Bug 510465 - Initial zoom level of print preview depends on the zoom level of galley presentation, r=roc

layout/base/nsDocumentViewer.cpp

@@ -3687,7 +3687,10 @@ DocumentViewerImpl::Print(nsIPrintSettings*       aPrintSettings,
     NS_ENSURE_TRUE(mPrintEngine, NS_ERROR_OUT_OF_MEMORY);
 
     rv = mPrintEngine->Initialize(this, docShell, mDocument, 
-                                  mDeviceContext, mParentWidget,
+                                  float(mDeviceContext->AppUnitsPerInch()) /
+                                  float(mDeviceContext->AppUnitsPerDevPixel()) /
+                                  mPageZoom,
+                                  mParentWidget,
 #ifdef NS_DEBUG
                                   mDebugFile
 #else
@@ -3750,7 +3753,10 @@ DocumentViewerImpl::PrintPreview(nsIPrintSettings* aPrintSettings,
     NS_ENSURE_TRUE(mPrintEngine, NS_ERROR_OUT_OF_MEMORY);
 
     rv = mPrintEngine->Initialize(this, docShell, mDocument,
-                                  mDeviceContext, mParentWidget,
+                                  float(mDeviceContext->AppUnitsPerInch()) /
+                                  float(mDeviceContext->AppUnitsPerDevPixel()) /
+                                  mPageZoom,
+                                  mParentWidget,
 #ifdef NS_DEBUG
                                   mDebugFile
 #else

layout/printing/nsPrintEngine.cpp

@@ -258,7 +258,7 @@ nsPrintEngine::nsPrintEngine() :
   mIsDoingPrintPreview(PR_FALSE),
   mProgressDialogIsShown(PR_FALSE),
   mContainer(nsnull),
-  mDeviceContext(nsnull),
+  mScreenDPI(115.0f),
   mPrt(nsnull),
   mPagePrintTimer(nsnull),
   mPageSeqFrame(nsnull),
@@ -316,20 +316,19 @@ void nsPrintEngine::DestroyPrintingData()
 nsresult nsPrintEngine::Initialize(nsIDocumentViewerPrint* aDocViewerPrint, 
                                    nsISupports*            aContainer,
                                    nsIDocument*            aDocument,
-                                   nsIDeviceContext*       aDevContext,
+                                   float                   aScreenDPI,
                                    nsIWidget*              aParentWidget,
                                    FILE*                   aDebugFile)
 {
   NS_ENSURE_ARG_POINTER(aDocViewerPrint);
   NS_ENSURE_ARG_POINTER(aContainer);
   NS_ENSURE_ARG_POINTER(aDocument);
-  NS_ENSURE_ARG_POINTER(aDevContext);
   NS_ENSURE_ARG_POINTER(aParentWidget);
 
   mDocViewerPrint = aDocViewerPrint;
   mContainer      = aContainer;      // weak reference
   mDocument       = aDocument;
-  mDeviceContext  = aDevContext;     // weak reference
+  mScreenDPI      = aScreenDPI;
   mParentWidget   = aParentWidget;    
 
   mDebugFile      = aDebugFile;      // ok to be NULL
@@ -1991,9 +1990,7 @@ nsPrintEngine::ReflowPrintObject(nsPrintObject * aPO)
   // Calculate scale factor from printer to screen
   float printDPI = float(mPrt->mPrintDC->AppUnitsPerInch()) /
                    float(mPrt->mPrintDC->AppUnitsPerDevPixel());
-  float screenDPI = float(mDeviceContext->AppUnitsPerInch()) /
-                    float(mDeviceContext->AppUnitsPerDevPixel());
-  aPO->mPresContext->SetPrintPreviewScale(screenDPI / printDPI);
+  aPO->mPresContext->SetPrintPreviewScale(mScreenDPI / printDPI);
 
   rv = aPO->mPresShell->InitialReflow(adjSize.width, adjSize.height);
 

layout/printing/nsPrintEngine.h

@@ -104,7 +104,7 @@ public:
   nsresult Initialize(nsIDocumentViewerPrint* aDocViewerPrint, 
                       nsISupports*            aContainer,
                       nsIDocument*            aDocument,
-                      nsIDeviceContext*       aDevContext,
+                      float                   aScreenDPI,
                       nsIWidget*              aParentWidget,
                       FILE*                   aDebugFile);
 
@@ -282,7 +282,7 @@ protected:
 
   nsCOMPtr<nsIDocumentViewerPrint> mDocViewerPrint;
   nsISupports*            mContainer;      // [WEAK] it owns me!
-  nsIDeviceContext*       mDeviceContext;  // not ref counted
+  float                   mScreenDPI;
   
   nsPrintData*            mPrt;
   nsPagePrintTimer*       mPagePrintTimer;