确定ImageView中空白的大小

Question

I have a floor plan which is centred in an ImageView. The aspect ratio of the image is preserved so there is some space on either side of the image (indicated in red colour).

How can I determine the width of this red space in pixels or dp?

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".MyActivity"
    android:background="@color/red"
    android:orientation="vertical">

<ImageView
    android:id="@+id/floor_plan"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/floor_plan2"
    android:adjustViewBounds="true"
    android:layout_toStartOf="@+id/locateMe"
    android:layout_alignParentTop="true"
    android:layout_alignParentStart="true"
    android:layout_alignParentEnd="true"
    />

I note that the margins have been set to 0dp in the dimens.xml file.

Answer 1

That's only math :

int originalImgWidth  = bitmap.getWidth();
int originalImgHeight  = bitmap.getHeight();

float scale = screenHeight * 1f / originalImgHeight;  
// since your img will fill the screen vertically

float marginSize =  (screenWidth - (originalImgWidth * scale)) /2; 

Note that the size might be negative if the image is bigger than the screen horizontally ^^

see how to get the bitmap here

see how to get screen size here