如何在android中划一条线
有人能告诉我如何在Android中画一条线吗?也许举个例子吧?这条线在屏幕左上角画了两条十字线: DrawView.java如何在android中划一条线,android,Android,有人能告诉我如何在Android中画一条线吗?也许举个例子吧?这条线在屏幕左上角画了两条十字线: DrawView.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 Vie
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);
}
}
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);
}
}
要启动它的活动:
StartDraw.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);
}
}
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);
}
}
这将创建一条直线,希望有帮助 如果您想在布局中用一条简单的线分隔两个视图,您可以使用一个通用视图,该视图具有您希望该线具有的高度和宽度以及设置的背景色
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);
}
}
}
使用这种方法,您不需要重写视图或自己使用画布,只需简单明了地在xml中添加行即可
<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,该行的宽度填充屏幕,高度为1 dp
如果在小屏幕上画线有问题,考虑把线的高度改为PX。问题在于,在ldpi屏幕上,线条的高度将为0.75像素。有时,这可能导致舍入,使线消失。如果布局出现问题,请使用ressource文件定义行的宽度,并为小屏幕创建单独的ressource文件,将值设置为1px而不是1dp
仅当需要用于分割布局元素的水平线或垂直线时,此方法才可用。如果您想实现像画在图像中的十字架这样的效果,我的方法将不起作用。您可以使用开发者android中的Finger paint示例在视图中绘制多条直线。 只需评论:
mPath.quadTo(mX,mY,(x+mX)/2,(y+mY)/2)代码>
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;
}
}
}
或者如果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));
您可以通过xml中的形状制作可绘制的圆、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>
布局上的水平线:
<View
android:id="@+id/View03"
android:layout_width="fill_parent"
android:layout_height="5dip"
android:background="#0f0" />
<View
android:id="@+id/View04"
android:layout_width="5dip"
android:layout_height="fill_parent"
android:background="#0f0" />
对于布局上的垂直线:
<View
android:id="@+id/View03"
android:layout_width="fill_parent"
android:layout_height="5dip"
android:background="#0f0" />
<View
android:id="@+id/View04"
android:layout_width="5dip"
android:layout_height="fill_parent"
android:background="#0f0" />
改进@Janusz提供的答案
我将此添加到我的样式中:
<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>
匹配父项
1dp
?android:attr/listDivider
在我的布局中,代码更少,阅读更简单
<View style="@style/Divider"/>
如果要执行水平行距,请执行上述操作
对于两个视图之间的垂直线,您必须用android:layout\u height替换android:layout\u width参数(属性)有两种主要方法可以绘制线,即使用画布或使用视图
用帆布画线
从中可以看出,我们需要使用以下方法:
drawLine (float startX, float startY, float stopX, float stopY, Paint paint)
这是一张照片:
Paint
对象只告诉Canvas
绘制线条的颜色、宽度等等
以下是一些示例代码:
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直线,那么最简单的方法可能是在xml布局文件中使用视图。您可以这样做:
<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,以显示其外观:
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>
使用ImageView以编程方式绘制直线的另一种方法
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);
}
}
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);
简单的
如果您使用的是ConstraintLayout
,则需要定义至少两个约束才能显示该行。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" />
尽管我定义了3个约束条件。如果我想在其他一些活动(如R.layout.main)中添加一行,我如何添加?活动的布局必须包含一个视图对象-那么这没有问题。你只需要一个视图对象来绘制我想要绘制一条直线我怎么才能给startx start y stopx stopy这个值呢?实际上你可以在android开发者参考中发现,drawLine()有以下参数:drawLine(float startx,float startY,float stopx,float stopy,Paint Paint)我使用这个方法在背景上绘制直线。我想擦掉一条画好的线。对我有什么建议吗。你能建议我吗?如何在运行时添加相同的动态视图?Lakshmanan,给它一个id,并将其可见性设置为view.GONE或VISIBLE在运行时也可以使用此解决方案制作一个十字,只需根据你想要的十字在其中添加“rotation”属性,并使用两个视图。used view.addView(id)工作得很好!Kudos有人能帮助我如何在视图上看到相对布局上的xml元素吗??你可以通过上面的例子向我推荐,它们都是一样的。垂直和水平的区别是什么?@Burhan ARAS它们不一样,因为宽度和高度在两个视图中发生了变化。它只绘制垂直和水平线。你是一个天才兄弟。。。我一直在试图弄清楚他们在用画笔画视图时是如何得到坐标的…但是你贴的图片帮助我了解了很多。。。。是否有任何在线工具来模拟这样的图形,所以我在编码时使用它?是否有可能得到一个回调,以知道视图已经完成绘制。我正在尝试绘制两条不同的线。一旦画出了第一条线,我就必须画第二条线……为什么不在同一个onDraw中画两条线呢?@tientuyen07,如果你使用的是onDraw()
,那么在你的绘图代码周围加上if(someCondition){draw…}
,使someCondition=false
,然后在你的视图中调用invalidate()
。它将重新绘制没有线条的视图。