gecko-dev/layout/generic/nsViewportFrame.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/*
 * rendering object that is the root of the frame tree, which contains
 * the document's scrollbars and contains fixed-positioned elements
 */

#include "nsCOMPtr.h"
#include "nsViewportFrame.h"
#include "nsHTMLParts.h"
#include "nsLayoutAtoms.h"
#include "nsIViewManager.h"
#include "nsIScrollableFrame.h"
#include "nsIDeviceContext.h"
#include "nsPresContext.h"
#include "nsReflowPath.h"
#include "nsIPresShell.h"

nsIFrame*
NS_NewViewportFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
{
  return new (aPresShell) ViewportFrame(aContext);
}

NS_IMETHODIMP
ViewportFrame::Destroy(nsPresContext* aPresContext)
{
  mFixedContainer.DestroyFrames(this, aPresContext);
  return nsContainerFrame::Destroy(aPresContext);
}

NS_IMETHODIMP
ViewportFrame::SetInitialChildList(nsPresContext* aPresContext,
                                   nsIAtom*        aListName,
                                   nsIFrame*       aChildList)
{
  nsresult rv = NS_OK;

  // See which child list to add the frames to
#ifdef NS_DEBUG
  nsFrame::VerifyDirtyBitSet(aChildList);
#endif
  if (mFixedContainer.GetChildListName() == aListName) {
    rv = mFixedContainer.SetInitialChildList(this, aPresContext, aListName, aChildList);
  } 
  else {
    rv = nsContainerFrame::SetInitialChildList(aPresContext, aListName, aChildList);
  }

  return rv;
}

NS_IMETHODIMP
ViewportFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
                                const nsRect&           aDirtyRect,
                                const nsDisplayListSet& aLists)
{
  // We don't need any special painting or event handling. We just need to
  // mark our visible out-of-flow frames (i.e., the fixed position frames) so
  // that display list construction is guaranteed to recurse into their
  // ancestors.
  MarkOutOfFlowChildrenForDisplayList(mFixedContainer.GetFirstChild(), aDirtyRect);
  nsIFrame* kid = mFrames.FirstChild();
  nsresult rv = NS_OK;
  if (kid) {
    // make the kid's BorderBackground our own. This ensures that the canvas
    // frame's background becomes our own background and therefore appears
    // below negative z-index elements.
    rv = BuildDisplayListForChild(aBuilder, kid, aDirtyRect, aLists);
  }
  UnmarkOutOfFlowChildrenForDisplayList(mFixedContainer.GetFirstChild());
  return rv;
}

NS_IMETHODIMP
ViewportFrame::AppendFrames(nsIAtom*        aListName,
                            nsIFrame*       aFrameList)
{
  nsresult rv = NS_OK;

  if (mFixedContainer.GetChildListName() == aListName) {
    rv = mFixedContainer.AppendFrames(this, aListName, aFrameList);
  }
  else {
    // We only expect incremental changes for our fixed frames
    NS_ERROR("unexpected child list");
    rv = NS_ERROR_INVALID_ARG;
  }

  return rv;
}

NS_IMETHODIMP
ViewportFrame::InsertFrames(nsIAtom*        aListName,
                            nsIFrame*       aPrevFrame,
                            nsIFrame*       aFrameList)
{
  nsresult rv = NS_OK;

  if (mFixedContainer.GetChildListName() == aListName) {
    rv = mFixedContainer.InsertFrames(this, aListName, aPrevFrame, aFrameList);
  }
  else {
    // We only expect incremental changes for our fixed frames
    NS_ERROR("unexpected child list");
    rv = NS_ERROR_INVALID_ARG;
  }

  return rv;
}

NS_IMETHODIMP
ViewportFrame::RemoveFrame(nsIAtom*        aListName,
                           nsIFrame*       aOldFrame)
{
  nsresult rv = NS_OK;

  if (mFixedContainer.GetChildListName() == aListName) {
    rv = mFixedContainer.RemoveFrame(this, aListName, aOldFrame);
  }
  else {
    // We only expect incremental changes for our fixed frames
    NS_ERROR("unexpected child list");
    rv = NS_ERROR_INVALID_ARG;
  }

  return rv;
}

nsIAtom*
ViewportFrame::GetAdditionalChildListName(PRInt32 aIndex) const
{
  NS_PRECONDITION(aIndex >= 0, "illegal index");

  if (0 == aIndex) {
    return mFixedContainer.GetChildListName();
  }

  return nsnull;
}

nsIFrame*
ViewportFrame::GetFirstChild(nsIAtom* aListName) const
{
  if (mFixedContainer.GetChildListName() == aListName) {
    nsIFrame* result = nsnull;
    mFixedContainer.FirstChild(this, aListName, &result);
    return result;
  }

  return nsContainerFrame::GetFirstChild(aListName);
}

nsPoint
 ViewportFrame::AdjustReflowStateForScrollbars(nsHTMLReflowState* aReflowState) const
{
  // Calculate how much room is available for fixed frames. That means
  // determining if the viewport is scrollable and whether the vertical and/or
  // horizontal scrollbars are visible

  // Get our prinicpal child frame and see if we're scrollable
  nsIFrame* kidFrame = mFrames.FirstChild();
  nsCOMPtr<nsIScrollableFrame> scrollingFrame(do_QueryInterface(kidFrame));

  if (scrollingFrame) {
    nsMargin scrollbars = scrollingFrame->GetActualScrollbarSizes();
    aReflowState->mComputedWidth -= scrollbars.left + scrollbars.right;
    aReflowState->availableWidth -= scrollbars.left + scrollbars.right;
    aReflowState->mComputedHeight -= scrollbars.top + scrollbars.bottom;
    // XXX why don't we also adjust "aReflowState->availableHeight"?
    return nsPoint(scrollbars.left, scrollbars.top);
  }
  return nsPoint(0, 0);
}

