gecko-dev/layout/style/CSSCalc.h

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/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (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/MPL/
*
* 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 CSSCalc.h.
*
* The Initial Developer of the Original Code is the Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2009
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* L. David Baron <dbaron@dbaron.org>, Mozilla Corporation (original author)
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef CSSCalc_h_
#define CSSCalc_h_
#include "nsCSSValue.h"
#include "nsStyleCoord.h"
#include <math.h>
namespace mozilla {
namespace css {
/**
* ComputeCalc computes the result of a calc() expression tree.
*
* It is templatized over a CalcOps class that is expected to provide:
*
* // input_type and input_array_type have a bunch of very specific
* // expectations (which happen to be met by two classes (nsCSSValue
* // and nsStyleCoord). There must be methods (roughly):
* // input_array_type* input_type::GetArrayValue();
* // PRUint32 input_array_type::Count() const;
* // input_type& input_array_type::Item(PRUint32);
* typedef ... input_type;
* typedef ... input_array_type;
*
* typedef ... result_type;
*
* // GetUnit(avalue) must return the correct nsCSSUnit for any
* // value that represents a calc tree node (eCSSUnit_Calc*). For
* // other nodes, it may return any non eCSSUnit_Calc* unit.
* static nsCSSUnit GetUnit(const input_type& aValue);
*
* result_type
* MergeAdditive(nsCSSUnit aCalcFunction,
* result_type aValue1, result_type aValue2);
*
* result_type
* MergeMultiplicativeL(nsCSSUnit aCalcFunction,
* float aValue1, result_type aValue2);
*
* result_type
* MergeMultiplicativeR(nsCSSUnit aCalcFunction,
* result_type aValue1, float aValue2);
*
* result_type
* ComputeLeafValue(const input_type& aValue);
*
* float
* ComputeNumber(const input_type& aValue);
*
* The CalcOps methods might compute the calc() expression down to a
* number, reduce some parts of it to a number but replicate other
* parts, or produce a tree with a different data structure (for
* example, nsCSS* for specified values vs nsStyle* for computed
* values).
*
* For each leaf in the calc() expression, ComputeCalc will call either
* ComputeNumber (when the leaf is the left side of a Times_L or the
* right side of a Times_R or Divided) or ComputeLeafValue (otherwise).
* (The CalcOps in the CSS parser that reduces purely numeric
* expressions in turn calls ComputeCalc on numbers; other ops can
* presume that expressions in the number positions have already been
* normalized to a single numeric value and derive from
* NumbersAlreadyNormalizedCalcOps.)
*
* For non-leaves, one of the Merge functions will be called:
* MergeAdditive for Plus and Minus
* MergeMultiplicativeL for Times_L (number * value)
* MergeMultiplicativeR for Times_R (value * number) and Divided
*/
template <class CalcOps>
static typename CalcOps::result_type
ComputeCalc(const typename CalcOps::input_type& aValue, CalcOps &aOps)
{
switch (CalcOps::GetUnit(aValue)) {
case eCSSUnit_Calc: {
typename CalcOps::input_array_type *arr = aValue.GetArrayValue();
NS_ABORT_IF_FALSE(arr->Count() == 1, "unexpected length");
return ComputeCalc(arr->Item(0), aOps);
}
case eCSSUnit_Calc_Plus:
case eCSSUnit_Calc_Minus: {
typename CalcOps::input_array_type *arr = aValue.GetArrayValue();
NS_ABORT_IF_FALSE(arr->Count() == 2, "unexpected length");
typename CalcOps::result_type lhs = ComputeCalc(arr->Item(0), aOps),
rhs = ComputeCalc(arr->Item(1), aOps);
return aOps.MergeAdditive(CalcOps::GetUnit(aValue), lhs, rhs);
}
case eCSSUnit_Calc_Times_L: {
typename CalcOps::input_array_type *arr = aValue.GetArrayValue();
NS_ABORT_IF_FALSE(arr->Count() == 2, "unexpected length");
float lhs = aOps.ComputeNumber(arr->Item(0));
typename CalcOps::result_type rhs = ComputeCalc(arr->Item(1), aOps);
return aOps.MergeMultiplicativeL(CalcOps::GetUnit(aValue), lhs, rhs);
}
case eCSSUnit_Calc_Times_R:
case eCSSUnit_Calc_Divided: {
typename CalcOps::input_array_type *arr = aValue.GetArrayValue();
NS_ABORT_IF_FALSE(arr->Count() == 2, "unexpected length");
typename CalcOps::result_type lhs = ComputeCalc(arr->Item(0), aOps);
float rhs = aOps.ComputeNumber(arr->Item(1));
return aOps.MergeMultiplicativeR(CalcOps::GetUnit(aValue), lhs, rhs);
}
default: {
return aOps.ComputeLeafValue(aValue);
}
}
}
/**
* The input unit operation for input_type being nsCSSValue.
