Android example source code file (Vertices.java)

This example Android source code file (Vertices.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, bitmapshader, drawing, graphics, graphicsactivity, io, matrix, override, paint, sampleview, shader, ui, vertices, view

The Vertices.java Android example source code

/*
 * Copyright (C) 2008 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 com.example.android.apis.graphics;

import com.example.android.apis.R;

import android.app.Activity;
import android.content.Context;
import android.graphics.*;
import android.graphics.drawable.*;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.*;

import java.io.IOException;
import java.io.InputStream;

public class Vertices extends GraphicsActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new SampleView(this));
    }
    
    private static class SampleView extends View {
        private final Paint mPaint = new Paint();
        private final float[] mVerts = new float[10];
        private final float[] mTexs = new float[10];
        private final int[] mColors = new int[10];
        private final short[] mIndices = { 0, 1, 2, 3, 4, 1 };
        
        private final Matrix mMatrix = new Matrix();
        private final Matrix mInverse = new Matrix();

        private static void setXY(float[] array, int index, float x, float y) {
            array[index*2 + 0] = x;
            array[index*2 + 1] = y;
        }

        public SampleView(Context context) {
            super(context);
            setFocusable(true);

            Bitmap bm = BitmapFactory.decodeResource(getResources(),
                                                     R.drawable.beach);
            Shader s = new BitmapShader(bm, Shader.TileMode.CLAMP,
                                        Shader.TileMode.CLAMP);
            mPaint.setShader(s);
            
            float w = bm.getWidth();
            float h = bm.getHeight();
            // construct our mesh
            setXY(mTexs, 0, w/2, h/2);
            setXY(mTexs, 1, 0, 0);
            setXY(mTexs, 2, w, 0);
            setXY(mTexs, 3, w, h);
            setXY(mTexs, 4, 0, h);
            
            setXY(mVerts, 0, w/2, h/2);
            setXY(mVerts, 1, 0, 0);
            setXY(mVerts, 2, w, 0);
            setXY(mVerts, 3, w, h);
            setXY(mVerts, 4, 0, h);
            
            mMatrix.setScale(0.8f, 0.8f);
            mMatrix.preTranslate(20, 20);
            mMatrix.invert(mInverse);
        }
        
        @Override protected void onDraw(Canvas canvas) {
            canvas.drawColor(0xFFCCCCCC);
            canvas.save();
            canvas.concat(mMatrix);

            canvas.drawVertices(Canvas.VertexMode.TRIANGLE_FAN, 10, mVerts, 0,
                                mTexs, 0, null, 0, null, 0, 0, mPaint);

            canvas.translate(0, 240);
            canvas.drawVertices(Canvas.VertexMode.TRIANGLE_FAN, 10, mVerts, 0,
                                mTexs, 0, null, 0, mIndices, 0, 6, mPaint);

            canvas.restore();
        }

        @Override public boolean onTouchEvent(MotionEvent event) {
            float[] pt = { event.getX(), event.getY() };
            mInverse.mapPoints(pt);
            setXY(mVerts, 0, pt[0], pt[1]);
            invalidate();
            return true;
        }
        
    }
}