patterns.java

android 例子中的确良ApiDemos。很有代表意义

/*
 * 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;
        }
    }
}