前言
柱状波形图是一种常见的图形。一个个柱子按顺序排列,构成一个波形图。
柱子的高度由输入数据决定。如果输入的是音频的音量,则可得到一个声波图。
在一些音频软件中,我们也可以左右拖动声波,来改变音频的播放进度
本文举例的自定View,实现如下功能:
- 以柱状形式展示数据的大小
- 标明图形当前最中间的数据
- 可以横向拖动进度,进度就是让某个特定的数据居中展示
- 可以改变左右两边的柱子颜色
- 可以调整柱子的宽度
- 拖动完毕后监听当前进度
实现
首先创建类SoundWaveView继承自View
我们可以先记录给定的宽高,方便后面找到View的中间点
private int viewWid = 1000; // px private int viewHeight = 100; // px @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); viewWid = w; viewHeight = h; // .. }
基本属性
例如柱子的颜色,宽度。可以设置个属性来记录,并开放出去可由外部来设置。
private float barWidDp = 1.5f; private float barWidPx = 3f; private float barGapPx = barWidPx / 2; private int barCount = 1; // 当前宽度能绘制多少个柱子 private final Paint paint = new Paint(); private int leftColor = Color.GREEN; private int rightColor = Color.LTGRAY; private int middleLineColor = Color.parseColor("#55000000");
设计监听器
拖动完毕后,可以将当前进度通知出去。也可以直接把触摸事件传出去。
public interface OnEvent { void onMoveEnd(); // 停止拖动了 void onDragTouchEvent(MotionEvent event); } private OnEvent onEventListener; private void tellOnMoveEnd() { if (onEventListener != null) { onEventListener.onMoveEnd(); } }
绘制图形
在onDraw
方法中根据数据绘制图形
本例没有设计背景,直接绘制数据。
图形需求之一是要求某个数据能居中显示,我们用midIndex
来标记这个数据的下标。
比较简单粗暴的实现方法,遍历整个数据列表,计算出每个数据的x坐标。超出范围的不绘制,范围内的逐一绘制。
@Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); if (dataList == null || dataList.isEmpty()) { // draw nothing drawMiddleLine(canvas); return; } float x0 = viewWid / 2.0f; if (midIndex > 0) { x0 = x0 - (barGapPx + barWidPx) * midIndex; // 可能是负数 } for (int i = 0; i < dataList.size(); i++) { float d = dataList.get(i); float x = x0 + (barWidPx + barGapPx) * i; if (x < 0) { continue; } if (x > viewWid) { break; } if (i <= midIndex) { paint.setColor(leftColor); } else { paint.setColor(rightColor); } paint.setStrokeWidth(barWidPx); float bh = (d / showMaxData) * viewHeight; bh = Math.max(bh, 4); // 最小也要一点高度 (1) float bhGap = (viewHeight - bh) / 2f; canvas.drawLine(x, bhGap, x, viewHeight - bhGap, paint); } drawMiddleLine(canvas); } private void drawMiddleLine(Canvas canvas) { paint.setColor(middleLineColor); canvas.drawLine(viewWid / 2f, 0, viewWid / 2f, viewHeight, paint); }
如果数据太小,为了更美观,也要显示一点东西
左右拖动
本例给出的思路是在SoundWaveView中直接获取触摸事件并进行处理。
简单区分一下模式,分为纯展示和可拖动模式
/** * 单纯播放 展示 无交互 */ public static final int MODE_PLAY = 1; /** * 允许左右拖动 */ public static final int MODE_CAN_DRAG = 2;
复写onTouchEvent
方法,如果是MODE_CAN_DRAG
模式,则拦截触摸事件。判断拖动的横向(x)距离。
@Override public boolean onTouchEvent(MotionEvent event) { if (mode == MODE_CAN_DRAG) { switch (event.getAction()) { case MotionEvent.ACTION_MOVE: float dx = (downX - event.getX()); // 不要那么灵敏 float movePercent = dx / viewWid; int dIndex = (int) (movePercent * barCount); int targetMidIndex = downOldMidIndex + dIndex; targetMidIndex = Math.max(0, targetMidIndex); targetMidIndex = Math.min(targetMidIndex, dataList.size() - 1); setMidIndex(targetMidIndex); Log.d(TAG, "onTouchEvent-MOVE; dx: " + dx + ", dIndex: " + dIndex + "; targetMidIndex: " + targetMidIndex); break; case MotionEvent.ACTION_DOWN: downX = event.getX(); downOldMidIndex = midIndex; break; case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: downOldMidIndex = midIndex; tellOnMoveEnd(); break; } if (onEventListener != null) { onEventListener.onDragTouchEvent(event); } return true; } return super.onTouchEvent(event); }
完整代码
文件SoundWaveView.java,这个view主要目的是展现声波,取名为「SoundWave」
import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.util.AttributeSet; import android.util.Log; import android.view.MotionEvent; import android.view.View; import androidx.annotation.Nullable; import java.util.ArrayList; import java.util.List; /** * @author an.rustfisher.com */ public class SoundWaveView extends View { private static final String TAG = "rustAppSoundWaveView"; /** * 单纯播放 展示 无交互 */ public static final int MODE_PLAY = 1; /** * 允许左右拖动 */ public static final int MODE_CAN_DRAG = 2; private int mode = MODE_PLAY; // 1 播放 private ListdataList = new ArrayList<>(100); private float showMaxData = 40f; // 能显示的最大数据 private int midIndex = 0; // 在中间显示的数据的下标 private float barWidDp = 1.5f; private float barWidPx = 3f; private float barGapPx = barWidPx / 2; private int barCount = 1; // 当前宽度能绘制多少个柱子 private int viewWid = 1000; // px private int viewHeight = 100; // px private final Paint paint = new Paint(); private int leftColor = Color.GREEN; private int rightColor = Color.LTGRAY; private int middleLineColor = Color.parseColor("#55000000"); private float downX = 0; // getX private int downOldMidIndex = 0; public interface OnEvent { void onMoveEnd(); // 停止拖动了 void onDragTouchEvent(MotionEvent event); } private OnEvent onEventListener; public SoundWaveView(Context