svx: fix font rendering in the style preview

If the style does not actually have any font items, as is the case for
frame, page and number styles in Writer, the maFont will be
default-initialized and the maPixelSize incorrect.
Avoid using these variables.

(cherry picked from commit 07df816d)

Change-Id: I084cd8faa90a3d53310ceec55e8dae3af3dd586c
Reviewed-on: https://gerrit.libreoffice.org/18383Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Miklos Vajna <vmiklos@collabora.co.uk>

include/svx/CommonStylePreviewRenderer.hxx

@@ -22,7 +22,7 @@ namespace svx
 
 class SVX_DLLPUBLIC CommonStylePreviewRenderer : public sfx2::StylePreviewRenderer
 {
-    SvxFont maFont;
+    std::unique_ptr<SvxFont> m_pFont;
     Color maFontColor;
     Color maBackgroundColor;
     Size maPixelSize;

svx/source/styles/CommonStylePreviewRenderer.cxx

@@ -47,7 +47,7 @@ CommonStylePreviewRenderer::CommonStylePreviewRenderer(
                                 const SfxObjectShell& rShell, OutputDevice& rOutputDev,
                                 SfxStyleSheetBase* pStyle, long nMaxHeight)
     : StylePreviewRenderer(rShell, rOutputDev, pStyle, nMaxHeight)
-    , maFont()
+    , m_pFont()
     , maFontColor(COL_AUTO)
     , maBackgroundColor(COL_AUTO)
     , maPixelSize()
@@ -60,53 +60,55 @@ CommonStylePreviewRenderer::~CommonStylePreviewRenderer()
 
 bool CommonStylePreviewRenderer::recalculate()
 {
-    maFont = SvxFont();
+    m_pFont.reset();
 
     std::unique_ptr<SfxItemSet> pItemSet(mpStyle->GetItemSetForPreview());
 
     if (!pItemSet) return false;
 
+    std::unique_ptr<SvxFont> pFont(new SvxFont);
+
     const SfxPoolItem* pItem;
 
     if ((pItem = pItemSet->GetItem(SID_ATTR_CHAR_WEIGHT)) != nullptr)
     {
-        maFont.SetWeight(static_cast<const SvxWeightItem*>(pItem)->GetWeight());
+        pFont->SetWeight(static_cast<const SvxWeightItem*>(pItem)->GetWeight());
     }
     if ((pItem = pItemSet->GetItem(SID_ATTR_CHAR_POSTURE)) != nullptr)
     {
-        maFont.SetItalic(static_cast<const SvxPostureItem*>(pItem)->GetPosture());
+        pFont->SetItalic(static_cast<const SvxPostureItem*>(pItem)->GetPosture());
     }
     if ((pItem = pItemSet->GetItem(SID_ATTR_CHAR_CONTOUR)) != nullptr)
     {
-        maFont.SetOutline(static_cast< const SvxContourItem*>(pItem)->GetValue());
+        pFont->SetOutline(static_cast< const SvxContourItem*>(pItem)->GetValue());
     }
     if ((pItem = pItemSet->GetItem(SID_ATTR_CHAR_SHADOWED)) != nullptr)
     {
-        maFont.SetShadow(static_cast<const SvxShadowedItem*>(pItem)->GetValue());
+        pFont->SetShadow(static_cast<const SvxShadowedItem*>(pItem)->GetValue());
     }
     if ((pItem = pItemSet->GetItem(SID_ATTR_CHAR_RELIEF)) != nullptr)
     {
-        maFont.SetRelief(static_cast<FontRelief>(static_cast<const SvxCharReliefItem*>(pItem)->GetValue()));
+        pFont->SetRelief(static_cast<FontRelief>(static_cast<const SvxCharReliefItem*>(pItem)->GetValue()));
     }
     if ((pItem = pItemSet->GetItem(SID_ATTR_CHAR_UNDERLINE)) != nullptr)
     {
-        maFont.SetUnderline(static_cast< const SvxUnderlineItem*>(pItem)->GetLineStyle());
+        pFont->SetUnderline(static_cast< const SvxUnderlineItem*>(pItem)->GetLineStyle());
     }
     if ((pItem = pItemSet->GetItem(SID_ATTR_CHAR_OVERLINE)) != nullptr)
     {
-        maFont.SetOverline(static_cast<FontUnderline>(static_cast<const SvxOverlineItem*>(pItem)->GetValue()));
+        pFont->SetOverline(static_cast<FontUnderline>(static_cast<const SvxOverlineItem*>(pItem)->GetValue()));
     }
     if ((pItem = pItemSet->GetItem(SID_ATTR_CHAR_STRIKEOUT)) != nullptr)
     {
-        maFont.SetStrikeout(static_cast<const SvxCrossedOutItem*>(pItem)->GetStrikeout());
+        pFont->SetStrikeout(static_cast<const SvxCrossedOutItem*>(pItem)->GetStrikeout());
     }
     if ((pItem = pItemSet->GetItem(SID_ATTR_CHAR_CASEMAP)) != nullptr)
     {
-        maFont.SetCaseMap(static_cast<const SvxCaseMapItem*>(pItem)->GetCaseMap());
+        pFont->SetCaseMap(static_cast<const SvxCaseMapItem*>(pItem)->GetCaseMap());
     }
     if ((pItem = pItemSet->GetItem(SID_ATTR_CHAR_EMPHASISMARK)) != nullptr)
     {
-        maFont.SetEmphasisMark(static_cast<const SvxEmphasisMarkItem*>(pItem)->GetEmphasisMark());
+        pFont->SetEmphasisMark(static_cast<const SvxEmphasisMarkItem*>(pItem)->GetEmphasisMark());
     }
     if ((pItem = pItemSet->GetItem(SID_ATTR_CHAR_COLOR)) != nullptr)
     {
@@ -131,8 +133,8 @@ bool CommonStylePreviewRenderer::recalculate()
     if ((pItem = pItemSet->GetItem(SID_ATTR_CHAR_FONT)) != nullptr)
     {
         const SvxFontItem* pFontItem = static_cast<const SvxFontItem*>(pItem);
-        maFont.SetName(pFontItem->GetFamilyName());
-        maFont.SetStyleName(pFontItem->GetStyleName());
+        pFont->SetName(pFontItem->GetFamilyName());
+        pFont->SetStyleName(pFontItem->GetStyleName());
     }
     else
     {
@@ -144,11 +146,11 @@ bool CommonStylePreviewRenderer::recalculate()
         const SvxFontHeightItem* pFontHeightItem = static_cast<const SvxFontHeightItem*>(pItem);
         Size aFontSize(0, pFontHeightItem->GetHeight());
         maPixelSize = Size(mrOutputDev.LogicToPixel(aFontSize, mrShell.GetMapUnit()));
-        maFont.SetSize(maPixelSize);
+        pFont->SetSize(maPixelSize);
 
