我想实现一个滑块,它基本上是两条线,一条垂直的和一条水平的,在屏幕被触摸的地方相交。我已经成功制作了一个,但是有两个问题:
- 滑块不太平滑,当我移动手指时会有轻微的延迟。
- 如果我放置两个滑块,则不支持多点触控,并且我希望同时使用这两个滑块。
以下是代码:
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;
}
}
}
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>