android中尺寸转化

/**
* dp转px
*
* @param context 上下文
* @param dpValue dp值
* @return px值
*/
public static int dp2px(Context context, float dpValue) {
final float scale = context.getResources().getDisplayMetrics().density;
return (int) (dpValue * scale + 0.5f);
}

/**
* px转dp
*
* @param context 上下文
* @param pxValue px值
* @return dp值
*/
public static int px2dp(Context context, float pxValue) {
final float scale = context.getResources().getDisplayMetrics().density;
return (int) (pxValue / scale + 0.5f);
}

/**
* sp转px
*
* @param context 上下文
* @param spValue sp值
* @return px值
*/
public static int sp2px(Context context, float spValue) {
final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;
return (int) (spValue * fontScale + 0.5f);
}

/**
* px转sp
*
* @param context 上下文
* @param pxValue px值
* @return sp值
*/
public static int px2sp(Context context, float pxValue) {
final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;
return (int) (pxValue / fontScale + 0.5f);
}

/**
* 各种单位转换
* <p>该方法存在于TypedValue</p>
*
* @param unit    单位
* @param value   值
* @param metrics DisplayMetrics
* @return 转换结果
*/
public static float applyDimension(int unit, float value, DisplayMetrics metrics) {
switch (unit) {
case TypedValue.COMPLEX_UNIT_PX:
return value;
case TypedValue.COMPLEX_UNIT_DIP:
return value * metrics.density;
case TypedValue.COMPLEX_UNIT_SP:
return value * metrics.scaledDensity;
case TypedValue.COMPLEX_UNIT_PT:
return value * metrics.xdpi * (1.0f / 72);
case TypedValue.COMPLEX_UNIT_IN:
return value * metrics.xdpi;
case TypedValue.COMPLEX_UNIT_MM:
return value * metrics.xdpi * (1.0f / 25.4f);
}
return 0;
}

/**
* 在onCreate()即可强行获取View的尺寸
* <p>需回调onGetSizeListener接口，在onGetSize中获取view宽高</p>
* <p>用法示例如下所示</p>
* <pre>{@code
* SizeUtils.forceGetViewSize(view);
* SizeUtils.setListener(new SizeUtils.onGetSizeListener() {
*     public void onGetSize(View view) {
*         Log.d("tag", view.getWidth() + " " + view.getHeight());
*     }
* });}
* </pre>
*
* @param view 视图
*/
public static void forceGetViewSize(final View view) {
view.post(new Runnable() {
@Override
public void run() {
if (mListener != null) {
mListener.onGetSize(view);
}
}
});
}

/**
* 获取到View尺寸的监听
*/
public interface onGetSizeListener {
void onGetSize(View view);
}

public static void setListener(onGetSizeListener listener) {
mListener = listener;
}

private static onGetSizeListener mListener;

/**
* ListView中提前测量View尺寸，如headerView
* <p>用的时候去掉注释拷贝到ListView中即可</p>
* <p>参照以下注释代码</p>
*
* @param view 视图
*/
public static void measureViewInLV(View view) {
Log.i("tips", "U should copy the following code.");
/*
ViewGroup.LayoutParams p = view.getLayoutParams();
if (p == null) {
p = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
}
int width = ViewGroup.getChildMeasureSpec(0, 0, p.width);
int height;
int tempHeight = p.height;
if (tempHeight > 0) {
height = MeasureSpec.makeMeasureSpec(tempHeight,
MeasureSpec.EXACTLY);
} else {
height = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
}
view.measure(width, height);
*/
}