void TextTrackCue::calculateDisplayParameters()
{
// Steps 10.2, 10.3
determineTextDirection();
// 10.4 If the text track cue writing direction is horizontal, then let
// block-flow be 'tb'. Otherwise, if the text track cue writing direction is
// vertical growing left, then let block-flow be 'lr'. Otherwise, the text
// track cue writing direction is vertical growing right; let block-flow be
// 'rl'.
m_displayWritingMode = m_displayWritingModeMap[m_writingDirection];
// 10.5 Determine the value of maximum size for cue as per the appropriate
// rules from the following list:
int maximumSize = m_textPosition;
if ((m_writingDirection == Horizontal && m_cueAlignment == Start && m_displayDirection == CSSValueLtr)
|| (m_writingDirection == Horizontal && m_cueAlignment == End && m_displayDirection == CSSValueRtl)
|| (m_writingDirection == VerticalGrowingLeft && m_cueAlignment == Start)
|| (m_writingDirection == VerticalGrowingRight && m_cueAlignment == Start)) {
maximumSize = 100 - m_textPosition;
} else if ((m_writingDirection == Horizontal && m_cueAlignment == End && m_displayDirection == CSSValueLtr)
|| (m_writingDirection == Horizontal && m_cueAlignment == Start && m_displayDirection == CSSValueRtl)
|| (m_writingDirection == VerticalGrowingLeft && m_cueAlignment == End)
|| (m_writingDirection == VerticalGrowingRight && m_cueAlignment == End)) {
maximumSize = m_textPosition;
} else if (m_cueAlignment == Middle) {
maximumSize = m_textPosition <= 50 ? m_textPosition : (100 - m_textPosition);
maximumSize = maximumSize * 2;
}
// 10.6 If the text track cue size is less than maximum size, then let size
// be text track cue size. Otherwise, let size be maximum size.
m_displaySize = std::min(m_cueSize, maximumSize);
// 10.8 Determine the value of x-position or y-position for cue as per the
// appropriate rules from the following list:
if (m_writingDirection == Horizontal) {
if (m_cueAlignment == Start) {
if (m_displayDirection == CSSValueLtr)
m_displayPosition.first = m_textPosition;
else
m_displayPosition.first = 100 - m_textPosition - m_displaySize;
} else if (m_cueAlignment == End) {
if (m_displayDirection == CSSValueRtl)
m_displayPosition.first = 100 - m_textPosition;
else
m_displayPosition.first = m_textPosition - m_displaySize;
}
}
if ((m_writingDirection == VerticalGrowingLeft && m_cueAlignment == Start)
|| (m_writingDirection == VerticalGrowingRight && m_cueAlignment == Start)) {
m_displayPosition.second = m_textPosition;
} else if ((m_writingDirection == VerticalGrowingLeft && m_cueAlignment == End)
|| (m_writingDirection == VerticalGrowingRight && m_cueAlignment == End)) {
m_displayPosition.second = 100 - m_textPosition;
}
if (m_writingDirection == Horizontal && m_cueAlignment == Middle) {
if (m_displayDirection == CSSValueLtr)
m_displayPosition.first = m_textPosition - m_displaySize / 2;
else
m_displayPosition.first = 100 - m_textPosition - m_displaySize / 2;
}
if ((m_writingDirection == VerticalGrowingLeft && m_cueAlignment == Middle)
|| (m_writingDirection == VerticalGrowingRight && m_cueAlignment == Middle))
m_displayPosition.second = m_textPosition - m_displaySize / 2;
// 10.9 Determine the value of whichever of x-position or y-position is not
// yet calculated for cue as per the appropriate rules from the following
// list:
if (m_snapToLines && m_displayPosition.second == undefinedPosition && m_writingDirection == Horizontal)
m_displayPosition.second = 0;
if (!m_snapToLines && m_displayPosition.second == undefinedPosition && m_writingDirection == Horizontal)
m_displayPosition.second = m_computedLinePosition;
if (m_snapToLines && m_displayPosition.first == undefinedPosition
&& (m_writingDirection == VerticalGrowingLeft || m_writingDirection == VerticalGrowingRight))
m_displayPosition.first = 0;
if (!m_snapToLines && (m_writingDirection == VerticalGrowingLeft || m_writingDirection == VerticalGrowingRight))
m_displayPosition.first = m_computedLinePosition;
// A text track cue has a text track cue computed line position whose value
// is defined in terms of the other aspects of the cue.
m_computedLinePosition = calculateComputedLinePosition();
}
void VTTCue::calculateDisplayParameters()
{
createVTTNodeTree();
// Steps 10.2, 10.3
m_displayDirection = determineTextDirection(m_vttNodeTree.get());
if (m_displayDirection == CSSValueRtl)
UseCounter::count(document(), UseCounter::VTTCueRenderRtl);
// 10.4 If the text track cue writing direction is horizontal, then let
// block-flow be 'tb'. Otherwise, if the text track cue writing direction is
// vertical growing left, then let block-flow be 'lr'. Otherwise, the text
// track cue writing direction is vertical growing right; let block-flow be
// 'rl'.
