[移动开发]android带边框的RelativeLayout

概述

这个是小众需求，主要用于某些需要手动控制边框线是否显示的场景，例如底层通过数据参数的形式，配置边框显示的形式。多用于基于c语言实现功能android端展示的场景。

代码实现

public class BorderRelativeLayout extends RelativeLayout {
    //画笔
    private Paint mPain;
    //边框颜色
    private int mPaintColor;
    //边框粗细
    private float mBorderStrokeWidth = 1.0f;
    //底边边线左边断开距离
    private int mBorderBottomLeftBreakSize;
    //底边边线右边断开距离
    private int mBorderBottomRightBreakSize;
    //是否需要上边框
    private boolean isNeedTopBorder = false;
    //是否需要左边框
    private boolean isNeedLeftBorder = false;
    //是否需要右边框
    private boolean isNeedRightBorder = true;
    //是否需要下边框
    private boolean isNeedBottomBorder = true;
    private DisplayMetrics displayMetrics;

    public BorderRelativeLayout(Context context) {
        this(context, null);
    }

    public BorderRelativeLayout(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public BorderRelativeLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

        displayMetrics = context.getResources().getDisplayMetrics();

        init();
    }

    private void init() {
        mPain = new Paint();
        mPain.setColor(Color.parseColor("#000000"));
        //设置画笔为无锯齿
        mPain.setAntiAlias(true);
        //线宽
        mPain.setStrokeWidth(mBorderStrokeWidth);
    }

    @Override
    protected void dispatchDraw(Canvas canvas) {
        super.dispatchDraw(canvas);
        //画4个边
        if (isNeedTopBorder) {
            canvas.drawLine(0, 0, this.getWidth(), 0, mPain);
        }
        if (isNeedBottomBorder) {
            canvas.drawLine(mBorderBottomLeftBreakSize, this.getHeight(), this.getWidth() - mBorderBottomRightBreakSize, this.getHeight(), mPain);
        }
        if (isNeedLeftBorder) {
            canvas.drawLine(0, 0, 0, this.getHeight(), mPain);
        }
        if (isNeedRightBorder) {
            canvas.drawLine(this.getWidth(), 0, this.getWidth(), this.getHeight(), mPain);
        }

    }

    /**
     * 设置边框颜色
     *
     * @param color 颜色
     */
    public void setBorderColor(int color) {
        if (mPain.getColor() == color) {
            return;
        } else {
            mPain.setColor(color);
            invalidate();
        }
    }

    /**
     * 设置边框宽度
     *
     * @param size 宽度
     */
    public void setBorderStrokeWidth(float size) {
        if (mPain.getStrokeWidth() == size) {
            return;
        } else {
            mPain.setStrokeWidth(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, size, displayMetrics));
            invalidate();
        }
    }

    /**
     * 设置是否需要顶部边框
     *
     * @param needtopborder boolean类型
     */
    public void setNeedTopBorder(boolean needtopborder) {
        isNeedTopBorder = needtopborder;
        invalidate();
    }

    /**
     * 设置是否需要底部边框
     *
     * @param needbottomborder boolean类型
     */
    public void setNeedBottomBorder(boolean needbottomborder) {
        isNeedBottomBorder = needbottomborder;
        invalidate();
    }

    public void setNeedLeftBorder(boolean needLeftBorder) {
        isNeedLeftBorder = needLeftBorder;
        invalidate();
    }

    public void setNeedRightBorder(boolean needRightBorder) {
        isNeedRightBorder = needRightBorder;
        invalidate();
    }

    /**
     * 设置四个边框是否显示，修改单独更新为一次更新，减少invalidate()调用次数，过频会闪退
     * @param needtopborder
     * @param needbottomborder
     * @param needLeftBorder
     * @param needRightBorder
     */
    public void setBorderState(boolean needtopborder, boolean needbottomborder, boolean needLeftBorder, boolean needRightBorder) {
        isNeedTopBorder = needtopborder;
        isNeedBottomBorder = needbottomborder;
        isNeedLeftBorder = needLeftBorder;
        isNeedRightBorder = needRightBorder;
        invalidate();
    }

}