Modifying the Android seekbar widget to operate vertically
I'm trying to get a vertical seekbar going with the emulator, but I'm sort of stuck. I can get the seekbar to display the way I want it to, and I can get the progress to do what I want, and I can modify the onTouchEvent to get the thumb to go vertically instead of horizontally. What I can't do is get the thumb to move outside of the default 29 horizontal pixels without using setThumbOffset(). This in itself isn't a problem. The problem is coming from the fact that I don't understand the thumbOffset at all -- I guess. I think I could (properly) resize the widget, which I am pretty sure I'm not doing right. Or maybe I could just use the thumbOffset if I could figure it out. Since I can calculate the progress correctly I thought I would just use a linear function of progress * (getTop() - getBottom()) of the widget but that doesn't seem to do it. But I can't figure out what the offset is centered around.
As a somewhat aside, I am really unsure if what I am doing in onSizeChanged() is sane or if it's going to bite me in the ass later on.
Here's the main.xml layout:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<com.mobilsemantic.mobipoll.SlideBar
android:id="@+id/slide"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:max="100"
android:progress="0"
android:secondaryProgress="25" />
<Button android:id="@+id/button"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:text="Hello, I am a Button" />
<TextView android:id="@+id/tracking"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
</LinearLayout>
And the class (ignore the debugging junk):
import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.SeekBar;
public class SlideBar extends SeekBar {
private int oHeight = 320, oWidth = 29;
private int oProgress = -1, oOffset = -1;;
private float xPos = -1, yPos = -1;
private int top = -1, bottom = -1, left = -1, right = -1;
public SlideBar(Context context) {
super(context);
}
public SlideBar(Context context, AttributeSet attrs)
{
super(context, attrs);
oOffset = this.getThumbOffset();
oProgress = this.getProgress();
}
public SlideBar(Context context, AttributeSet attrs, int defStyle)
{
super(context, attrs, defStyle);
}
protected synchronized void onMeasure(int widthMeasureSpec, intheightMeasureSpec)
{
int height = View.MeasureSpec.getSize(heightMeasureSpec);
oHeight = height;
this.setMeasuredDimension(oWidth, oHeight);
}
protected void onSizeChanged(int w, int h, int oldw, int oldh)
{
super.onSizeChanged(h, w, oldw, oldh);
}
protected void onLayout(boolean changed, int l, int t, int r, int b)
{
super.onLayout(changed, l, t, r, b);
left = l;
right = r;
top = t;
bottom = b;
}
protected void onDraw(Canvas c)
{
c.rotate(90);
c.translate(0,-29);
super.onDraw(c);
}
public boolean onTouchEvent(MotionEvent event)
{
xPos = event.getX();
yPos = event.getY();
float progress = (yPos-this.getTop())/(this.getBottom()-this.getTop());
oOffset = this.getThumbOffset();
oProgress = this.getProgress();
Log.d("offset" + System.nanoTime(), new Integer(oOffset).toString());
Log.d("progress" + System.nanoTime(), new Integer(oProgress).toString());
float offset;
offset = progress * (this.getBottom()-this.getTop());
this.setThumbOffset((int)offset);
Log.d("offset_postsetprogress" + System.nanoTime(), new Integer(oOffset).toString());
Log.d("progress_postsetprogress" + System.nanoTime(), new Integer(oProgress).toString());
this.setProgress((int)(100*event.getY()/this.getBottom()));
return true;
}
}
Answer
I've created a solution which works (at least for me, anyway) and creates a vertical SeekBar. http://hackskrieg.wordpress.com/2012/04/20/working-vertical-seekbar-for-android/
This code will correctly select/deselect the thumb, move correctly, update the listener correctly (only when the progress changes!), update/draw the progress correctly, etc. I hope it helps you.
public class VerticalSeekBar extends SeekBar {
public VerticalSeekBar(Context context) {
super(context);
}
public VerticalSeekBar(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public VerticalSeekBar(Context context, AttributeSet attrs) {
super(context, attrs);
}
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(h, w, oldh, oldw);
}
@Override
protected synchronized void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(heightMeasureSpec, widthMeasureSpec);
setMeasuredDimension(getMeasuredHeight(), getMeasuredWidth());
}
protected void onDraw(Canvas c) {
c.rotate(-90);
c.translate(-getHeight(), 0);
super.onDraw(c);
}
private OnSeekBarChangeListener onChangeListener;
@Override
public void setOnSeekBarChangeListener(OnSeekBarChangeListener onChangeListener){
this.onChangeListener = onChangeListener;
}
private int lastProgress = 0;
@Override
public boolean onTouchEvent(MotionEvent event) {
if (!isEnabled()) {
return false;
}
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
onChangeListener.onStartTrackingTouch(this);
setPressed(true);
setSelected(true);
break;
case MotionEvent.ACTION_MOVE:
// Calling the super seems to help fix drawing problems
super.onTouchEvent(event);
int progress = getMax() - (int) (getMax() * event.getY() / getHeight());
// Ensure progress stays within boundaries of the seekbar
if(progress < 0) {progress = 0;}
if(progress > getMax()) {progress = getMax();}
// Draw progress
setProgress(progress);
// Only enact listener if the progress has actually changed
// Otherwise the listener gets called ~5 times per change
if(progress != lastProgress) {
lastProgress = progress;
onChangeListener.onProgressChanged(this, progress, true);
}
onSizeChanged(getWidth(), getHeight() , 0, 0);
onChangeListener.onProgressChanged(this, getMax() - (int) (getMax() * event.getY() / getHeight()), true);
setPressed(true);
setSelected(true);
break;
case MotionEvent.ACTION_UP:
onChangeListener.onStopTrackingTouch(this);
setPressed(false);
setSelected(false);
break;
case MotionEvent.ACTION_CANCEL:
super.onTouchEvent(event);
setPressed(false);
setSelected(false);
break;
}
return true;
}
public synchronized void setProgressAndThumb(int progress) {
setProgress(getMax() - (getMax()- progress));
onSizeChanged(getWidth(), getHeight() , 0, 0);
}
public synchronized void setMaximum(int maximum) {
setMax(maximum);
}
public synchronized int getMaximum() {
return getMax();
}
}
I just placed this vertical SeekBar inside a LinearLayout with layout_height set to FILL_PARENT and layout_width set to WRAP_CONTENT.
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:orientation="vertical" >
<com.safetyculture.jsadroidtablet.VerticalSeekBar
android:id="@+id/calculatorVerticalSeekBar"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_gravity="bottom"
android:max="4"
android:progress="2" />
</LinearLayout>
NOTE: You must set an OnSeekBarChangeListener, otherwise interacting with the SeekBar will produce NullPointerException.