如何在机器人中画线

有人能告诉我如何在安卓系统中划清界限吗，也许举个例子？

414888 次浏览
小开
最佳答案

这个在屏幕左上角画了两条交叉线:

Java

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.View;


public class DrawView extends View {
Paint paint = new Paint();


private void init() {
paint.setColor(Color.BLACK);
}


public DrawView(Context context) {
super(context);
init();
}


public DrawView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}


public DrawView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}


@Override
public void onDraw(Canvas canvas) {
canvas.drawLine(0, 0, 20, 20, paint);
canvas.drawLine(20, 0, 0, 20, paint);
}


}

启动活动:

开始绘制 java

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;


public class StartDraw extends Activity {
DrawView drawView;


@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);


drawView = new DrawView(this);
drawView.setBackgroundColor(Color.WHITE);
setContentView(drawView);


}
}
小开 
canvas.drawLine(10, 10, 90, 10, paint);
canvas.drawLine(10, 20, 90, 20, paint);

这将创建一个直线水平线，希望它有所帮助。

小开 
package com.example.helloandroid;


import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.View;


public class HelloAndroid2Activity extends Activity {
/** Called when the activity is first created. */
DrawView drawView;


@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);


drawView = new DrawView(this);
drawView.setBackgroundColor(Color.WHITE);
setContentView(drawView);
}
class DrawView extends View {
Paint paint = new Paint();


public DrawView(Context context) {
super(context);
paint.setColor(Color.BLUE);
}
@Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawLine(10, 20, 30, 40, paint);
canvas.drawLine(20, 10, 50, 20, paint);


}
}
}
小开

如果您想在布局中使用一个简单的线条来分隔两个视图，那么您可以使用一个具有您希望线条具有的高度和宽度以及设置背景颜色的通用视图。

使用这种方法，您不需要覆盖视图或自己使用 Canvas，只需简单地在 xml 中添加代码行即可。

<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="@android:color/black" />

我提供的示例代码将生成一行，填充屏幕的宽度和高度为1 dp。

如果在小屏幕上绘制线条时遇到问题，可以考虑将线条的高度改为 px。问题在于，在 LDPI 屏幕上，这条线的高度是0.75像素。有时，这可能会导致舍入，使该行消失。如果这是你的布局问题，定义一个资源文件的行宽，并为小屏幕创建一个单独的资源文件，将值设置为1px 而不是1dp。

此方法只有在需要用于分割布局元素的水平或垂直线时才可用。如果你想实现像一个十字架被画成一个形象，我的方法不会工作。

小开

可以使用 Developer android 中的 Finger 油漆示例在视图中绘制多条直线。 示例连结

评论: mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2); 你将能够画出直线。

import android.app.Activity;
import android.content.Context;
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.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;


public class JoinPointsActivity extends Activity  {
/** Called when the activity is first created. */
Paint mPaint;
float Mx1,My1;
float x,y;
@Override


public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// setContentView(R.layout.main);
MyView view1 =new MyView(this);
view1.setBackgroundResource(R.drawable.image_0031_layer_1);
setContentView(view1);




mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(0xFFFF0000);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
// mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(10);


}


public class MyView extends View {


private static final float MINP = 0.25f;
private static final float MAXP = 0.75f;


private Bitmap  mBitmap;
private Canvas  mCanvas;
private Path    mPath;
private Paint   mBitmapPaint;


public MyView(Context c) {
super(c);


mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
}


@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
}


@Override
protected void onDraw(Canvas canvas) {
canvas.drawColor(0xFFAAAAAA);
// canvas.drawLine(mX, mY, Mx1, My1, mPaint);
// canvas.drawLine(mX, mY, x, y, mPaint);
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
canvas.drawPath(mPath, mPaint);


}


private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;


private void touch_start(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
mX = x;
mY = y;
}
private void touch_move(float x, float y) {
float dx = Math.abs(x - mX);
float dy = Math.abs(y - mY);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
// mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
mX = x;
mY = y;
}
}
private void touch_up() {
mPath.lineTo(mX, mY);
// commit the path to our offscreen
mCanvas.drawPath(mPath, mPaint);
// kill this so we don't double draw
mPath.reset();
}


@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();
//   Mx1=(int) event.getX();
//  My1= (int) event.getY();
invalidate();
break;
}
return true;
}
}


}
小开 
  final SurfaceView surf = (SurfaceView)findViewById(R.id.surface_home);
surf.setOnTouchListener( new SurfaceView.OnTouchListener(){
private boolean moving = false;//stupid state
public boolean onTouch(View v, MotionEvent event) {
switch( event.getAction() ){
case MotionEvent.ACTION_DOWN:
final int x = (int)event.getX();
final int y = (int)event.getY();
final Rect bounds = mTiles.getBounds();
moving = bounds.intersects(x, y, x+1, y+1);
return true;
case MotionEvent.ACTION_MOVE:
if( moving ){
final int x_new = (int)event.getX();
final int y_new = (int)event.getY();
mDrawTiles.draw( new DrawLogic(){
public void draw(Rect _surface) {
mTiles.setBounds(
x_new - mDrawWidth/2,
y_new - mDrawHeight/2,
x_new + mDrawWidth/2,
y_new + mDrawHeight/2);
}
});
小开

或者你只是想要一句台词

TextView line = new TextView(this);
line.setBackgroundResource(android.R.color.holo_red_dark);
line.setHeight((int) Utility.convertDpToPixel(1,this));
小开

您可以通过 xml 中的形状创建可绘制的圆、线、矩形等，如下所示:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="line" >


