From db15e9988474840e9518c7d2a8f70648add5f370 Mon Sep 17 00:00:00 2001
From: Graham Dawes <graham.dawes@geoteric.com>
Date: Wed, 12 Dec 2018 09:03:10 +0000
Subject: [PATCH] Fix wxBitmap::GetRawData() in wxQt

This method used to return a dangling pointer to a temporary buffer,
which resulted in a crash when using it, e.g. in the unit test.

Fix this by keeping a QImage as a member in wxBitmapRefData, so that the
pointer to its data remain valid until UngetRawData() is called.

Also check that GetRawData() returns a non-null pointer in the test.

Closes https://github.com/wxWidgets/wxWidgets/pull/1067
---
 src/qt/bitmap.cpp         | 25 +++++++++++++++----------
 tests/graphics/bitmap.cpp |  1 +
 2 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/src/qt/bitmap.cpp b/src/qt/bitmap.cpp
index 6f632a1931..31f1380c06 100644
--- a/src/qt/bitmap.cpp
+++ b/src/qt/bitmap.cpp
@@ -144,6 +144,7 @@ class wxBitmapRefData: public wxGDIRefData
         virtual ~wxBitmapRefData() { delete m_mask; }
 
         QPixmap m_qtPixmap;
+        QImage m_rawPixelSource;
         wxMask *m_mask;
 
 private:
@@ -409,17 +410,19 @@ void wxBitmap::SetDepth(int depth)
 void *wxBitmap::GetRawData(wxPixelDataBase& data, int bpp)
 {
     void* bits = NULL;
-    // allow access if bpp is valid and matches existence of alpha
-    if ( !M_PIXDATA.isNull() )
+
+    wxBitmapRefData *refData = static_cast<wxBitmapRefData *>(m_refData);
+
+    // allow access if bpp is valid
+    if ( !refData->m_qtPixmap.isNull() )
     {
-        QImage qimage = M_PIXDATA.toImage();
-        bool hasAlpha = M_PIXDATA.hasAlphaChannel();
-        if ((bpp == 24 && !hasAlpha) || (bpp == 32 && hasAlpha))
+        if ( bpp == 32 )
         {
-            data.m_height = qimage.height();
-            data.m_width = qimage.width();
-            data.m_stride = qimage.bytesPerLine();
-            bits = (void*) qimage.bits();
+            refData->m_rawPixelSource = refData->m_qtPixmap.toImage().convertToFormat(QImage::Format_RGBA8888);
+            data.m_height = refData->m_rawPixelSource.height();
+            data.m_width = refData->m_rawPixelSource.width();
+            data.m_stride = refData->m_rawPixelSource.bytesPerLine();
+            bits = refData->m_rawPixelSource.bits();
         }
     }
     return bits;
@@ -427,7 +430,9 @@ void *wxBitmap::GetRawData(wxPixelDataBase& data, int bpp)
 
 void wxBitmap::UngetRawData(wxPixelDataBase& WXUNUSED(data))
 {
-    wxMISSING_IMPLEMENTATION( __FUNCTION__ );
+    wxBitmapRefData *refData = static_cast<wxBitmapRefData *>(m_refData);
+    refData->m_qtPixmap = QPixmap::fromImage(refData->m_rawPixelSource);
+    refData->m_rawPixelSource = QImage();
 }
 
 QPixmap *wxBitmap::GetHandle() const
diff --git a/tests/graphics/bitmap.cpp b/tests/graphics/bitmap.cpp
index a93062e157..b07f348b08 100644
--- a/tests/graphics/bitmap.cpp
+++ b/tests/graphics/bitmap.cpp
@@ -126,6 +126,7 @@ void BitmapTestCase::OverlappingBlit()
     if ( m_bmp.GetDepth() == 32 )
     {
         wxAlphaPixelData npd( m_bmp );
+        CPPUNIT_ASSERT_MESSAGE( "Expected raw pixels to not be NULL", npd );
         wxAlphaPixelData::Iterator it( npd );
 
         ASSERT_EQUAL_RGB( it, 255, 0, 0 );