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Android RecyclerView折线图效果
本文实例为大家分享了Android开发RecyclerView实现折线图效果的具体代码，供大家参考，具体内容如下
效果图如下：
实现的关键是自定义的控件：
package com.example.recyclelinechart.test;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;
import androidx.annotation.Nullable;
public class LineView extends View {
private int maxValue;//最大值
private int minValue;//最小值
private int currentValue;//当前值
private int lastValue;//上一个值
private int nextValue;//下一个值
private Paint mPaint;
private int viewHeight;//控件高度
private int viewWidth;//控件宽度
private int distance;//文字高度
private int pointX;//所有点的x坐标
private int pointY;//当前点的Y
private boolean drawLeftLine = true;//是否画左边的线
private boolean drawRightLine = true;//是否画右边的线
private float scale;//每一份占多少像素
public LineView(Context context) {
super(context);
init();
}
public LineView(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
init();
}
public LineView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
public void setCurrentValue(int currentValue) {
this.currentValue = currentValue;
invalidate();
}
public void setMaxValue(int maxValue) {
this.maxValue = maxValue;
}
public void setMinValue(int minValue) {
this.minValue = minValue;
}
private void init() {
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setStyle(Paint.Style.FILL);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
initValues();
}
private void initValues() {
//计算文字高度
mPaint.setTextSize(40);
Paint.FontMetrics fontMetrics = mPaint.getFontMetrics();
distance = (int) (fontMetrics.descent + Math.abs(fontMetrics.ascent));
viewHeight = getMeasuredHeight();
viewWidth = getMeasuredWidth();
//lineView的x轴的中心
pointX = viewWidth / 2;
//(viewHeight - 2 * distance 上下各留出文字的高度，防止显示不全
scale = (viewHeight - 2 * distance) / (maxValue - minValue);
}
@Override
public void draw(Canvas canvas) {
super.draw(canvas);
pointY = (int) (scale * (maxValue - currentValue) + distance);
drawGraph(canvas);
drawPoint(canvas);
drawValue(canvas);
}
/**
* 画数字
*
* @param canvas
*/
private void drawValue(Canvas canvas) {
mPaint.setTextSize(40);
mPaint.setColor(Color.parseColor("#ff333333"));
mPaint.setTextAlign(Paint.Align.CENTER);
Paint.FontMetrics fontMetrics = mPaint.getFontMetrics();
//取字体高度的三分之一
canvas.drawText(currentValue + "", viewWidth / 2, pointY - (fontMetrics.descent + Math.abs(fontMetrics.ascent)) / 3, mPaint);
}
public void setlastValue(int lastValue) {
this.lastValue = lastValue;
}
public void setNextValue(int nextValue) {
this.nextValue = nextValue;
}
/**
* 画折线
*
* @param canvas
*/
private void drawGraph(Canvas canvas) {
mPaint.setColor(Color.BLUE);
mPaint.setStrokeWidth(8);
if (drawLeftLine) {
float middleValue = (currentValue + lastValue) / 2f;
float middleY = (scale * (maxValue - middleValue) + distance);
//ax+b = y 二元一次方程，向左多画一点计算y值
float a = (middleY - pointY) * 1f / (0 - pointX);
float b = (0 * pointY - pointX * middleY) * 1f / (0 - pointX);
middleY = a * (0 - 10) + b;
canvas.drawLine(0 - 10, middleY, pointX, pointY, mPaint);
}
if (drawRightLine) {
float middleValue = (currentValue + nextValue) / 2f;
float middleY = scale * (maxValue - middleValue) + distance;
//向右多画一点，机制同上
float a = (middleY - pointY) * 1f / (viewWidth - pointX);
float b = (pointX * middleY - viewWidth * pointY) * 1f / (pointX - viewWidth);
middleY = a * (viewWidth + 10) + b;
canvas.drawLine(pointX, pointY, viewWidth + 10, middleY, mPaint);
}
}
/**
* 画数字下面的小圆圈
*
* @param canvas
*/
private void drawPoint(Canvas canvas) {
mPaint.setColor(Color.RED);
mPaint.setPathEffect(null);
mPaint.setStrokeWidth(10);
mPaint.setStyle(Paint.Style.FILL);
canvas.drawCircle(pointX, pointY, 10, mPaint);
}
public void setDrawLeftLine(boolean drawLeftLine) {
this.drawLeftLine = drawLeftLine;
}
public void setDrawRightLine(boolean drawRightLine) {
this.drawRightLine = drawRightLine;
}
}适配器
public class MyAdapter extends RecyclerView.Adapter{ private int minValue; private int maxValue; private List data; public MyAdapter(int minValue, int maxValue, List data) { this.minValue = minValue; this.maxValue = maxValue; this.data = data; } @Override public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { View layout = LayoutInflater.from(parent.getContext()).inflate(R.layout.test_line, parent, false); return new ViewHolder(layout); } @Override public void onBindViewHolder(ViewHolder holder, int position) { if (position == 0) { holder.lineView.setDrawLeftLine(false); } else { holder.lineView.setDrawLeftLine(true); holder.lineView.setlastValue((data.get(position - 1))); } holder.lineView.setMaxValue(maxValue); holder.lineView.setMinValue(minValue); holder.lineView.setCurrentValue((data.get(position))); if (position == data.size() - 1) { holder.lineView.setDrawRightLine(false); } else { holder.lineView.setDrawRightLine(true); holder.lineView.setNextValue((data.get(position + 1))); } } @Override public int getItemCount() { return data.size(); } class ViewHolder extends RecyclerView.ViewHolder { LineView lineView; public ViewHolder(View itemView) { super(itemView); this.lineView = itemView.findViewById(R.id.item); } } }
item的布局文件
使用
MyAdapter myAdapter = new MyAdapter(2, 30, integers); recyclerView.setLayoutManager(new LinearLayoutManager(this, RecyclerView.HORIZONTAL, false)); recyclerView.setAdapter(myAdapter);
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持码农之家。