         vcl::Font aOldFont(mrOutputDev.GetFont());
 
-        mrOutputDev.SetFont(maFont);
+        mrOutputDev.SetFont(*pFont);
         Rectangle aTextRect;
         mrOutputDev.GetTextBoundRect(aTextRect, mpStyle->GetName());
         if (aTextRect.Bottom() > mnMaxHeight)
@@ -156,7 +158,7 @@ bool CommonStylePreviewRenderer::recalculate()
             double ratio = double(mnMaxHeight) / aTextRect.Bottom();
             maPixelSize.Width() *= ratio;
             maPixelSize.Height() *= ratio;
-            maFont.SetSize(maPixelSize);
+            pFont->SetSize(maPixelSize);
         }
         mrOutputDev.SetFont(aOldFont);
     }
@@ -165,12 +167,14 @@ bool CommonStylePreviewRenderer::recalculate()
         return false;
     }
 
+    m_pFont = std::move(pFont);
     return true;
 }
 
 Size CommonStylePreviewRenderer::getRenderSize()
 {
-    maPixelSize = maFont.GetTextSize(&mrOutputDev, maStyleName);
+    assert(m_pFont);
+    maPixelSize = m_pFont->GetTextSize(&mrOutputDev, maStyleName);
     if (maPixelSize.Height() > mnMaxHeight)
         maPixelSize.Height() = mnMaxHeight;
     return maPixelSize;
@@ -189,13 +193,18 @@ bool CommonStylePreviewRenderer::render(const Rectangle& aRectangle)
         mrOutputDev.DrawRect(aRectangle);
     }
 
-    mrOutputDev.SetFont(maFont);
+    if (m_pFont)
+    {
+        mrOutputDev.SetFont(*m_pFont);
+    }
     if (maFontColor != COL_AUTO)
         mrOutputDev.SetTextColor(maFontColor);
 
+    Size aPixelSize((m_pFont) ? maPixelSize : mrOutputDev.GetFont().GetSize());
+
     Point aFontDrawPosition = aRectangle.TopLeft();
-    if (aRectangle.GetHeight() > maPixelSize.Height())
-        aFontDrawPosition.Y() += ( aRectangle.GetHeight() - maPixelSize.Height() ) / 2;
+    if (aRectangle.GetHeight() > aPixelSize.Height())
+        aFontDrawPosition.Y() += (aRectangle.GetHeight() - aPixelSize.Height()) / 2;
 
     mrOutputDev.DrawText(aFontDrawPosition, maStyleName);