1 /*
2  * Copyright (C) 2007 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 // Need the following import to get access to the app resources, since this
20 // class is in a sub-package.
21 //import com.example.android.apis.R;
22 
23 import android.content.Context;
24 import android.graphics.*;
25 import android.os.Bundle;
26 import android.view.View;
27 
28 public class PolyToPoly extends GraphicsActivity {
29 
30     @Override
onCreate(Bundle savedInstanceState)31     protected void onCreate(Bundle savedInstanceState) {
32         super.onCreate(savedInstanceState);
33         setContentView(new SampleView(this));
34     }
35 
36     private static class SampleView extends View {
37         private Paint   mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
38         private Matrix  mMatrix = new Matrix();
39         private Paint.FontMetrics mFontMetrics;
40 
doDraw(Canvas canvas, float src[], float dst[])41         private void doDraw(Canvas canvas, float src[], float dst[]) {
42             canvas.save();
43             mMatrix.setPolyToPoly(src, 0, dst, 0, src.length >> 1);
44             canvas.concat(mMatrix);
45 
46             mPaint.setColor(Color.GRAY);
47             mPaint.setStyle(Paint.Style.STROKE);
48             canvas.drawRect(0, 0, 64, 64, mPaint);
49             canvas.drawLine(0, 0, 64, 64, mPaint);
50             canvas.drawLine(0, 64, 64, 0, mPaint);
51 
52             mPaint.setColor(Color.RED);
53             mPaint.setStyle(Paint.Style.FILL);
54             // how to draw the text center on our square
55             // centering in X is easy... use alignment (and X at midpoint)
56             float x = 64/2;
57             // centering in Y, we need to measure ascent/descent first
58             float y = 64/2 - (mFontMetrics.ascent + mFontMetrics.descent)/2;
59             canvas.drawText(src.length/2 + "", x, y, mPaint);
60 
61             canvas.restore();
62         }
63 
SampleView(Context context)64         public SampleView(Context context) {
65             super(context);
66 
67             // for when the style is STROKE
68             mPaint.setStrokeWidth(4);
69             // for when we draw text
70             mPaint.setTextSize(40);
71             mPaint.setTextAlign(Paint.Align.CENTER);
72             mFontMetrics = mPaint.getFontMetrics();
73         }
74 
75         @Override
onDraw(Canvas canvas)76         protected void onDraw(Canvas canvas) {
77             canvas.drawColor(Color.WHITE);
78 
79             canvas.save();
80             canvas.translate(10, 10);
81             // translate (1 point)
82             doDraw(canvas, new float[] { 0, 0 }, new float[] { 5, 5 });
83             canvas.restore();
84 
85             canvas.save();
86             canvas.translate(160, 10);
87             // rotate/uniform-scale (2 points)
88             doDraw(canvas, new float[] { 32, 32, 64, 32 },
89                            new float[] { 32, 32, 64, 48 });
90             canvas.restore();
91 
92             canvas.save();
93             canvas.translate(10, 110);
94             // rotate/skew (3 points)
95             doDraw(canvas, new float[] { 0, 0, 64, 0, 0, 64 },
96                            new float[] { 0, 0, 96, 0, 24, 64 });
97             canvas.restore();
98 
99             canvas.save();
100             canvas.translate(160, 110);
101             // perspective (4 points)
102             doDraw(canvas, new float[] { 0, 0, 64, 0, 64, 64, 0, 64 },
103                            new float[] { 0, 0, 96, 0, 64, 96, 0, 64 });
104             canvas.restore();
105         }
106     }
107 }
108