Android 滑动刻度尺实现

最新推荐文章于 2025-04-11 00:15:00 发布

书晴

最新推荐文章于 2025-04-11 00:15:00 发布

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分类专栏： Andoird开发文章标签： android

本文链接：https://blog.youkuaiyun.com/mzoneseven/article/details/128614296

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本文详细介绍了如何在Android应用中实现一个可滑动的刻度尺组件，包括步骤、关键代码和注意事项，帮助开发者创建具有交互性的用户界面。

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public class ScaleRulerLayout extends ViewGroup implements ScaleRulerView.ScrollSelected {

    private ScaleRulerView mRulerView;
    private ImageView mCenterPointer;
    private Paint mLinePaint;
    private Paint mPointPaint;
    private int mLineWidth;
    private int mPointWidth;
    private int mPadding;
    private ScaleRulerView.ScrollSelected scrollSelected;

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

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

    public ScaleRulerLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        mLinePaint = new Paint();
        mLinePaint.setAntiAlias(true);
        mLineWidth = dp2px(1);
        mLinePaint.setStrokeWidth(mLineWidth);
        mLinePaint.setStyle(Paint.Style.FILL);
        mLinePaint.setColor(Color.GRAY);
        mPadding = dp2px(10);

        mPointPaint = new Paint();
        mPointPaint.setAntiAlias(true);
        mPointWidth = dp2px(2);
        mPointPaint.setStrokeWidth(mPointWidth);
        mPointPaint.setStyle(Paint.Style.FILL);
        mPointPaint.setColor(getResources().getColor(R.color.common_blue));
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if (null != mRulerView) {
            mRulerView.measure(widthMeasureSpec, heightMeasureSpec);
        }
        if (null != mCenterPointer) {
            LayoutParams layoutParams = mCenterPointer.getLayoutParams();
            mCenterPointer.measure(layoutParams.width, heightMeasureSpec);
        }
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        if (null != mRulerView) {
            MarginLayoutParams lp = (MarginLayoutParams) mRulerView.getLayoutParams();
            int left = getPaddingLeft();
            int top = getPaddingTop();
            int right = getPaddingRight() + getMeasuredWidth();
            int bottom = getPaddingBottom() + getMeasuredHeight() - mLineWidth;
            mRulerView.layout(left, top, right, bottom);
        }
        /*if (null != mCenterPointer) {
            int measuredWidth = mCenterPointer.getMeasuredWidth();
            int width = getWidth() + getPaddingLeft() + getPaddingRight();
            int left = width / 2 - measuredWidth / 2;
            int right = width / 2 + measuredWidth / 2;
            mCenterPointer.layout(left, 0, right, getHeight());
        }*/
    }

    @Override
    protected void dispatchDraw(Canvas canvas) {
        super.dispatchDraw(canvas);
        canvas.drawLine(0, getHeight(), getWidth(), getHeight(), mLinePaint);

        int start = getWidth() / 2;
        canvas.drawLine(start, getHeight() / 2, start, getHeight(), mPointPaint);
    }

    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();
        mRulerView = new ScaleRulerView(getContext());
        MarginLayoutParams layoutParams = new MarginLayoutParams(L

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