*/
struct CSSValueInputCalcOps
{
typedef nsCSSValue input_type;
typedef nsCSSValue::Array input_array_type;
static nsCSSUnit GetUnit(const nsCSSValue& aValue)
{
return aValue.GetUnit();
}
};
/**
* Basic*CalcOps provide a partial implementation of the CalcOps
* template parameter to ComputeCalc, for those callers whose merging
* just consists of mathematics (rather than tree construction).
*/
struct BasicCoordCalcOps
{
typedef nscoord result_type;
result_type
MergeAdditive(nsCSSUnit aCalcFunction,
result_type aValue1, result_type aValue2)
{
if (aCalcFunction == eCSSUnit_Calc_Plus) {
return NSCoordSaturatingAdd(aValue1, aValue2);
}
NS_ABORT_IF_FALSE(aCalcFunction == eCSSUnit_Calc_Minus,
"unexpected unit");
return NSCoordSaturatingSubtract(aValue1, aValue2, 0);
}
result_type
MergeMultiplicativeL(nsCSSUnit aCalcFunction,
float aValue1, result_type aValue2)
{
NS_ABORT_IF_FALSE(aCalcFunction == eCSSUnit_Calc_Times_L,
"unexpected unit");
return NSCoordSaturatingMultiply(aValue2, aValue1);
}
result_type
MergeMultiplicativeR(nsCSSUnit aCalcFunction,
result_type aValue1, float aValue2)
{
NS_ABORT_IF_FALSE(aCalcFunction == eCSSUnit_Calc_Times_R ||
aCalcFunction == eCSSUnit_Calc_Divided,
"unexpected unit");
if (aCalcFunction == eCSSUnit_Calc_Divided) {
aValue2 = 1.0f / aValue2;
}
return NSCoordSaturatingMultiply(aValue1, aValue2);
}
};
struct BasicFloatCalcOps
{
typedef float result_type;
result_type
MergeAdditive(nsCSSUnit aCalcFunction,
result_type aValue1, result_type aValue2)
{
if (aCalcFunction == eCSSUnit_Calc_Plus) {
return aValue1 + aValue2;
}
NS_ABORT_IF_FALSE(aCalcFunction == eCSSUnit_Calc_Minus,
"unexpected unit");
return aValue1 - aValue2;
}
result_type
MergeMultiplicativeL(nsCSSUnit aCalcFunction,
float aValue1, result_type aValue2)
{
NS_ABORT_IF_FALSE(aCalcFunction == eCSSUnit_Calc_Times_L,
"unexpected unit");
return aValue1 * aValue2;
}
result_type
MergeMultiplicativeR(nsCSSUnit aCalcFunction,
result_type aValue1, float aValue2)
{
if (aCalcFunction == eCSSUnit_Calc_Times_R) {
return aValue1 * aValue2;
}
NS_ABORT_IF_FALSE(aCalcFunction == eCSSUnit_Calc_Divided,
"unexpected unit");
return aValue1 / aValue2;
}
};
/**
* A ComputeNumber implementation for callers that can assume numbers
* are already normalized (i.e., anything past the parser).
*/
struct NumbersAlreadyNormalizedOps : public CSSValueInputCalcOps
{
float ComputeNumber(const nsCSSValue& aValue)
{
NS_ABORT_IF_FALSE(aValue.GetUnit() == eCSSUnit_Number, "unexpected unit");
return aValue.GetFloatValue();
}
};
/**
* SerializeCalc appends the serialization of aValue to a string.
