Android example source code file (ScaleDrawable.java)

This example Android source code file (ScaleDrawable.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, constantstate, content, drawable, drawing, illegalargumentexception, io, ioexception, no, override, rect, resources, runnable, scaledrawable, scalestate, string, ui, view, xmlpullparser, xmlpullparserexception

The ScaleDrawable.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.graphics.drawable;

import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;

import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.*;
import android.view.Gravity;
import android.util.AttributeSet;

import java.io.IOException;

/**
 * A Drawable that changes the size of another Drawable based on its current
 * level value.  You can control how much the child Drawable changes in width
 * and height based on the level, as well as a gravity to control where it is
 * placed in its overall container.  Most often used to implement things like
 * progress bars.
 *
 * <p>It can be defined in an XML file with the <scale> element.

 *
 * @attr ref android.R.styleable#ScaleDrawable_scaleWidth
 * @attr ref android.R.styleable#ScaleDrawable_scaleHeight
 * @attr ref android.R.styleable#ScaleDrawable_scaleGravity
 * @attr ref android.R.styleable#ScaleDrawable_drawable
 */
public class ScaleDrawable extends Drawable implements Drawable.Callback {
    private ScaleState mScaleState;
    private boolean mMutated;
    private final Rect mTmpRect = new Rect();

    ScaleDrawable() {
        this(null, null);
    }

    public ScaleDrawable(Drawable drawable, int gravity, float scaleWidth, float scaleHeight) {
        this(null, null);

        mScaleState.mDrawable = drawable;
        mScaleState.mGravity = gravity;
        mScaleState.mScaleWidth = scaleWidth;
        mScaleState.mScaleHeight = scaleHeight;

        if (drawable != null) {
            drawable.setCallback(this);
        }
    }

    /**
     * Returns the drawable scaled by this ScaleDrawable.
     */
    public Drawable getDrawable() {
        return mScaleState.mDrawable;
    }

    private static float getPercent(TypedArray a, int name) {
        String s = a.getString(name);
        if (s != null) {
            if (s.endsWith("%")) {
                String f = s.substring(0, s.length() - 1);
                return Float.parseFloat(f) / 100.0f;
            }
        }
        return -1;
    }

    @Override
    public void inflate(Resources r, XmlPullParser parser, AttributeSet attrs)
            throws XmlPullParserException, IOException {
        super.inflate(r, parser, attrs);

        int type;

        TypedArray a = r.obtainAttributes(attrs, com.android.internal.R.styleable.ScaleDrawable);

        float sw = getPercent(a, com.android.internal.R.styleable.ScaleDrawable_scaleWidth);
        float sh = getPercent(a, com.android.internal.R.styleable.ScaleDrawable_scaleHeight);
        int g = a.getInt(com.android.internal.R.styleable.ScaleDrawable_scaleGravity, Gravity.LEFT);
        Drawable dr = a.getDrawable(com.android.internal.R.styleable.ScaleDrawable_drawable);

        a.recycle();

        final int outerDepth = parser.getDepth();
        while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
                && (type != XmlPullParser.END_TAG || parser.getDepth() > outerDepth)) {
            if (type != XmlPullParser.START_TAG) {
                continue;
            }
            dr = Drawable.createFromXmlInner(r, parser, attrs);
        }

        if (dr == null) {
            throw new IllegalArgumentException("No drawable specified for <scale>");
        }

        mScaleState.mDrawable = dr;
        mScaleState.mScaleWidth = sw;
        mScaleState.mScaleHeight = sh;
        mScaleState.mGravity = g;
        if (dr != null) {
            dr.setCallback(this);
        }
    }

    // overrides from Drawable.Callback

    public void invalidateDrawable(Drawable who) {
        if (mCallback != null) {
            mCallback.invalidateDrawable(this);
        }
    }

    public void scheduleDrawable(Drawable who, Runnable what, long when) {
        if (mCallback != null) {
            mCallback.scheduleDrawable(this, what, when);
        }
    }

    public void unscheduleDrawable(Drawable who, Runnable what) {
        if (mCallback != null) {
            mCallback.unscheduleDrawable(this, what);
        }
    }

    // overrides from Drawable

    @Override
    public void draw(Canvas canvas) {
        if (mScaleState.mDrawable.getLevel() != 0)
            mScaleState.mDrawable.draw(canvas);
    }