// The above step is done through the writing direction static map.
// 10.5 Determine the value of maximum size for cue as per the appropriate
// rules from the following list:
int maximumSize = m_textPosition;
if ((m_writingDirection == Horizontal && m_cueAlignment == Start && m_displayDirection == CSSValueLtr)
|| (m_writingDirection == Horizontal && m_cueAlignment == End && m_displayDirection == CSSValueRtl)
|| (m_writingDirection == Horizontal && m_cueAlignment == Left)
|| (m_writingDirection == VerticalGrowingLeft && (m_cueAlignment == Start || m_cueAlignment == Left))
|| (m_writingDirection == VerticalGrowingRight && (m_cueAlignment == Start || m_cueAlignment == Left))) {
maximumSize = 100 - m_textPosition;
} else if ((m_writingDirection == Horizontal && m_cueAlignment == End && m_displayDirection == CSSValueLtr)
|| (m_writingDirection == Horizontal && m_cueAlignment == Start && m_displayDirection == CSSValueRtl)
|| (m_writingDirection == Horizontal && m_cueAlignment == Right)
|| (m_writingDirection == VerticalGrowingLeft && (m_cueAlignment == End || m_cueAlignment == Right))
|| (m_writingDirection == VerticalGrowingRight && (m_cueAlignment == End || m_cueAlignment == Right))) {
maximumSize = m_textPosition;
} else if (m_cueAlignment == Middle) {
maximumSize = m_textPosition <= 50 ? m_textPosition : (100 - m_textPosition);
maximumSize = maximumSize * 2;
} else {
ASSERT_NOT_REACHED();
}
// 10.6 If the text track cue size is less than maximum size, then let size
// be text track cue size. Otherwise, let size be maximum size.
m_displaySize = std::min(m_cueSize, maximumSize);
// FIXME: Understand why step 10.7 is missing (just a copy/paste error?)
// Could be done within a spec implementation check - http://crbug.com/301580
// 10.8 Determine the value of x-position or y-position for cue as per the
// appropriate rules from the following list:
if (m_writingDirection == Horizontal) {
switch (m_cueAlignment) {
case Start:
if (m_displayDirection == CSSValueLtr)
m_displayPosition.first = m_textPosition;
else
m_displayPosition.first = 100 - m_textPosition - m_displaySize;
break;
case End:
if (m_displayDirection == CSSValueRtl)
m_displayPosition.first = 100 - m_textPosition;
else
m_displayPosition.first = m_textPosition - m_displaySize;
break;
case Left:
if (m_displayDirection == CSSValueLtr)
m_displayPosition.first = m_textPosition;
else
m_displayPosition.first = 100 - m_textPosition;
break;
case Right:
if (m_displayDirection == CSSValueLtr)
m_displayPosition.first = m_textPosition - m_displaySize;
else
m_displayPosition.first = 100 - m_textPosition - m_displaySize;
break;
case Middle:
if (m_displayDirection == CSSValueLtr)
m_displayPosition.first = m_textPosition - m_displaySize / 2;
else
m_displayPosition.first = 100 - m_textPosition - m_displaySize / 2;
break;
default:
ASSERT_NOT_REACHED();
}
} else {
// Cases for m_writingDirection being VerticalGrowing{Left|Right}
switch (m_cueAlignment) {
case Start:
case Left:
m_displayPosition.second = m_textPosition;
break;
case End:
case Right:
m_displayPosition.second = m_textPosition - m_displaySize;
break;
case Middle:
m_displayPosition.second = m_textPosition - m_displaySize / 2;
break;
default:
ASSERT_NOT_REACHED();
}
}
// A text track cue has a text track cue computed line position whose value
// is defined in terms of the other aspects of the cue.
