Andorid 自定义 类似iOS活动指示器 UIActivityIndicatorView

由于个人喜好， 比较喜欢iOS 原生的东西，现在学习Android开发，可能有先入为主的思想吧，所以总想在Andorid中找与iOS相同的控件。

在使用活动指示器的时候，发现Android的是ProgressBar，动画的方式与iOS的不一样，一直都想弄一个一样的。

我自己比较喜欢自定义View，不是太喜欢GIF，虽然GIF方便，但学习嘛，空余时间多让脑筋转转动动手也好。

这里就自定义一个iOS “菊花”式的活动指示器，

详细代码如下：

UIAcivityIndicatorView.java

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Handler;
import android.util.AttributeSet;
import android.view.View;

/**
 * Created by wantao on 17/1/7.
 */
public class UIActivityIndicatorView extends View {
    public UIActivityIndicatorView(Context context) {
        this(context, null);
    }

    private int startColor = Color.argb(255, 255, 255, 255);
    private float strokeWidth = 0;
    private int startAngle = 0;

    public UIActivityIndicatorView(Context context, AttributeSet attrs) {
        super(context, attrs);

        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.UIActivityIndicatorView);
        for (int i = 0; i < typedArray.getIndexCount(); i++) {
            int i1 = typedArray.getIndex(i);
            if (i1 == R.styleable.UIActivityIndicatorView_AIV_startColor) {
                startColor = typedArray.getColor(R.styleable.UIActivityIndicatorView_AIV_startColor, startColor);

            } else if (i1 == R.styleable.UIActivityIndicatorView_AIV_startAngle) {
                startAngle = typedArray.getInt(R.styleable.UIActivityIndicatorView_AIV_startAngle, startAngle);

            } else if (i1 == R.styleable.UIActivityIndicatorView_AIV_strokeWidth) {
                strokeWidth = typedArray.getDimension(R.styleable.UIActivityIndicatorView_AIV_strokeWidth, strokeWidth);

            }
        }

        initialize();
    }

    private final int LineCount = 12;
    private final int MinAlpha = 0;
    private final int AngleGradient = 360 / LineCount;
    private Paint paint;
    private int[] colors = new int[LineCount];
    private void initialize() {
        paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        int alpha = Color.alpha(startColor);
        int red = Color.red(startColor);
        int green = Color.green(startColor);
        int blue = Color.blue(startColor);
        int alpha_gradient = Math.abs(alpha - MinAlpha) / LineCount;
        for (int i = 0; i < colors.length; i++) {
            colors[i] = Color.argb(alpha - alpha_gradient * i, red, green, blue);
        }
        paint.setStrokeCap(Paint.Cap.ROUND);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        int centerX = getWidth()/2;
        int centerY = getHeight()/2;
        float radius = Math.min(getWidth()-getPaddingLeft()-getPaddingRight(), getHeight()-getPaddingTop()-getPaddingBottom()) * 0.5f;
        if (strokeWidth == 0) strokeWidth = pointX(AngleGradient/2, radius/2)/2;
        paint.setStrokeWidth(strokeWidth);
        for (int i = 0; i < colors.length; i++) {
            paint.setColor(colors[i]);
            canvas.drawLine(
                    centerX + pointX(-AngleGradient*i + startAngle, radius/2),
                    centerY + pointY(-AngleGradient*i + startAngle, radius/2),
                    centerX + pointX(-AngleGradient*i + startAngle, radius - strokeWidth/2),   //  这里计算Y值时, 之所以减去线宽/2, 是防止没有设置的Padding时,图像会超出View范围
                    centerY + pointY(-AngleGradient*i + startAngle, radius - strokeWidth/2),   //  这里计算Y值时, 之所以减去线宽/2, 是防止没有设置的Padding时,图像会超出View范围
                    paint);
        }
    }

    private float pointX(int angle, float radius) {
        return (float) (radius * Math.cos(angle * Math.PI / 180));
    }

    private float pointY(int angle, float radius) {
        return (float) (radius * Math.sin(angle * Math.PI / 180));
    }

    private Handler animHandler = new Handler();
    private Runnable animRunnable = new Runnable() {
        @Override
        public void run() {
            startAngle += AngleGradient;
            invalidate();
            animHandler.postDelayed(animRunnable, 50);
        }
    };

    public void start() {
        animHandler.post(animRunnable);
    }

    public void stop() {
        animHandler.removeCallbacks(animRunnable);
    }

    public void setStartColor(int startColor) {
        this.startColor = startColor;
    }

    public void setStrokeWidth(float strokeWidth) {
        this.strokeWidth = strokeWidth;
    }

    public void setStartAngle(int startAngle) {
        this.startAngle = startAngle;
    }
}

自定义xml属性文件， app→res→values→attrs.xml(这个xml文件没有的话，自己新建一个)内添加内容如下：

另外，我还打包了一个“.aar”包，导入项目后可直接使用。

文件地址，还没有审核通过，等通过后再更新，或者可以到我的资源页查看。

对于怎么导入“.aar”包到项目，这里简单介绍，【针对Android Studio(因为我也刚学习Andorid，只用过Android Studio)】:

1. 将需要的.aar文件拷贝到Project的app→libs中； 2. 修改build.grade(Module:app): 添加 

repositories {
	flatDir {
		dirs 'libs'
	}
}

然后在下面的dependencies(){}中添加

compile(name:'(.aar文件名)', ext:'aar')