Android图形graphics--饼图：HoloGraphLibrary源码修改

最新推荐文章于 2021-06-04 01:04:44 发布

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本文介绍了一种使用PieGraph类实现饼图动态更新的方法，包括饼图的基本绘制、添加切片以及饼图类型的特殊处理，旨在提供一种高效、灵活的饼图绘制解决方案。

public class PieSlice {

    private int color;
    private float value;


    public int getColor() {
        return color;
    }

    public void setColor(int color) {
        this.color = color;
    }

    public float getValue() {
        return value;
    }

    public void setValue(float value) {
        this.value = value;
    }


}

public class PieGraph extends View {

	private ArrayList<PieSlice> slices = new ArrayList<PieSlice>();
	private Paint paint = new Paint();

	private int thickness = 50;

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

    public void update() { postInvalidate(); }

	public void onDraw(Canvas canvas) {
		canvas.drawColor(Color.TRANSPARENT);
		paint.reset();
		paint.setAntiAlias(true);
		float midX, midY, radius, innerRadius;

		float currentAngle = 270;//起始角度
        float currentSweep;
        int totalValue = 0;

		midX = getWidth()/2;
		midY = getHeight()/2;
		if (midX < midY){
			radius = midX;
		} else {
			radius = midY;
		}
		innerRadius = radius - thickness;
		//用arcTo方法画360度的弧形是画不出来的，因此只有一种类型时考虑用画圆的方式
		if(slices!=null && slices.size()<=1){
			int saveCount = canvas.saveLayer(0, 0, getWidth(), getHeight(), null,
					Canvas.ALL_SAVE_FLAG);
			paint.reset();
			paint.setAntiAlias(true);
			if(slices.size()==1){
				paint.setColor(slices.get(0).getColor());
			}else {
				paint.setColor(Color.parseColor("#F0F1F2"));//没有类型时，默认显示一个灰色的饼图
			}
			canvas.drawCircle(midX, midY, radius, paint);
			paint.reset();
			paint.setAntiAlias(true);
			paint.setColor(Color.YELLOW);
			paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
			canvas.drawCircle(midX, midY, innerRadius, paint);
			canvas.restoreToCount(saveCount);
			return;
		}
		for (PieSlice slice : slices){
			totalValue += slice.getValue();
		}
		for (PieSlice slice : slices){
			Path p = new Path();
			paint.setColor(slice.getColor());
			currentSweep = (slice.getValue()/totalValue)*(360);
			p.arcTo(new RectF(midX - radius, midY - radius, midX + radius, midY + radius), currentAngle, currentSweep);
			p.arcTo(new RectF(midX - innerRadius, midY - innerRadius, midX + innerRadius, midY + innerRadius), currentAngle + currentSweep, -currentSweep);
			p.close();
			canvas.drawPath(p, paint);
			currentAngle = currentAngle+currentSweep;
		}
	}
	public void addSlice(PieSlice slice) {
		this.slices.add(slice);
		postInvalidate();
	}
}