如何在android中使用XML形状创建一个正确的箭头(雪佛龙)？

Question

如何在android中使用xml形状创建一个正确的箭头？

Answer 1

我有类似的问题.这是我解决它的方式:

<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
    <item>
        <shape>
            <solid android:color="@android:color/transparent"/>
            <size android:width="2dp" android:height="50dp"/>
        </shape>
    </item>

    <item android:bottom="20dp">
        <rotate
            android:fromDegrees="-45"
            android:toDegrees="45">
            <shape android:shape="rectangle">
                <solid android:color="@android:color/black"/>
                <corners
                    android:radius="1dp"
                    android:bottomRightRadius="0dp"
                    android:bottomLeftRadius="0dp"/>
            </shape>
        </rotate>
    </item>

    <item android:top="20dp">
        <rotate
            android:fromDegrees="45"
            android:toDegrees="45">
            <shape android:shape="rectangle">
                <solid android:color="@android:color/black"/>
                <corners
                    android:radius="1dp"
                    android:topRightRadius="0dp"
                    android:topLeftRadius="0dp"/>
            </shape>
        </rotate>
    </item>
</layer-list>

第一个项目是一个空的形状,以扩展drawable.然后,我使用了2个矩形.每个都有两个圆形的边.

您需要通过以下方式使用此drawable ImageView:

<ImageView
    android:layout_width="60dp"
    android:layout_height="60dp"
    android:src="@drawable/arrow"
    android:contentDescription="@string/arrow_descriptor"/>

这是结果:

注意: AndroidStudio不会渲染不同的边角尺寸,但会在设备上正确显示.

Answer 2

无需编写自己的XML,有一个标准的Material Design V形.

在Android Studio中,单击File- > New- > Vector Asset,然后单击图标(带有Android徽标的按钮)并搜索"箭头".

选择所需的箭头,它将添加到您的项目中.您可以打开XML文件并根据需要编辑尺寸和颜色.

Answer 3

仅要使用drawable xml创建这种形状是不可能的（请参阅user3249477的答案），如果要以编程方式创建这种形状，可以创建自定义的drawable或view。这里是右侧箭头形状的代码。（颜色和直径可以使用styleable在xml中配置）

package com.kiriyard.stackoverflow24723040.views;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Path.Direction;
import android.util.AttributeSet;
import android.view.View;

public class ArrowView extends View {



    private Paint arrowPaint;
    private Path arrowPath;
    private int arrowColor = 0xFF888888;
    private float density;
    private int diameter = 25, diameter_calc, radius_calc;

    public ArrowView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        stuff();
    }

    public ArrowView(Context context, AttributeSet attrs) {
        super(context, attrs);
        stuff();
    }

    public ArrowView(Context context) {
        super(context);
        stuff();
    }

    private void stuff() {

        //Getting density "dp"
        density = getContext().getResources().getDisplayMetrics().scaledDensity;
        //Calculating actual diameter
        diameter_calc = (int) density * diameter;
        radius_calc = diameter/2;

        //Creating paint
        arrowPaint = new Paint();
        arrowPaint.setAntiAlias(true);
        arrowPaint.setColor(arrowColor);

        //Initialize path
        arrowPath = new Path();

        this.setWillNotDraw(false);
    }

    private int startX,startY, currentX, currentY;

    protected void onDraw(Canvas c) {

        startX = c.getWidth();
        startY = c.getHeight()/2;

        c.rotate(-45, startX, startY);

        arrowPath.reset();
        currentX = startX;
        currentY = startY;
        //Move to right end side center of the canvas
        arrowPath.moveTo(currentX,currentY);
        //Lets move up
        currentY = radius_calc;
        arrowPath.lineTo(currentX, currentY);
        //Now draw circle
        currentX-=radius_calc;
        arrowPath.addCircle(currentX, radius_calc, radius_calc, Direction.CCW);
        currentX-=radius_calc;

        arrowPath.lineTo(currentX,currentY);
        // Go to inner side center point
        currentX = startX - diameter_calc;
        currentY = startY - diameter_calc;
        arrowPath.lineTo(currentX,currentY);
        // Go left
        currentX = startX - startY + radius_calc;
        arrowPath.lineTo(currentX, currentY);       
        //Draw circle
        currentY+=radius_calc;
        c.drawCircle(currentX, currentY, radius_calc, arrowPaint);
        currentY+=radius_calc;
        arrowPath.lineTo(currentX, currentY);
        //Go to start
        arrowPath.lineTo(startX, startY);

        c.drawPath(arrowPath, arrowPaint);
    }

}

屏幕截图

所以这就是方法之一！.....可绘制图像是更简单的方法。