Android 实现缩小图片像素

自定义View类控制焦点以及android现实缩小图片的像素和如何通过BitmapFactory读得图片资源，做了笔记。以下代码提供给大伙参考。

package com.view;

import java.util.HashMap;

import com.pojo.Constants;
import com.test.R;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.util.Log;
import android.view.KeyEvent;
import android.view.View;
import android.view.ViewGroup;

public class ADWView extends View {
    Context myContext = this.getContext();
    //读得String.xml里面的资源
    private String a = myContext.getString(R.string.app_a);
    private String b = myContext.getString(R.string.app_b);
    private String c = myContext.getString(R.string.app_c);
    private String d = myContext.getString(R.string.app_d);
    private String e = myContext.getString(R.string.app_e);
    private int focusID = 0;
    private Bitmap focusbmp, progressBar_A,progressBar_B,progressBar_C,progressBar_D,progressBar_E,progressBar;
    private Bitmap  bitmap_A,bitmap_B,bitmap_C,bitmap_D,bitmap_E;
    HashMap<Integer, Integer> progressBarMap = null;
        
    public ADWView(Context context) {
        super(context);
        this.setFocusable(true);
        this.requestFocus();
        initData();
        //焦点图片通过BitmapFactory来得到图片资源R.drawable.shortcut_bg_sel
        focusbmp = BitmapFactory.decodeResource(this.getResources(), R.drawable.shortcut_bg_sel);      
     }
    

    
    @Override
    protected void onDraw(Canvas canvas) {
    	//焦点图片初始位置
        if (focusbmp != null) {
            canvas.drawBitmap(focusbmp, this.getPaddingLeft()-20,
                this.getPaddingTop() + focusID * 100 + 230, null);
        } 
        super.onDraw(canvas);
        Paint paint = new Paint();
        paint.setColor(Color.WHITE);
        paint.setTextSize(25);
        paint.setAntiAlias(true);
        //获得图片的集合progressBarMap.get(Constants.progressBarValueA)
        progressBar_A = BitmapFactory.decodeResource(this.getResources(),progressBarMap.get(Constants.progressBarValueA));
        progressBar_B = BitmapFactory.decodeResource(this.getResources(),progressBarMap.get(Constants.progressBarValueB));
        progressBar_C = BitmapFactory.decodeResource(this.getResources(),progressBarMap.get(Constants.progressBarValueC));
        progressBar_D = BitmapFactory.decodeResource(this.getResources(),progressBarMap.get(Constants.progressBarValueD));
        progressBar_E = BitmapFactory.decodeResource(this.getResources(),progressBarMap.get(Constants.progressBarValueE));
        //获得图片的宽和高
        int w = 22000/progressBar_A.getWidth();
        int h = 22000/progressBar_A.getHeight();
        //刷新图片的像素大小
	    bitmap_A = progressBar.createScaledBitmap(progressBar_A, w, h, true);
	    bitmap_B = progressBar.createScaledBitmap(progressBar_B, w, h, true);
	    bitmap_C = progressBar.createScaledBitmap(progressBar_C, w, h, true);
	    bitmap_D = progressBar.createScaledBitmap(progressBar_D, w, h, true);
	    bitmap_E = progressBar.createScaledBitmap(progressBar_E, w, h, true);
            
	        //文字放置在屏幕的位置
	        canvas.drawText(a + "   " + String.valueOf(Constants.A),
	            getPaddingLeft() + 80, getPaddingTop() + 300, paint);
	        //图片的放置在屏幕的位置
	        canvas.drawBitmap(bitmap_A,getPaddingLeft()+ 244,
	                getPaddingTop() + 247, null);

            canvas.drawText(b + "   " + String.valueOf(Constants.B),
                getPaddingLeft() + 80, getPaddingTop() + 400, paint);
            canvas.drawBitmap(bitmap_B, getPaddingLeft()+ 244,
                    getPaddingTop() + 347, null); 
            
            canvas.drawText(c + "   " + String.valueOf(Constants.C),
                getPaddingLeft() + 80,getPaddingTop() + 500, paint);
            canvas.drawBitmap(bitmap_C, getPaddingLeft()+ 244,
                    getPaddingTop() + 447, null); 

            canvas.drawText(d + "   " + String.valueOf(Constants.D),
                getPaddingLeft() + 80,getPaddingTop() + 600, paint);
            canvas.drawBitmap(bitmap_D, getPaddingLeft()+ 244,
                    getPaddingTop() + 547, null); 

            canvas.drawText(e + "   " + String.valueOf(Constants.E),
                getPaddingLeft() + 80,getPaddingTop() + 700, paint);
            canvas.drawBitmap(bitmap_E, getPaddingLeft()+ 244,
                    getPaddingTop() + 647, null); 

