安卓开发自己写的刻度尺测量，精确到mm.

ゝ一纸荒年。 2022-08-04 10:51 37阅读 0赞

我也是刚学安卓不久，只不过去实习有个项目需要这样的功能就写了，有些也是参考前人的。今天发出来希望对各位朋友有所启发。源码已经注释很清楚。  
效果如下图：显示

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![Center 1][]

![Center 2][]

下面是源码.

MainActivity.java

package cizi.com.example.cizi;
    
    import android.annotation.SuppressLint;
    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.Paint;
    import android.graphics.Paint.FontMetrics;
    import android.graphics.Rect;
    import android.os.Bundle;
    import android.util.DisplayMetrics;
    import android.view.MotionEvent;
    import android.view.View;
    import android.view.WindowManager;
    import android.widget.ImageView;
    import android.widget.RelativeLayout;
    import android.widget.TextView;
    
    public class MainActivity extends Activity {
    	// 自定义布局
    	public RelativeLayout rtLayout;
    	// 类对象
    	public MyBgrView myBgrView;
    	private MyDrawLine myDrawLine;
    	public TextView tv_num;
    	// 屏幕属性
    	private int scr_w;
    	// 结果提示信息
    	public String str = "100";
    	// 第一次布局View.lyout(View.Layout放在Acticity无效)
    	private boolean b_ctlView = false;
    	// 距离顶部
    	final public int top = 50;
    	// 背景边距剪切
    	public float ali_cut;
    	//屏幕分辨率
    	public DisplayMetrics dm = new DisplayMetrics();
    	@Override
    	protected void onCreate(Bundle savedInstanceState) {
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.activity_main);
    		
    		//这个是动态添加布局
    		rtLayout = (RelativeLayout) findViewById(R.id.myRtLayout);
    		myBgrView = new MyBgrView(this);
    		myDrawLine = new MyDrawLine(this);
    		rtLayout.addView(myBgrView);
    		rtLayout.addView(myDrawLine);
    		
    		myBgrView.setOnTouchListener(keduListener);
    		// 获取屏幕高宽
    		WindowManager wmManager = this.getWindowManager();
    		scr_w = wmManager.getDefaultDisplay().getWidth();
    	}
    
    	public int getScr_w() {
    		return scr_w;
    	}
    
    	public boolean getCtlView() {
    		return b_ctlView;
    	}
    
    	public void CclNum(View v, MotionEvent event,int lastX, int lastY){
    		double f;
    		// 移动中动态设置位置
    		int dx = (int) event.getRawX() - lastX;
    		//int dy = (int) event.getRawY() - lastY;
    		int left = v.getLeft() + dx;
    		int top = v.getTop();
    		int right = v.getRight() + dx;
    		int bottom = v.getBottom();
    		// 防止超出刻度线
    		if (left > scr_w >> 1) {
    			left = scr_w >> 1;
    			right = left + v.getWidth();
    		}
    		if (right < (scr_w >> 1) + ali_cut * 2) {
    			right = (scr_w >> 1) + (int) ali_cut * 2;
    			left = right - v.getWidth();
    		}
    		//这个是以图片最左端位置来计算刻度与数字显示的正确位置
    		//(算法原理大概是以长度计算占总长度的几分之几*乘以划分的份数此处刻度份数200)
    		f = (((scr_w >> 1) - v.getLeft() + ali_cut) * 200.0 / ((v
    				.getRight() - ali_cut) - (v.getLeft() + ali_cut)));
    		int f1 = (int) f;
    		//偏差1，可能算法问题
    		if (f1 < 0)
    			f1 = 0;
    		else if (f1 > 201)
    			f1 = 201;
    		f1--;
    		//赋值显示
    		str = f1 + "mm";
    		//重新移动布局
    		v.layout(left, top, right, bottom);
    	}
    	
    	// 监听
    	@SuppressLint("ClickableViewAccessibility")
    	private ImageView.OnTouchListener keduListener = new ImageView.OnTouchListener() {
    		int lastX, lastY;
    		/**
    		 * @param v
    		 * @param event
    		 * @return
    		 */
    		public boolean onTouch(View v, MotionEvent event) {
    			int action = event.getAction();
    			switch (action) {
    			case MotionEvent.ACTION_DOWN:
    				b_ctlView = true;
    				// getRaw相对于手机左上角
    				lastX = (int) event.getRawX();
    				lastY = (int) event.getRawY();
    				break;
    			case MotionEvent.ACTION_MOVE:
    				CclNum(v, event, lastX, lastY);
    				lastX = (int) event.getRawX();
    				lastY = (int) event.getRawY();
    				break;
    			case MotionEvent.ACTION_UP:
    				break;
    			default:
    				break;
    			}
    			return true;
    		}
    	};
    
