pjs/layout/generic/nsBRFrame.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * The contents of this file are subject to the Netscape Public License
 * Version 1.0 (the "NPL"); you may not use this file except in
 * compliance with the NPL.  You may obtain a copy of the NPL at
 * http://www.mozilla.org/NPL/
 *
 * Software distributed under the NPL is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
 * for the specific language governing rights and limitations under the
 * NPL.
 *
 * The Initial Developer of this code under the NPL is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation.  All Rights
 * Reserved.
 */
#include "nsCOMPtr.h"
#include "nsFrame.h"
#include "nsHTMLParts.h"
#include "nsHTMLIIDs.h"
#include "nsIPresContext.h"
#include "nsLineLayout.h"
#include "nsStyleConsts.h"
#include "nsHTMLAtoms.h"
#include "nsIStyleContext.h"
#include "nsIFontMetrics.h"
#include "nsIRenderingContext.h"

class BRFrame : public nsFrame {
public:
  // nsIFrame
  NS_IMETHOD Paint(nsIPresContext& aPresContext,
                   nsIRenderingContext& aRenderingContext,
                   const nsRect& aDirtyRect,
                   nsFramePaintLayer aWhichLayer);

  // nsIHTMLReflow
  NS_IMETHOD Reflow(nsIPresContext& aPresContext,
                    nsHTMLReflowMetrics& aDesiredSize,
                    const nsHTMLReflowState& aReflowState,
                    nsReflowStatus& aStatus);
  NS_IMETHOD GetPosition(nsIPresContext& aCX,
                         nscoord aXCoord,
                         nsIContent** aNewContent,
                         PRInt32& aContentOffset,
                         PRInt32& aContentOffsetEnd);

protected:
  virtual ~BRFrame();
};

nsresult
NS_NewBRFrame(nsIFrame** aNewFrame)
{
  NS_PRECONDITION(aNewFrame, "null OUT ptr");
  if (nsnull == aNewFrame) {
    return NS_ERROR_NULL_POINTER;
  }
  nsIFrame* frame = new BRFrame;
  if (nsnull == frame) {
    return NS_ERROR_OUT_OF_MEMORY;
  }
  *aNewFrame = frame;
  return NS_OK;
}

BRFrame::~BRFrame()
{
}

NS_IMETHODIMP
BRFrame::Paint(nsIPresContext& aPresContext,
               nsIRenderingContext& aRenderingContext,
               const nsRect& aDirtyRect,
               nsFramePaintLayer aWhichLayer)
{
  if ((NS_FRAME_PAINT_LAYER_DEBUG == aWhichLayer) && GetShowFrameBorders()) {
    float p2t;
    aPresContext.GetPixelsToTwips(&p2t);
    nscoord five = NSIntPixelsToTwips(5, p2t);
    aRenderingContext.SetColor(NS_RGB(0, 255, 255));
    aRenderingContext.FillRect(0, 0, five, five*2);
  }
  return NS_OK;
}

NS_IMETHODIMP
BRFrame::Reflow(nsIPresContext& aPresContext,
                nsHTMLReflowMetrics& aMetrics,
                const nsHTMLReflowState& aReflowState,
                nsReflowStatus& aStatus)
{
  if (aMetrics.maxElementSize) {
    aMetrics.maxElementSize->width = 0;
    aMetrics.maxElementSize->height = 0;
  }
  aMetrics.height = 0;
  aMetrics.width = 0;
  aMetrics.ascent = 0;
  aMetrics.descent = 0;

  // Only when the BR is operating in a line-layout situation will it
  // behave like a BR.
  if (nsnull != aReflowState.mLineLayout) {
    if (aReflowState.mLineLayout->CanPlaceFloaterNow()) {
      // If we can place a floater on the line now it means that the
      // line is effectively empty (there may be zero sized compressed
      // white-space frames on the line, but they are to be ignored).
      //
      // Because this frame is going to terminate the line we know
      // that nothing else will go on the line. Therefore, in this
      // case only, we provide some height for the BR frame so that it
      // creates some vertical whitespace.
      const nsStyleFont* font = (const nsStyleFont*)
        mStyleContext->GetStyleData(eStyleStruct_Font);
      aReflowState.rendContext->SetFont(font->mFont);
      nsCOMPtr<nsIFontMetrics> fm;
      aReflowState.rendContext->GetFontMetrics(*getter_AddRefs(fm));
      if (fm) {
        fm->GetHeight(aMetrics.height);
        aMetrics.ascent = aMetrics.height;
      }
      else {
        aMetrics.ascent = aMetrics.height = 0;
      }

      // XXX temporary until I figure out a better solution; see the
      // code in nsLineLayout::VerticalAlignFrames that zaps minY/maxY
      // if the width is zero.
      // XXX This also fixes bug 10036!
      aMetrics.width = 1;

      // Update max-element-size to keep us honest
      if (aMetrics.maxElementSize) {
        if (aMetrics.width > aMetrics.maxElementSize->width) {
          aMetrics.maxElementSize->width = aMetrics.width;
        }
        if (aMetrics.height > aMetrics.maxElementSize->height) {
          aMetrics.maxElementSize->height = aMetrics.height;
        }
      }
    }

    // Return our reflow status
    PRUint32 breakType = aReflowState.mStyleDisplay->mBreakType;
    if (NS_STYLE_CLEAR_NONE == breakType) {
      breakType = NS_STYLE_CLEAR_LINE;
    }

    aStatus = NS_INLINE_BREAK | NS_INLINE_BREAK_AFTER |
      NS_INLINE_MAKE_BREAK_TYPE(breakType);
  }
  else {
    aStatus = NS_FRAME_COMPLETE;
  }
  return NS_OK;
}



NS_IMETHODIMP BRFrame::GetPosition(nsIPresContext& aCX,
                         nscoord         aCoord,
                         nsIContent **   aContent,
                         PRInt32&        aOffsetBegin,
                         PRInt32&        aOffsetEnd)
{
  nsresult returnval = nsFrame::GetPosition(aCX,aCoord,aContent,aOffsetBegin,aOffsetEnd);
  if (NS_SUCCEEDED(returnval))
    aOffsetEnd = aOffsetBegin;//BRFrames should return a collapsed selection before itself
  return returnval;
}