Android example source code file (StateListDrawable.java)

This example Android source code file (StateListDrawable.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, attributeset, content, default_dither, drawable, drawablecontainer, drawablecontainerstate, io, ioexception, override, resources, statelistdrawable, stateliststate, typedarray, util, utilities, utils, xmlpullparserexception

The StateListDrawable.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 java.io.IOException;

import android.content.res.Resources;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.util.StateSet;

/**
 * Lets you assign a number of graphic images to a single Drawable and swap out the visible item by a string
 * ID value.
 * <p/>
 * <p>It can be defined in an XML file with the <selector> element.
 * Each state Drawable is defined in a nested <code><item> element.

 *
 * @attr ref android.R.styleable#StateListDrawable_visible
 * @attr ref android.R.styleable#StateListDrawable_variablePadding
 * @attr ref android.R.styleable#StateListDrawable_constantSize
 * @attr ref android.R.styleable#DrawableStates_state_focused
 * @attr ref android.R.styleable#DrawableStates_state_window_focused
 * @attr ref android.R.styleable#DrawableStates_state_enabled
 * @attr ref android.R.styleable#DrawableStates_state_checkable
 * @attr ref android.R.styleable#DrawableStates_state_checked
 * @attr ref android.R.styleable#DrawableStates_state_selected
 * @attr ref android.R.styleable#DrawableStates_state_active
 * @attr ref android.R.styleable#DrawableStates_state_single
 * @attr ref android.R.styleable#DrawableStates_state_first
 * @attr ref android.R.styleable#DrawableStates_state_middle
 * @attr ref android.R.styleable#DrawableStates_state_last
 * @attr ref android.R.styleable#DrawableStates_state_pressed
 */
public class StateListDrawable extends DrawableContainer {
    /**
     * To be proper, we should have a getter for dither (and alpha, etc.)
     * so that proxy classes like this can save/restore their delegates'
     * values, but we don't have getters. Since we do have setters
     * (e.g. setDither), which this proxy forwards on, we have to have some
     * default/initial setting.
     *
     * The initial setting for dither is now true, since it almost always seems
     * to improve the quality at negligible cost.
     */
    private static final boolean DEFAULT_DITHER = true;
    private final StateListState mStateListState;
    private boolean mMutated;

    public StateListDrawable() {
        this(null, null);
    }

    /**
     * Add a new image/string ID to the set of images.
     *
     * @param stateSet - An array of resource Ids to associate with the image.
     *                 Switch to this image by calling setState().
     * @param drawable -The image to show.
     */
    public void addState(int[] stateSet, Drawable drawable) {
        if (drawable != null) {
            mStateListState.addStateSet(stateSet, drawable);
            // in case the new state matches our current state...
            onStateChange(getState());
        }
    }

    @Override
    public boolean isStateful() {
        return true;
    }

    @Override
    protected boolean onStateChange(int[] stateSet) {
        int idx = mStateListState.indexOfStateSet(stateSet);
        if (idx < 0) {
            idx = mStateListState.indexOfStateSet(StateSet.WILD_CARD);
        }
        if (selectDrawable(idx)) {
            return true;
        }
        return super.onStateChange(stateSet);
    }

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

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

        super.inflateWithAttributes(r, parser, a,
                com.android.internal.R.styleable.StateListDrawable_visible);

        mStateListState.setVariablePadding(a.getBoolean(
                com.android.internal.R.styleable.StateListDrawable_variablePadding, false));
        mStateListState.setConstantSize(a.getBoolean(
                com.android.internal.R.styleable.StateListDrawable_constantSize, false));

        setDither(a.getBoolean(com.android.internal.R.styleable.StateListDrawable_dither,
                               DEFAULT_DITHER));

        a.recycle();

        int type;

        final int innerDepth = parser.getDepth() + 1;
        int depth;
        while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
                && ((depth = parser.getDepth()) >= innerDepth
                || type != XmlPullParser.END_TAG)) {
            if (type != XmlPullParser.START_TAG) {
                continue;
            }

            if (depth > innerDepth || !parser.getName().equals("item")) {
                continue;
            }

            int drawableRes = 0;

            int i;
            int j = 0;
            final int numAttrs = attrs.getAttributeCount();
            int[] states = new int[numAttrs];
            for (i = 0; i < numAttrs; i++) {
                final int stateResId = attrs.getAttributeNameResource(i);
                if (stateResId == 0) break;
                if (stateResId == com.android.internal.R.attr.drawable) {
                    drawableRes = attrs.getAttributeResourceValue(i, 0);
                } else {
                    states[j++] = attrs.getAttributeBooleanValue(i, false)
                            ? stateResId
                            : -stateResId;
                }
            }
            states = StateSet.trimStateSet(states, j);

