android自己写的类似刻度尺的东西。
刚学android不久，因为公司项目要求，写了个类似刻度尺的东西，拿出来献丑，希望大家给点意见。
先上代码，注：KeduView中的浮点数计算我没处理（因为精度问题，浮点数直接计算出来的结果可能不对）。StaffView中的浮点数计算我进行了处理，我在Arithmetic中封装了加减乘除方法：
package com.hyx.suiyipaint;import android.app.Activity;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.graphics.Rect;import android.os.Bundle;import android.view.KeyEvent;import android.view.MotionEvent;import android.view.SurfaceHolder;import android.view.SurfaceView;import android.view.View;import android.widget.ImageView;import android.widget.LinearLayout;public class KeduActivity extends Activity {private ImageView kedu_tiao;private LinearLayout kedu_linear;private LinearLayout staff_linear;private KeduView kedu;private StaffView staff;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.kedu);kedu_linear = (LinearLayout)findViewById(R.id.kedu_linear);kedu = new KeduView(this, 0f, 0.1f);kedu_linear.addView(kedu);staff_linear = (LinearLayout)findViewById(R.id.staff_linear);staff = new StaffView(this, 7.5f, 0.5f, "cm");staff_linear.addView(staff);kedu_tiao = (ImageView)findViewById(R.id.kedu_tiao);kedu_tiao.setOnTouchListener(keduListener);}private ImageView.OnTouchListener keduListener = new ImageView.OnTouchListener(){private float initx = 0;@Overridepublic boolean onTouch(View v, MotionEvent event) {switch(event.getAction()){case MotionEvent.ACTION_DOWN:initx = event.getX();break;case MotionEvent.ACTION_MOVE:float lastx = event.getX();if(lastx > initx + 5){kedu.draw(1);initx = lastx;}else if(lastx < initx -5){kedu.draw(-1);initx = lastx;}break;}return true;}};class KeduView extends SurfaceView implements SurfaceHolder.Callback, Runnable{private SurfaceHolder mSurfaceHolder = null; private Canvas canvas;//画布背景private Bitmap background;//刻度游标private Bitmap pointer;//总刻度数private static final int KEDU_COUNT = 25;//刻度最小值private float init_min;//每个刻度的单位值private float interval;public KeduView(Context context, float init_min, float interval) {super(context);mSurfaceHolder = this.getHolder(); mSurfaceHolder.addCallback(this); this.setFocusable(true);background = BitmapFactory.decodeResource(getResources(), R.drawable.kedu_bg);pointer = BitmapFactory.decodeResource(getResources(), R.drawable.kedu_pointer);this.init_min = init_min;this.interval = interval;}@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}@Overridepublic void surfaceCreated(SurfaceHolder holder) {new Thread(this).start();}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {}@Overridepublic void run() {draw(0);}//每次X轴移动的像素private static final int MOVE = 10;//游标在最左边时X轴的位置private static final int INIT_POINTER_LEFT = 20;//游标在最右边时X轴的位置private static final int INIT_POINTER_RIGHT = 270;//游标顶端Y轴的位置private static final int INIT_POINTER_TOP = 36;//底下刻度数字最左边的X轴位置private static final int INIT_NUM_X = 18;//结果的X轴位置private static final int RESULT_X = 36;//结果的Y轴位置private static final int RESULT_Y = 25;//结果的字体大小private static final int RESULT_SIZE = 24;//游标X轴的位置private int POINTER_X = INIT_POINTER_LEFT;//底下刻度数字X轴位置private int NUM_X = INIT_NUM_X;//底下刻度数字的Y轴位置private int NUM_Y = 85;//结果private float result = 0;/** * @param direction 方向，-1向左，1向右，0不动 */public void draw(int direction){//获取画布canvas = mSurfaceHolder.lockCanvas();if (mSurfaceHolder == null || canvas == null) { return; }canvas.drawColor(Color.WHITE);Paint paint = new Paint(); paint.setAntiAlias(true); paint.setColor(Color.GRAY);canvas.drawBitmap(background, new Matrix(), paint);switch(direction){case -1:POINTER_X -= MOVE;result -= interval;if(result <= 0){result = init_min;POINTER_X = INIT_POINTER_LEFT;}else{if(POINTER_X < INIT_POINTER_LEFT){POINTER_X = INIT_POINTER_RIGHT;result = init_min;init_min -= KEDU_COUNT * interval;}}break;case 1:POINTER_X += MOVE;result += interval;if(POINTER_X > INIT_POINTER_RIGHT){POINTER_X = INIT_POINTER_LEFT;init_min += KEDU_COUNT * interval;result = init_min;}break;}canvas.drawBitmap(pointer, POINTER_X, INIT_POINTER_TOP, paint);for(int i=0; i<6; i++){if(i == 0){NUM_X = INIT_NUM_X;}canvas.drawText(Float.toString(i * 5f * interval + init_min), NUM_X, NUM_Y, paint);NUM_X += 50;}paint.setColor(Color.BLACK);paint.setTextSize(RESULT_SIZE);canvas.drawText(Float.toString(result), RESULT_X, RESULT_Y, paint);//解锁画布，提交画好的图像 mSurfaceHolder.unlockCanvasAndPost(canvas); }}class StaffView extends SurfaceView implements