android 自定义动画4 RotateAnimation源码分析

源码如下:

/*
* Copyright (C) 2006 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

译: 版权信息: 略

package android.view.animation;

import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;

/**
* An animation that controls the rotation of an object. This rotation takes
* place int the X-Y plane. You can specify the point to use for the center of
* the rotation, where (0,0) is the top left point. If not specified, (0,0) is
* the default rotation point.
*/

译: 类的说明:一个控制对象旋转的动画类, 本旋转发生在x,y平面上, 你可以指定旋转的中心点,

不指定的话,默认为0,0点.0,0点是左上角的点(是屏幕左上角还是View的左上角? 应该说的是View的).

public class RotateAnimation extends Animation {
private float mFromDegrees;  　　　　//开始角度

private float mToDegrees;　　　　　　//结束角度

private int mPivotXType = ABSOLUTE;
private int mPivotYType = ABSOLUTE;
private float mPivotXValue = 0.0f;    //中心点
private float mPivotYValue = 0.0f;    //中心点

private float mPivotX;             
private float mPivotY;

/**
* Constructor used when a RotateAnimation is loaded from a resource.
*
* @param context Application context to use
* @param attrs Attribute set from which to read values
*/
public RotateAnimation(Context context, AttributeSet attrs) {
super(context, attrs);

TypedArray a = context.obtainStyledAttributes(attrs,
com.android.internal.R.styleable.RotateAnimation);

mFromDegrees = a.getFloat(
com.android.internal.R.styleable.RotateAnimation_fromDegrees, 0.0f);
mToDegrees = a.getFloat(com.android.internal.R.styleable.RotateAnimation_toDegrees, 0.0f);

Description d = Description.parseValue(a.peekValue(
com.android.internal.R.styleable.RotateAnimation_pivotX));
mPivotXType = d.type;
mPivotXValue = d.value;

d = Description.parseValue(a.peekValue(
com.android.internal.R.styleable.RotateAnimation_pivotY));
mPivotYType = d.type;
mPivotYValue = d.value;

a.recycle();
}

/**
* Constructor to use when building a RotateAnimation from code.
* Default pivotX/pivotY point is (0,0).
*
* @param fromDegrees Rotation offset to apply at the start of the
* animation.
*
* @param toDegrees Rotation offset to apply at the end of the animation.
*/
public RotateAnimation(float fromDegrees, float toDegrees) {
mFromDegrees = fromDegrees;
mToDegrees = toDegrees;
mPivotX = 0.0f;
mPivotY = 0.0f;
}

/**
* Constructor to use when building a RotateAnimation from code
*
* @param fromDegrees Rotation offset to apply at the start of the
* animation.
*
* @param toDegrees Rotation offset to apply at the end of the animation.
*
* @param pivotX The X coordinate of the point about which the object is
* being rotated, specified as an absolute number where 0 is the left
* edge.
* @param pivotY The Y coordinate of the point about which the object is
* being rotated, specified as an absolute number where 0 is the top
* edge.
*/
public RotateAnimation(float fromDegrees, float toDegrees, float pivotX, float pivotY) {
mFromDegrees = fromDegrees;
mToDegrees = toDegrees;

mPivotXType = ABSOLUTE;
mPivotYType = ABSOLUTE;
mPivotXValue = pivotX;
mPivotYValue = pivotY;
}

/**
* Constructor to use when building a RotateAnimation from code
*
* @param fromDegrees Rotation offset to apply at the start of the
* animation.
*
* @param toDegrees Rotation offset to apply at the end of the animation.
*
* @param pivotXType Specifies how pivotXValue should be interpreted. One of
* Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or
* Animation.RELATIVE_TO_PARENT.
* @param pivotXValue The X coordinate of the point about which the object
* is being rotated, specified as an absolute number where 0 is the
* left edge. This value can either be an absolute number if
* pivotXType is ABSOLUTE, or a percentage (where 1.0 is 100%)
* otherwise.
* @param pivotYType Specifies how pivotYValue should be interpreted. One of
* Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or
* Animation.RELATIVE_TO_PARENT.
* @param pivotYValue The Y coordinate of the point about which the object
* is being rotated, specified as an absolute number where 0 is the
* top edge. This value can either be an absolute number if
* pivotYType is ABSOLUTE, or a percentage (where 1.0 is 100%)
* otherwise.
*/
public RotateAnimation(float fromDegrees, float toDegrees, int pivotXType, float pivotXValue,
int pivotYType, float pivotYValue) {
mFromDegrees = fromDegrees;
mToDegrees = toDegrees;

mPivotXValue = pivotXValue;
mPivotXType = pivotXType;
mPivotYValue = pivotYValue;
mPivotYType = pivotYType;
}

@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
float degrees = mFromDegrees + ((mToDegrees - mFromDegrees) * interpolatedTime);
float scale = getScaleFactor();

if (mPivotX == 0.0f && mPivotY == 0.0f) {
t.getMatrix().setRotate(degrees);它也是用matrix来实现旋转的,不是matrix的按z轴旋转和它一样, 是它就是这样实现的.
} else {
t.getMatrix().setRotate(degrees, mPivotX * scale, mPivotY * scale);
}
}

@Override
public void initialize(int width, int height, int parentWidth, int parentHeight) {
super.initialize(width, height, parentWidth, parentHeight);
mPivotX = resolveSize(mPivotXType, mPivotXValue, width, parentWidth);
mPivotY = resolveSize(mPivotYType, mPivotYValue, height, parentHeight);
}
}

这篇文章有点糙啊,啥也没写, 本想深入分析一下实现过程, 也没什么,就四个构造器, 加两个方法 (一个initialize()一个applayTransformation()).