计算音乐搜索栏的轨道位置

Question

如何计算音乐曲目在搜索栏上的位置？

我创建了一个普通的音乐播放器 GUI 作为 midi 音频播放器的演示，我想为它创建一个搜索栏。我已经为它创建了一切，但我一直在努力计算搜索位置指示器的 x 位置。

播放了 2 秒（尺寸：640x480）（TrackPosX：260/475，其中 475 是搜索栏 endX）

我的渲染方法的片段

int trackPosY = this.getHeight()/2+this.getHeight()/4+40; //Y coordinate of seek bar/seek indicator/end and begin points

//Draws seek bar with end points        
g.drawLine(this.getWidth()/4, trackPosY, this.getWidth()/2+this.getWidth()/4, trackPosY);  //Draws Seek bar
g.drawLine(this.getWidth()/4, trackPosY-10, this.getWidth()/4, trackPosY+10); //Draws Begin point
g.drawLine(this.getWidth()/2+this.getWidth()/4+1, trackPosY-10, this.getWidth()/2+this.getWidth()/4+1, trackPosY+10); //Draws End line (Not sure why I have to add 1 to the x but if I don't the seek bar breaches the width of the end line.)

if(midiPlayer != null && (midiPlayer.getState() == SimpleMidiPlayer.PLAY || midiPlayer.getState() == SimpleMidiPlayer.PAUSE)){
    int trackLineLength = (this.getWidth()/4+this.getWidth()/2 - this.getWidth()/4); //Length of the line, not sure if necessary
    int trackPosX = (int) ((midiPlayer.getTickPosition()/trackLineLength*midiPlayer.getTicksTotal()/trackLineLength) + (this.getWidth()/4)); //Attempt at finding X Coordinate
    g.fillOval( trackPosX-3, trackPosY-3, 6, 6); //Draws Seek position indicator
    debugTrackPos.setDebugText("TrackPosX: "+trackPosX+"/"+(this.getWidth()/4+this.getWidth()/2)+" Tick: "+midiPlayer.getTickPosition()+"/"+midiPlayer.getTicksTotal()); //Debugging purposes (top left of pic)
}

Answer 1

看起来你很接近，基本情况是这样的：

ratio = var/total;
position = (max-min)*ratio +min

您的变量是：

var = midiPlayer.getTickPosition()
total = midiPlayer.getTicksTotal()
ratio = midiPlayer.getTickPosition()/midiPlayer.getTicksTotal()

(you already have max-min defined as trackLineLength)
max = this.getWidth()/4+this.getWidth()/2 
min = this.getWidth()/4

所以使用这些变量你会得到这样的结果：

int trackPosX = (int)( ((double)midiPlayer.getTickPosition())/midiPlayer.getTicksTotal()
                * trackLineLength + this.getWidth()/4)

请注意，我在 getTickPosition/getTicksTotal 的分区中添加了 (double)cast。我的猜测是这些是返回的整数值，除非您将其转换为双精度，否则每次除法都会导致 0。

计算音乐搜索栏的轨道位置

Calculating track position for a music seek bar

java

math

midi