SurfaceHolder.Callback, Runnable{private SurfaceHolder mSurfaceHolder = null; private Canvas canvas;private Paint paint;//画布背景private Bitmap background;//刻度private Bitmap staff;//刻度游标private Bitmap pointer;//初始值private float initValue;//刻度单位最小值private float interval;//单位private String unit;//是否初始private boolean isInit = true;public StaffView(Context context, float initValue, float interval, String unit) {super(context);mSurfaceHolder = this.getHolder(); mSurfaceHolder.addCallback(this); paint = new Paint();this.setFocusable(true);background = BitmapFactory.decodeResource(getResources(), R.drawable.staff_bg);staff = BitmapFactory.decodeResource(getResources(), R.drawable.staff0);pointer = BitmapFactory.decodeResource(getResources(), R.drawable.kedu_pointer); this.initValue = initValue;this.interval = interval;this.unit = unit;}@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}@Overridepublic void surfaceCreated(SurfaceHolder holder) {new Thread(this).start();}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {}@Overridepublic void run() {draw(0);}private int move = 10;//每次移动的距离private int initBx = 77;//图片上X坐标private int by = 0;//图片上Y坐标private int bw = 258;//图片宽度private int bh = 31;//图片高度private int sx = 18;//画布X坐标private int sy = 36;//画布Y坐标private int jiange = 51; //大刻度之间距离private int num_left = 33;//最左边数字到左边的距离private int RESULT_X = 36;//结果的X轴位置private int RESULT_Y = 25;//结果的Y轴位置private int RESULT_SIZE = 24;//结果的字体大小private float result = 0;/** * @param direction 方向，-1向左，1向右，0不动 */public void draw(int direction){//获取画布canvas = mSurfaceHolder.lockCanvas();if (mSurfaceHolder == null || canvas == null) { return; }canvas.drawColor(Color.WHITE);paint.setAntiAlias(true); paint.setColor(Color.GRAY);canvas.drawBitmap(background, new Matrix(), paint);if(isInit){result = initValue;}else{switch(direction){case 1:result = Arithmetic.add(result, interval);break;case -1:result = Arithmetic.sub(result, interval);if(result < 0){result = 0;}break;}}initStaff();canvas.drawBitmap(pointer, 143, 36, paint);Paint reslutPaint = new Paint();reslutPaint.setColor(Color.BLACK);reslutPaint.setTextSize(RESULT_SIZE);canvas.drawText(Float.toString(result) + " " + unit, RESULT_X, RESULT_Y, reslutPaint);//解锁画布，提交画好的图像 mSurfaceHolder.unlockCanvasAndPost(canvas); }private void initStaff(){int bx = initBx;int num_x = num_left;int mod = 0;int midd = 2;if(result != 0){mod = (int)(Arithmetic.div(result, interval, 1) % 5);bx += mod * move;}if(mod >= 3){midd = 1;num_x += (5 - mod) * move;}else{num_x -= mod * move;}float text = 0;for(int i=0; i<5; i++){if(i < midd){text = result - mod * interval - (midd - i) * 5 * interval;}else if(i == midd){text = result - mod * interval;}else{text += 5 * interval;}text = Arithmetic.round(text, 1);if(text >= 0){canvas.drawText(Float.toString(text), num_x, 85, paint);}num_x += jiange;}//要绘制的图片矩形区域设置Rect src = new Rect();src.left = bx;src.top = by;src.right = bx + bw;src.bottom = bh;//要绘制的画布矩形区域设置Rect dst = new Rect();dst.left = sx;dst.top = sy;dst.right = sx + bw;dst.bottom = sy + bh;canvas.drawBitmap(staff, src, dst, paint);}private float initx = 0;@Overridepublic boolean onTouchEvent(MotionEvent event) {switch(event.getAction()){case MotionEvent.ACTION_DOWN:initx = event.getX();break;case MotionEvent.ACTION_MOVE:float lastx = event.getX();if(lastx > initx + 5){isInit = false;draw(-1);initx = lastx;}else if(lastx < initx -5){isInit = false;draw(1);initx = lastx;}break;}return true;}public float getResult(){return result;}}@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {if(keyCode == KeyEvent.KEYCODE_VOLUME_DOWN){staff.isInit = false;staff.draw(-1);return true;}if(keyCode == KeyEvent.KEYCODE_VOLUME_UP){staff.isInit = false;staff.draw(1);return true;}return super.onKeyDown(keyCode, event);}}?布局文件：
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" android:gravity="center" android:background="#fff"> <LinearLayout android:id="@+id/kedu_linear" android:layout_width="294dp" android:layout_height="101dp"/> <ImageView android:layout_height="wrap_content" android:layout_width="wrap_content" android:id="@+id/kedu_tiao" android:src="@drawable/kedu_wheel_01" android:layout_margin="20dp"/> <LinearLayout android:id="@+id/staff_linear" android:layout_width="294dp" android:layout_height="101dp"/> </LinearLayout>
?附件是运行效果截图。