本文小编为大家详细介绍“android怎么实现可以滑动的平滑曲线图”，内容详细，步骤清晰，细节处理妥当，希望这篇“android怎么实现可以滑动的平滑曲线图”文章能帮助大家解决疑惑，下面跟着小编的思路慢慢深入，一起来学习新知识吧。
1 attr 属性编写
<!-- xy坐标轴颜色 --><attr name="xy_line_color" format="color" /> <!-- xy坐标轴宽度 --> <attr name="xy_line_width" format="dimension" /> <!-- xy坐标轴文字颜色 --> <attr name="xy_text_color" format="color" /> <!-- xy坐标轴文字大小 --> <attr name="xy_text_size" format="dimension" /> <!-- 折线图中折线的颜色 --> <attr name="line_color" format="color" /> <!-- x轴各个坐标点水平间距 --> <attr name="interval" format="dimension" /> <!-- 背景颜色 --> <attr name="bg_color" format="color" /> <!-- 曲线选中外部颜色 --> <attr name="select_circle_color" format="color" /> <!-- 曲线选中内部颜色 --> <attr name="select_reminder_color" format="color" /> <!--是否抬手滚动--> <attr name="isScroll" format="boolean" /> <declare-styleable name="ChartView"> <attr name="xy_line_color" /> <attr name="xy_line_width" /> <attr name="xy_text_color" /> <attr name="xy_text_size" /> <attr name="line_color" /> <attr name="interval" /> <attr name="bg_color" /> <attr name="select_circle_color" /> <attr name="select_reminder_color" /> <attr name="isScroll" /> <!--提示框跟滑动显示的位置--> <attr name="show_position"> <enum name="first" value="1" /> <enum name="middle" value="2" /> <enum name="end" value="3" /> </attr></declare-styleable>2 ChartView
package com.laisontech.commonuilibrary.customviews;import android.animation.Animator;import android.animation.ValueAnimator;import android.content.Context;import android.content.res.TypedArray;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Path;import android.graphics.PorterDuff;import android.graphics.PorterDuffXfermode;import android.graphics.Rect;import android.graphics.RectF;import android.util.AttributeSet;import android.util.Log;import android.util.TypedValue;import android.view.MotionEvent;import android.view.VelocityTracker;import android.view.View;import android.view.animation.DecelerateInterpolator;import com.laisontech.commonuilibrary.R;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;public class ChartView extends View { private static final int FIRST = 1; private static final int MIDDLE = 2; private static final int END = 3; //xy坐标轴颜色 private int xyLineColor = 0xffCFE2CF; //折线选中的圆形颜色 private int selectCircleColor = 0xff00A8FF; //选中数据提示框颜色 private int selectReminderColor = 0xff00A8FF; //折线中圆形内部部颜色 private int xyTextColor = 0xff0014FF; //折线图中折线的颜色 private int lineColor = 0xffFD00FF; //xy坐标轴宽度 private int xyLineWidth = dpToPx(1); //xy坐标轴文字大小 private int xyTextSize = spToPx(12); //x轴各个坐标点水平间距 private int interval = dpToPx(40); //背景颜色 private int bgColor = 0xffffffff; //是否有起手时的滑动感 private boolean isScroll = false; //提示框显示位置 private int mShowPositionType = 3; //绘制XY轴坐标对应的画笔 private Paint mXYPaint; //绘制XY轴的文本对应的画笔 private Paint mXYTextPaint; //画折线对应的画笔 private Paint mSpinnerLinePaint; private int width; private int height; //x轴的原点坐标 private int mXOri; //y轴的原点坐标 private int mYOri; //第一个点X的坐标 private float mXInit; //第一个点对应的最大X坐标 private float maxXInit; //第一个点对应的最小X坐标 private float minXInit; //x轴坐标对应的数据 private List<String> mXData = new ArrayList<>(); //y轴坐标对应的数据 private List<Integer> mYData = new ArrayList<>(); //折线对应的数据 private