    	//DrawImg
    	public void DrawImg(Canvas canvas, Bitmap bmp, int x, int y, int w, int h,int bx, int by) {
    		Rect src_rect = new Rect();
    		Rect dst_rect = new Rect();
    	
    		// src_rect表示绘制图片的部分
    		src_rect.left = bx;
    		src_rect.top = by;
    		src_rect.right = bx + w;
    		src_rect.bottom = by + h;
    	
    		// dst_rect表示绘制的屏幕上的区域
    		dst_rect.left = x;
    		dst_rect.top = y;
    		dst_rect.right = x + w;
    		dst_rect.bottom = y + h;
    		canvas.drawBitmap(bmp, src_rect, dst_rect, null);
    	}
    
    	public void DrawText(Canvas canvas,String strText,String strNum) {
    		Paint paint = new Paint();
    		paint.setStyle(Paint.Style.FILL);
    		paint.setStrokeWidth(4);
    		// 字体显示提示
    		// 设置此项之后绘制的x，y表示字体的中心
    		paint.setTextAlign(Paint.Align.CENTER);
    
    		// 计算或者试着字体属性
    		paint.setTextSize(35);
    		paint.setColor(Color.LTGRAY);
    		FontMetrics fontMetrics = paint.getFontMetrics();
    
    		//获取字体宽高
    		float fh = fontMetrics.bottom - fontMetrics.top;
    		float fw = paint.measureText(strNum);
    		
    		//还差半个字
    		float fw1 = paint.measureText("壠");
    		canvas.drawText(strText, ((int)fw >> 1) + ((int)fw1 >> 1), 60 - ((int) fh >> 1), paint);
    		//字体颜色
    		paint.setColor(Color.GREEN);
    		fh = fontMetrics.bottom - fontMetrics.top;
    		canvas.drawText(strNum, (getScr_w() >> 1) + 10 + ((int)fw1 >> 1), 60 - ((int) fh >> 1), paint);
    	}
    	
    	//画线游标
    	public void DrawLine(Canvas canvas,Paint paint){	
    		canvas.drawLine(getScr_w() >> 1, 50, getScr_w() >> 1, 100,paint);
    	}
    }
    
    //用于绘制背景
    class MyBgrView extends View {
    	static MainActivity mActivity = null;
    	// 绘制属性
    	private int w;
    	private int h;
    	private Bitmap bmp;
    	// 屏幕宽度
    	private int scr_w;
    
    	public MyBgrView(Context context) {
    		super(context);
    		// TODO Auto-generated constructor stub
    		mActivity = (MainActivity) context;
    		bmp = BitmapFactory.decodeResource(getResources(), R.drawable.kedu);
    		w = bmp.getWidth();
    		h = bmp.getHeight();
    		//如果有多个可以这样设置标签
    		//this.setTag("MyBgrView");
    	}
    	
    	//
    	@Override
    	protected void onDraw(Canvas canvas) {
    		// TODO Auto-generated method stub
    		super.onDraw(canvas);
    		 if (mActivity.getCtlView() == false)
    	        {
    				scr_w = mActivity.getScr_w();
    				// 计算应该剪切空白边距
    				mActivity.ali_cut = w / (float) 203.6 * (float) 1.8;
    				// 中间显示
    				int sw = (scr_w >> 1) - (w >> 1) + (int) mActivity.ali_cut;
    				this.layout(sw, 0, w + sw, h + mActivity.top);
    				this.setTop(mActivity.top);
    			}
    		mActivity.DrawImg(canvas, bmp, 0, 0, w, h, 0,0);
    	}
    
    }
    
    //画线类
    @SuppressLint("DrawAllocation")
    class MyDrawLine extends View {
    	private MainActivity mActivity = null;
    
    	public MyDrawLine(Context context) {
    		super(context);
    		mActivity = (MainActivity) context;
    	}
    
    	@Override
    	protected void onDraw(Canvas canvas) {
    		super.onDraw(canvas);
    		Paint paint = new Paint();
    		paint.setColor(Color.RED);
    		paint.setStyle(Paint.Style.FILL);
    		paint.setStrokeWidth(4);
    		mActivity.DrawText(canvas, "总量",mActivity.str);
    		mActivity.DrawLine(canvas,paint);
    		invalidate();
    	}
    }

布局文件:activity_main.xml

下面是DEMO链接，是百度云，为什么在这找不到上传文件的地方![惊恐][panic.gif]。要是有什么问题可以发我QQ邮箱:724989068@qq.com.

链接：http://pan.baidu.com/s/1sj85soX 密码：elc0

[Center]: /images/20220731/9689e30be0e84f3d8af22a6a331fa1fd.png
[Center 1]: /images/20220731/25f939c1b00b48ada2e3e7de54e4039b.png
[Center 2]: /images/20220731/74db4c2243ea42379bfa7b2ad4b8e429.png
[panic.gif]: /images/20220731/e074aad05e0047648d1f722d4e91caa8.png