Android example source code file (ScaleAnimation.java)

This example Android source code file (ScaleAnimation.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

absolute, android, attributeset, content, description, override, scaleanimation, transformation, typedarray, util, utilities, utils

The ScaleAnimation.java Android example source code

/*
 * 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 scale of an object. You can specify the point
 * to use for the center of scaling.
 * 
 */
public class ScaleAnimation extends Animation {
    private float mFromX;
    private float mToX;
    private float mFromY;
    private float mToY;

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

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

        mFromX = a.getFloat(com.android.internal.R.styleable.ScaleAnimation_fromXScale, 0.0f);
        mToX = a.getFloat(com.android.internal.R.styleable.ScaleAnimation_toXScale, 0.0f);

        mFromY = a.getFloat(com.android.internal.R.styleable.ScaleAnimation_fromYScale, 0.0f);
        mToY = a.getFloat(com.android.internal.R.styleable.ScaleAnimation_toYScale, 0.0f);

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

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

        a.recycle();
    }

    /**
     * Constructor to use when building a ScaleAnimation from code
     * 
     * @param fromX Horizontal scaling factor to apply at the start of the
     *        animation
     * @param toX Horizontal scaling factor to apply at the end of the animation
     * @param fromY Vertical scaling factor to apply at the start of the
     *        animation
     * @param toY Vertical scaling factor to apply at the end of the animation
     */
    public ScaleAnimation(float fromX, float toX, float fromY, float toY) {
        mFromX = fromX;
        mToX = toX;
        mFromY = fromY;
        mToY = toY;
        mPivotX = 0;
        mPivotY = 0;
    }

    /**
     * Constructor to use when building a ScaleAnimation from code
     * 
     * @param fromX Horizontal scaling factor to apply at the start of the
     *        animation
     * @param toX Horizontal scaling factor to apply at the end of the animation
     * @param fromY Vertical scaling factor to apply at the start of the
     *        animation
     * @param toY Vertical scaling factor to apply at the end of the animation
     * @param pivotX The X coordinate of the point about which the object is
     *        being scaled, specified as an absolute number where 0 is the left
     *        edge. (This point remains fixed while the object changes size.)
     * @param pivotY The Y coordinate of the point about which the object is
     *        being scaled, specified as an absolute number where 0 is the top
     *        edge. (This point remains fixed while the object changes size.)
     */
    public ScaleAnimation(float fromX, float toX, float fromY, float toY,
            float pivotX, float pivotY) {
        mFromX = fromX;
        mToX = toX;
        mFromY = fromY;
        mToY = toY;

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

    /**
     * Constructor to use when building a ScaleAnimation from code
     * 
     * @param fromX Horizontal scaling factor to apply at the start of the
     *        animation
     * @param toX Horizontal scaling factor to apply at the end of the animation
     * @param fromY Vertical scaling factor to apply at the start of the
     *        animation
     * @param toY Vertical scaling factor 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 scaled, specified as an absolute number where 0 is the
     *        left edge. (This point remains fixed while the object changes
     *        size.) 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 scaled, specified as an absolute number where 0 is the
     *        top edge. (This point remains fixed while the object changes
     *        size.) This value can either be an absolute number if pivotYType
     *        is ABSOLUTE, or a percentage (where 1.0 is 100%) otherwise.
     */
    public ScaleAnimation(float fromX, float toX, float fromY, float toY,
            int pivotXType, float pivotXValue, int pivotYType, float pivotYValue) {
        mFromX = fromX;
        mToX = toX;
        mFromY = fromY;
        mToY = toY;

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

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        float sx = 1.0f;
        float sy = 1.0f;

        if (mFromX != 1.0f || mToX != 1.0f) {
            sx = mFromX + ((mToX - mFromX) * interpolatedTime);
        }
        if (mFromY != 1.0f || mToY != 1.0f) {
            sy = mFromY + ((mToY - mFromY) * interpolatedTime);
        }

        if (mPivotX == 0 && mPivotY == 0) {
            t.getMatrix().setScale(sx, sy);
        } else {
            t.getMatrix().setScale(sx, sy, mPivotX, mPivotY);
        }
    }

    @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);
    }
}