1 /*
2  * Copyright (C) 2008 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.example.android.apis.graphics;
18 
19 import android.content.Context;
20 import android.graphics.*;
21 import android.os.Bundle;
22 import android.view.View;
23 
24 public class Regions extends GraphicsActivity {
25 
26     @Override
onCreate(Bundle savedInstanceState)27     protected void onCreate(Bundle savedInstanceState) {
28         super.onCreate(savedInstanceState);
29         setContentView(new SampleView(this));
30     }
31 
32     private static class SampleView extends View {
33         private final Paint mPaint = new Paint();
34         private final Rect  mRect1 = new Rect();
35         private final Rect  mRect2 = new Rect();
36 
SampleView(Context context)37         public SampleView(Context context) {
38             super(context);
39             setFocusable(true);
40 
41             mPaint.setAntiAlias(true);
42             mPaint.setTextSize(16);
43             mPaint.setTextAlign(Paint.Align.CENTER);
44 
45             mRect1.set(10, 10, 100, 80);
46             mRect2.set(50, 50, 130, 110);
47         }
48 
drawOriginalRects(Canvas canvas, int alpha)49         private void drawOriginalRects(Canvas canvas, int alpha) {
50             mPaint.setStyle(Paint.Style.STROKE);
51             mPaint.setColor(Color.RED);
52             mPaint.setAlpha(alpha);
53             drawCentered(canvas, mRect1, mPaint);
54             mPaint.setColor(Color.BLUE);
55             mPaint.setAlpha(alpha);
56             drawCentered(canvas, mRect2, mPaint);
57 
58             // restore style
59             mPaint.setStyle(Paint.Style.FILL);
60         }
61 
drawRgn(Canvas canvas, int color, String str, Region.Op op)62         private void drawRgn(Canvas canvas, int color, String str, Region.Op op) {
63             if (str != null) {
64                 mPaint.setColor(Color.BLACK);
65                 canvas.drawText(str, 80, 24, mPaint);
66             }
67 
68             Region rgn = new Region();
69             rgn.set(mRect1);
70             rgn.op(mRect2, op);
71 
72             mPaint.setColor(color);
73             RegionIterator iter = new RegionIterator(rgn);
74             Rect r = new Rect();
75 
76             canvas.translate(0, 30);
77             mPaint.setColor(color);
78             while (iter.next(r)) {
79                 canvas.drawRect(r, mPaint);
80             }
81             drawOriginalRects(canvas, 0x80);
82         }
83 
drawCentered(Canvas c, Rect r, Paint p)84         private static void drawCentered(Canvas c, Rect r, Paint p) {
85             float inset = p.getStrokeWidth() * 0.5f;
86             if (inset == 0) {   // catch hairlines
87                 inset = 0.5f;
88             }
89             c.drawRect(r.left + inset, r.top + inset,
90                        r.right - inset, r.bottom - inset, p);
91         }
92 
93         @Override
onDraw(Canvas canvas)94         protected void onDraw(Canvas canvas) {
95             canvas.drawColor(Color.GRAY);
96 
97             canvas.save();
98             canvas.translate(80, 5);
99             drawOriginalRects(canvas, 0xFF);
100             canvas.restore();
101 
102             mPaint.setStyle(Paint.Style.FILL);
103 
104             canvas.save();
105             canvas.translate(0, 140);
106             drawRgn(canvas, Color.RED, "Union", Region.Op.UNION);
107             canvas.restore();
108 
109             canvas.save();
110             canvas.translate(0, 280);
111             drawRgn(canvas, Color.BLUE, "Xor", Region.Op.XOR);
112             canvas.restore();
113 
114             canvas.save();
115             canvas.translate(160, 140);
116             drawRgn(canvas, Color.GREEN, "Difference", Region.Op.DIFFERENCE);
117             canvas.restore();
118 
119             canvas.save();
120             canvas.translate(160, 280);
121             drawRgn(canvas, Color.WHITE, "Intersect", Region.Op.INTERSECT);
122             canvas.restore();
123         }
124     }
125 }
126 
127