gecko-dev/layout/style/nsStyleAnimation.h

173 lines
6.9 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** 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 nsStyleAnimation.
*
* The Initial Developer of the Original Code is
* The Mozilla Corporation.
* Portions created by the Initial Developer are Copyright (C) 2009
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Daniel Holbert <dholbert@mozilla.com>, Mozilla Corporation
* L. David Baron <dbaron@dbaron.org>, Mozilla Corporation
*
* 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 ***** */
/* Utilities for animation of computed style values */
#ifndef nsStyleAnimation_h_
#define nsStyleAnimation_h_
#include "prtypes.h"
#include "nsAString.h"
#include "nsCSSProperty.h"
class nsCSSDeclaration;
class nsIContent;
class nsPresContext;
class nsStyleCoord;
class nsStyleContext;
/**
* Utility class to handle animated style values
*/
class nsStyleAnimation {
public:
// Mathematical methods
// --------------------
/**
* Adds |aCount| copies of |aValueToAdd| to |aDest|. The result of this
* addition is stored in aDest.
*
* Note that if |aCount| is 0, then |aDest| will be unchanged. Also, if
* this method fails, then |aDest| will be unchanged.
*
* @param aDest The value to add to.
* @param aValueToAdd The value to add.
* @param aCount The number of times to add aValueToAdd.
* @return PR_TRUE on success, PR_FALSE on failure.
*/
static PRBool Add(nsStyleCoord& aDest, const nsStyleCoord& aValueToAdd,
PRUint32 aCount);
/**
* Calculates a measure of 'distance' between two values.
*
* If this method succeeds, the returned distance value is guaranteed to be
* non-negative.
*
* @param aStartValue The start of the interval for which the distance
* should be calculated.
* @param aEndValue The end of the interval for which the distance
* should be calculated.
* @param aDistance The result of the calculation.
* @return PR_TRUE on success, PR_FALSE on failure.
*/
static PRBool ComputeDistance(const nsStyleCoord& aStartValue,
const nsStyleCoord& aEndValue,
double& aDistance);
/**
* Calculates an interpolated value that is the specified |aPortion| between
* the two given values.
*
* This really just does the following calculation:
* aResultValue = (1.0 - aPortion) * aStartValue + aPortion * aEndValue
*
* @param aStartValue The value defining the start of the interval of
* interpolation.
* @param aEndValue The value defining the end of the interval of
* interpolation.
* @param aPortion A number in the range [0.0, 1.0] defining the
* distance of the interpolated value in the interval.
* @param [out] aResultValue The resulting interpolated value.
* @return PR_TRUE on success, PR_FALSE on failure.
*/
static PRBool Interpolate(const nsStyleCoord& aStartValue,
const nsStyleCoord& aEndValue,
double aPortion,
nsStyleCoord& aResultValue);
// Type-conversion methods
// -----------------------
/**
* Creates a computed value (nsStyleCoord) for the given specified value
* (property ID + string). A style context is needed in case the
* specified value depends on inherited style or on the values of other
* properties.
*
* NOTE: This method uses GetPrimaryShell() to access the style system,
* so it should only be used for style that applies to all presentations,
* rather than for style that only applies to a particular presentation.
* XXX Once we get rid of multiple presentations, we can remove the above
* note.
*
* @param aProperty The property whose value we're computing.
* @param aTargetElement The content node to which our computed value is
* applicable.
* @param aSpecifiedValue The specified value, from which we'll build our
* computed value.
* @param [out] aComputedValue The resulting computed value.
* @return PR_TRUE on success, PR_FALSE on failure.
*/
static PRBool ComputeValue(nsCSSProperty aProperty,
nsIContent* aElement,
const nsAString& aSpecifiedValue,
nsStyleCoord& aComputedValue);
/**
* Gets the computed value for the given property from the given style
* context.
*
* @param aProperty The property whose value we're looking up.
* @param aStyleContext The style context to check for the computed value.
* @param [out] aComputedValue The resulting computed value.
* @return PR_TRUE on success, PR_FALSE on failure.
*/
static PRBool ExtractComputedValue(nsCSSProperty aProperty,
nsStyleContext* aStyleContext,
nsStyleCoord& aComputedValue);
/**
* Sets the computed value for the given property in the given style
* struct.
*
* @param aProperty The property whose value we're setting.
* @param aPresContext The pres context associated with aStyleStruct.
* @param aStyleStruct The style struct in which to set the value.
* @param aComputedValue The computed value.
* @return PR_TRUE on success, PR_FALSE on failure.
*/
static PRBool StoreComputedValue(nsCSSProperty aProperty,
nsPresContext* aPresContext,
void* aStyleStruct,
const nsStyleCoord& aComputedValue);
};
#endif