Map<String, Integer> mSpinnerValue = new HashMap<>(); //点击的点对应的X轴的第几个点，默认1 private int selectIndex = 1; //X轴刻度文本对应的最大矩形，为了选中时，在x轴文本画的框框大小一致，获取从数据中得到的x轴数据，获得最长数据 private Rect xValueRect; //速度检测器 private VelocityTracker mTracker; //是否为短距离滑动 private boolean isShortSlide = false; //获取尺寸的的中间 private int mSelectMiddle = 0; //曲线切率 private float mLineSmoothness = 0.18f; public ChartView(Context context) { this(context, null); } public ChartView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public ChartView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); init(context, attrs, defStyleAttr); initPaint(); } //设置切率 public void setLineSmoothness(float lineSmoothness) { if (lineSmoothness != this.mLineSmoothness) { this.mLineSmoothness = lineSmoothness; } } private void initPaint() { mXYPaint = new Paint(); mXYPaint.setAntiAlias(true); mXYPaint.setStrokeWidth(xyLineWidth); mXYPaint.setStrokeJoin(Paint.Join.ROUND); mXYPaint.setColor(xyLineColor); mXYTextPaint = new Paint(); mXYTextPaint.setAntiAlias(true); mXYTextPaint.setTextSize(xyTextSize); mXYTextPaint.setStrokeJoin(Paint.Join.ROUND); mXYTextPaint.setColor(xyTextColor); mXYTextPaint.setStyle(Paint.Style.STROKE); mSpinnerLinePaint = new Paint(); mSpinnerLinePaint.setAntiAlias(true); mSpinnerLinePaint.setStrokeWidth(xyLineWidth); mSpinnerLinePaint.setColor(lineColor); mSpinnerLinePaint.setStyle(Paint.Style.STROKE); mSpinnerLinePaint.setStrokeJoin(Paint.Join.ROUND); } private void init(Context context, AttributeSet attrs, int defStyleAttr) { TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.ChartView, defStyleAttr, 0); int count = array.getIndexCount(); for (int i = 0; i < count; i++) { int attr = array.getIndex(i); if (attr == R.styleable.ChartView_xy_line_color) { xyLineColor = array.getColor(attr, xyLineColor); } else if (attr == R.styleable.ChartView_xy_line_width) { xyLineWidth = (int) array.getDimension(attr, TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_PX, xyLineWidth, getResources().getDisplayMetrics())); } else if (attr == R.styleable.ChartView_xy_text_color) { xyTextColor = array.getColor(attr, xyTextColor); } else if (attr == R.styleable.ChartView_xy_text_size) { xyTextSize = (int) array.getDimension(attr, TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_PX, xyTextSize, getResources().getDisplayMetrics())); } else if (attr == R.styleable.ChartView_line_color) { lineColor = array.getColor(attr, lineColor); } else if (attr == R.styleable.ChartView_interval) { interval = (int) array.getDimension(attr, TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_PX, interval, getResources().getDisplayMetrics())); } else if (attr == R.styleable.ChartView_bg_color) { bgColor = array.getColor(attr, bgColor); } else if (attr == R.styleable.ChartView_select_circle_color) { selectCircleColor = array.getColor(attr, selectCircleColor); } else if (attr == R.styleable.ChartView_select_reminder_color) { selectReminderColor = array.getColor(attr, selectReminderColor); } else if (attr == R.styleable.ChartView_isScroll) { isScroll = array.getBoolean(attr, isScroll); } else if (attr == R.styleable.ChartView_show_position) { mShowPositionType = array.getInt(attr, mShowPositionType); } } array.recycle(); } @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { if (changed) { width = getWidth(); height = getHeight(); //Y轴文本的最大宽度 float textYWdith = getTextBounds(mYData.get(getListItemMaxIndex(mYData)) + "", mXYTextPaint).width(); for (int i = 0; i < mYData.size(); i++) {//求取y轴文本最大的宽度 float temp = getTextBounds(mYData.get(i) + "", mXYTextPaint).width(); if (temp > textYWdith) textYWdith = temp; } int dp2 = dpToPx(2); int dp3 = dpToPx(3); mXOri = (int) (dp2 + textYWdith + dp2 + xyLineWidth); //获取x轴的最长文本的宽度所占的矩形 xValueRect = getTextBounds(mXData.get(getListItemMaxIndex(mXData)), mXYTextPaint); //X轴文本高度 float textXHeight = xValueRect.height(); for (int i = 0; i < mXData.size(); i++) { Rect rect = getTextBounds(mXData.get(i) + "", mXYTextPaint); if (rect.height() > textXHeight) textXHeight = rect.height(); if (rect.width() > xValueRect.width()) xValueRect = rect; } mYOri = (int) (height - dp2 - textXHeight - dp3 - xyLineWidth); mXInit = mXOri + xValueRect.width() / 2 + dpToPx(5); minXInit = width - (width - mXOri) * 0.1f - interval * (mXData.size() - 1); maxXInit = mXInit; } selectIndex = getSelectIndexFromShowType(mShowPositionType); super.onLayout(changed, left, top, right, bottom); } @Override protected void onDraw(Canvas canvas) { canvas.drawColor(bgColor); drawXY(canvas); drawBrokenLineAndPoint(canvas); } private void drawBrokenLineAndPoint(Canvas canvas) { if (mXData.size() <= 0) return; int layerId = canvas.saveLayer(0, 0, width, height, null, Canvas.ALL_SAVE_FLAG); drawBrokenLine(canvas); drawBrokenPoint(canvas); // 将超出x轴坐标的部分截掉 mSpinnerLinePaint.setStyle(Paint.Style.FILL); mSpinnerLinePaint.setColor(bgColor); mSpinnerLinePaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR)); RectF rectF = new RectF(0, 0, mXOri, height); canvas.drawRect(rectF, mSpinnerLinePaint); mSpinnerLinePaint.setXfermode(null); canvas.restoreToCount(layerId); } private void drawBrokenPoint(Canvas canvas) { float dp2 = dpToPx(2); float dp4 = dpToPx(4); float dp7 = dpToPx(7); Log.e("selectIndex", "index:" + selectIndex); //绘制节点 for (int i = 0; i < mXData.size(); i++) { float x = mXInit + interval * i; float y = mYOri - mYOri * (1 - 0.1f) * mSpinnerValue.get(mXData.get(i)) / mYData.get(mYData.size() - 1); //绘制选中点 if (i == selectIndex - 1) { mSpinnerLinePaint.setStyle(Paint.Style.FILL); //设置选中颜色 mSpinnerLinePaint.setColor(selectCircleColor); canvas.drawCircle(x, y, dp7, mSpinnerLinePaint); mSpinnerLinePaint.setColor(selectReminderColor); canvas.drawCircle(x, y, dp4, mSpinnerLinePaint); drawFloatTextBox(canvas, x, y - dp7, mSpinnerValue.get(mXData.get(i))); } //绘制普通节点 mSpinnerLinePaint.setStyle(Paint.Style.FILL); mSpinnerLinePaint.setColor(Color.WHITE); canvas.drawCircle(x, y, dp2, mSpinnerLinePaint); mSpinnerLinePaint.setStyle(Paint.Style.STROKE); mSpinnerLinePaint.setColor(lineColor); canvas.drawCircle(x, y, dp2, mSpinnerLinePaint); } } private void drawFloatTextBox(Canvas canvas, float x, float y, int text) { int dp6 = dpToPx(6); int dp18 = dpToPx(18); //p1 Path path = new Path(); path.moveTo(x, y); //p2 path.lineTo(x - dp6, y - dp6); //p3 path.lineTo(x - dp18, y - dp6); //p4 path.lineTo(x - dp18, y - dp6 - dp18); //p5 path.lineTo(x + dp18, y - dp6 - dp18); //p6 path.lineTo(x + dp18, y - dp6); //p7 path.lineTo(x + dp6, y - dp6); //p1 path.lineTo(x, y); canvas.drawPath(path, mSpinnerLinePaint); mSpinnerLinePaint.setColor(Color.WHITE); mSpinnerLinePaint.setTextSize(spToPx(14)); Rect rect = getTextBounds(text + "", mSpinnerLinePaint); canvas.drawText(text + "", x - rect.width() / 2, y - dp6 - (dp18 - rect.height()) / 2, mSpinnerLinePaint); } private void drawBrokenLine(Canvas canvas) { mSpinnerLinePaint.setStyle(Paint.Style.STROKE); mSpinnerLinePaint.setColor(lineColor); //绘制折线 Path path = new Path(); float prePreviousPointX = Float.NaN; float prePreviousPointY = Float.NaN; float previousPointX = Float.NaN; float previousPointY = Float.NaN; float currentPointX = Float.NaN; float currentPointY = Float.NaN; float nextPointX; float nextPointY; int lineSize = mXData.size(); for (int i = 0; i < lineSize; i++) { float x; float y; if (Float.isNaN(currentPointX)) { currentPointX = getSpinnerPoint(i).x; currentPointY = getSpinnerPoint(i).y; } if (Float.isNaN(previousPointX)) { //是第一个点? if (i > 0) { previousPointX = getSpinnerPoint(i - 1).x; previousPointY = getSpinnerPoint(i - 1).y; } else { //用当前点表示上一个点 previousPointX = currentPointX; previousPointY = currentPointY; } } if (Float.isNaN(prePreviousPointX)) { //是前两个点? if (i > 1) { prePreviousPointX = getSpinnerPoint(i - 2).x; prePreviousPointY = getSpinnerPoint(i - 2).y; } else { //当前点表示上上个点 prePreviousPointX = previousPointX; prePreviousPointY = previousPointY; } } // 判断是不是最后一个点了 if (i < lineSize - 1) { nextPointX = getSpinnerPoint(i + 1).x; nextPointY = getSpinnerPoint(i + 1).y; } else { //用当前点表示下一个点 nextPointX = currentPointX; nextPointY = currentPointY; } if (i == 0) { // 将Path移动到开始点 path.moveTo(currentPointX, currentPointY); } else { // 求出控制点坐标 final float firstDiffX = (currentPointX - prePreviousPointX); final float firstDiffY = (currentPointY - prePreviousPointY); final float secondDiffX = (nextPointX - previousPointX); final float secondDiffY = (nextPointY - previousPointY); final float firstControlPointX = previousPointX + (mLineSmoothness * firstDiffX); final float firstControlPointY = previousPointY + (mLineSmoothness * firstDiffY); final float secondControlPointX = currentPointX - (mLineSmoothness * secondDiffX); final float secondControlPointY = currentPointY - (mLineSmoothness * secondDiffY); //画出曲线 path.cubicTo(firstControlPointX, firstControlPointY, secondControlPointX, secondControlPointY, currentPointX, currentPointY); } // 更新 prePreviousPointX = previousPointX; prePreviousPointY = previousPointY; previousPointX = currentPointX; previousPointY = currentPointY; currentPointX = nextPointX; currentPointY = nextPointY; } canvas.drawPath(path, mSpinnerLinePaint); } private void drawXY(Canvas canvas) { int length = dpToPx(5);//刻度的长度 //绘制Y坐标 canvas.drawLine(mXOri - xyLineWidth / 2, 0, mXOri - xyLineWidth / 2, mYOri, mXYPaint); //绘制箭头 mXYPaint.setStyle(Paint.Style.STROKE); Path path = new Path(); path.moveTo(mXOri - xyLineWidth / 2 - dpToPx(5), dpToPx(12)); path.lineTo(mXOri - xyLineWidth / 2, xyLineWidth / 2); path.lineTo(mXOri - xyLineWidth / 2 + dpToPx(5), dpToPx(12)); canvas.drawPath(path, mXYPaint); //绘制刻度 int yLength = (int) (mYOri * (1 - 0.1f) / (mYData.size() - 1));//y轴上面空出10%,计算出y轴刻度间距 for (int i = 0; i < mYData.size(); i++) { //绘制刻度 canvas.drawLine(mXOri, mYOri - yLength * i + xyLineWidth / 2, mXOri + length, mYOri - yLength * i + xyLineWidth / 2, mXYPaint); mXYTextPaint.setColor(xyTextColor); //绘制文本 String text = mYData.get(i) + ""; Rect rect = getTextBounds(text, mXYTextPaint); canvas.drawText(text, 0, text.length(), mXOri - xyLineWidth - dpToPx(2) - rect.width(), mYOri - yLength * i + rect.height() / 2, mXYTextPaint); } //绘制坐标 canvas.drawLine(mXOri, mYOri + xyLineWidth / 2, width, mYOri + xyLineWidth / 2, mXYPaint); //绘制箭头 mXYPaint.setStyle(Paint.Style.STROKE); path = new Path(); //整个长度 float xLength = mXInit + interval * (mXData.size() - 1) + (width - mXOri) * 0.1f; if (xLength < width) xLength = width; path.moveTo(xLength - dpToPx(12), mYOri + xyLineWidth / 2 - dpToPx(5)); path.lineTo(xLength - xyLineWidth / 2, mYOri + xyLineWidth / 2); path.lineTo(xLength - dpToPx(12), mYOri + xyLineWidth / 2 + dpToPx(5)); canvas.drawPath(path, mXYPaint); //绘制x轴刻度 for (int i = 0; i < mXData.size(); i++) { float x = mXInit + interval * i; if (x >= mXOri) {//只绘制从原点开始的区域 mXYTextPaint.setColor(xyTextColor); canvas.drawLine(x, mYOri, x, mYOri - length, mXYPaint); //绘制X轴文本 String text = mXData.get(i); Rect rect = getTextBounds(text, mXYTextPaint); if (i == selectIndex - 1) { mXYTextPaint.setColor(lineColor); canvas.drawText(text, 0, text.length(), x - rect.width() / 2, mYOri + xyLineWidth + dpToPx(2) + rect.height(), mXYTextPaint); canvas.drawRoundRect(x - xValueRect.width() / 2 - dpToPx(3), mYOri + xyLineWidth + dpToPx(1), x + xValueRect.width() / 2 + dpToPx(3), mYOri + xyLineWidth + dpToPx(2) + xValueRect.height() + dpToPx(2), dpToPx(2), dpToPx(2), mXYTextPaint); } else { canvas.drawText(text, 0, text.length(), x - rect.width() / 2, mYOri + xyLineWidth + dpToPx(2) + rect.height(), mXYTextPaint); } } } } private float startX; private float startx; @Override public boolean onTouchEvent(MotionEvent event) { if (isScrolling) return super.onTouchEvent(event); //当该view获得点击事件，就请求父控件不拦截事件 this.getParent().requestDisallowInterceptTouchEvent(true); obtainVelocityTracker(event); switch (event.getAction()) { case MotionEvent.ACTION_DOWN: startX = event.getX(); startx = event.getX(); Log.e("XXXX", "down:" + startX + ""); break; case MotionEvent.ACTION_MOVE: //滑动距离小于等于8的时候任务为短距离滑动 //当前x轴的尺寸与设置的x轴间隔的距离之乘积大于 屏幕中的显示布局宽度与x轴七点之差时，开始移动 if (interval * mXData.size() > width - mXOri) { //获取滑动的距离 float dis = event.getX() - startX; //重新赋值给startX startX = event.getX(); //当前x原点距离与左右滑动的距离之和没有最小值大，则将当前x距离赋值为最小，以下相似 if (mXInit + dis < minXInit) { mXInit = minXInit; } else if (mXInit + dis > maxXInit) { mXInit = maxXInit; } else { mXInit = mXInit + dis; } invalidate(); } break; case MotionEvent.ACTION_UP: isShortSlide = Math.abs(event.getX() - startx) <= dpToPx(8); clickAction(event); scrollAfterActionUp(); this.getParent().requestDisallowInterceptTouchEvent(false); recycleVelocityTracker(); break; case MotionEvent.ACTION_CANCEL: //增加这行代码防止与父类的滑动事件冲突 this.getParent().requestDisallowInterceptTouchEvent(false); recycleVelocityTracker(); break; } return true; } //是否正在滑动 private boolean isScrolling = false; private void scrollAfterActionUp() { if (!isScroll) return; final float velocity = getVelocity(); float scrollLength = maxXInit - minXInit; if (Math.abs(velocity) < 10000) scrollLength = (maxXInit - minXInit) * Math.abs(velocity) / 10000; ValueAnimator animator = ValueAnimator.ofFloat(0, scrollLength); animator.setDuration((long) (scrollLength / (maxXInit - minXInit) * 1000));//时间最大为1000毫秒，此处使用比例进行换算 animator.setInterpolator(new DecelerateInterpolator()); animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimator valueAnimator) { float value = (float) valueAnimator.getAnimatedValue(); if (velocity < 0 && mXInit > minXInit) {//向左滑动 if (mXInit - value <= minXInit) mXInit = minXInit; else mXInit = mXInit - value; } else if (velocity > 0 && mXInit < maxXInit) {//向右滑动 if (mXInit + value >= maxXInit) mXInit = maxXInit; else mXInit = mXInit + value; } invalidate(); } }); animator.addListener(new Animator.AnimatorListener() { @Override public void onAnimationStart(Animator animator) { isScrolling = true; } @Override public void onAnimationEnd(Animator animator) { isScrolling = false; } @Override public void onAnimationCancel(Animator animator) { isScrolling = false; } @Override public void onAnimationRepeat(Animator animator) { } }); animator.start(); } private float getVelocity() { if (mTracker != null) { mTracker.computeCurrentVelocity(1000); return mTracker.getXVelocity(); } return 0; } // 44 142 139 private void clickAction(MotionEvent event) { int dp8 = dpToPx(8); float eventX = event.getX(); float eventY = event.getY(); if (!isShortSlide) { for (int i = 0; i < mXData.size(); i++) { float x = mXInit + interval * i; float start = mXOri; if (x >= start + (mSelectMiddle - 1) * interval && x < start + mSelectMiddle * interval) { selectIndex = i + 1; invalidate(); } } return; } for (int i = 0; i < mXData.size(); i++) { //节点 float x = mXInit + interval * i; float y = mYOri - mYOri * (1 - 0.1f) * mSpinnerValue.get(mXData.get(i)) / mYData.get(mYData.size() - 1); if (eventX >= x - dp8 && eventX <= x + dp8 && eventY >= y - dp8 && eventY <= y + dp8 && selectIndex != i + 1) {//每个节点周围范围内都是可点击区域 selectIndex = i + 1; invalidate(); return; } //X轴刻度 String text = mXData.get(i); Rect rect = getTextBounds(text, mXYTextPaint); x = mXInit + interval * i; y = mYOri + xyLineWidth + dpToPx(2); if (eventX >= x - rect.width() / 2 - dp8 && eventX <= x + rect.width() + dp8 / 2 && eventY >= y - dp8 && eventY <= y + rect.height() + dp8 && selectIndex != i + 1) { selectIndex = i + 1; invalidate(); return; } } } private void obtainVelocityTracker(MotionEvent event) { if (!isScroll) return; if (mTracker == null) { mTracker = VelocityTracker.obtain(); } mTracker.addMovement(event); } private void recycleVelocityTracker() { if (mTracker != null) { mTracker.recycle(); mTracker = null; } } private int getSelectIndexFromShowType(int showPositionType) { int visibleScale = (width - mXOri) / interval; switch (showPositionType) { case FIRST: mSelectMiddle = 1; return mSelectMiddle; case MIDDLE: if (mXData.size() <= visibleScale) { mSelectMiddle = middleIndex(mXData.size()); } else { mSelectMiddle = middleIndex(visibleScale); } return mSelectMiddle; //屏幕可显示的刻度 case END: if (mXData.size() <= visibleScale) { mSelectMiddle = mXData.size(); } else { mSelectMiddle = visibleScale; } return visibleScale; default: mSelectMiddle = 0; return mSelectMiddle; } } public void setValue(Map<String, Integer> value) { this.mSpinnerValue = value; invalidate(); } public void setValue(Map<String, Integer> value, List<String> xValue, List<Integer> yValue) { this.mSpinnerValue = value; this.mXData = xValue; this.mYData = yValue; invalidate(); } public Map<String, Integer> getValue() { return mSpinnerValue; } private Rect getTextBounds(String text, Paint paint) { Rect rect = new Rect(); paint.getTextBounds(text, 0, text.length(), rect); return rect; } private int dpToPx(int dp) { float density = getContext().getResources().getDisplayMetrics().density; return (int) (dp * density + 0.5f * (dp >= 0 ? 1 : -1)); } private int spToPx(int sp) { float scaledDensity = getContext().getResources().getDisplayMetrics().scaledDensity; return (int) (scaledDensity * sp + 0.5f * (sp >= 0 ? 1 : -1)); } private static final int NULL_INDEX = -1; public int getListItemMaxIndex(List<?> data) { if (data == null || data.size() < 1) { return NULL_INDEX; } int max = (data.get(0) + "").length(); for (int i = 0; i < data.size(); i++) { String s = data.get(i) + ""; if (s.length() > max) { return i; } } return NULL_INDEX; } //获得在滑动结束的时候在屏幕内的点 private int middleIndex(int size) { if (size % 2 == 0) { return size / 2; } else { return size / 2 + 1; } } //获取已知点的斜率 y = kx+b private float getSlope(Point from, Point to) { float k = (to.y - from.y) / (to.x - from.x); Log.e("Point", "参数b：" + k); return k; } //获取参数 b private float getParams(Point from, Point to) { float b = from.y - (getSlope(from, to) * from.x); Log.e("Point", "参数b：" + b); return b; } //根据两点间的坐标获取x轴的任意一个坐标x值, private float getArbitrarilyX(Point from, Point to, int grade, int needGrade) { //获得输入的新坐标 float x = ((to.x - from.x) * needGrade) / grade + from.x; Log.e("Point", "x坐标值：" + x); return x; } //获取坐标值 private Point getPoint(Point from, Point to, int grade, int needGrade) { Point point = new Point(); point.setX(getArbitrarilyX(from, to, grade, needGrade)); float slope = getSlope(from, to); point.setY(slope * point.x + getParams(from, to)); return point; } //获取绘制折线的点 private Point getSpinnerPoint(int valueIndex) { float x = mXInit + interval * (valueIndex); float y = mYOri - mYOri * (1 - 0.1f) * mSpinnerValue.get(mXData.get(valueIndex)) / mYData.get(mYData.size() - 1); return new Point(x, y); } private class Point { float x; float y; public Point() { } public float getX() { return x; } public void setX(float x) { this.x = x; } public float getY() { return y; } public void setY(float y) { this.y = y; } public Point(float x, float y) { this.x = x; this.y = y; } @Override public String toString() { return "Point{" + "x=" + x + ", y=" + y + '}'; } }}读到这里，这篇“android怎么实现可以滑动的平滑曲线图”文章已经介绍完毕，想要掌握这篇文章的知识点还需要大家自己动手实践使用过才能领会，如果想了解更多相关内容的文章，欢迎关注编程网行业资讯频道。
