android - 将自定义 View 与屏幕底部对齐

Question

我已经创建了自己的 View 。它是一个半圆。我想让它对齐到屏幕底部。因为，我使用 drawArc 绘制它，它没有与底部对齐。我尝试过设置一个圆，中心的 y 坐标与屏幕底部坐标重合。我不想使用它，因为我希望为它实现一些额外的东西。这是我的自定义 View 代码。

package legacy_systems.customview;

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

public class CircleView extends View{

    private Paint markerPaint;
    private Paint textPaint;
    private Paint circlePaint;
    private int textHeight;

    public CircleView(Context context)
    {
        super(context);
        initCircleView();
    }

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

    public CircleView(Context context, AttributeSet attrs, int defaultStyle)
    {
        super(context, attrs, defaultStyle);
        initCircleView();
    }

    protected void initCircleView()
    {
        setFocusable(true);

        circlePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        circlePaint.setColor(getResources().getColor(android.R.color.black));
        circlePaint.setStrokeWidth(3);
        circlePaint.setStyle(Paint.Style.STROKE);

        markerPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        markerPaint.setColor(getResources().getColor(android.R.color.darker_gray));
    }

    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
    {
        int measuredWidth = measure(widthMeasureSpec);
        int measuredHeight = measure(heightMeasureSpec);

        int d = Math.min(measuredWidth, measuredHeight);

        setMeasuredDimension(d,d);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        int px, py;

        px = getMeasuredWidth()/2;
        py = getMeasuredHeight()/2;

        int radius = Math.min(px, py);

        RectF oval = new RectF();
        oval.set(px-radius, py-radius, px+radius, py+radius);

        canvas.drawArc(oval,180,180,false, circlePaint);
        //canvas.drawCircle(px, py, radius, circlePaint);
        canvas.save();



    }

    private int measure(int measureSpec)
    {
        int result = 0;

        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);

        if(specMode == MeasureSpec.UNSPECIFIED)
        {
            result = 200;
        }
        else
        {
            result = specSize;
        }

        return result;
    }

}

我想将半圆与屏幕底部对齐。我有什么想法可以做到吗？

Answer 1

首先感谢大家的回答。您的回答部分正确。是的，用

android:layout_alignParentBottom="true"

会成功一半。假设我要画一个圆。在自定义 View 中，(0,0) 表示 View 最左边的坐标，而不是屏幕的坐标。假设有人想要半圆位于屏幕底部，就像我想做的那样，坐标猜测结果是一个问题。这是我实际解决它的方法。

px = getMeasuredWidth()/2;
py = getMeasuredHeight();

canvas.drawCircle(px, py, radius, paint);

此处，px 将是整个 View 宽度的中心， View 宽度的中点，py 将是分配给 View 的最后一个屏幕 y 轴坐标。

希望它对其他人也有帮助。