java - 2 点之间的道线

Question

我正在尝试在两点之间画一条线。我可以在两点之间画一条线，例如:A 到 B 到 C。但我想在它们之间画线，例如 A 到 C 或 C 到 A。

我还想在图像背景上绘制这些线条。我在那里有一个背景，但是当我用背景画一条线时，我的应用程序滞后。

代码如下:

package com.example.grzegorz.kropy;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Point;
import android.graphics.drawable.*;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.MotionEvent;
import android.view.View;
import android.graphics.BitmapFactory;
import java.util.ArrayList;
import java.util.List;
public class PaintView extends View {

private Bitmap mBitmap;
private Canvas mCanvas; // holds the "draw" calls
private Path mPath; //Create an empty path
private Paint mPaint; // the style and color information about how to draw geometries, text and bitmaps.
private static final int TOUCH_TOLERANCE_DP = 24;
private static final int BACKGROUND =0xFFCC00 ;

private List<Point> mPoints = new ArrayList<Point>();
private int mLastPointIndex = 0;
private int mTouchTolerance;
private boolean isPathStarted = false;


public PaintView(Context context) {
    super(context);

    mCanvas = new Canvas();
    mPath = new Path();
    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setDither(true);
    mPaint.setColor(Color.BLACK);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setStrokeWidth(12);
    mTouchTolerance = dp2px(TOUCH_TOLERANCE_DP);

    // TODO just test points
    Point p1 = new Point(20, 20);
    Point p2 = new Point(100, 100);
    Point p3 = new Point(200, 250);
    Point p4 = new Point(280, 400);
    Point p5 = new Point(350, 600);
    Point p6 = new Point(400, 500);
    Point p7 = new Point(450, 500);
    mPoints.add(p1);
    mPoints.add(p2);
    mPoints.add(p3);
    mPoints.add(p4);
    mPoints.add(p5);
    mPoints.add(p6);
    mPoints.add(p7);
}

public PaintView(Context context, AttributeSet attrs) {
    super(context, attrs);
    mBitmap = BitmapFactory.decodeResource(getResources(),R.drawable.polacz);
    mCanvas = new Canvas();
    mPath = new Path();
    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setDither(true);
    mPaint.setColor(Color.BLACK);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setStrokeWidth(12);
    mTouchTolerance = dp2px(TOUCH_TOLERANCE_DP);

    // TODO just test points
    Point p1 = new Point(20, 20);
    Point p2 = new Point(100, 100);
    Point p3 = new Point(200, 250);
    Point p4 = new Point(280, 400);
    Point p5 = new Point(350, 600);
    Point p6 = new Point(400, 500);
    Point p7 = new Point(450, 500);
    mPoints.add(p1);
    mPoints.add(p2);
    mPoints.add(p3);
    mPoints.add(p4);
    mPoints.add(p5);
    mPoints.add(p6);
    mPoints.add(p7);
}

public PaintView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    // TODO Auto-generated constructor stub

    mCanvas = new Canvas();
    mPath = new Path();
    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setDither(true);
    mPaint.setColor(Color.BLACK);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setStrokeWidth(12);
    mTouchTolerance = dp2px(TOUCH_TOLERANCE_DP);

}

@Override
protected void onSizeChanged(int width, int height, int oldWidth, int oldHeight) {
    super.onSizeChanged(width, height, oldWidth, oldHeight);
    clear();
}
@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    //canvas.drawColor(BACKGROUND);

    Drawable d = getResources().getDrawable(R.drawable.polacz);
    d.setBounds(canvas.getClipBounds());
    d.draw(canvas);
 //   mCustomImage.setBounds(canvas.getClipBounds());
 //   mCustomImage.draw(canvas);
    canvas.drawBitmap(mBitmap, 0, 0, null);
    //   canvas.drawBitmap(BitmapFactory.decodeResource(getResources(),   R.drawable.polacz1), 0, 0, null);
    canvas.drawPath(mPath, mPaint);

    // TODO remove if you dont want points to be drawn
    for (Point point : mPoints) {
        canvas.drawPoint(point.x, point.y, mPaint);
    }
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    float x = event.getX();
    float y = event.getY();

    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            touch_start(x, y);
            invalidate();
            break;
        case MotionEvent.ACTION_MOVE:
            touch_move(x, y);
            invalidate();
            break;
        case MotionEvent.ACTION_UP:
            touch_up(x, y);
            invalidate();
            break;
    }
    return true;
}

private void touch_start(float x, float y) {

    if (checkPoint(x, y, mLastPointIndex)) {
        mPath.reset();
        // user starts from given point so path can beis started
        isPathStarted = true;
    } else {
        // user starts move from point which doen's belongs to mPinst list
        isPathStarted = false;
    }

