测量＆QUOT的保证金; fitCenter＆QUOT; ImageView的Andr​​oid中 [英] Measuring margin of a "fitCenter" imageView in Android

问题描述

给出一个简单的RelativeLayout是这样的：

Given a simple RelativeLayout like this:

    <RelativeLayout
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="#0fffff">
    <ImageView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_gravity="center"
        android:adjustViewBounds="true"
        android:scaleType="fitCenter"
        android:src="@drawable/img001" />
    </RelativeLayout>

的布局边界和图象边界之间的左/顶间距取决于在ImageView的所述图像被负载的W / H比值

the left/top spacing between the layout border and the image border depends on the W/H ratio of the image being load in the imageView.

我怎么能知道（编程）图像后，真正的保证金（宽度和青色区域的高度）在此布局显示？

How can I know (programmatically) the real margin (width and height of the cyan area) after an image is shown in this layout?

推荐答案

这个方法计算出的新的矩形这之后FIT_CENTER 和所有的等相关数值界定的对象。

This method will calculate the new rectangle which bounds the object after FIT_CENTER and all other related values.

它应该在目标和容器的所有情况下工作。

It should work on all cases of object and container.

 public static Rect calculateFitCenterObjectRect (float containerWidth, float containerHeight, float objectWidth, float objectHeight) {

        // scale value to make fit center
        double scale = Math.min( (double)containerWidth/(double)objectWidth, (double)containerHeight/(double)objectHeight );

        int h = (int) (scale * objectHeight); // new height of the object
        int w = (int) (scale * objectWidth); // new width of the object

        int x = (int) ((containerWidth - w)*0.5f); // new x location of the object relative to the container
        int y = (int) ((containerHeight - h)*0.5f); // new y  location of the object relative to the container

        // calculate the empty space between the object and the container after fit center
        int marginRight = (int) ((containerWidth - w) * 0.5f);
        int marginLeft = (int) ((containerWidth - w) * 0.5f);
        int marginTop = (int) ((containerHeight - h) * 0.5f);
        int marginBottom = (int) ((containerHeight - h) * 0.5f);

        return new Rect( x, y, x + w, y + h );
    }

您可以使用的的FrameLayout 的，无论你使用previous方法与新的X，Y，宽度，缩放对象的高度后，要视图位置。

You can use FrameLayout to position the view wherever you want after using the previous method with the new x,y,width,height of the scaled object.

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