gecko-dev/layout/generic/nsPlaceholderFrame.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
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 *
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/*
 * rendering object for the point that anchors out-of-flow rendering
 * objects such as floats and absolutely positioned elements
 */

#include "nsPlaceholderFrame.h"
#include "nsLineLayout.h"
#include "nsIContent.h"
#include "nsPresContext.h"
#include "nsIRenderingContext.h"
#include "nsLayoutAtoms.h"
#include "nsFrameManager.h"
#include "nsDisplayList.h"

nsIFrame*
NS_NewPlaceholderFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
{
  return new (aPresShell) nsPlaceholderFrame(aContext);
}

nsPlaceholderFrame::~nsPlaceholderFrame()
{
}

NS_IMETHODIMP
nsPlaceholderFrame::Reflow(nsPresContext*          aPresContext,
                           nsHTMLReflowMetrics&     aDesiredSize,
                           const nsHTMLReflowState& aReflowState,
                           nsReflowStatus&          aStatus)
{
  DO_GLOBAL_REFLOW_COUNT("nsPlaceholderFrame", aReflowState.reason);
  DISPLAY_REFLOW(aPresContext, this, aReflowState, aDesiredSize, aStatus);
  aDesiredSize.width = 0;
  aDesiredSize.height = 0;
  aDesiredSize.ascent = 0;
  aDesiredSize.descent = 0;
  if (aDesiredSize.mComputeMEW) {
    aDesiredSize.mMaxElementWidth = 0;
  }

  aStatus = NS_FRAME_COMPLETE;
  NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aDesiredSize);
  return NS_OK;
}

void
nsPlaceholderFrame::Destroy()
{
  nsIPresShell* shell = GetPresContext()->GetPresShell();
  if (shell && mOutOfFlowFrame) {
    NS_ASSERTION(!shell->FrameManager()->GetPlaceholderFrameFor(mOutOfFlowFrame),
                 "Placeholder relationship should have been torn down");
  }

  nsSplittableFrame::Destroy();
}

nsIAtom*
nsPlaceholderFrame::GetType() const
{
  return nsLayoutAtoms::placeholderFrame; 
}

#ifdef DEBUG
static void
PaintDebugPlaceholder(nsIFrame* aFrame, nsIRenderingContext* aCtx,
                      const nsRect& aDirtyRect, nsPoint aPt)
{
  float p2t;
  p2t = aFrame->GetPresContext()->PixelsToTwips();
  aCtx->SetColor(NS_RGB(0, 255, 255));
  nscoord x = NSIntPixelsToTwips(-5, p2t);
  aCtx->FillRect(aPt.x + x, aPt.y,
                 NSIntPixelsToTwips(13, p2t), NSIntPixelsToTwips(3, p2t));
  nscoord y = NSIntPixelsToTwips(-10, p2t);
  aCtx->FillRect(aPt.x, aPt.y + y,
                 NSIntPixelsToTwips(3, p2t), NSIntPixelsToTwips(10, p2t));
}

NS_IMETHODIMP
nsPlaceholderFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
                                     const nsRect&           aDirtyRect,
                                     const nsDisplayListSet& aLists)
{
  if (!GetShowFrameBorders())
    return NS_OK;
  
  return aLists.Outlines()->AppendNewToTop(new (aBuilder)
      nsDisplayGeneric(this, PaintDebugPlaceholder, "DebugPlaceholder"));
}

NS_IMETHODIMP
nsPlaceholderFrame::GetFrameName(nsAString& aResult) const
{
  return MakeFrameName(NS_LITERAL_STRING("Placeholder"), aResult);
}

NS_IMETHODIMP
nsPlaceholderFrame::List(FILE* out, PRInt32 aIndent) const
{
  IndentBy(out, aIndent);
  ListTag(out);
#ifdef DEBUG_waterson
  fprintf(out, " [parent=%p]", NS_STATIC_CAST(void*, mParent));
#endif
  if (HasView()) {
    fprintf(out, " [view=%p]", (void*)GetView());
  }
  fprintf(out, " {%d,%d,%d,%d}", mRect.x, mRect.y, mRect.width, mRect.height);
  if (0 != mState) {
    fprintf(out, " [state=%08x]", mState);
  }
  nsIFrame* prevInFlow = GetPrevInFlow();
  nsIFrame* nextInFlow = GetNextInFlow();
  if (nsnull != prevInFlow) {
    fprintf(out, " prev-in-flow=%p", NS_STATIC_CAST(void*, prevInFlow));
  }
  if (nsnull != nextInFlow) {
    fprintf(out, " next-in-flow=%p", NS_STATIC_CAST(void*, nextInFlow));
  }
  if (mOutOfFlowFrame) {
    fprintf(out, " outOfFlowFrame=");
    nsFrame::ListTag(out, mOutOfFlowFrame);
  }
  fputs("\n", out);
  return NS_OK;
}
#endif