gecko-dev/layout/generic/nsBlockReflowContext.cpp

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/* -*- 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 "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/NPL/
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* The Original Code is Mozilla Communicator client code.
*
* The Initial Developer of the Original Code is Netscape Communications
* Corporation. Portions created by Netscape are Copyright (C) 1998
* Netscape Communications Corporation. All Rights Reserved.
*/
#include "nsBlockReflowContext.h"
#include "nsFrameReflowState.h"
#include "nsLineLayout.h"
#include "nsHTMLIIDs.h"
#include "nsISpaceManager.h"
#include "nsIFontMetrics.h"
#include "nsIPresContext.h"
#include "nsIStyleContext.h"
#include "nsHTMLContainerFrame.h"
#ifdef NS_DEBUG
#define NOISY_SPECULATIVE_TOP_MARGIN
#else
#undef NOISY_SPECULATIVE_TOP_MARGIN
#endif
nsBlockReflowContext::nsBlockReflowContext(nsIPresContext& aPresContext,
nsLineLayout& aLineLayout,
nsFrameReflowState& aParentRS)
: mPresContext(aPresContext),
mLineLayout(aLineLayout),
mOuterReflowState(aParentRS),
mMetrics(aParentRS.mComputeMaxElementSize ? &mMaxElementSize : nsnull)
{
mRunInFrame = nsnull;
mCompactMarginWidth = 0;
mSpacing = nsnull;
}
void
nsBlockReflowContext::ComputeMarginsFor(nsIPresContext& aPresContext,
nsIFrame* aFrame,
const nsStyleSpacing* aSpacing,
const nsFrameReflowState& aParentRS,
nsMargin& aResult)
{
// XXX pass in mSpacing to ComputeMarginFor
nsHTMLReflowState::ComputeMarginFor(aFrame, &aParentRS, aResult);
// Compute auto top/bottom margin values
nsStyleUnit topUnit = aSpacing->mMargin.GetTopUnit();
nsStyleUnit bottomUnit = aSpacing->mMargin.GetBottomUnit();
nscoord fontHeight = 0;
if ((eStyleUnit_Auto == topUnit) || (eStyleUnit_Auto == bottomUnit)) {
// XXX Use the font for the frame, not the default font???
const nsFont& defaultFont = aPresContext.GetDefaultFontDeprecated();
nsIFontMetrics* fm;
aPresContext.GetMetricsFor(defaultFont, &fm);
fm->GetHeight(fontHeight);
NS_RELEASE(fm);
}
// For auto margins use the font height computed above
if (eStyleUnit_Auto == topUnit) {
aResult.top = fontHeight;
}
if (eStyleUnit_Auto == bottomUnit) {
aResult.bottom = fontHeight;
}
}
nsresult
nsBlockReflowContext::ReflowBlock(nsIFrame* aFrame,
const nsRect& aSpace,
#ifdef SPECULATIVE_TOP_MARGIN
PRBool aApplyTopMargin,
nscoord aPrevBottomMargin,
#endif
PRBool aIsAdjacentWithTop,
nsMargin& aComputedOffsets,
nsReflowStatus& aFrameReflowStatus)
{
nsresult rv = NS_OK;
mFrame = aFrame;
mSpace = aSpace;
// Compute the raw margins (including auto margins)
aFrame->GetStyleData(eStyleStruct_Spacing, (const nsStyleStruct*&)mSpacing);
ComputeMarginsFor(mPresContext, aFrame, mSpacing, mOuterReflowState,
mMargin);
#ifdef SPECULATIVE_TOP_MARGIN
#ifdef NOISY_SPECULATIVE_TOP_MARGIN
PRIntn pass = 0;
#endif
mSpeculativeTopMargin = 0;
if (aApplyTopMargin) {
// Compute a "speculative" collapsed top-margin value. Its
// speculative because we don't yet have the
// carried-out-top-margin value so the final collapsed value isn't
// knowable yet. We want to pre-apply the collapsed top-margin
// value so that when a block is flowing around floaters that we
// don't have to reflow it twice (we can't just slide it down when
// its flowing around a floater after discovering the final top
// margin value).
mSpeculativeTopMargin = MaxMargin(mMargin.top, aPrevBottomMargin);
}
again:
#else
mSpeculativeTopMargin = 0;
#endif
// Compute x/y coordinate where reflow will begin. Use the rules
// from 10.3.3 to determine what to apply. At this point in the
// reflow auto left/right margins will have a zero value.
