bool LayoutReplaced::needsPreferredWidthsRecalculation() const {
// If the height is a percentage and the width is auto, then the
// containingBlocks's height changing can cause this node to change it's
// preferred width because it maintains aspect ratio.
return hasRelativeLogicalHeight() && style()->logicalWidth().isAuto() &&
!hasAutoHeightOrContainingBlockWithAutoHeight();
}
LayoutUnit RenderReplaced::computeReplacedLogicalWidth(ShouldComputePreferred shouldComputePreferred) const
{
if (style()->logicalWidth().isSpecified() || style()->logicalWidth().isIntrinsic())
return computeReplacedLogicalWidthRespectingMinMaxWidth(computeReplacedLogicalWidthUsing(style()->logicalWidth()), shouldComputePreferred);
// 10.3.2 Inline, replaced elements: http://www.w3.org/TR/CSS21/visudet.html#inline-replaced-width
double intrinsicRatio = 0;
FloatSize constrainedSize;
computeAspectRatioInformationForRenderBox(constrainedSize, intrinsicRatio);
if (style()->logicalWidth().isAuto()) {
bool computedHeightIsAuto = hasAutoHeightOrContainingBlockWithAutoHeight();
bool hasIntrinsicWidth = constrainedSize.width() > 0;
// If 'height' and 'width' both have computed values of 'auto' and the element also has an intrinsic width, then that intrinsic width is the used value of 'width'.
if (computedHeightIsAuto && hasIntrinsicWidth)
return computeReplacedLogicalWidthRespectingMinMaxWidth(constrainedSize.width(), shouldComputePreferred);
bool hasIntrinsicHeight = constrainedSize.height() > 0;
if (intrinsicRatio) {
// If 'height' and 'width' both have computed values of 'auto' and the element has no intrinsic width, but does have an intrinsic height and intrinsic ratio;
// or if 'width' has a computed value of 'auto', 'height' has some other computed value, and the element does have an intrinsic ratio; then the used value
// of 'width' is: (used height) * (intrinsic ratio)
if (intrinsicRatio && ((computedHeightIsAuto && !hasIntrinsicWidth && hasIntrinsicHeight) || !computedHeightIsAuto)) {
LayoutUnit logicalHeight = computeReplacedLogicalHeight();
return computeReplacedLogicalWidthRespectingMinMaxWidth(roundToInt(round(logicalHeight * intrinsicRatio)), shouldComputePreferred);
}
// If 'height' and 'width' both have computed values of 'auto' and the element has an intrinsic ratio but no intrinsic height or width, then the used value of
// 'width' is undefined in CSS 2.1. However, it is suggested that, if the containing block's width does not itself depend on the replaced element's width, then
// the used value of 'width' is calculated from the constraint equation used for block-level, non-replaced elements in normal flow.
if (computedHeightIsAuto && !hasIntrinsicWidth && !hasIntrinsicHeight) {
if (shouldComputePreferred == ComputePreferred)
return 0;
// The aforementioned 'constraint equation' used for block-level, non-replaced elements in normal flow:
// 'margin-left' + 'border-left-width' + 'padding-left' + 'width' + 'padding-right' + 'border-right-width' + 'margin-right' = width of containing block
LayoutUnit logicalWidth = containingBlock()->availableLogicalWidth();
// This solves above equation for 'width' (== logicalWidth).
LayoutUnit marginStart = minimumValueForLength(style()->marginStart(), logicalWidth);
LayoutUnit marginEnd = minimumValueForLength(style()->marginEnd(), logicalWidth);
logicalWidth = std::max<LayoutUnit>(0, logicalWidth - (marginStart + marginEnd + (width() - clientWidth())));
return computeReplacedLogicalWidthRespectingMinMaxWidth(logicalWidth, shouldComputePreferred);
}
}
// Otherwise, if 'width' has a computed value of 'auto', and the element has an intrinsic width, then that intrinsic width is the used value of 'width'.
if (hasIntrinsicWidth)
return computeReplacedLogicalWidthRespectingMinMaxWidth(constrainedSize.width(), shouldComputePreferred);
// Otherwise, if 'width' has a computed value of 'auto', but none of the conditions above are met, then the used value of 'width' becomes 300px. If 300px is too
// wide to fit the device, UAs should use the width of the largest rectangle that has a 2:1 ratio and fits the device instead.
// Note: We fall through and instead return intrinsicLogicalWidth() here - to preserve existing WebKit behavior, which might or might not be correct, or desired.
// Changing this to return cDefaultWidth, will affect lots of test results. Eg. some tests assume that a blank <img> tag (which implies width/height=auto)
// has no intrinsic size, which is wrong per CSS 2.1, but matches our behavior since a long time.
}
return computeReplacedLogicalWidthRespectingMinMaxWidth(intrinsicLogicalWidth(), shouldComputePreferred);
}
bool RenderReplaced::hasReplacedLogicalHeight() const
{
if (style()->logicalHeight().isAuto())
return false;
if (style()->logicalHeight().isSpecified()) {
if (hasAutoHeightOrContainingBlockWithAutoHeight())
return false;
return true;
}
return false;
}