    @Override
    public int getChangingConfigurations() {
        return super.getChangingConfigurations()
                | mScaleState.mChangingConfigurations
                | mScaleState.mDrawable.getChangingConfigurations();
    }

    @Override
    public boolean getPadding(Rect padding) {
        // XXX need to adjust padding!
        return mScaleState.mDrawable.getPadding(padding);
    }

    @Override
    public boolean setVisible(boolean visible, boolean restart) {
        mScaleState.mDrawable.setVisible(visible, restart);
        return super.setVisible(visible, restart);
    }

    @Override
    public void setAlpha(int alpha) {
        mScaleState.mDrawable.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(ColorFilter cf) {
        mScaleState.mDrawable.setColorFilter(cf);
    }

    @Override
    public int getOpacity() {
        return mScaleState.mDrawable.getOpacity();
    }

    @Override
    public boolean isStateful() {
        return mScaleState.mDrawable.isStateful();
    }

    @Override
    protected boolean onStateChange(int[] state) {
        boolean changed = mScaleState.mDrawable.setState(state);
        onBoundsChange(getBounds());
        return changed;
    }

    @Override
    protected boolean onLevelChange(int level) {
        mScaleState.mDrawable.setLevel(level);
        onBoundsChange(getBounds());
        invalidateSelf();
        return true;
    }

    @Override
    protected void onBoundsChange(Rect bounds) {
        final Rect r = mTmpRect;
        int level = getLevel();
        int w = bounds.width();
        final int iw = 0; //mScaleState.mDrawable.getIntrinsicWidth();
        if (mScaleState.mScaleWidth > 0) {
            w -= (int) ((w - iw) * (10000 - level) * mScaleState.mScaleWidth / 10000);
        }
        int h = bounds.height();
        final int ih = 0; //mScaleState.mDrawable.getIntrinsicHeight();
        if (mScaleState.mScaleHeight > 0) {
            h -= (int) ((h - ih) * (10000 - level) * mScaleState.mScaleHeight / 10000);
        }
        Gravity.apply(mScaleState.mGravity, w, h, bounds, r);

        if (w > 0 && h > 0) {
            mScaleState.mDrawable.setBounds(r.left, r.top, r.right, r.bottom);
        }
    }

    @Override
    public int getIntrinsicWidth() {
        return mScaleState.mDrawable.getIntrinsicWidth();
    }

    @Override
    public int getIntrinsicHeight() {
        return mScaleState.mDrawable.getIntrinsicHeight();
    }

    @Override
    public ConstantState getConstantState() {
        if (mScaleState.canConstantState()) {
            mScaleState.mChangingConfigurations = super.getChangingConfigurations();
            return mScaleState;
        }
        return null;
    }

    @Override
    public Drawable mutate() {
        if (!mMutated && super.mutate() == this) {
            mScaleState.mDrawable.mutate();
            mMutated = true;
        }
        return this;
    }

    final static class ScaleState extends ConstantState {
        Drawable mDrawable;
        int mChangingConfigurations;
        float mScaleWidth;
        float mScaleHeight;
        int mGravity;

        private boolean mCheckedConstantState;
        private boolean mCanConstantState;

        ScaleState(ScaleState orig, ScaleDrawable owner, Resources res) {
            if (orig != null) {
                if (res != null) {
                    mDrawable = orig.mDrawable.getConstantState().newDrawable(res);
                } else {
                    mDrawable = orig.mDrawable.getConstantState().newDrawable();
                }
                mDrawable.setCallback(owner);
                mScaleWidth = orig.mScaleWidth;
                mScaleHeight = orig.mScaleHeight;
                mGravity = orig.mGravity;
                mCheckedConstantState = mCanConstantState = true;
            }
        }

        @Override
        public Drawable newDrawable() {
            return new ScaleDrawable(this, null);
        }

        @Override
        public Drawable newDrawable(Resources res) {
            return new ScaleDrawable(this, res);
        }

        @Override
        public int getChangingConfigurations() {
            return mChangingConfigurations;
        }

        boolean canConstantState() {
            if (!mCheckedConstantState) {
                mCanConstantState = mDrawable.getConstantState() != null;
                mCheckedConstantState = true;
            }

            return mCanConstantState;
        }
    }

    private ScaleDrawable(ScaleState state, Resources res) {
        mScaleState = new ScaleState(state, this, res);
    }
}