1/*
2 * Copyright (C) 2012 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
17package com.example.android.snake;
18
19import android.content.Context;
20import android.content.res.TypedArray;
21import android.graphics.Canvas;
22import android.graphics.Color;
23import android.graphics.Paint;
24import android.util.AttributeSet;
25import android.view.View;
26
27import java.util.Arrays;
28
29/**
30 * Background View: Draw 4 full-screen RGBY triangles
31 */
32public class BackgroundView extends View {
33
34    private int[] mColors = new int[4];
35
36    private final short[] mIndices =
37            { 0, 1, 2, 0, 3, 4, 0, 1, 4 // Corner points for triangles (with offset = 2)
38    };
39
40    private float[] mVertexPoints = null;
41
42    public BackgroundView(Context context, AttributeSet attrs) {
43        super(context, attrs);
44        setFocusable(true);
45
46        // retrieve colors for 4 segments from styleable properties
47        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.BackgroundView);
48        mColors[0] = a.getColor(R.styleable.BackgroundView_colorSegmentOne, Color.RED);
49        mColors[1] = a.getColor(R.styleable.BackgroundView_colorSegmentTwo, Color.YELLOW);
50        mColors[2] = a.getColor(R.styleable.BackgroundView_colorSegmentThree, Color.BLUE);
51        mColors[3] = a.getColor(R.styleable.BackgroundView_colorSegmentFour, Color.GREEN);
52
53        a.recycle();
54    }
55
56    @Override
57    protected void onDraw(Canvas canvas) {
58        assert(mVertexPoints != null);
59
60        // Colors for each vertex
61        int[] mFillColors = new int[mVertexPoints.length];
62
63        for (int triangle = 0; triangle < mColors.length; triangle++) {
64            // Set color for all vertex points to current triangle color
65            Arrays.fill(mFillColors, mColors[triangle]);
66
67            // Draw one triangle
68            canvas.drawVertices(Canvas.VertexMode.TRIANGLES, mVertexPoints.length, mVertexPoints,
69                    0, null, 0, // No Textures
70                    mFillColors, 0, mIndices,
71                    triangle * 2, 3, // Use 3 vertices via Index Array with offset 2
72                    new Paint());
73        }
74    }
75
76    @Override
77    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
78        super.onSizeChanged(w, h, oldw, oldh);
79
80     // Construct our center and four corners
81        mVertexPoints = new float[] {
82                w / 2, h / 2,
83                0, 0,
84                w, 0,
85                w, h,
86                0, h
87        };
88    }
89
90}
91