    }

    public boolean onKeyDown(int keyCode, KeyEvent event) {
        super.onKeyDown(keyCode, event);
        switch (keyCode) {
            case KeyEvent.KEYCODE_DPAD_UP:
                if (focusID > 0) {
                    focusID--;
                } else {
                    focusID = 4;
                }
                this.invalidate();
                break;
            case KeyEvent.KEYCODE_DPAD_DOWN:
                if (focusID < 4) {
                    focusID++;
                } else {
                    focusID = 0;
                }
                this.invalidate();
                break;
                //左键的响应
            case KeyEvent.KEYCODE_DPAD_LEFT:
                if (focusID == 0) {
                    if (Constants.A >-10) {
                        Constants.A--;
                        Constants.progressBarValueA--;
                    } else {
                        Constants.A = -10;
                        Constants.progressBarValueA=6;
                    }
                    this.invalidate();
                } else if (focusID == 1) {
                    if (Constants.B > -10) {
                        Constants.B--;
                        Constants.progressBarValueB--;
                    } else {
                        Constants.B = -10;
                        Constants.progressBarValueB=6;
                    }
                    this.invalidate();
                }else if (focusID == 2) {
                    if (Constants.C > -10) {
                        Constants.C--;
                        Constants.progressBarValueC--;
                    } else {
                        Constants.C = -10;
                        Constants.progressBarValueC=6;
                    }
                    this.invalidate();
                }else if (focusID == 3) {
                    if (Constants.D > -10) {
                        Constants.D--;
                        Constants.progressBarValueD--;
                    } else {
                        Constants.D = -10;
                        Constants.progressBarValueD=6;
                    }
                    this.invalidate();
                }else if (focusID == 4) {
                    if (Constants.E > -10) {
                        Constants.E--;
                        Constants.progressBarValueE--;
                    } else {
                        Constants.E = -10;
                        Constants.progressBarValueE=6;
                    }
                    this.invalidate();
                }
                break;
             //右键的响应
            case KeyEvent.KEYCODE_DPAD_RIGHT:
                if (focusID == 0) {
                    if (Constants.A < (10-1)) {
                        Constants.A++;
                        Constants.progressBarValueA++;
                    } else {
                        Constants.A = 10;
                        Constants.progressBarValueA = 26;
                    }
                    this.invalidate();
                } else if (focusID == 1) {
                    if (Constants.B < (10 - 1)) {
                        Constants.B++;
                        Constants.progressBarValueB++;
                    } else {
                        Constants.B = 10;
                        Constants.progressBarValueB = 26;
                    }
                    this.invalidate();
                }else if (focusID == 2) {
                    if (Constants.C < (10 - 1)) {
                        Constants.C++;
                        Constants.progressBarValueC++;
                    } else {
                        Constants.C = 10;
                        Constants.progressBarValueC = 26;
                    }
                    this.invalidate();
                }else if (focusID == 3) {
                    if (Constants.D < (10 - 1)) {
                        Constants.D++;
                        Constants.progressBarValueD++;
                    } else {
                        Constants.D = 10;
                        Constants.progressBarValueD = 26;
                    }
                    this.invalidate();
                }else if (focusID == 4) {
                    if (Constants.E < (10 - 1)) {
                        Constants.E++;
                        Constants.progressBarValueE++;
                    } else {
                        Constants.E = 10;
                        Constants.progressBarValueE = 26;
                    }
                    this.invalidate();
                }
                break;
                
            //焦点的控制    
            case KeyEvent.KEYCODE_ENTER:
                switch (focusID) {
                    case 0:
                        focusID = 1;
                        break;
                    case 1:
                        focusID = 2;
                        break;
                    case 2:
                        focusID = 3;
                        break;
                    case 3:
                        focusID = 4;
                        break;
                    case 4:
                        focusID = 0;
                        break;
                    default:
                        break;
                }
                this.invalidate();
                break;
             //退出按键的响应
            case KeyEvent.KEYCODE_BACK:
                ((ViewGroup) (this.getParent())).removeView(this);
                break;
            default:
                break;
        }
        return true;
    }
    
    //做一个图片资源的集合
    public void initData() {
        progressBarMap = new HashMap<Integer, Integer>();
        progressBarMap.put(1, R.drawable.sound_1);
        progressBarMap.put(2, R.drawable.sound_2);
        progressBarMap.put(3, R.drawable.sound_3);
        progressBarMap.put(4, R.drawable.sound_4);
        progressBarMap.put(5, R.drawable.sound_5);
        progressBarMap.put(6, R.drawable.sound_6);
        progressBarMap.put(7, R.drawable.sound_7);
        progressBarMap.put(8, R.drawable.sound_8);
        progressBarMap.put(9, R.drawable.sound_9);
        progressBarMap.put(10, R.drawable.sound_10);
        progressBarMap.put(11, R.drawable.sound_11);
        progressBarMap.put(12, R.drawable.sound_12);
        progressBarMap.put(13, R.drawable.sound_13);
        progressBarMap.put(14, R.drawable.sound_14);
        progressBarMap.put(15, R.drawable.sound_15);
        progressBarMap.put(16, R.drawable.sound_16);
        progressBarMap.put(17, R.drawable.sound_17);
        progressBarMap.put(18, R.drawable.sound_18);
        progressBarMap.put(19, R.drawable.sound_19);
        progressBarMap.put(20, R.drawable.sound_20);
        progressBarMap.put(21, R.drawable.sound_21);
        progressBarMap.put(22, R.drawable.sound_22);
        progressBarMap.put(23, R.drawable.sound_23);
        progressBarMap.put(24, R.drawable.sound_24);
        progressBarMap.put(25, R.drawable.sound_25);
        progressBarMap.put(26, R.drawable.sound_26);
        progressBarMap.put(27, R.drawable.sound_27);
        progressBarMap.put(28, R.drawable.sound_28);
        progressBarMap.put(29, R.drawable.sound_29);
        progressBarMap.put(30, R.drawable.sound_30);
        progressBarMap.put(31, R.drawable.sound_31);
        progressBarMap.put(32, R.drawable.sound_32);
    }
    
}