Api Demo - .graphics(19)

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);//不方便给画笔加过滤效果的，可以DrawFilter直接作用于canvas, 这里是增强bitmap效果
    
            mShader1 = new BitmapShader(makeBitmap1(), Shader.TileMode.REPEAT,
                                        Shader.TileMode.REPEAT);//图形阴影（要填充的图形，X方向填充模式，Y方向填充模式。
            mShader2 = new BitmapShader(makeBitmap2(), Shader.TileMode.REPEAT,
                                        Shader.TileMode.REPEAT);
            
            Matrix m = new Matrix();
            m.setRotate(30);
            mShader2.setLocalMatrix(m);//给shader应用形变
            
            mPaint = new Paint(Paint.FILTER_BITMAP_FLAG);
        }
        
        @Override protected void onDraw(Canvas canvas) {
            canvas.setDrawFilter(mDF);//给画布增效过滤。

            mPaint.setShader(mShader1);
            canvas.drawPaint(mPaint);//绘制底层方格
            
            canvas.translate(mTouchCurrX - mTouchStartX,
                             mTouchCurrY - mTouchStartY);//移动画布，然后绘制，达到拖动效果

            mPaint.setShader(mShader2);//上层圆形
            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;
        }
    }
}