueryGetData: %s ok"),