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Android example source code file (Region.java)

This example Android source code file (Region.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, creator, intersect, nullpointerexception, op, os, override, parcelable, path, rect, region, reverse_difference, runtimeexception, throwable, union, xor

The Region.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;

import android.os.Parcel;
import android.os.Parcelable;

public class Region implements Parcelable {

    // the native values for these must match up with the enum in SkRegion.h
    public enum Op {
        DIFFERENCE(0),
        INTERSECT(1),
        UNION(2),
        XOR(3),
        REVERSE_DIFFERENCE(4),
        REPLACE(5);

        Op(int nativeInt) {
            this.nativeInt = nativeInt;
        }
        final int nativeInt;
    }

    /** Create an empty region
    */
    public Region() {
        this(nativeConstructor());
    }

    /** Return a copy of the specified region
    */
    public Region(Region region) {
        this(nativeConstructor());
        nativeSetRegion(mNativeRegion, region.mNativeRegion);
    }

    /** Return a region set to the specified rectangle
    */
    public Region(Rect r) {
        mNativeRegion = nativeConstructor();
        nativeSetRect(mNativeRegion, r.left, r.top, r.right, r.bottom);
    }

    /** Return a region set to the specified rectangle
    */
    public Region(int left, int top, int right, int bottom) {
        mNativeRegion = nativeConstructor();
        nativeSetRect(mNativeRegion, left, top, right, bottom);
    }

    /** Set the region to the empty region
    */
    public void setEmpty() {
        nativeSetRect(mNativeRegion, 0, 0, 0, 0);
    }

    /** Set the region to the specified region.
    */
    public boolean set(Region region) {
        return nativeSetRegion(mNativeRegion, region.mNativeRegion);
    }

    /** Set the region to the specified rectangle
    */
    public boolean set(Rect r) {
        return nativeSetRect(mNativeRegion, r.left, r.top, r.right, r.bottom);
    }
    
    /** Set the region to the specified rectangle
    */
    public boolean set(int left, int top, int right, int bottom) {
        return nativeSetRect(mNativeRegion, left, top, right, bottom);
    }

    /**
     * Set the region to the area described by the path and clip.
     * Return true if the resulting region is non-empty. This produces a region
     * that is identical to the pixels that would be drawn by the path
     * (with no antialiasing).
     */
    public boolean setPath(Path path, Region clip) {
        return nativeSetPath(mNativeRegion, path.ni(), clip.mNativeRegion);
    }

    /**
     * Return true if this region is empty
     */
    public native boolean isEmpty();
    
    /**
     * Return true if the region contains a single rectangle
     */
    public native boolean isRect();
    
    /**
     * Return true if the region contains more than one rectangle
     */
    public native boolean isComplex();

    /**
     * Return a new Rect set to the bounds of the region. If the region is
     * empty, the Rect will be set to [0, 0, 0, 0]
     */
    public Rect getBounds() {
        Rect r = new Rect();
        nativeGetBounds(mNativeRegion, r);
        return r;
    }
    
    /**
     * Set the Rect to the bounds of the region. If the region is empty, the
     * Rect will be set to [0, 0, 0, 0]
     */
    public boolean getBounds(Rect r) {
        if (r == null) {
            throw new NullPointerException();
        }
        return nativeGetBounds(mNativeRegion, r);
    }

    /**
     * Return the boundary of the region as a new Path. If the region is empty,
     * the path will also be empty.
     */
    public Path getBoundaryPath() {
        Path path = new Path();
        nativeGetBoundaryPath(mNativeRegion, path.ni());
        return path;
    }

    /**
     * Set the path to the boundary of the region. If the region is empty, the
     * path will also be empty.
     */
    public boolean getBoundaryPath(Path path) {
        return nativeGetBoundaryPath(mNativeRegion, path.ni());
    }
        
    /**
     * Return true if the region contains the specified point
     */
    public native boolean contains(int x, int y);

    /**
     * Return true if the region is a single rectangle (not complex) and it
     * contains the specified rectangle. Returning false is not a guarantee
     * that the rectangle is not contained by this region, but return true is a
     * guarantee that the rectangle is contained by this region.
     */
    public boolean quickContains(Rect r) {
        return quickContains(r.left, r.top, r.right, r.bottom);
    }

    /**
     * Return true if the region is a single rectangle (not complex) and it
     * contains the specified rectangle. Returning false is not a guarantee
     * that the rectangle is not contained by this region, but return true is a
     * guarantee that the rectangle is contained by this region.
     */
    public native boolean quickContains(int left, int top, int right,
                                        int bottom);

    /**
     * Return true if the region is empty, or if the specified rectangle does
     * not intersect the region. Returning false is not a guarantee that they
     * intersect, but returning true is a guarantee that they do not.
     */
    public boolean quickReject(Rect r) {
        return quickReject(r.left, r.top, r.right, r.bottom);
    }

    /**
     * Return true if the region is empty, or if the specified rectangle does
     * not intersect the region. Returning false is not a guarantee that they
     * intersect, but returning true is a guarantee that they do not.
     */
    public native boolean quickReject(int left, int top, int right, int bottom);

    /**
     * Return true if the region is empty, or if the specified region does not
     * intersect the region. Returning false is not a guarantee that they
     * intersect, but returning true is a guarantee that they do not.
     */
    public native boolean quickReject(Region rgn);

