獲取View寬高的幾種方式及View和ViewGroup測量的簡單實現
阿新 • • 發佈:2019-02-13
自己指定測量規則
//這裡自己指定寬wrap_content 高100,
view = (Button) findViewById(R.id.button1);
int widthMeasureSpec = MeasureSpec.makeMeasureSpec((1 << 30) - 1, MeasureSpec.AT_MOST);
int heightMeasureSpec = MeasureSpec.makeMeasureSpec(100, MeasureSpec.EXACTLY);
view.measure(widthMeasureSpec, heightMeasureSpec);
增加View樹監聽
ViewTreeObserver observer = view.getViewTreeObserver();
observer.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
@SuppressWarnings("deprecation")
@Override
public void onGlobalLayout() {
view.getViewTreeObserver().removeGlobalOnLayoutListener(this );
int width = view.getMeasuredWidth();
int height = view.getMeasuredHeight();
}
});
onWindowFocusChanged中拿到
@Override
public void onWindowFocusChanged(boolean hasFocus) {
super.onWindowFocusChanged(hasFocus);
if (hasFocus) {
int width = view.getMeasuredWidth();
int height = view.getMeasuredHeight();
Log.d(TAG, "onWindowFocusChanged, width= " + view.getMeasuredWidth() + " height= " + view.getMeasuredHeight());
}
}
view的onMeasure
//如果寬高都是wrap_content 就指定為200,如果其中一個為wrap_content就指定為200
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);
int widthSpecSize = MeasureSpec.getSize(widthMeasureSpec);
int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);
int heightSpecSize = MeasureSpec.getSize(heightMeasureSpec);
if (widthSpecMode == MeasureSpec.AT_MOST
&& heightSpecMode == MeasureSpec.AT_MOST) {
setMeasuredDimension(200, 200);
} else if (widthSpecMode == MeasureSpec.AT_MOST) {
setMeasuredDimension(200, heightSpecSize);
} else if (heightSpecMode == MeasureSpec.AT_MOST) {
setMeasuredDimension(widthSpecSize, 200);
}
}
ViewGroup的onMeature
//如果不是精確的,即getSize獲取不到值,用getMeasuredWidth來獲取測量的值
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int measuredWidth = 0;
int measuredHeight = 0;
final int childCount = getChildCount();
measureChildren(widthMeasureSpec, heightMeasureSpec);
int widthSpaceSize = MeasureSpec.getSize(widthMeasureSpec);
int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);
int heightSpaceSize = MeasureSpec.getSize(heightMeasureSpec);
int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);
if (childCount == 0) {
setMeasuredDimension(0, 0);
} else if (widthSpecMode == MeasureSpec.AT_MOST && heightSpecMode == MeasureSpec.AT_MOST) {
final View childView = getChildAt(0);
measuredWidth = childView.getMeasuredWidth() * childCount;
measuredHeight = childView.getMeasuredHeight();
setMeasuredDimension(measuredWidth, measuredHeight);
} else if (heightSpecMode == MeasureSpec.AT_MOST) {
final View childView = getChildAt(0);
measuredHeight = childView.getMeasuredHeight();
setMeasuredDimension(widthSpaceSize, childView.getMeasuredHeight());
} else if (widthSpecMode == MeasureSpec.AT_MOST) {
final View childView = getChildAt(0);
measuredWidth = childView.getMeasuredWidth() * childCount;
setMeasuredDimension(measuredWidth, heightSpaceSize);
}
}