Android系统的进度条控件默认的设计的不是很周全,比如没有包含文字的显示,那么如何在Android进度条控件上显示文字呢? 来自Google内部的代码来了解下,主要使用的addView这样的方法通过覆盖一层Chronometer秒表控件来实现,整个代码如下
public class TextProgressBar extends RelativeLayout implements OnChronometerTickListener {
public static final String TAG = "TextProgressBar";
static final int CHRONOMETER_ID = android.R.id.text1;
static final int PROGRESSBAR_ID = android.R.id.progress;
Chronometer mChronometer = null;
ProgressBar mProgressBar = null;
long mDurationBase = -1;
int mDuration = -1;
boolean mChronometerFollow = false;
int mChronometerGravity = Gravity.NO_GRAVITY;
public TextProgressBar(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public TextProgressBar(Context context, AttributeSet attrs) {
super(context, attrs);
}
public TextProgressBar(Context context) {
super(context);
}
//Android开发网提示关键部分在这里
@Override
public void addView(View child, int index, ViewGroup.LayoutParams params) {
super.addView(child, index, params);
int childId = child.getId();
if (childId == CHRONOMETER_ID && child instanceof Chronometer) {
mChronometer = (Chronometer) child;
mChronometer.setOnChronometerTickListener(this);
// Check if Chronometer should move with with ProgressBar
mChronometerFollow = (params.width == ViewGroup.LayoutParams.WRAP_CONTENT);
mChronometerGravity = (mChronometer.getGravity() & Gravity.HORIZONTAL_GRAVITY_MASK);
} else if (childId == PROGRESSBAR_ID && child instanceof ProgressBar) {
mProgressBar = (ProgressBar) child;
}
}
@android.view.RemotableViewMethod
public void setDurationBase(long durationBase) {
mDurationBase = durationBase;
if (mProgressBar == null || mChronometer == null) {
throw new RuntimeException("Expecting child ProgressBar with id " +
"’android.R.id.progress’ and Chronometer id ‘android.R.id.text1’");
}
// Update the ProgressBar maximum relative to Chronometer base
mDuration = (int) (durationBase – mChronometer.getBase());
if (mDuration <= 0) {
mDuration = 1;
}
mProgressBar.setMax(mDuration);
}
public void onChronometerTick(Chronometer chronometer) {
if (mProgressBar == null) {
throw new RuntimeException(
"Expecting child ProgressBar with id ‘android.R.id.progress’");
}
// Stop Chronometer if we’re past duration
long now = SystemClock.elapsedRealtime();
if (now >= mDurationBase) {
mChronometer.stop();
}
int remaining = (int) (mDurationBase – now);
mProgressBar.setProgress(mDuration – remaining);
if (mChronometerFollow) {
RelativeLayout.LayoutParams params;
params = (RelativeLayout.LayoutParams) mProgressBar.getLayoutParams();
int contentWidth = mProgressBar.getWidth() – (params.leftMargin + params.rightMargin);
int leadingEdge = ((contentWidth * mProgressBar.getProgress()) /
mProgressBar.getMax()) + params.leftMargin;
int adjustLeft = 0;
int textWidth = mChronometer.getWidth();
if (mChronometerGravity == Gravity.RIGHT) {
adjustLeft = -textWidth;
} else if (mChronometerGravity == Gravity.CENTER_HORIZONTAL) {
adjustLeft = -(textWidth / 2);
}
leadingEdge += adjustLeft;
int rightLimit = contentWidth – params.rightMargin – textWidth;
if (leadingEdge < params.leftMargin) {
leadingEdge = params.leftMargin;
} else if (leadingEdge > rightLimit) {
leadingEdge = rightLimit;
}
params = (RelativeLayout.LayoutParams) mChronometer.getLayoutParams();
params.leftMargin = leadingEdge;
mChronometer.requestLayout();
}
}
}
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