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相机调焦：原理，使用竖直seekbar，根据用户拖拉来获得距离，然后以Parameter的形式设置到Camera。

实现OnSeekBarChangeListener

/*

* (non-Javadoc)

* 

* @see

* android.widget.SeekBar.OnSeekBarChangeListener#onProgressChanged(android

* .widget.SeekBar, int, boolean)

*/

@Override

public void onProgressChanged(SeekBar arg0, int arg1, boolean arg2) {

// TODO Auto-generated method stub

if (myCamera == null || arg2) {

arg0.setProgress(0);

return;

}

try {

Parameters p = myCamera.getParameters();

int maxPa = p.getMaxZoom();

int maxCa = arg0.getMax();

p.setZoom(maxPa * arg1 / maxCa);

myCamera.setParameters(p);

} catch (Exception e) {

// TODO: handle exception

arg0.setProgress(0);

}

}

而实现OnSeekBarChangeListener如下

public class CameraSeekBar extends SeekBar {

/**

 * 

 */

/**

* @param context

*/

public CameraSeekBar(Context context) {

super(context);

// TODO Auto-generated constructor stub

setThumb(getResources().getDrawable(R.drawable.camera_thumb));

setThumbOffset(6);

setProgressDrawable(getResources().getDrawable(R.drawable.color1));

setIndeterminateDrawable(getResources().getDrawable(R.drawable.color1));

}

public CameraSeekBar(Context context, AttributeSet attrs, int defStyle) {

super(context, attrs, defStyle);

}

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);

c.drawColor(0x00000000);

super.onDraw(c);

}

@Override

public boolean onTouchEvent(MotionEvent event) {

if (!isEnabled()) {

return false;

}

switch (event.getAction()) {

case MotionEvent.ACTION_DOWN:

// case MotionEvent.ACTION_MOVE:

case MotionEvent.ACTION_UP:

int i = 0;

i = getMax() - (int) (getMax() * event.getY() / getHeight());

setProgress(i);

onSizeChanged(getWidth(), getHeight(), 0, 0);

break;

case MotionEvent.ACTION_CANCEL:

break;

}

return true;

}

}

设置背景和thumb只能在构造方法里设置，其他地方设置无效，另外seekbar倒立主要采用Canvas的rotate方法；而滚动主要靠获得手触高度，来设置进度。camera_thumb是我找的一张小图片，而color1是一个像素的图片。

最后如何把这个控件添加到屏幕上，本例采用WindowManager操作

public void addSeekBar() {

// TODO Auto-generated method stub

if (cameraSeekBar != null) {

return;

}

wManager = (WindowManager) context

.getSystemService(Context.WINDOW_SERVICE);

cameraSeekBar = new CameraSeekBar(context);

cameraSeekBar.setBackgroundColor(0x00000000);

if (wmParams == null) {

initFloatView();

}

wManager.addView(cameraSeekBar, wmParams);

cameraSeekBar.setOnSeekBarChangeListener(this);

}

// 悬浮菜单

private WindowManager.LayoutParams wmParams = null;

private void initFloatView() {

// 设置LayoutParams(全局变量）相关参数

wmParams = new WindowManager.LayoutParams();

wmParams.type = LayoutParams.TYPE_PHONE; // 设置window type

wmParams.format = PixelFormat.RGBA_8888; // 设置图片格式，效果为背景透明

// 设置Window flag

wmParams.flags = LayoutParams.FLAG_NOT_TOUCH_MODAL

| LayoutParams.FLAG_NOT_FOCUSABLE;

// 以屏幕左上角为原点，设置x、y初始值

wmParams.x = 100;

wmParams.y = 0;

// 设置悬浮窗口长宽数据

wmParams.width = CWWindowManager.getScreenWidth() / 20;

wmParams.height = CWWindowManager.getScreenHeight() - 170;

;

// 调整悬浮窗口

wmParams.gravity = Gravity.LEFT | Gravity.CENTER_VERTICAL;

}

这样就完成项目的初步要求。

另外如果需要tab间的切换，你可以使用发通知的方式来添加和清除SeekBar

public void removeSeekBar() {

// TODO Auto-generated method stub

if (cameraSeekBar == null) {

return;

}

wManager.removeView(cameraSeekBar);

cameraSeekBar = null;

}