NS_IMETHODIMP
ViewportFrame::Reflow(nsPresContext*          aPresContext,
                      nsHTMLReflowMetrics&     aDesiredSize,
                      const nsHTMLReflowState& aReflowState,
                      nsReflowStatus&          aStatus)
{
  DO_GLOBAL_REFLOW_COUNT("ViewportFrame", aReflowState.reason);
  DISPLAY_REFLOW(aPresContext, this, aReflowState, aDesiredSize, aStatus);
  NS_FRAME_TRACE_REFLOW_IN("ViewportFrame::Reflow");
  NS_PRECONDITION(!aDesiredSize.mComputeMEW, "unexpected request");

  // Initialize OUT parameters
  aStatus = NS_FRAME_COMPLETE;

  // Reflow the main content first so that the placeholders of the
  // fixed-position frames will be in the right places on an initial
  // reflow.
  nsRect kidRect(0,0,aReflowState.availableWidth,aReflowState.availableHeight);

  nsresult rv = NS_OK;
  
  if (mFrames.NotEmpty()) {
    // Deal with a non-incremental reflow or an incremental reflow
    // targeted at our one-and-only principal child frame.
    if (eReflowReason_Incremental != aReflowState.reason ||
        aReflowState.path->HasChild(mFrames.FirstChild())) {
      // Reflow our one-and-only principal child frame
      nsIFrame*           kidFrame = mFrames.FirstChild();
      nsHTMLReflowMetrics kidDesiredSize(nsnull);
      nsSize              availableSpace(aReflowState.availableWidth,
                                         aReflowState.availableHeight);
      nsHTMLReflowState   kidReflowState(aPresContext, aReflowState,
                                         kidFrame, availableSpace);

      // Reflow the frame
      kidReflowState.mComputedHeight = aReflowState.availableHeight;
      rv = ReflowChild(kidFrame, aPresContext, kidDesiredSize, kidReflowState,
                       0, 0, 0, aStatus);
      kidRect.width = kidDesiredSize.width;
      kidRect.height = kidDesiredSize.height;

      FinishReflowChild(kidFrame, aPresContext, nsnull, kidDesiredSize, 0, 0, 0);
    }
  }

  // If we were flowed initially at both an unconstrained width and height, 
  // this is a hint that we should return our child's intrinsic size.
  if ((eReflowReason_Initial == aReflowState.reason ||
       eReflowReason_Resize == aReflowState.reason) &&
      aReflowState.availableWidth == NS_UNCONSTRAINEDSIZE &&
      aReflowState.availableHeight == NS_UNCONSTRAINEDSIZE) {
    aDesiredSize.width = kidRect.width;
    aDesiredSize.height = kidRect.height;
    aDesiredSize.ascent = kidRect.height;
    aDesiredSize.descent = 0;
  }
  else {
    // Return the max size as our desired size
    aDesiredSize.width = aReflowState.availableWidth;
    aDesiredSize.height = aReflowState.availableHeight;
    aDesiredSize.ascent = aReflowState.availableHeight;
    aDesiredSize.descent = 0;
  }

  // Make a copy of the reflow state and change the computed width and height
  // to reflect the available space for the fixed items
  nsHTMLReflowState reflowState(aReflowState);
  nsPoint offset = AdjustReflowStateForScrollbars(&reflowState);
  
#ifdef DEBUG
  nsIFrame* f;
  mFixedContainer.FirstChild(this, nsLayoutAtoms::fixedList, &f);
  NS_ASSERTION(!f || (offset.x == 0 && offset.y == 0),
               "We don't handle correct positioning of fixed frames with "
               "scrollbars in odd positions");
#endif

  nsReflowType reflowType = eReflowType_ContentChanged;
  if (aReflowState.path) {
    // XXXwaterson this is more restrictive than the previous code
    // was: it insists that the UserDefined reflow be targeted at
    // _this_ frame.
    nsHTMLReflowCommand *command = aReflowState.path->mReflowCommand;
    if (command)
      command->GetType(reflowType);
  }

  if (reflowType != eReflowType_UserDefined &&
      aReflowState.reason == eReflowReason_Incremental) {
    // Incremental reflow
     mFixedContainer.IncrementalReflow(this, aPresContext, reflowState,
                                       reflowState.mComputedWidth,
                                       reflowState.mComputedHeight);
  }

  // Just reflow all the fixed-pos frames.
  rv = mFixedContainer.Reflow(this, aPresContext, reflowState,
                              reflowState.mComputedWidth, 
                              reflowState.mComputedHeight);

  // If this is an initial reflow, resize reflow, or style change reflow
  // then do a repaint
  if ((eReflowReason_Initial == aReflowState.reason) ||
      (eReflowReason_Resize == aReflowState.reason) ||
      (eReflowReason_StyleChange == aReflowState.reason)) {
    nsRect damageRect(0, 0, aDesiredSize.width, aDesiredSize.height);
    Invalidate(damageRect, PR_FALSE);
  }

  NS_FRAME_TRACE_REFLOW_OUT("ViewportFrame::Reflow", aStatus);
  NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aDesiredSize);
  return rv; 
}

nsIAtom*
ViewportFrame::GetType() const
{
  return nsLayoutAtoms::viewportFrame;
}

/* virtual */ PRBool
ViewportFrame::IsContainingBlock() const
{
  return PR_TRUE;
}

#ifdef DEBUG
NS_IMETHODIMP
ViewportFrame::GetFrameName(nsAString& aResult) const
{
  return MakeFrameName(NS_LITERAL_STRING("Viewport"), aResult);
}
#endif