context) { this(context, null); } public SoundWaveView(Context context, @Nullable AttributeSet attrs) { this(context, attrs, 0); } public SoundWaveView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); paint.setColor(Color.BLUE); } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); viewWid = w; viewHeight = h; calBarPara(); Log.d(TAG, "onSizeChanged: " + w + ", " + h); Log.d(TAG, "onSizeChanged: barWidPx: " + barWidPx); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); if (dataList == null || dataList.isEmpty()) { // draw nothing drawMiddleLine(canvas); return; } float x0 = viewWid / 2.0f; // 绘制数据 if (midIndex > 0) { x0 = x0 - (barGapPx + barWidPx) * midIndex; // 可能是负数 } for (int i = 0; i < dataList.size(); i++) { float d = dataList.get(i); float x = x0 + (barWidPx + barGapPx) * i; if (x < 0) { continue; } if (x > viewWid) { break; } if (i <= midIndex) { paint.setColor(leftColor); } else { paint.setColor(rightColor); } paint.setStrokeWidth(barWidPx); float bh = (d / showMaxData) * viewHeight; bh = Math.max(bh, 4); // 最小也要一点高度 float bhGap = (viewHeight - bh) / 2f; canvas.drawLine(x, bhGap, x, viewHeight - bhGap, paint); } drawMiddleLine(canvas); } private void drawMiddleLine(Canvas canvas) { paint.setColor(middleLineColor); canvas.drawLine(viewWid / 2f, 0, viewWid / 2f, viewHeight, paint); } public float getMidByPercent() { return midIndex / (float) (dataList.size() - 1); } @Override public boolean onTouchEvent(MotionEvent event) { if (mode == MODE_CAN_DRAG) { switch (event.getAction()) { case MotionEvent.ACTION_MOVE: float dx = (downX - event.getX()); // 不要那么灵敏 float movePercent = dx / viewWid; int dIndex = (int) (movePercent * barCount); int targetMidIndex = downOldMidIndex + dIndex; targetMidIndex = Math.max(0, targetMidIndex); targetMidIndex = Math.min(targetMidIndex, dataList.size() - 1); setMidIndex(targetMidIndex); Log.d(TAG, "onTouchEvent-MOVE; dx: " + dx + ", dIndex: " + dIndex + "; targetMidIndex: " + targetMidIndex); break; case MotionEvent.ACTION_DOWN: downX = event.getX(); downOldMidIndex = midIndex; break; case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: downOldMidIndex = midIndex; tellOnMoveEnd(); break; } if (onEventListener != null) { onEventListener.onDragTouchEvent(event); } return true; } return super.onTouchEvent(event); } public void setMode(int mode) { this.mode = mode; } public int getMode() { return mode; } public int getMidIndex() { return midIndex; } public List getDataList() { return dataList; } public void setOnEventListener(OnEvent onEventListener) { this.onEventListener = onEventListener; } public void clear() { dataList = new ArrayList<>(); midIndex = 0; invalidate(); } private void calBarPara() { barWidPx = dp2Px(barWidDp); barGapPx = barWidPx; barCount = (int) ((viewWid - barGapPx) / (barWidPx + barGapPx)); paint.setStrokeWidth(barWidPx); Log.d(TAG, "calBarPara: barCount: " + barCount); } public void setDataList(List input) { dataList = new ArrayList<>(input); midIndex = 0; invalidate(); } public void setMidIndex(int midIndex) { this.midIndex = midIndex; invalidate(); } public void setMidEnd() { setMidIndex(dataList.size() - 1); } // 设置当前播放进度 public void setPlayPercent(float percent) { midIndex = (int) (percent * (dataList.size() - 1)); if (percent >= 1) { midIndex = dataList.size() - 1; } invalidate(); } public void setShowMaxData(float showMaxData) { this.showMaxData = showMaxData; } public float getShowMaxData() { return showMaxData; } // 不停地插入数据 public void addDataEnd(float f) { dataList.add(f); midIndex = dataList.size() - 1; invalidate(); } public void setLeftColor(int leftColor) { this.leftColor = leftColor; } public void setRightColor(int rightColor) { this.rightColor = rightColor; } private float dp2Px(float dp) { float density = getContext().getResources().getDisplayMetrics().density; int mark = dp > 0 ? 1 : -1; return dp * density * mark; } private void tellOnMoveEnd() { if (onEventListener != null) { onEventListener.onMoveEnd(); } } }
layout中使用
activity中使用模拟数据
private void setData1() { ListdataList = new ArrayList<>(); for (int i = 0; i < 1000; i++) { dataList.add((float) (Math.random() * soundWaveView.getShowMaxData())); } soundWaveView.setDataList(dataList); soundWaveView.setMidIndex(0); soundWaveView.setOnEventListener(new SoundWaveView.OnEvent() { @Override public void onMoveEnd() { Log.d(TAG, "onMoveEnd: " + soundWaveView.getMidIndex()); } @Override public void onDragTouchEvent(MotionEvent event) { // 在这里可以收到触摸事件 } }); }
运行示例:
我们也可以扩展一下,假设不使用柱子,也可以把相邻点连接起来,形成折线图的样子。
相关代码在: AndroidTutorial - gitee
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