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Android example source code file (Transformation.java)

This example Android source code file (Transformation.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

android, drawing, graphics, io, matrix, override, paint, string, stringbuilder, transformation, type_alpha, type_both, type_identity, type_matrix, ui

The Transformation.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.graphics.Matrix;

import java.io.PrintWriter;

/**
 * Defines the transformation to be applied at
 * one point in time of an Animation.
 *
 */
public class Transformation {
    /**
     * Indicates a transformation that has no effect (alpha = 1 and identity matrix.)
     */
    public static int TYPE_IDENTITY = 0x0;
    /**
     * Indicates a transformation that applies an alpha only (uses an identity matrix.)
     */
    public static int TYPE_ALPHA = 0x1;
    /**
     * Indicates a transformation that applies a matrix only (alpha = 1.)
     */
    public static int TYPE_MATRIX = 0x2;
    /**
     * Indicates a transformation that applies an alpha and a matrix.
     */
    public static int TYPE_BOTH = TYPE_ALPHA | TYPE_MATRIX;

    protected Matrix mMatrix;
    protected float mAlpha;
    protected int mTransformationType;

    /**
     * Creates a new transformation with alpha = 1 and the identity matrix.
     */
    public Transformation() {
        clear();
    }

    /**
     * Reset the transformation to a state that leaves the object
     * being animated in an unmodified state. The transformation type is
     * {@link #TYPE_BOTH} by default.
     */
    public void clear() {
        if (mMatrix == null) {
            mMatrix = new Matrix();
        } else {
            mMatrix.reset();
        }
        mAlpha = 1.0f;
        mTransformationType = TYPE_BOTH;
    }

    /**
     * Indicates the nature of this transformation.
     *
     * @return {@link #TYPE_ALPHA}, {@link #TYPE_MATRIX},
     *         {@link #TYPE_BOTH} or {@link #TYPE_IDENTITY}.
     */
    public int getTransformationType() {
        return mTransformationType;
    }

    /**
     * Sets the transformation type.
     *
     * @param transformationType One of {@link #TYPE_ALPHA},
     *        {@link #TYPE_MATRIX}, {@link #TYPE_BOTH} or
     *        {@link #TYPE_IDENTITY}.
     */
    public void setTransformationType(int transformationType) {
        mTransformationType = transformationType;
    }

    /**
     * Clones the specified transformation.
     *
     * @param t The transformation to clone.
     */
    public void set(Transformation t) {
        mAlpha = t.getAlpha();
        mMatrix.set(t.getMatrix());
        mTransformationType = t.getTransformationType();
    }
    
    /**
     * Apply this Transformation to an existing Transformation, e.g. apply
     * a scale effect to something that has already been rotated.
     * @param t
     */
    public void compose(Transformation t) {
        mAlpha *= t.getAlpha();
        mMatrix.preConcat(t.getMatrix());
    }
    
    /**
     * @return The 3x3 Matrix representing the trnasformation to apply to the
     * coordinates of the object being animated
     */
    public Matrix getMatrix() {
        return mMatrix;
    }
    
    /**
     * Sets the degree of transparency
     * @param alpha 1.0 means fully opaqe and 0.0 means fully transparent
     */
    public void setAlpha(float alpha) {
        mAlpha = alpha;
    }

    /**
     * @return The degree of transparency
     */
    public float getAlpha() {
        return mAlpha;
    }
    
    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder(64);
        sb.append("Transformation");
        toShortString(sb);
        return sb.toString();
    }
    
    /**
     * Return a string representation of the transformation in a compact form.
     */
    public String toShortString() {
        StringBuilder sb = new StringBuilder(64);
        toShortString(sb);
        return sb.toString();
    }
    
    /**
     * @hide
     */
    public void toShortString(StringBuilder sb) {
        sb.append("{alpha="); sb.append(mAlpha);
        sb.append(" matrix="); mMatrix.toShortString(sb);
        sb.append('}');
    }
    
    /**
     * Print short string, to optimize dumping.
     * @hide
     */
    public void printShortString(PrintWriter pw) {
        pw.print("{alpha="); pw.print(mAlpha);
        pw.print(" matrix=");
        mMatrix.printShortString(pw);
        pw.print('}');
    }
}

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