之前自己一直手工编写函数来实现dip值到px值，今天无意中发现android本身就带有类似的函数来实现这种转换过程，就是 TypedValue.applyDimension
public class TypedValueApiUseDemoActivity extends AppCompatActivity {
public static final String TAG = "xp.chen";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_typed_value_api_use_demo);
int dipValue = 20;
float density = getResources().getDisplayMetrics().density;
int finalPx = (int) (dipValue * density);
int pxValue = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dipValue, getResources().getDisplayMetrics());
Log.i(TAG, "finalPx: "+finalPx+", pxValue: "+pxValue);
}
}Log:
I/xp.chen: finalPx: 60, pxValue: 60
查看下源码，android的实现和我们自己的实现是一样的：
/**
* Converts an unpacked complex data value holding a dimension to its final floating
* point value. The two parameters <var>unit</var> and <var>value</var>
* are as in {@link #TYPE_DIMENSION}.
*
* @param unit The unit to convert from.
* @param value The value to apply the unit to.
* @param metrics Current display metrics to use in the conversion --
* supplies display density and scaling information.
*
* @return The complex floating point value multiplied by the appropriate
* metrics depending on its unit.
*/
public static float applyDimension(int unit, float value,
DisplayMetrics metrics)
{
switch (unit) {
case COMPLEX_UNIT_PX:
return value;
case COMPLEX_UNIT_DIP:
return value * metrics.density;
case COMPLEX_UNIT_SP:
return value * metrics.scaledDensity;
case COMPLEX_UNIT_PT:
return value * metrics.xdpi * (1.0f/72);
case COMPLEX_UNIT_IN:
return value * metrics.xdpi;
case COMPLEX_UNIT_MM:
return value * metrics.xdpi * (1.0f/25.4f);
}
return 0;
}