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如何在安卓系统中画一条线

android
172

有人能告诉我如何在安卓上画一条线，最好带个例子吗？

16个回答
3
如果有人可以从简化的解决方案中受益： 不需要使用 Point 类。直接在 MotionEvent.ACTION_MOVE 中移动到从 MotionEvent.ACTION_DOWN 获取的起始 X 和 Y 坐标。这种方法更好，因为我们使用 drawPath 而不是 drawLine，drawPath 的计算复杂度较低，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
    }
}
3

您可以通过XML中的形状（如圆、线、矩形等）制作可绘制物：

<?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>
2
  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);
                                        }
                                    });
1

为了改进@Janusz提供的答案

我将以下内容添加到我的样式中：

<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>

那么在我的布局中，代码更少，更易于阅读。

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

如果您想进行水平行间距，则请执行上述操作。

如果要在两个视图之间建立垂直线，则需要使用 android:layout_height 替换android:layout_width参数（属性）

1

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);

  }
}
-1

或者如果你只想要一行

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