Commit 45fd50ca authored by Jonathan Watt's avatar Jonathan Watt
Browse files

Bug 1769993 - Bring some sanity to nsPrintJob's scaling/shrink-to-fit logic. r=emilio 

The comments and structure of this code no longer made much sense after the
last 20 years of churn, including those made in bug 1659432 and bug 1552785.

Differential Revision: https://phabricator.services.mozilla.com/D146717
parent 00e1fb45

layout/printing/nsPrintJob.cpp

+23 −38
Original line number Diff line number Diff line
@@ -731,7 +731,7 @@ void nsPrintJob::FirePrintingErrorEvent(nsresult aPrintError) { 
//-- Section: Reflow Methods

//-----------------------------------------------------------------



nsresult nsPrintJob::ReconstructAndReflow(bool doSetPixelScale) {

nsresult nsPrintJob::ReconstructAndReflow() {

  if (NS_WARN_IF(!mPrt)) {

    return NS_ERROR_FAILURE;

  }
@@ -767,7 +767,7 @@ nsresult nsPrintJob::ReconstructAndReflow(bool doSetPixelScale) { 
               "print object "

               "has been marked as \"print the document\"");



    UpdateZoomRatio(po, doSetPixelScale);

    UpdateZoomRatio(po);



    po->mPresContext->SetPageScale(po->mZoomRatio);
@@ -866,7 +866,7 @@ nsresult nsPrintJob::SetupToPrintContent() { 
  // If some new content got loaded since the initial reflow rebuild

  // everything.

  if (mDidLoadDataForPrinting) {

    nsresult rv = ReconstructAndReflow(DoSetPixelScale());

    nsresult rv = ReconstructAndReflow();

    if (NS_WARN_IF(NS_FAILED(rv))) {

      return rv;

    }
@@ -886,7 +886,7 @@ nsresult nsPrintJob::SetupToPrintContent() { 
    printData->mShrinkRatio = printData->mPrintObject->mShrinkRatio;



    if (printData->mShrinkRatio < 0.998f) {

      nsresult rv = ReconstructAndReflow(true);

      nsresult rv = ReconstructAndReflow();

      if (NS_WARN_IF(NS_FAILED(rv))) {

        return rv;

      }
@@ -1011,8 +1011,7 @@ nsresult nsPrintJob::SetupToPrintContent() { 
//-------------------------------------------------------

// Recursively reflow each sub-doc and then calc

// all the frame locations of the sub-docs

nsresult nsPrintJob::ReflowDocList(const UniquePtr<nsPrintObject>& aPO,

                                   bool aSetPixelScale) {

nsresult nsPrintJob::ReflowDocList(const UniquePtr<nsPrintObject>& aPO) {

  NS_ENSURE_ARG_POINTER(aPO);



  // Check to see if the subdocument's element has been hidden by the parent
@@ -1027,13 +1026,13 @@ nsresult nsPrintJob::ReflowDocList(const UniquePtr<nsPrintObject>& aPO, 
    }

  }



  UpdateZoomRatio(aPO.get(), aSetPixelScale);

  UpdateZoomRatio(aPO.get());



  // Reflow the PO

  MOZ_TRY(ReflowPrintObject(aPO));



  for (const UniquePtr<nsPrintObject>& kid : aPO->mKids) {

    MOZ_TRY(ReflowDocList(kid, aSetPixelScale));

    MOZ_TRY(ReflowDocList(kid));

  }

  return NS_OK;

}
@@ -1070,7 +1069,7 @@ nsresult nsPrintJob::InitPrintDocConstruction(bool aHandleError) { 
    webProgress->AddProgressListener(static_cast<nsIWebProgressListener*>(this),

                                     nsIWebProgress::NOTIFY_STATE_REQUEST);



    MOZ_TRY(ReflowDocList(printData->mPrintObject, DoSetPixelScale()));

    MOZ_TRY(ReflowDocList(printData->mPrintObject));



    FirePrintPreviewUpdateEvent();

  }
@@ -1186,20 +1185,23 @@ nsPrintJob::OnContentBlockingEvent(nsIWebProgress* aWebProgress, 


//-------------------------------------------------------



void nsPrintJob::UpdateZoomRatio(nsPrintObject* aPO, bool aSetPixelScale) {

  // Here is where we set the shrinkage value into the DC

  // and this is what actually makes it shrink

  if (aSetPixelScale && aPO->mFrameType != eIFrame) {

    // Round down

    aPO->mZoomRatio = mPrt->mPrintSettings->GetPrintSelectionOnly()

                          ? aPO->mShrinkRatio - 0.005f

                          : mPrt->mShrinkRatio - 0.005f;

  } else if (!mPrt->mShrinkToFit) {

void nsPrintJob::UpdateZoomRatio(nsPrintObject* aPO) {

  if (!aPO->mParent) {

    if (mPrt->mShrinkToFit) {

      aPO->mZoomRatio = mPrt->mShrinkRatio;