    /**
     * Translate the region by [dx, dy]. If the region is empty, do nothing.
     */
    public void translate(int dx, int dy) {
        translate(dx, dy, null);
    }

    /**
     * Set the dst region to the result of translating this region by [dx, dy].
     * If this region is empty, then dst will be set to empty.
     */
    public native void translate(int dx, int dy, Region dst);

    /**
     * Scale the region by the given scale amount. This re-constructs new region by
     * scaling the rects that this region consists of. New rectis are computed by scaling 
     * coordinates by float, then rounded by roundf() function to integers. This may results
     * in less internal rects if 0 < scale < 1. Zero and Negative scale result in
     * an empty region. If this region is empty, do nothing.
     *
     * @hide
     */
    public void scale(float scale) {
        scale(scale, null);
    }

    /**
     * Set the dst region to the result of scaling this region by the given scale amount.
     * If this region is empty, then dst will be set to empty.
     * @hide
     */
    public native void scale(float scale, Region dst);

    public final boolean union(Rect r) {
        return op(r, Op.UNION);
    }

    /**
     * Perform the specified Op on this region and the specified rect. Return
     * true if the result of the op is not empty.
     */
    public boolean op(Rect r, Op op) {
        return nativeOp(mNativeRegion, r.left, r.top, r.right, r.bottom,
                        op.nativeInt);
    }

    /**
     * Perform the specified Op on this region and the specified rect. Return
     * true if the result of the op is not empty.
     */
    public boolean op(int left, int top, int right, int bottom, Op op) {
        return nativeOp(mNativeRegion, left, top, right, bottom,
                        op.nativeInt);
    }

    /**
     * Perform the specified Op on this region and the specified region. Return
     * true if the result of the op is not empty.
     */
    public boolean op(Region region, Op op) {
        return op(this, region, op);
    }

    /**
     * Set this region to the result of performing the Op on the specified rect
     * and region. Return true if the result is not empty.
     */
    public boolean op(Rect rect, Region region, Op op) {
        return nativeOp(mNativeRegion, rect, region.mNativeRegion,
                        op.nativeInt);
    }

    /**
     * Set this region to the result of performing the Op on the specified
     * regions. Return true if the result is not empty.
     */
    public boolean op(Region region1, Region region2, Op op) {
        return nativeOp(mNativeRegion, region1.mNativeRegion,
                        region2.mNativeRegion, op.nativeInt);
    }

    //////////////////////////////////////////////////////////////////////////
    
    public static final Parcelable.Creator<Region> CREATOR
        = new Parcelable.Creator<Region>() {
            /**
            * Rebuild a Region previously stored with writeToParcel().
             * @param p    Parcel object to read the region from
             * @return a new region created from the data in the parcel
             */
            public Region createFromParcel(Parcel p) {
                int ni = nativeCreateFromParcel(p);
                if (ni == 0) {
                    throw new RuntimeException();
                }
                return new Region(ni);
            }
            public Region[] newArray(int size) {
                return new Region[size];
            }
    };
    
    public int describeContents() {
        return 0;
    }

    /**
     * Write the region and its pixels to the parcel. The region can be
     * rebuilt from the parcel by calling CREATOR.createFromParcel().
     * @param p    Parcel object to write the region data into
     */
    public void writeToParcel(Parcel p, int flags) {
        if (!nativeWriteToParcel(mNativeRegion, p)) {
            throw new RuntimeException();
        }
    }

    @Override
    public boolean equals(Object obj) {
        if (obj == null || !(obj instanceof Region)) {
            return false;
        }
        Region peer = (Region) obj;
        return nativeEquals(mNativeRegion, peer.mNativeRegion);
    }

    protected void finalize() throws Throwable {
        nativeDestructor(mNativeRegion);
    }
    
    /*package*/ Region(int ni) {
        if (ni == 0) {
            throw new RuntimeException();
        }
        mNativeRegion = ni;
    }

    /* add dummy parameter so constructor can be called from jni without
       triggering 'not cloneable' exception */
    private Region(int ni, int dummy) {
        this(ni);
    }

    /*package*/ final int ni() {
        return mNativeRegion;
    }

    private static native int nativeConstructor();
    private static native void nativeDestructor(int native_region);

    private static native boolean nativeSetRegion(int native_dst,
                                                  int native_src);
    private static native boolean nativeSetRect(int native_dst, int left,
                                                int top, int right, int bottom);
    private static native boolean nativeSetPath(int native_dst, int native_path,
                                                int native_clip);
    private static native boolean nativeGetBounds(int native_region, Rect rect);
    private static native boolean nativeGetBoundaryPath(int native_region,
                                                        int native_path);

    private static native boolean nativeOp(int native_dst, int left, int top,
                                           int right, int bottom, int op);
    private static native boolean nativeOp(int native_dst, Rect rect,
                                           int native_region, int op);
    private static native boolean nativeOp(int native_dst, int native_region1,
                                           int native_region2, int op);

    private static native int nativeCreateFromParcel(Parcel p);
    private static native boolean nativeWriteToParcel(int native_region,
                                                      Parcel p);

    private static native boolean nativeEquals(int native_r1, int native_r2);

    private final int mNativeRegion;
}

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