core/java/android/view/animation/RotateAnimation.java

/*
 * 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.
 */

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 in 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.
 * 
 */
public class RotateAnimation extends Animation {
    private float mFromDegrees;
    private float mToDegrees;

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

    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();

        initializePivotPoint();
    }

    /**
     * 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;
        initializePivotPoint();
    }

    /**
     * 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;
        initializePivotPoint();
    }

    /**
     * Called at the end of constructor methods to initialize, if possible, values for
     * the pivot point. This is only possible for ABSOLUTE pivot values.
     */
    private void initializePivotPoint() {
        if (mPivotXType == ABSOLUTE) {
            mPivotX = mPivotXValue;
        }
        if (mPivotYType == ABSOLUTE) {
            mPivotY = mPivotYValue;
        }
    }

    @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);
        } 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);
    }
}