            Drawable dr;
            if (drawableRes != 0) {
                dr = r.getDrawable(drawableRes);
            } else {
                while ((type = parser.next()) == XmlPullParser.TEXT) {
                }
                if (type != XmlPullParser.START_TAG) {
                    throw new XmlPullParserException(
                            parser.getPositionDescription()
                                    + ": <item> tag requires a 'drawable' attribute or "
                                    + "child tag defining a drawable");
                }
                dr = Drawable.createFromXmlInner(r, parser, attrs);
            }

            mStateListState.addStateSet(states, dr);
        }

        onStateChange(getState());
    }

    StateListState getStateListState() {
        return mStateListState;
    }

    /**
     * Gets the number of states contained in this drawable.
     *
     * @return The number of states contained in this drawable.
     * @hide pending API council
     * @see #getStateSet(int)
     * @see #getStateDrawable(int)
     */
    public int getStateCount() {
        return mStateListState.getChildCount();
    }

    /**
     * Gets the state set at an index.
     *
     * @param index The index of the state set.
     * @return The state set at the index.
     * @hide pending API council
     * @see #getStateCount()
     * @see #getStateDrawable(int)
     */
    public int[] getStateSet(int index) {
        return mStateListState.mStateSets[index];
    }

    /**
     * Gets the drawable at an index.
     *
     * @param index The index of the drawable.
     * @return The drawable at the index.
     * @hide pending API council
     * @see #getStateCount()
     * @see #getStateSet(int)
     */
    public Drawable getStateDrawable(int index) {
        return mStateListState.getChildren()[index];
    }
    
    /**
     * Gets the index of the drawable with the provided state set.
     * 
     * @param stateSet the state set to look up
     * @return the index of the provided state set, or -1 if not found
     * @hide pending API council
     * @see #getStateDrawable(int)
     * @see #getStateSet(int)
     */
    public int getStateDrawableIndex(int[] stateSet) {
        return mStateListState.indexOfStateSet(stateSet);
    }
    
    @Override
    public Drawable mutate() {
        if (!mMutated && super.mutate() == this) {
            final int[][] sets = mStateListState.mStateSets;
            final int count = sets.length;
            mStateListState.mStateSets = new int[count][];
            for (int i = 0; i < count; i++) {
                final int[] set = sets[i];
                if (set != null) {
                    mStateListState.mStateSets[i] = set.clone();
                }
            }
            mMutated = true;
        }
        return this;
    }

    static final class StateListState extends DrawableContainerState {
        private int[][] mStateSets;

        StateListState(StateListState orig, StateListDrawable owner, Resources res) {
            super(orig, owner, res);

            if (orig != null) {
                mStateSets = orig.mStateSets;
            } else {
                mStateSets = new int[getChildren().length][];
            }
        }

        int addStateSet(int[] stateSet, Drawable drawable) {
            final int pos = addChild(drawable);
            mStateSets[pos] = stateSet;
            return pos;
        }

        private int indexOfStateSet(int[] stateSet) {
            final int[][] stateSets = mStateSets;
            final int N = getChildCount();
            for (int i = 0; i < N; i++) {
                if (StateSet.stateSetMatches(stateSets[i], stateSet)) {
                    return i;
                }
            }
            return -1;
        }

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

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

        @Override
        public void growArray(int oldSize, int newSize) {
            super.growArray(oldSize, newSize);
            final int[][] newStateSets = new int[newSize][];
            System.arraycopy(mStateSets, 0, newStateSets, 0, oldSize);
            mStateSets = newStateSets;
        }
    }

    private StateListDrawable(StateListState state, Resources res) {
        StateListState as = new StateListState(state, this, res);
        mStateListState = as;
        setConstantState(as);
        onStateChange(getState());
    }
}