C++ nsMargin::LeftRight方法代码示例

// Helper function to compute the offset needed to center a child
// page-frame's margin-box inside our content-box.
nscoord
nsSimplePageSequenceFrame::ComputeCenteringMargin(
  nscoord aContainerContentBoxWidth,
  nscoord aChildPaddingBoxWidth,
  const nsMargin& aChildPhysicalMargin)
{
  // We'll be centering our child's margin-box, so get the size of that:
  nscoord childMarginBoxWidth =
    aChildPaddingBoxWidth + aChildPhysicalMargin.LeftRight();

  // When rendered, our child's rect will actually be scaled up by the
  // print-preview scale factor, via ComputePageSequenceTransform().
  // We really want to center *that scaled-up rendering* inside of
  // aContainerContentBoxWidth.  So, we scale up its margin-box here...
  auto ppScale = PresContext()->GetPrintPreviewScale();
  nscoord scaledChildMarginBoxWidth =
    NSToCoordRound(childMarginBoxWidth * ppScale);

  // ...and see we how much space is left over, when we subtract that scaled-up
  // size from the container width:
  nscoord scaledExtraSpace =
    aContainerContentBoxWidth - scaledChildMarginBoxWidth;

  if (scaledExtraSpace <= 0) {
    // (Don't bother centering if there's zero/negative space.)
    return 0;
  }

  // To center the child, we want to give it an additional left-margin of half
  // of the extra space.  And then, we have to scale that space back down, so
  // that it'll produce the correct scaled-up amount when we render (because
  // rendering will scale it back up):
  return NSToCoordRound(scaledExtraSpace * 0.5 / ppScale);
}

// Deflate the rect by the specified margin
void nsRect::Deflate(const nsMargin &aMargin)
{
  x += aMargin.left;
  y += aMargin.top;
  width = PR_MAX(0, width - aMargin.LeftRight());
  height = PR_MAX(0, height - aMargin.TopBottom());
}

// Helper-function that lets us clone the button's reflow state, but with its
// ComputedWidth and ComputedHeight reduced by the amount of renderer-specific
// focus border and padding that we're using. (This lets us provide a more
// appropriate content-box size for descendents' percent sizes to resolve
// against.)
static nsHTMLReflowState
CloneReflowStateWithReducedContentBox(
  const nsHTMLReflowState& aButtonReflowState,
  const nsMargin& aFocusPadding)
{
  nscoord adjustedWidth =
    aButtonReflowState.ComputedWidth() - aFocusPadding.LeftRight();
  adjustedWidth = std::max(0, adjustedWidth);

  // (Only adjust height if it's an actual length.)
  nscoord adjustedHeight = aButtonReflowState.ComputedHeight();
  if (adjustedHeight != NS_INTRINSICSIZE) {
    adjustedHeight -= aFocusPadding.TopBottom();
    adjustedHeight = std::max(0, adjustedHeight);
  }

  nsHTMLReflowState clone(aButtonReflowState);
  clone.SetComputedWidth(adjustedWidth);
  clone.SetComputedHeight(adjustedHeight);

  return clone;
}

void
nsHTMLButtonControlFrame::ReflowButtonContents(nsPresContext* aPresContext,
                                               nsHTMLReflowMetrics& aDesiredSize,
                                               const nsHTMLReflowState& aReflowState,
                                               nsIFrame* aFirstKid,
                                               nsMargin aFocusPadding,
                                               nsReflowStatus& aStatus)
{
  nsSize availSize(aReflowState.ComputedWidth(), NS_INTRINSICSIZE);

  // Indent the child inside us by the focus border. We must do this separate
  // from the regular border.
  availSize.width -= aFocusPadding.LeftRight();
  
  // See whether out availSize's width is big enough.  If it's smaller than our
  // intrinsic min width, that means that the kid wouldn't really fit; for a
  // better look in such cases we adjust the available width and our left
  // offset to allow the kid to spill left into our padding.
  nscoord xoffset = aFocusPadding.left + aReflowState.mComputedBorderPadding.left;
  nscoord extrawidth = GetMinWidth(aReflowState.rendContext) -
    aReflowState.ComputedWidth();
  if (extrawidth > 0) {
    nscoord extraleft = extrawidth / 2;
    nscoord extraright = extrawidth - extraleft;
    NS_ASSERTION(extraright >=0, "How'd that happen?");
    
    // Do not allow the extras to be bigger than the relevant padding
    extraleft = std::min(extraleft, aReflowState.mComputedPadding.left);
    extraright = std::min(extraright, aReflowState.mComputedPadding.right);
    xoffset -= extraleft;
    availSize.width += extraleft + extraright;
  }
  availSize.width = std::max(availSize.width,0);
  
  nsHTMLReflowState reflowState(aPresContext, aReflowState, aFirstKid,
                                availSize);

  ReflowChild(aFirstKid, aPresContext, aDesiredSize, reflowState,
              xoffset,
              aFocusPadding.top + aReflowState.mComputedBorderPadding.top,
              0, aStatus);