nscoord x = aSpace.x + mMargin.left;
nscoord y = aSpace.y + mSpeculativeTopMargin;
mX = x;
mY = y;
nsSize availSize(aSpace.width, aSpace.height);
if (NS_UNCONSTRAINEDSIZE != aSpace.width) {
availSize.width -= mMargin.left + mMargin.right;
}
if (NS_UNCONSTRAINEDSIZE != aSpace.height) {
availSize.height -= mMargin.top + mMargin.bottom;
}
// Get reflow reason set correctly. It's possible that a child was
// created and then it was decided that it could not be reflowed
// (for example, a block frame that isn't at the start of a
// line). In this case the reason will be wrong so we need to check
// the frame state.
nsReflowReason reason = eReflowReason_Resize;
nsFrameState state;
aFrame->GetFrameState(&state);
if (NS_FRAME_FIRST_REFLOW & state) {
reason = eReflowReason_Initial;
}
else if (mOuterReflowState.mNextRCFrame == aFrame) {
reason = eReflowReason_Incremental;
// Make sure we only incrementally reflow once
// XXX caller should do this, yes?
mOuterReflowState.mNextRCFrame = nsnull;
}
// XXX update to use the computedMargin information from the reflow-state
// XXX eliminate circular dependency in reflow-state ctor - eliminate
// availSize argument (since we need margins to compute it!)
// Setup reflow state for reflowing the frame
nsHTMLReflowState reflowState(mPresContext, aFrame, mOuterReflowState,
availSize);
aComputedOffsets = reflowState.computedOffsets;
reflowState.lineLayout = nsnull;
reflowState.mRunInFrame = mRunInFrame;
reflowState.mCompactMarginWidth = mCompactMarginWidth;
reflowState.reason = reason;
if (!aIsAdjacentWithTop) {
reflowState.isTopOfPage = PR_FALSE; // make sure this is cleared
}
mLineLayout.SetUnderstandsWhiteSpace(PR_FALSE);
// Let frame know that we are reflowing it
nsIHTMLReflow* htmlReflow;
rv = aFrame->QueryInterface(kIHTMLReflowIID, (void**)&htmlReflow);
if (NS_FAILED(rv)) {
return rv;
}
htmlReflow->WillReflow(mPresContext);
// Adjust spacemanager coordinate system for the frame. The
// spacemanager coordinates are <b>inside</b> the callers
// border+padding, but the x/y coordinates are not (recall that
// frame coordinates are relative to the parents origin and that the
// parents border/padding is <b>inside</b> the parent
// frame. Therefore we have to subtract out the parents
// border+padding before translating.
nscoord tx = x - mOuterReflowState.mBorderPadding.left;
nscoord ty = y - mOuterReflowState.mBorderPadding.top;
aFrame->MoveTo(x, y);
mOuterReflowState.spaceManager->Translate(tx, ty);
rv = htmlReflow->Reflow(mPresContext, mMetrics, reflowState,
aFrameReflowStatus);
mOuterReflowState.spaceManager->Translate(-tx, -ty);
aFrame->GetFrameState(&state);
if (0 == (NS_FRAME_OUTSIDE_CHILDREN & state)) {
// Provide combined area for child that doesn't have any
mMetrics.mCombinedArea.x = 0;
mMetrics.mCombinedArea.y = 0;
mMetrics.mCombinedArea.width = mMetrics.width;
mMetrics.mCombinedArea.height = mMetrics.height;
}
// Now that frame has been reflowed at least one time make sure that
// the NS_FRAME_FIRST_REFLOW bit is cleared so that never give it an
// initial reflow reason again.
if (eReflowReason_Initial == reason) {
aFrame->SetFrameState(state & ~NS_FRAME_FIRST_REFLOW);
}
if (!NS_INLINE_IS_BREAK_BEFORE(aFrameReflowStatus)) {
// If frame is complete and has a next-in-flow, we need to delete
// them now. Do not do this when a break-before is signaled because
// the frame is going to get reflowed again (and may end up wanting
// a next-in-flow where it ends up).
