Android example source code file (Patterns.java)

This example Android source code file (Patterns.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, app, bitmap, bitmapshader, canvas, content, drawfilter, graphicsactivity, matrix, os, override, paint, patterns, sampleview, shader, ui, view

The Patterns.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 android.app.Activity;
import android.content.Context;
import android.graphics.*;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.*;

public class Patterns extends GraphicsActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new SampleView(this));
    }
    
    private static Bitmap makeBitmap1() {
        Bitmap bm = Bitmap.createBitmap(40, 40, Bitmap.Config.RGB_565);
        Canvas c = new Canvas(bm);
        c.drawColor(Color.RED);
        Paint p = new Paint();
        p.setColor(Color.BLUE);
        c.drawRect(5, 5, 35, 35, p);
        return bm;
    }
    
    private static Bitmap makeBitmap2() {
        Bitmap bm = Bitmap.createBitmap(64, 64, Bitmap.Config.ARGB_8888);
        Canvas c = new Canvas(bm);
        Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);
        p.setColor(Color.GREEN);
        p.setAlpha(0xCC);
        c.drawCircle(32, 32, 27, p);
        return bm;
    }
    
    private static class SampleView extends View {
        private final Shader mShader1;
        private final Shader mShader2;
        private final Paint mPaint;
        private final DrawFilter mFastDF;
        
        private float mTouchStartX;
        private float mTouchStartY;
        private float mTouchCurrX;
        private float mTouchCurrY;
        private DrawFilter mDF;

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

            mFastDF = new PaintFlagsDrawFilter(Paint.FILTER_BITMAP_FLAG |
                                               Paint.DITHER_FLAG,
                                               0);
    
            mShader1 = new BitmapShader(makeBitmap1(), Shader.TileMode.REPEAT,
                                        Shader.TileMode.REPEAT);
            mShader2 = new BitmapShader(makeBitmap2(), Shader.TileMode.REPEAT,
                                        Shader.TileMode.REPEAT);
            
            Matrix m = new Matrix();
            m.setRotate(30);
            mShader2.setLocalMatrix(m);
            
            mPaint = new Paint(Paint.FILTER_BITMAP_FLAG);
        }
        
        @Override protected void onDraw(Canvas canvas) {
            canvas.setDrawFilter(mDF);

            mPaint.setShader(mShader1);
            canvas.drawPaint(mPaint);
            
            canvas.translate(mTouchCurrX - mTouchStartX,
                             mTouchCurrY - mTouchStartY);

            mPaint.setShader(mShader2);
            canvas.drawPaint(mPaint);
        }

        @Override
        public boolean onTouchEvent(MotionEvent event) {
            float x = event.getX();
            float y = event.getY();
            
            switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    mTouchStartX = mTouchCurrX = x;
                    mTouchStartY = mTouchCurrY = y;
                    mDF = mFastDF;
                    invalidate();
                    break;
                case MotionEvent.ACTION_MOVE:
                    mTouchCurrX = x;
                    mTouchCurrY = y;
                    invalidate();
                    break;
                case MotionEvent.ACTION_UP:
                    mDF = null;
                    invalidate();
                    break;
            }
            return true;
        }
    }
}