      // If we're actually going to scale (the factor is less than 1), we

      // reduce the scale factor slightly to avoid the possibility of floating

      // point rounding error causing slight clipping of the longest lines.

      if (aPO->mZoomRatio != 1.0f) {

        aPO->mZoomRatio -= 0.005f;

      }

    } else {

      double scaling;

      mPrt->mPrintSettings->GetScaling(&scaling);

      aPO->mZoomRatio = float(scaling);

    }

  }

}



nsresult nsPrintJob::UpdateSelectionAndShrinkPrintObject(

    nsPrintObject* aPO, bool aDocumentIsTopLevel) {
@@ -1252,23 +1254,6 @@ nsresult nsPrintJob::UpdateSelectionAndShrinkPrintObject( 
  return NS_OK;

}



bool nsPrintJob::DoSetPixelScale() {

  // This is an Optimization

  // If we are in PP then we already know all the shrinkage information

  // so just transfer it to the PrintData and we will skip the extra shrinkage

  // reflow

  //

  // doSetPixelScale tells Reflow whether to set the shrinkage value into the DC

  // The first time we do not want to do this, the second time through we do

  bool doSetPixelScale = false;

  bool ppIsShrinkToFit = mPrtPreview && mPrtPreview->mShrinkToFit;

  if (ppIsShrinkToFit) {

    mPrt->mShrinkRatio = mPrtPreview->mShrinkRatio;

    doSetPixelScale = true;

  }

  return doSetPixelScale;

}



nsView* nsPrintJob::GetParentViewForRoot() {

  if (mIsCreatingPrintPreview) {

    if (nsCOMPtr<nsIContentViewer> cv = do_QueryInterface(mDocViewerPrint)) {

layout/printing/nsPrintJob.h

+3 −5
Original line number Diff line number Diff line
@@ -166,8 +166,7 @@ class nsPrintJob final : public nsIWebProgressListener, 
                       nsresult& aStatus);

  nsresult DoPrint(const mozilla::UniquePtr<nsPrintObject>& aPO);



  nsresult ReflowDocList(const mozilla::UniquePtr<nsPrintObject>& aPO,

                         bool aSetPixelScale);

  nsresult ReflowDocList(const mozilla::UniquePtr<nsPrintObject>& aPO);



  MOZ_CAN_RUN_SCRIPT_BOUNDARY

  nsresult ReflowPrintObject(const mozilla::UniquePtr<nsPrintObject>& aPO);
@@ -223,9 +222,8 @@ class nsPrintJob final : public nsIWebProgressListener, 
  nsresult SetRootView(nsPrintObject* aPO, bool& aDoReturn,

                       bool& aDocumentIsTopLevel, nsSize& aAdjSize);

  nsView* GetParentViewForRoot();

  bool DoSetPixelScale();

  void UpdateZoomRatio(nsPrintObject* aPO, bool aSetPixelScale);

  MOZ_CAN_RUN_SCRIPT nsresult ReconstructAndReflow(bool aDoSetPixelScale);

  void UpdateZoomRatio(nsPrintObject* aPO);

  MOZ_CAN_RUN_SCRIPT nsresult ReconstructAndReflow();

  MOZ_CAN_RUN_SCRIPT_BOUNDARY nsresult UpdateSelectionAndShrinkPrintObject(

      nsPrintObject* aPO, bool aDocumentIsTopLevel);

  MOZ_CAN_RUN_SCRIPT nsresult InitPrintDocConstruction(bool aHandleError);

layout/printing/nsPrintObject.cpp

+1 −3
Original line number Diff line number Diff line
@@ -35,9 +35,7 @@ nsPrintObject::nsPrintObject() 
      mFrameType(eDoc),

      mParent(nullptr),

      mHasBeenPrinted(false),

      mInvisible(false),

      mShrinkRatio(1.0),

      mZoomRatio(1.0) {

      mInvisible(false) {

  MOZ_COUNT_CTOR(nsPrintObject);

}

layout/printing/nsPrintObject.h

+11 −2
Original line number Diff line number Diff line
@@ -72,8 +72,17 @@ class nsPrintObject { 
  nsPrintObject* mParent;  // This is a non-owning pointer.

  bool mHasBeenPrinted;

  bool mInvisible;  // Indicates PO is set to not visible by CSS

  float mShrinkRatio;

  float mZoomRatio;



  // The scale factor that sheets should be scaled by. This is either the

  // explicit scale chosen by the user or else the shrink-to-fit scale factor

  // if the user selects shrink-to-fit. Only set on the top-level nsPrintObject

  // since this is only used by nsPageFrame (via nsPresContext::GetPageScale()).

  float mZoomRatio = 1.0;



  // If the user selects the shrink-to-fit option, the shrink-to-fit scale

  // factor is calculated and stored here. Only set on the top-level

  // nsPrintObject.

  float mShrinkRatio = 1.0;



 private:

  nsPrintObject& operator=(const nsPrintObject& aOther) = delete;