if (NS_FRAME_IS_COMPLETE(aFrameReflowStatus)) {
nsIFrame* kidNextInFlow;
aFrame->GetNextInFlow(&kidNextInFlow);
if (nsnull != kidNextInFlow) {
// Remove all of the childs next-in-flows. Make sure that we ask
// the right parent to do the removal (it's possible that the
// parent is not this because we are executing pullup code)
/* XXX promote DeleteChildsNextInFlow to nsIFrame to elminate this cast */
nsHTMLContainerFrame* parent;
aFrame->GetParent((nsIFrame**)&parent);
parent->DeleteChildsNextInFlow(mPresContext, aFrame);
}
}
#ifdef SPECULATIVE_TOP_MARGIN
if (aApplyTopMargin) {
// Compute final collapsed margin value
CollapseMargins(mMargin, mMetrics.mCarriedOutTopMargin,
mMetrics.mCarriedOutBottomMargin,
mMetrics.height, aPrevBottomMargin,
mTopMargin, mBottomMargin);
if (mSpeculativeTopMargin != mTopMargin) {
// We lost our speculative gamble. Use new computed margin
// value as the speculative value and try the reflow again.
#ifdef NOISY_SPECULATIVE_TOP_MARGIN
nsFrame::ListTag(stdout, mOuterReflowState.frame);
printf(": reflowing again: ");
nsFrame::ListTag(stdout, aFrame);
printf(" guess=%d actual=%d [pass %d]\n",
mSpeculativeTopMargin, mTopMargin, pass);
pass++;
#endif
mSpeculativeTopMargin = mTopMargin;
goto again;
}
}
#endif
}
return rv;
}
/**
* The CSS2 spec, section 8.3.1 defines margin collapsing to apply to
* vertical margins of block boxes. And the spec also indicates that
* this should be done for two or more adjacent vertical margins. It
* also indicates that the margins collapse between boxes that are
* next to each other or nested.
*/
void
nsBlockReflowContext::CollapseMargins(const nsMargin& aMargin,
nscoord aCarriedOutTopMargin,
nscoord aCarriedOutBottomMargin,
nscoord aFrameHeight,
nscoord aPrevBottomMargin,
nscoord& aTopMarginResult,
nscoord& aBottomMarginResult)
{
// Compute the collapsed top margin value. The top margin value is a
// 3 way margin collapse. First we collapse the carried out top
// margin with the block frames top margin (this is a CSS2 "nested"
// collapse). Then we collapse that value with the previous bottom
// margin (because the collapsed margin is adjacent to the previous
// bottom margin).
nscoord carriedTopMargin = aCarriedOutTopMargin;
nscoord topMargin = aMargin.top;
topMargin = MaxMargin(topMargin, carriedTopMargin);
topMargin = MaxMargin(topMargin, aPrevBottomMargin);
// Compute the collapsed bottom margin value. The bottom margin
// value is a 2 way margin collapse. Collapse the carried out bottom
// margin with the block frames bottom margin (this is a CSS2
// "nested" collapse).
nscoord carriedBottomMargin = aCarriedOutBottomMargin;
nscoord bottomMargin = aMargin.bottom;
bottomMargin = MaxMargin(bottomMargin, carriedBottomMargin);
// If the block line is empty then we collapse the top and bottom
// margin values (because the margins are adjacent).
if (0 == aFrameHeight) {
nscoord collapsedMargin = MaxMargin(topMargin, bottomMargin);
topMargin = 0;
bottomMargin = collapsedMargin;
}
aTopMarginResult = topMargin;
aBottomMarginResult = bottomMargin;
}
/**
* Attempt to place the block frame within the available space. If
* it fits, apply horizontal positioning (CSS 10.3.3), collapse
* margins (CSS2 8.3.1). Also apply relative positioning.
*/
PRBool
nsBlockReflowContext::PlaceBlock(PRBool aForceFit,
#ifndef SPECULATIVE_TOP_MARGIN
PRBool aApplyTopMargin,
nscoord aPrevBottomMargin,
#endif
const nsMargin& aComputedOffsets,
nsRect& aInFlowBounds,
nsRect& aCombinedRect)
{
#ifndef SPECULATIVE_TOP_MARGIN
// Compute final collapsed margin value
CollapseMargins(mMargin, mMetrics.mCarriedOutTopMargin,
mMetrics.mCarriedOutBottomMargin,
mMetrics.height, aPrevBottomMargin,
mTopMargin, mBottomMargin);
#endif
// See if the block will fit in the available space
PRBool fits;
if (0 == mMetrics.height) {
// Empty blocks do not have anything special done to them and they
// always fit.
nsRect r(mX, mY, 0, 0);
mFrame->SetRect(r);
aInFlowBounds = r;
aCombinedRect = r;
fits = PR_TRUE;
}
else {
nscoord x = mX;
nscoord y = mY;
// Apply top margin unless it's going to be carried out.