*
* It is templatized over a CalcOps class that is expected to provide:
*
* // input_type and input_array_type have a bunch of very specific
* // expectations (which happen to be met by two classes (nsCSSValue
* // and nsStyleCoord). There must be methods (roughly):
* // input_array_type* input_type::GetArrayValue();
* // PRUint32 input_array_type::Count() const;
* // input_type& input_array_type::Item(PRUint32);
* typedef ... input_type;
* typedef ... input_array_type;
*
* static nsCSSUnit GetUnit(const input_type& aValue);
*
* void Append(const char* aString);
* void AppendLeafValue(const input_type& aValue);
* void AppendNumber(const input_type& aValue);
*
* Data structures given may or may not have a toplevel eCSSUnit_Calc
* node representing a calc whose toplevel is not min() or max().
*/
template <class CalcOps>
static void
SerializeCalcInternal(const typename CalcOps::input_type& aValue, CalcOps &aOps);
// Serialize the toplevel value in a calc() tree. See big comment
// above.
template <class CalcOps>
static void
SerializeCalc(const typename CalcOps::input_type& aValue, CalcOps &aOps)
{
aOps.Append("-moz-calc(");
nsCSSUnit unit = CalcOps::GetUnit(aValue);
if (unit == eCSSUnit_Calc) {
const typename CalcOps::input_array_type *array = aValue.GetArrayValue();
NS_ABORT_IF_FALSE(array->Count() == 1, "unexpected length");
SerializeCalcInternal(array->Item(0), aOps);
} else {
SerializeCalcInternal(aValue, aOps);
}
aOps.Append(")");
}
static inline bool
IsCalcAdditiveUnit(nsCSSUnit aUnit)
{
return aUnit == eCSSUnit_Calc_Plus ||
aUnit == eCSSUnit_Calc_Minus;
}
static inline bool
IsCalcMultiplicativeUnit(nsCSSUnit aUnit)
{
return aUnit == eCSSUnit_Calc_Times_L ||
aUnit == eCSSUnit_Calc_Times_R ||
aUnit == eCSSUnit_Calc_Divided;
}
// Serialize a non-toplevel value in a calc() tree. See big comment
// above.
template <class CalcOps>
/* static */ void
SerializeCalcInternal(const typename CalcOps::input_type& aValue, CalcOps &aOps)
{
nsCSSUnit unit = CalcOps::GetUnit(aValue);
if (IsCalcAdditiveUnit(unit)) {
const typename CalcOps::input_array_type *array = aValue.GetArrayValue();
NS_ABORT_IF_FALSE(array->Count() == 2, "unexpected length");
SerializeCalcInternal(array->Item(0), aOps);
if (eCSSUnit_Calc_Plus == unit) {
aOps.Append(" + ");
} else {
NS_ABORT_IF_FALSE(eCSSUnit_Calc_Minus == unit, "unexpected unit");
aOps.Append(" - ");
}
bool needParens = IsCalcAdditiveUnit(CalcOps::GetUnit(array->Item(1)));
if (needParens) {
aOps.Append("(");
}
SerializeCalcInternal(array->Item(1), aOps);
if (needParens) {
aOps.Append(")");
}
} else if (IsCalcMultiplicativeUnit(unit)) {
const typename CalcOps::input_array_type *array = aValue.GetArrayValue();
NS_ABORT_IF_FALSE(array->Count() == 2, "unexpected length");
bool needParens = IsCalcAdditiveUnit(CalcOps::GetUnit(array->Item(0)));
if (needParens) {
aOps.Append("(");
}
if (unit == eCSSUnit_Calc_Times_L) {
aOps.AppendNumber(array->Item(0));
} else {
SerializeCalcInternal(array->Item(0), aOps);
}
if (needParens) {
aOps.Append(")");
}
if (eCSSUnit_Calc_Times_L == unit || eCSSUnit_Calc_Times_R == unit) {
aOps.Append(" * ");
} else {
NS_ABORT_IF_FALSE(eCSSUnit_Calc_Divided == unit, "unexpected unit");
aOps.Append(" / ");
}
nsCSSUnit subUnit = CalcOps::GetUnit(array->Item(1));
needParens = IsCalcAdditiveUnit(subUnit) ||
IsCalcMultiplicativeUnit(subUnit);
if (needParens) {
aOps.Append("(");
}
if (unit == eCSSUnit_Calc_Times_L) {
SerializeCalcInternal(array->Item(1), aOps);
} else {
aOps.AppendNumber(array->Item(1));
}
if (needParens) {
aOps.Append(")");
}
} else {
aOps.AppendLeafValue(aValue);
}
}
}
}
#endif /* !defined(CSSCalc_h_) */