m_computedLinePosition = calculateComputedLinePosition();
// 10.9 Determine the value of whichever of x-position or y-position is not
// yet calculated for cue as per the appropriate rules from the following
// list:
if (m_snapToLines && m_displayPosition.second == undefinedPosition && m_writingDirection == Horizontal)
m_displayPosition.second = 0;
if (!m_snapToLines && m_displayPosition.second == undefinedPosition && m_writingDirection == Horizontal)
m_displayPosition.second = m_computedLinePosition;
if (m_snapToLines && m_displayPosition.first == undefinedPosition
&& (m_writingDirection == VerticalGrowingLeft || m_writingDirection == VerticalGrowingRight))
m_displayPosition.first = 0;
if (!m_snapToLines && (m_writingDirection == VerticalGrowingLeft || m_writingDirection == VerticalGrowingRight))
m_displayPosition.first = m_computedLinePosition;
}
VTTDisplayParameters VTTCue::calculateDisplayParameters() const
{
// http://dev.w3.org/html5/webvtt/#dfn-apply-webvtt-cue-settings
VTTDisplayParameters displayParameters;
// Steps 1 and 2.
displayParameters.direction = determineTextDirection(m_vttNodeTree.get());
if (displayParameters.direction == CSSValueRtl)
UseCounter::count(document(), UseCounter::VTTCueRenderRtl);
// Note: The 'text-align' property is also determined here so that
// VTTCueBox::applyCSSProperties need not have access to a VTTCue.
displayParameters.textAlign = displayAlignmentMap[getCueAlignment()];
// 3. If the cue writing direction is horizontal, then let block-flow be
// 'tb'. Otherwise, if the cue writing direction is vertical growing left,
// then let block-flow be 'lr'. Otherwise, the cue writing direction is
// vertical growing right; let block-flow be 'rl'.
displayParameters.writingMode = displayWritingModeMap[m_writingDirection];
// Resolve the cue alignment to one of the values {start, end, middle}.
CueAlignment computedCueAlignment = calculateComputedCueAlignment();
// 4. Determine the value of maximum size for cue as per the appropriate
// rules from the following list:
float computedTextPosition = calculateComputedTextPosition();
float maximumSize = computedTextPosition;
if (computedCueAlignment == Start) {
maximumSize = 100 - computedTextPosition;
} else if (computedCueAlignment == End) {
maximumSize = computedTextPosition;
} else if (computedCueAlignment == Middle) {
maximumSize = computedTextPosition <= 50 ? computedTextPosition : (100 - computedTextPosition);
maximumSize = maximumSize * 2;
} else {
ASSERT_NOT_REACHED();
}
// 5. If the cue size is less than maximum size, then let size
// be cue size. Otherwise, let size be maximum size.
displayParameters.size = std::min(m_cueSize, maximumSize);
// 6. If the cue writing direction is horizontal, then let width
// be 'size vw' and height be 'auto'. Otherwise, let width be 'auto' and
// height be 'size vh'. (These are CSS values used by the next section to
// set CSS properties for the rendering; 'vw' and 'vh' are CSS units.)
// (Emulated in VTTCueBox::applyCSSProperties.)
// 7. Determine the value of x-position or y-position for cue as per the
// appropriate rules from the following list:
if (m_writingDirection == Horizontal) {
switch (computedCueAlignment) {
case Start:
displayParameters.position.setX(computedTextPosition);
break;
case End:
displayParameters.position.setX(computedTextPosition - displayParameters.size);
break;
case Middle:
displayParameters.position.setX(computedTextPosition - displayParameters.size / 2);
break;
default:
ASSERT_NOT_REACHED();
}
} else {
// Cases for m_writingDirection being VerticalGrowing{Left|Right}
switch (computedCueAlignment) {
case Start:
displayParameters.position.setY(computedTextPosition);
break;
case End:
displayParameters.position.setY(computedTextPosition - displayParameters.size);
break;
case Middle:
displayParameters.position.setY(computedTextPosition - displayParameters.size / 2);
break;
default:
ASSERT_NOT_REACHED();
}
}
// A cue has a computed line whose value is defined in terms of
// the other aspects of the cue.
float computedLinePosition = calculateComputedLinePosition();
// 8. Determine the value of whichever of x-position or y-position is not
// yet calculated for cue as per the appropriate rules from the following
// list:
if (!m_snapToLines) {
if (m_writingDirection == Horizontal)
displayParameters.position.setY(computedLinePosition);
else
displayParameters.position.setX(computedLinePosition);
} else {
if (m_writingDirection == Horizontal)
displayParameters.position.setY(0);
else
displayParameters.position.setX(0);
}
// Step 9 not implemented (margin == 0).
// The snap-to-lines position is propagated to LayoutVTTCue.
displayParameters.snapToLinesPosition = m_snapToLines
? computedLinePosition
: std::numeric_limits<float>::quiet_NaN();
ASSERT(std::isfinite(displayParameters.size));
ASSERT(displayParameters.direction != CSSValueNone);
ASSERT(displayParameters.writingMode != CSSValueNone);
return displayParameters;
}