}
private void touch_move(float x, float y) {
// draw line with finger move
    if (isPathStarted) {
        mPath.reset();
        Point p = mPoints.get(mLastPointIndex);
        mPath.moveTo(p.x, p.y);
        if (checkPoint(x, y, mLastPointIndex + 1)) {
            p = mPoints.get(mLastPointIndex + 1);
            mPath.lineTo(p.x, p.y);
            mCanvas.drawPath(mPath, mPaint);
            mPath.reset();
            ++mLastPointIndex;
        } else {
           mPath.lineTo(x, y);
       }
    }
}

/**
 * Draws line.
 */
private void touch_up(float x, float y) {
    mPath.reset();
    if (checkPoint(x, y, mLastPointIndex + 1) && isPathStarted) {
        // move finished at valid point so draw whole line

        // start point
        Point p = mPoints.get(mLastPointIndex);
        mPath.moveTo(p.x, p.y);
        // end point
        p = mPoints.get(mLastPointIndex + 1);
        mPath.lineTo(p.x, p.y);
        mCanvas.drawPath(mPath, mPaint);
        mPath.reset();
        // increment point index
        ++mLastPointIndex;
        isPathStarted = false;
    }

}

/**
 * Sets paint
 *
 * @param paint
 */
public void setPaint(Paint paint) {
    this.mPaint = paint;
}

/**
 * Returns image as bitmap
 *
 * @return
 */
public Bitmap getBitmap() {
    return mBitmap;
}

/**
 * Clears canvas
 */
public void clear() {
    mBitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
    mBitmap.eraseColor(BACKGROUND);
    mCanvas.setBitmap(mBitmap);
    invalidate();
}

/**
 * Checks if user touch point with some tolerance
 */
private boolean checkPoint(float x, float y, int pointIndex) {
    if (pointIndex == mPoints.size()) {
        // out of bounds
        return false;
    }
    Point point = mPoints.get(pointIndex);
    //EDIT changed point.y to poin.x in the first if statement
    if (x > (point.x - mTouchTolerance) && x < (point.x + mTouchTolerance)) {
        if (y > (point.y - mTouchTolerance) && y < (point.y + mTouchTolerance)) {
            return true;
        }
    }
    return false;
}

public List<Point> getPoints() {
    return mPoints;
}

public void setPoints(List<Point> points) {
    this.mPoints = points;
}

private int dp2px(int dp) {
    Resources r = getContext().getResources();
    float px = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, r.getDisplayMetrics());
    return (int) px;
}
}

XML:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
android:focusableInTouchMode="false">
<com.example.grzegorz.kropy.PaintView
android:layout_width="670dp"
android:layout_height="820dp"
 />

<!--<Button-->
    <!--android:layout_width="wrap_content"-->
    <!--android:layout_height="wrap_content"-->
    <!--android:text="graj"-->
    <!--android:id="@+id/button"-->
    <!--android:layout_alignParentTop="true"-->
    <!--android:layout_alignParentLeft="true"-->
    <!--android:onClick="gra"-->
    <!--android:layout_alignParentStart="true" />-->
    </RelativeLayout>

Answer 1

尝试解决方案对我有用

public class DrawView extends View {
    		Paint paint = new Paint();
    		View startView1;
    		View endView1; 
    		int myToken;
    		float sX,sY,eX,eY;
    		public DrawView(Context context,View startView ,View endView) {
    			super(context); 
    			paint.reset();
    			myToken=token;
    			paint.setStrokeWidth(3);
    			this.startView1 = startView;
    			this.endView1 = endView;
    	
    		}
    
    public void onDraw(Canvas canvas) {
    
    			paint.setColor(Color.GREEN);
    			canvas.drawLine(startView1.getX()+startView1.getWidth() / 2.F,    startView1.getY()+startView1.getHeight()/ 2.F, endView1.getX()+endView1.getWidth() / 2.F, endView1.getY()+endView1.getHeight() / 2.F, paint);
    			
    		}
    
    	}
    
    
    and call this DrawView class as :
    
    Button btn1=(Button) findViewById(id1);
    									Button btn2=(Button) findViewById(id2);
    									DrawView drawView = new DrawView(RoasterScreen.this,btn1,btn2);
rootLayout.addView(drawView);