自定义View 滚动条

最新推荐文章于 2024-07-04 17:02:14 发布

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最新推荐文章于 2024-07-04 17:02:14 发布

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分类专栏： Android

本文链接：https://blog.youkuaiyun.com/zhangboy1234/article/details/46727269

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本文介绍了一个自定义View——CustomScrollBarView的实现。该视图在Android系统中使用，继承自View类，并在onDraw方法中绘制滚动条。通过设置颜色、高度和位置，实现了滚动条的显示效果。同时提供了invalidateLayout方法更新布局参数。

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package com.android.systemui.statusbar.phone;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import com.android.systemui.R;

public class CustomScrollBarView extends View {
	
	private Paint mPaint;
	private int mCount;
	private int mIndex;
	private Context mContext;
	private int mOldIndex;

	public CustomScrollBarView(Context context, AttributeSet attrs) {
		super(context, attrs);
		// TODO Auto-generated constructor stub
		mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
		this.mContext = context;
	}
	
	@Override
	protected void onDraw(Canvas canvas) {
		if (mCount == 0 || mIndex == 0) {
			return;
		}
		if (mIndex == mOldIndex) {
			// return;
		}
		Log.d("SSSSS", "count = " + mCount +", index = " + mIndex);
		mPaint.setColor(mContext.getResources().getColor(R.color.black_alpha_10));

		int height = getHeight() / mCount;

		int showHeight = height * mIndex;
		
		Log.d("SSSSS", "showHeight - height = " + (showHeight - height) + ",showHeight = " + showHeight +", height = " + height);

		canvas.drawRect(0, showHeight - height, getWidth(), showHeight, mPaint);
		mOldIndex = mIndex;
		super.onDraw(canvas);
	}

	public void invalidateLayout(int count, int index) {
		mCount = count;
		mIndex = index;
		invalidate();
	}

}