圆内画圆，分成几块？

Question

请帮忙。

我需要在一个圆圈中画下一个圆圈。并根据给定的数字画出内圈的一部分。

如有任何提示，我将不胜感激。

谢谢。

Answer 1

创建自定义视图（一个圆圈！）

首先是我们的自定义样式属性。

values/attrs.xml

<resources>
    <declare-styleable name="circleview">
        <attr name="cRadius" format="integer" />
        <attr name="cFillColor" format="color" />
        <attr name="cStrokeColor" format="color" />
        <attr name="cAngleStart" format="integer" />
        <attr name="cAngleEnd" format="integer" />
    </declare-styleable>
</resources>

让我们看看包含我的 CircleView 的主要布局 class。

layout/main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              xmlns:circleview="http://schemas.android.com/apk/res/se.adanware.canvasplaying"
              android:orientation="vertical"
              android:layout_width="fill_parent"
              android:layout_height="fill_parent">
    <TextView
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="Hello World, CanvasActivity"
            />
    <se.adanware.canvasplaying.CircleView
            android:id="@+id/pieCircle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            circleview:cFillColor="#DDaa99"
            circleview:cStrokeColor="@android:color/white"
            circleview:cRadius="80"
            circleview:cAngleStart="30"
            circleview:cAngleEnd="290"
            />
    <TextView
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="Hello World, CanvasActivity"
            />
</LinearLayout>

src/CircleView.java

package se.adanware.canvasplaying;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;

public class CircleView extends View {

        private Paint circlePaint;
        private Paint circleStrokePaint;
        private RectF circleArc;

        // Attrs
        private int circleRadius;
        private int circleFillColor;
        private int circleStrokeColor;
        private int circleStartAngle;
        private int circleEndAngle;

    public CircleView(Context context, AttributeSet attrs) {

        super(context, attrs);
        init(attrs); // Read all attributes

        circlePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        circlePaint.setStyle(Paint.Style.FILL);
        circleStrokePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        circleStrokePaint.setStyle(Paint.Style.STROKE);
        circleStrokePaint.setStrokeWidth(2);
        circleStrokePaint.setColor(circleStrokeColor);
    }

    public void init(AttributeSet attrs)
    {
        // Go through all custom attrs.
        TypedArray attrsArray = getContext().obtainStyledAttributes(attrs, R.styleable.circleview);
        circleRadius = attrsArray.getInteger(R.styleable.circleview_cRadius, 0);
        circleFillColor = attrsArray.getColor(R.styleable.circleview_cFillColor, 16777215);
        circleStrokeColor = attrsArray.getColor(R.styleable.circleview_cStrokeColor, -1);
        circleStartAngle = attrsArray.getInteger(R.styleable.circleview_cAngleStart, 0);
        circleEndAngle = attrsArray.getInteger(R.styleable.circleview_cAngleEnd, 360);
        // Google tells us to call recycle.
        attrsArray.recycle();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        // Move canvas down and right 1 pixel.
        // Otherwise the stroke gets cut off.
        canvas.translate(1,1);
        circlePaint.setColor(circleFillColor);
        canvas.drawArc(circleArc, circleStartAngle, circleEndAngle, true, circlePaint);
        canvas.drawArc(circleArc, circleStartAngle, circleEndAngle, true, circleStrokePaint);
    }

    @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
    {

        int measuredWidth = measureWidth(widthMeasureSpec);
        if(circleRadius == 0) // No radius specified.
        {                     // Lets see what we can make.
            // Check width size. Make radius half of available.
            circleRadius = measuredWidth / 2;
            int tempRadiusHeight = measureHeight(heightMeasureSpec) / 2;
            if(tempRadiusHeight < circleRadius)
                // Check height, if height is smaller than
                // width, then go half height as radius.
                circleRadius = tempRadiusHeight;
        }
        // Remove 2 pixels for the stroke.
        int circleDiameter = circleRadius * 2 - 2;
        // RectF(float left, float top, float right, float bottom)
        circleArc = new RectF(0, 0, circleDiameter, circleDiameter);
        int measuredHeight = measureHeight(heightMeasureSpec);
        setMeasuredDimension(measuredWidth, measuredHeight);
        Log.d("onMeasure() ::", "measuredHeight =>" + String.valueOf(measuredHeight) + "px measuredWidth => " + String.valueOf(measuredWidth) + "px");
    }

    private int measureHeight(int measureSpec) {
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);
        int result = 0;
        if (specMode == MeasureSpec.AT_MOST) {
            result = circleRadius * 2;
        } else if (specMode == MeasureSpec.EXACTLY) {
            result = specSize;
        }
        return result;
    }

    private int measureWidth(int measureSpec) {
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);
        int result = 0;
        if (specMode == MeasureSpec.AT_MOST) {
            result = specSize;
        } else if (specMode == MeasureSpec.EXACTLY) {
            result = specSize;
        }
         return result;
    }
}

src/CanvasActivity.java

package se.adanware.canvasplaying;

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

    public class CanvasActivity extends Activity {
        /**
         * Called when the activity is first created.
         */
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);
        }
    }

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