  // Compute our desired height before vertically centering our children
  nscoord actualDesiredHeight = 0;
  if (aReflowState.ComputedHeight() != NS_INTRINSICSIZE) {
    actualDesiredHeight = aReflowState.ComputedHeight();
  } else {
    actualDesiredHeight = aDesiredSize.height + aFocusPadding.TopBottom();

    // Make sure we obey min/max-height in the case when we're doing intrinsic
    // sizing (we get it for free when we have a non-intrinsic
    // aReflowState.ComputedHeight()).  Note that we do this before adjusting
    // for borderpadding, since mComputedMaxHeight and mComputedMinHeight are
    // content heights.
    actualDesiredHeight = NS_CSS_MINMAX(actualDesiredHeight,
                                        aReflowState.mComputedMinHeight,
                                        aReflowState.mComputedMaxHeight);
  }

  // center child vertically in the content area
  nscoord yoff = (actualDesiredHeight - aFocusPadding.TopBottom() - aDesiredSize.height) / 2;
  if (yoff < 0) {
    yoff = 0;
  }

  // Place the child
  FinishReflowChild(aFirstKid, aPresContext, &reflowState, aDesiredSize,
                    xoffset,
                    yoff + aFocusPadding.top + aReflowState.mComputedBorderPadding.top, 0);

  if (aDesiredSize.ascent == nsHTMLReflowMetrics::ASK_FOR_BASELINE)
    aDesiredSize.ascent = aFirstKid->GetBaseline();

  // Adjust the baseline by our offset (since we moved the child's
  // baseline by that much), and set our actual desired height.
  aDesiredSize.ascent += yoff;
  aDesiredSize.height = actualDesiredHeight;
}

void
nsHTMLButtonControlFrame::ReflowButtonContents(nsPresContext* aPresContext,
                                               nsHTMLReflowMetrics& aDesiredSize,
                                               const nsHTMLReflowState& aReflowState,
                                               nsIFrame* aFirstKid,
                                               nsMargin aFocusPadding,
                                               nsReflowStatus& aStatus)
{
  nsSize availSize(aReflowState.ComputedWidth(), NS_INTRINSICSIZE);

  // Indent the child inside us by the focus border. We must do this separate
  // from the regular border.
  availSize.width -= aFocusPadding.LeftRight();
  
  // See whether out availSize's width is big enough.  If it's smaller than our
  // intrinsic min width, that means that the kid wouldn't really fit; for a
  // better look in such cases we adjust the available width and our left
  // offset to allow the kid to spill left into our padding.
  nscoord xoffset = aFocusPadding.left + aReflowState.mComputedBorderPadding.left;
  nscoord extrawidth = GetMinWidth(aReflowState.rendContext) -
    aReflowState.ComputedWidth();
  if (extrawidth > 0) {
    nscoord extraleft = extrawidth / 2;
    nscoord extraright = extrawidth - extraleft;
    NS_ASSERTION(extraright >=0, "How'd that happen?");
    
    // Do not allow the extras to be bigger than the relevant padding
    extraleft = std::min(extraleft, aReflowState.mComputedPadding.left);
    extraright = std::min(extraright, aReflowState.mComputedPadding.right);
    xoffset -= extraleft;
    availSize.width += extraleft + extraright;
  }
  availSize.width = std::max(availSize.width,0);
  
  nsHTMLReflowState reflowState(aPresContext, aReflowState, aFirstKid,
                                availSize);

  ReflowChild(aFirstKid, aPresContext, aDesiredSize, reflowState,
              xoffset,
              aFocusPadding.top + aReflowState.mComputedBorderPadding.top,
              0, aStatus);
  
  // calculate the min internal height so the contents gets centered correctly.
  // XXXbz this assumes border-box sizing.
  nscoord minInternalHeight = aReflowState.mComputedMinHeight -
    aReflowState.mComputedBorderPadding.TopBottom();
  minInternalHeight = std::max(minInternalHeight, 0);

  // center child vertically
  nscoord yoff = 0;
  if (aReflowState.ComputedHeight() != NS_INTRINSICSIZE) {
    yoff = (aReflowState.ComputedHeight() - aDesiredSize.height)/2;
    if (yoff < 0) {
      yoff = 0;
    }
  } else if (aDesiredSize.height < minInternalHeight) {
    yoff = (minInternalHeight - aDesiredSize.height) / 2;
  }

  // Place the child
  FinishReflowChild(aFirstKid, aPresContext, &reflowState, aDesiredSize,
                    xoffset,
                    yoff + aFocusPadding.top + aReflowState.mComputedBorderPadding.top, 0);

  if (aDesiredSize.ascent == nsHTMLReflowMetrics::ASK_FOR_BASELINE)
    aDesiredSize.ascent = aFirstKid->GetBaseline();