#ifndef SPECULATIVE_TOP_MARGIN
if (aApplyTopMargin) {
y += mTopMargin;
}
#endif
// Position block horizontally according to CSS2 10.3.3
if (NS_UNCONSTRAINEDSIZE != mSpace.width) {
// XXX left/right block margins should be applied right here.
// Because of the issue with floaters and block-left/right
// margins this code is not yet complete. This code may need to
// move to before reflowing the frame instead of after (because
// of floater positioning).
nscoord remainder = mSpace.XMost() -
(x + mMetrics.width + mMargin.right);
if (remainder >= 0) {
// The block frame didn't use all of the available space. Apply
// auto margins.
nsStyleUnit leftUnit = mSpacing->mMargin.GetLeftUnit();
nsStyleUnit rightUnit = mSpacing->mMargin.GetRightUnit();
if (eStyleUnit_Auto == leftUnit) {
if (eStyleUnit_Auto == rightUnit) {
// When both margins are auto, we center the block
x += remainder / 2;
}
else {
x += remainder;
}
}
else if (eStyleUnit_Auto != rightUnit) {
// When neither margin is auto then text-align applies
const nsStyleText* styleText = mOuterReflowState.mStyleText;
switch (styleText->mTextAlign) {
case NS_STYLE_TEXT_ALIGN_DEFAULT:
case NS_STYLE_TEXT_ALIGN_JUSTIFY:
if (NS_STYLE_DIRECTION_RTL == mOuterReflowState.mDirection) {
// When given a default alignment, and a right-to-left
// direction, right align the frame.
x += remainder;
}
break;
case NS_STYLE_TEXT_ALIGN_RIGHT:
x += remainder;
break;
case NS_STYLE_TEXT_ALIGN_CENTER:
x += remainder / 2;
break;
}
}
}
else {
// XXX Handle over-constrained case by forcing the appropriate
// margin to be auto
}
}
// See if the frame fit. If its the first frame then it always
// fits.
if (aForceFit || (y + mMetrics.height <= mSpace.YMost())) {
fits = PR_TRUE;
// Update the in-flow bounding box's bounds. Include the margins.
aInFlowBounds.SetRect(x, y,
mMetrics.width + mMargin.right,
mMetrics.height);
// Apply CSS relative positioning to update x,y coordinates
const nsStylePosition* stylePos;
mFrame->GetStyleData(eStyleStruct_Position,
(const nsStyleStruct*&)stylePos);
if (NS_STYLE_POSITION_RELATIVE == stylePos->mPosition) {
x += aComputedOffsets.left;
y += aComputedOffsets.top;
}
// Compute combined-rect in callers coordinate system. The value
// returned in the reflow metrics is relative to the child
// frame.
aCombinedRect.x = mMetrics.mCombinedArea.x + x;
aCombinedRect.y = mMetrics.mCombinedArea.y + y;
aCombinedRect.width = mMetrics.mCombinedArea.width;
aCombinedRect.height = mMetrics.mCombinedArea.height;
// Now place the frame
mFrame->SetRect(nsRect(x, y, mMetrics.width, mMetrics.height));
// If the block frame ended up moving then we need to slide
// anything inside of it that impacts the space manager
// (otherwise the impacted space in the space manager will be
// out of sync with where the frames really are).
nscoord dx = x - mX;
nscoord dy = y - mY;
if ((0 != dx) || (0 != dy)) {
nsIHTMLReflow* htmlReflow;
nsresult rv;
rv = mFrame->QueryInterface(kIHTMLReflowIID, (void**)&htmlReflow);
if (NS_SUCCEEDED(rv)) {
// If the child has any floaters that impact the space manager,
// slide them now
htmlReflow->MoveInSpaceManager(mPresContext,
mOuterReflowState.spaceManager,
dx, dy);
}
}
// Adjust the max-element-size in the metrics to take into
// account the margins around the block element. Note that we
// use the collapsed top and bottom margin values.
if (mOuterReflowState.mComputeMaxElementSize) {
nsSize* m = mMetrics.maxElementSize;
m->width += mMargin.left + mMargin.right;
m->height += mTopMargin + mBottomMargin;
}
}
else {
fits = PR_FALSE;
}
}
return fits;
}