<solid android:color="#00000000" />


<stroke
android:width="2dp"
android:color="#808080" />


</shape>
小开

布局上的水平线:

 <View
android:id="@+id/View03"
android:layout_width="fill_parent"
android:layout_height="5dip"
android:background="#0f0" />

布局上的垂直线:

<View
android:id="@+id/View04"
android:layout_width="5dip"
android:layout_height="fill_parent"
android:background="#0f0" />
小开

改进@Janusz 提供的答案

我把这个加入到我的风格中:

<style name="Divider">
<item name="android:layout_width">match_parent</item>
<item name="android:layout_height">1dp</item>
<item name="android:background">?android:attr/listDivider</item>
</style>

然后在我的布局是更少的代码和更简单的阅读。

<View style="@style/Divider"/>

如果你想做水平线间距，然后做以上。

对于两个视图之间的垂直线，必须使用 使用 android 替换 android: lay_ width 参数(属性)

小开

有两种主要的方法可以画一条线，使用 Canvas或使用 View。

用画布画线

从 文件我们看到我们需要使用以下方法:

drawLine (float startX, float startY, float stopX, float stopY, Paint paint)

下面是一张图片:

canvas.drawLine

Paint对象只是告诉 Canvas绘制线条的颜色、线条的宽度等等。

下面是一些示例代码:

private Paint paint = new Paint();
....


private void init() {
paint.setColor(Color.BLACK);
paint.setStrokeWidth(1f);
}


@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);


startX = 20;
startY = 100;
stopX = 140;
stopY = 30;


canvas.drawLine(startX, startY, stopX, stopY, paint);
}

用视图画线

如果您只需要一条水平或垂直的直线，那么最简单的方法可能就是在 xml 布局文件中使用 View。你会这样做:

<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="@android:color/black" />

这是一张有两条线(一条水平线和一条垂直线)的图片，展示了它的样子:

drawing a line with a view in xml layout

下面是完整的 xml 布局:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >


<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="10dp"
android:text="TextView1 in vertical linear layout" />


<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="@android:color/black" />


<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="10dp"
android:text="TextView2 in vertical linear layout" />


<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content" >


<TextView
android:layout_width="100dp"
android:layout_height="100dp"
android:padding="10dp"
android:text="TextView3 in horizontal linear layout" />


<View
android:layout_width="1dp"
android:layout_height="match_parent"
android:background="@android:color/black" />


<TextView
android:layout_width="100dp"
android:layout_height="100dp"
android:padding="10dp"
android:text="TextView4 in horizontal linear layout" />
</LinearLayout>


</LinearLayout>
小开

使用 ImageView 以编程方式绘制线条的另一种方法

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Typeface;
import android.os.Bundle;
import android.widget.ImageView;


public class Test extends Activity {
ImageView drawingImageView;


@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
drawingImageView = (ImageView) this.findViewById(R.id.DrawingImageView);
Bitmap bitmap = Bitmap.createBitmap((int) getWindowManager()
.getDefaultDisplay().getWidth(), (int) getWindowManager()
.getDefaultDisplay().getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
drawingImageView.setImageBitmap(bitmap);


// Line
Paint paint = new Paint();
paint.setColor(Color.GREEN);
paint.setStrokeWidth(10);
int startx = 50;
int starty = 100;
int endx = 150;
int endy = 210;
canvas.drawLine(startx, starty, endx, endy, paint);


}
}
小开

此代码将水平线添加到线性布局中

View view = new View(this);
LinearLayout.LayoutParams lpView = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, 1); // --> horizontal
view.setLayoutParams(lpView);
view.setBackgroundColor(Color.DKGRAY);


linearLayout.addView(view);
小开

很简单

 <TextView
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="#c0c0c0"
android:id="@+id/your_id"
android:layout_marginTop="160dp" />
小开

如果使用 ConstraintLayout，则需要定义至少2个约束来显示该行。像这样:

<View
android:layout_width="0dp"
android:layout_height="1dp"
android:background="@android:color/black"
app:layout_constraintEnd_toEndOf="@+id/someView1"
app:layout_constraintStart_toStartOf="@+id/someView2"
app:layout_constraintTop_toBottomOf="@+id/someView3" />

虽然我定义了三个约束。

小开

如果有人能从一个简化的解决方案中受益:

不需要点类。直接在 ACTION _ MOVE中移动到从 ACTION _ Down得到的开始 X 和 Y 坐标。这种方法工作得更好，因为我们使用 牵引路径而不是 拉绳，拉绳的计算密集度较低，因此性能更好。

class DrawingView(context: Context,
attributeSet: AttributeSet): View(context, attributeSet) {


private val mPaint = Paint()
private var mPath = Path()
var startX = 0f
var startY = 0f
var endX = 0f
var endY = 0f
init {
mPaint.color = Color.GREEN
mPaint.style = Paint.Style.STROKE
mPaint.strokeJoin = Paint.Join.ROUND
mPaint.strokeCap = Paint.Cap.ROUND
mPaint.strokeWidth = 50f


}
override fun onDraw(canvas: Canvas) {
super.onDraw(canvas)
canvas.drawPath(mPath, mPaint)
}


override fun onTouchEvent(event: MotionEvent): Boolean {
when (event.action) {
MotionEvent.ACTION_DOWN -> {
startX = event.x
startY = event.y
invalidate()
}
MotionEvent.ACTION_MOVE -> {
endX = event.x
endY = event.y
val path = Path()
path.moveTo(startX, startY) <- // Important!
path.lineTo(endX, endY)
mPath = path
invalidate()
}
}
return true
}
}

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