如何在android中画一条线
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How to draw a line in android
提问by mohan
Can anybody tell how to draw a line in Android, perhaps with an example?
谁能告诉如何在Android中画一条线，也许举个例子？
回答by Janusz
If you want to have a simple Line in your Layout to separate two views you can use a generic View with the height and width you want the line to have and a set background color.
如果你想在你的 Layout 中有一个简单的 Line 来分隔两个视图，你可以使用一个通用的 View ，它具有你希望线条具有的高度和宽度以及设置的背景颜色。
With this approach you don't need to override a View or use a Canvas yourself just simple and clean add the line in xml.
使用这种方法，您不需要覆盖视图或自己使用画布，只需简单而干净地在 xml 中添加该行。
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="@android:color/black" />
The example code I provided will generate a line that fills the screen in width and has a height of one dp.
我提供的示例代码将生成一条宽度填充屏幕且高度为 1 dp 的线。
If you have problems with the drawing of the line on small screens consider to change the height of the line to px. The problem is that on a ldpi screen the line will be 0.75 pixel high. Sometimes this may result in a rounding that makes the line vanish. If this is a problem for your layout define the width of the line a ressource file and create a separate ressource file for small screens that sets the value to 1px instead of 1dp.
如果在小屏幕上绘制线条有问题，请考虑将线条的高度更改为 px。问题在于，在 ldpi 屏幕上，该行将是 0.75 像素高。有时这可能会导致四舍五入，使线条消失。如果这是您的布局的问题，请定义资源文件的行宽，并为小屏幕创建单独的资源文件，将值设置为 1px 而不是 1dp。
This approach is only usable if you want horizontal or vertical lines that are used to divide layout elements. If you want to achieve something like a cross that is drawn into an image my approach will not work.
此方法仅在您想要用于划分布局元素的水平或垂直线时可用。如果您想实现诸如绘制到图像中的十字架之类的东西，我的方法将不起作用。
回答by DonGru
This one draws 2 lines which form a cross on the top left of the screen:
这个画了两条线，在屏幕的左上角形成一个十字：
DrawView.java
绘制视图
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);
}
}
The activity to start it:
启动它的活动：
StartDraw.java
开始绘图
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);
}
}
回答by Suragch
There are two main ways you can draw a line, by using a Canvasor by using a View.
您可以通过两种主要方式绘制线条，使用 aCanvas或使用 a View。
Drawing a Line with Canvas
用画布画一条线
From the documentationwe see that we need to use the following method:
从文档中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)
Here is a picture:
这是一张图片：
The Paintobject just tells Canvaswhat color to paint the line, how wide it should be, and so on.
该Paint物体只是告诉Canvas什么颜色漆线，应该有多宽，等等。
Here is some sample code:
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);
}
Drawing a Line with View
用视图画一条线
If you only need a straight horizontal or vertical line, then the easiest way may be to just use a Viewin your xml layout file. You would do something like this:
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是View在您的 xml 布局文件中使用 a 。你会做这样的事情：
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="@android:color/black" />
Here is a picture with two lines (one horizontal and one vertical) to show what it would look like:
这是一张有两条线（一条水平线和一条垂直线）的图片，以显示它的外观：
And here is the complete xml layout for that:
这是完整的 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>
回答by Hema
You can draw multiple straight lines on view using Finger paint example which is in Developer android. example link
您可以使用开发人员 android 中的手指绘画示例在视图上绘制多条直线。 示例链接
Just comment: mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);You will be able to draw straight lines.
只是评论：mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);您将能够绘制直线。
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;
}
}
}
回答by vinay
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);
}
}
}
回答by Mohanraj
for horizontal line on the layout :
对于布局上的水平线：
<View
android:id="@+id/View03"
android:layout_width="fill_parent"
android:layout_height="5dip"
android:background="#0f0" />
for vertical line on the layout :
对于布局上的垂直线：
<View
android:id="@+id/View04"
android:layout_width="5dip"
android:layout_height="fill_parent"
android:background="#0f0" />
回答by shreedhar bhat
Simple one
简单的
<TextView
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="#c0c0c0"
android:id="@+id/your_id"
android:layout_marginTop="160dp" />
回答by user712051
canvas.drawLine(10, 10, 90, 10, paint);
canvas.drawLine(10, 20, 90, 20, paint);
This will create a straight horizontal line, hope it helps!.
这将创建一条直线水平线，希望它有所帮助！。
回答by Muhammad Aamir Ali
You can make a drawable like circle, line, rectangle etc through shapes in xml as follow:
您可以通过 xml 中的形状制作圆形、线条、矩形等可绘制对象，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>
回答by user4757345
this code adds horizontal line to a linear layout
此代码将水平线添加到线性布局
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);