  // Adjust the baseline by our offset (since we moved the child's
  // baseline by that much).
  aDesiredSize.ascent += yoff;
}

void
nsHTMLButtonControlFrame::ReflowButtonContents(nsPresContext* aPresContext,
                                               nsHTMLReflowMetrics& aButtonDesiredSize,
                                               const nsHTMLReflowState& aButtonReflowState,
                                               nsIFrame* aFirstKid)
{
  // Buttons have some bonus renderer-determined border/padding,
  // which occupies part of the button's content-box area:
  const nsMargin focusPadding = mRenderer.GetAddedButtonBorderAndPadding();

  nsSize availSize(aButtonReflowState.ComputedWidth(), NS_INTRINSICSIZE);

  // Indent the child inside us by the focus border. We must do this separate
  // from the regular border.
  availSize.width -= focusPadding.LeftRight();
  
  // See whether out availSize's width is big enough.  If it's smaller than our
  // intrinsic min width, that means that the kid wouldn't really fit; for a
  // better look in such cases we adjust the available width and our left
  // offset to allow the kid to spill left into our padding.
  nscoord xoffset = focusPadding.left +
    aButtonReflowState.ComputedPhysicalBorderPadding().left;
  nscoord extrawidth = GetMinWidth(aButtonReflowState.rendContext) -
    aButtonReflowState.ComputedWidth();
  if (extrawidth > 0) {
    nscoord extraleft = extrawidth / 2;
    nscoord extraright = extrawidth - extraleft;
    NS_ASSERTION(extraright >=0, "How'd that happen?");
    
    // Do not allow the extras to be bigger than the relevant padding
    extraleft = std::min(extraleft, aButtonReflowState.ComputedPhysicalPadding().left);
    extraright = std::min(extraright, aButtonReflowState.ComputedPhysicalPadding().right);
    xoffset -= extraleft;
    availSize.width += extraleft + extraright;
  }
  availSize.width = std::max(availSize.width,0);
  
  // Give child a clone of the button's reflow state, with height/width reduced
  // by focusPadding, so that descendants with height:100% don't protrude.
  nsHTMLReflowState adjustedButtonReflowState =
    CloneReflowStateWithReducedContentBox(aButtonReflowState, focusPadding);

  nsHTMLReflowState contentsReflowState(aPresContext,
                                        adjustedButtonReflowState,
                                        aFirstKid, availSize);

  nsReflowStatus contentsReflowStatus;
  nsHTMLReflowMetrics contentsDesiredSize(aButtonReflowState.GetWritingMode());
  ReflowChild(aFirstKid, aPresContext,
              contentsDesiredSize, contentsReflowState,
              xoffset,
              focusPadding.top + aButtonReflowState.ComputedPhysicalBorderPadding().top,
              0, contentsReflowStatus);
  MOZ_ASSERT(NS_FRAME_IS_COMPLETE(contentsReflowStatus),
             "We gave button-contents frame unconstrained available height, "
             "so it should be complete");

  // Compute the button's content-box height:
  nscoord buttonContentBoxHeight = 0;
  if (aButtonReflowState.ComputedHeight() != NS_INTRINSICSIZE) {
    // Button has a fixed height -- that's its content-box height.
    buttonContentBoxHeight = aButtonReflowState.ComputedHeight();
  } else {
    // Button is intrinsically sized -- it should shrinkwrap the
    // button-contents' height, plus any focus-padding space:
    buttonContentBoxHeight =
      contentsDesiredSize.Height() + focusPadding.TopBottom();

    // Make sure we obey min/max-height in the case when we're doing intrinsic
    // sizing (we get it for free when we have a non-intrinsic
    // aButtonReflowState.ComputedHeight()).  Note that we do this before
    // adjusting for borderpadding, since mComputedMaxHeight and
    // mComputedMinHeight are content heights.
    buttonContentBoxHeight =
      NS_CSS_MINMAX(buttonContentBoxHeight,
                    aButtonReflowState.ComputedMinHeight(),
                    aButtonReflowState.ComputedMaxHeight());
  }

  // Center child vertically in the button
  // (technically, inside of the button's focus-padding area)
  nscoord extraSpace =
    buttonContentBoxHeight - focusPadding.TopBottom() -
    contentsDesiredSize.Height();

  nscoord yoffset = std::max(0, extraSpace / 2);

  // Adjust yoffset to be in terms of the button's frame-rect, instead of
  // its focus-padding rect:
  yoffset += focusPadding.top + aButtonReflowState.ComputedPhysicalBorderPadding().top;

  // Place the child
  FinishReflowChild(aFirstKid, aPresContext,
                    contentsDesiredSize, &contentsReflowState,
                    xoffset, yoffset, 0);

  // Make sure we have a useful 'ascent' value for the child
  if (contentsDesiredSize.TopAscent() == nsHTMLReflowMetrics::ASK_FOR_BASELINE) {
    contentsDesiredSize.SetTopAscent(aFirstKid->GetBaseline());
  }
//.........这里部分代码省略.........