Android example source code file (Sweep.java)

This example Android source code file (Sweep.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, content, graphicsactivity, keyevent, matrix, os, override, paint, sampleview, shader, sweep, sweepgradient, ui, view

The Sweep.java Android example source code

/*
 * Copyright (C) 2007 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;

// Need the following import to get access to the app resources, since this
// class is in a sub-package.
//import com.example.android.apis.R;

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

public class Sweep extends GraphicsActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new SampleView(this));
    }
    
    private static class SampleView extends View {
        private Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        private float mRotate;
        private Matrix mMatrix = new Matrix();
        private Shader mShader;
        private boolean mDoTiming;

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

            float x = 160;
            float y = 100;
            mShader = new SweepGradient(x, y, new int[] { Color.GREEN,
                                                  Color.RED,
                                                  Color.BLUE,
                                                  Color.GREEN }, null);
            mPaint.setShader(mShader);
        }
        
        @Override protected void onDraw(Canvas canvas) {
            Paint paint = mPaint;
            float x = 160;
            float y = 100;

            canvas.drawColor(Color.WHITE);

            mMatrix.setRotate(mRotate, x, y);
            mShader.setLocalMatrix(mMatrix);
            mRotate += 3;
            if (mRotate >= 360) {
                mRotate = 0;
            }
            invalidate();

            if (mDoTiming) {
                long now = System.currentTimeMillis();
                for (int i = 0; i < 20; i++) {
                    canvas.drawCircle(x, y, 80, paint);
                }
                now = System.currentTimeMillis() - now;
                android.util.Log.d("skia", "sweep ms = " + (now/20.));
            }
            else {
                canvas.drawCircle(x, y, 80, paint);
            }
        }

        @Override public boolean onKeyDown(int keyCode, KeyEvent event) {
            switch (keyCode) {
                case KeyEvent.KEYCODE_D:
                    mPaint.setDither(!mPaint.isDither());
                    invalidate();
                    return true;
                case KeyEvent.KEYCODE_T:
                    mDoTiming = !mDoTiming;
                    invalidate();
                    return true;
            }
            return super.onKeyDown(keyCode, event);
        }
    }
}