我想实现一个 slider ,它基本上是两条线,一条垂直,一条水平,穿过屏幕被触摸的地方。我已经成功制作了一个,但我必须解决问题:
- slider 不是很流畅,移动手指时有轻微延迟
- 如果我放置两个 slider ,则不是多点触控,我想同时使用它们
代码如下:
public class Slider extends View {
private Controller controller = new Controller();
private boolean initialisedSlider;
private int sliderWidth, sliderHeight;
private Point pointStart;
private Paint white;
private int mode;
final static int VERTICAL = 0, HORIZONTAL = 1, BOTH = 2;
public Slider(Context context) {
super(context);
setFocusable(true);
// TODO Auto-generated constructor stub
}
public Slider(Context context, AttributeSet attrs) {
super(context, attrs);
setFocusable(true);
pointStart = new Point();
initialisedSlider = false;
mode = Slider.BOTH;
}
@Override
protected void onDraw(Canvas canvas) {
if(!initialisedSlider) {
initialisedSlider = true;
sliderWidth = getMeasuredWidth();
sliderHeight = getMeasuredHeight();
pointStart.x = (int)(sliderWidth/2.0);
pointStart.y = (int)(sliderHeight/2.0);
controller = new Controller(pointStart, 3);
white = new Paint();
white.setColor(0xFFFFFFFF);
}
canvas.drawLine(controller.getCoordX(),0,
controller.getCoordX(),sliderHeight,
white);
canvas.drawLine(0, controller.getCoordY(),
sliderWidth, controller.getCoordY(),
white);
}
public boolean onTouchEvent(MotionEvent event) {
int eventaction = event.getAction();
int X = (int)event.getX();
int Y = (int)event.getY();
switch (eventaction) {
case MotionEvent.ACTION_DOWN:
if(isInBounds(X,Y)) {
updateController(X, Y);
}
break;
case MotionEvent.ACTION_MOVE:
if(isInBounds(X,Y)) {
updateController(X, Y);
}
break;
case MotionEvent.ACTION_UP:
if(isInBounds(X,Y)) {
updateController(X, Y);
}
break;
}
invalidate();
return true;
}
private boolean isInBounds(int x, int y) {
return ((x<=(sliderWidth)) && (x>=(0))
&& (y<=(sliderHeight)) && (y>=(0)));
}
private void updateController(int x, int y) {
switch(mode) {
case Slider.HORIZONTAL:
controller.setCoordX(x);
break;
case Slider.VERTICAL:
controller.setCoordY(y);
break;
case Slider.BOTH:
controller.setCoordX(x);
controller.setCoordY(y);
break;
}
}
private class Controller {
private int coordX, coordY;
Controller() {
}
Controller(Point point, int width) {
setCoordX(point.x);
setCoordY(point.y);
}
public void setCoordX(int coordX) {
this.coordX = coordX;
}
public int getCoordX() {
return coordX;
}
public void setCoordY(int coordY) {
this.coordY = coordY;
}
public int getCoordY() {
return coordY;
}
}
}
还有 XML 文件:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello" />
<com.android.lasttest.Slider
android:id="@+id/slider"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_gravity="center_horizontal"
android:adjustViewBounds="true"/>
<com.android.lasttest.Slider
android:id="@+id/slider"
android:layout_width="150dp"
android:layout_height="150dp"
android:layout_gravity="center_horizontal"
android:adjustViewBounds="true"/>
<com.android.lasttest.Slider
android:id="@+id/slider"
android:layout_width="200dp"
android:layout_height="200dp"
android:layout_gravity="center_horizontal"
android:adjustViewBounds="true"/>
</LinearLayout>
最佳答案
如何实现 SeekBar
将 SeekBar 添加到您的布局中
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/textView"
android:layout_margin="20dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<SeekBar
android:id="@+id/seekBar"
android:max="100"
android:progress="50"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
注意事项
max
是搜索栏可以达到的最高值。默认值为100
。最小值为0
。 xmlmin
值仅适用于 API 26,但您可以通过编程将0-100
范围转换为早期版本所需的任何值。progress
是 slider 点的初始位置(称为“拇指”)。- 对于垂直 SeekBar,请使用
android:rotation="270"
。
监听代码变化
public class MainActivity extends AppCompatActivity {
TextView tvProgressLabel;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// set a change listener on the SeekBar
SeekBar seekBar = findViewById(R.id.seekBar);
seekBar.setOnSeekBarChangeListener(seekBarChangeListener);
int progress = seekBar.getProgress();
tvProgressLabel = findViewById(R.id.textView);
tvProgressLabel.setText("Progress: " + progress);
}
SeekBar.OnSeekBarChangeListener seekBarChangeListener = new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
// updated continuously as the user slides the thumb
tvProgressLabel.setText("Progress: " + progress);
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
// called when the user first touches the SeekBar
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
// called after the user finishes moving the SeekBar
}
};
}
注意事项
- 如果您在用户移动搜索栏时不需要进行任何更新,那么您可以在
onStopTrackingTouch
中更新 UI。
另见
关于android - 在 Android 中实现一个 slider (SeekBar),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/8629535/