如何在Fresco库中将DraweeView的尺寸设置为“ wrap_content”

Question

I'm using the Fresco library in my app to load images. The problem is that I can't set my images height to "wrap_content" because "wrap_content" is not supported in the Fresco library. So how can I make my images to look good using a DraweeView ? I looked here but I couldn't find a solution to this problem : frescolib/wrap_content

For example:

<com.facebook.drawee.view.SimpleDraweeView
         android:id="@+id/intro_image1"
         android:layout_width="match_parent"
         android:layout_height= // Can't use "wrap_content"
         fresco:placeholderImage="@drawable/placeholder_image" />

BTW the images dimensions are 730*760

Answer 1

Since you already know the exact dimensions of the image, you can simply calculate the aspect ratio of your image and then just set the aspect ratio in XML or Java. This works out-of-the-box and you don't need any custom views or DP / pixel calculations as suggested in other answers.

For your example, this would be w/h = 730/760 = 0.96052631578

Now you can just set it: In XML:

<com.facebook.drawee.view.SimpleDraweeView
    android:id="@+id/my_image_view"
    android:layout_width="match_parent" <!-- or the desired width -->
    android:layout_height="wrap_content"
    fresco:viewAspectRatio="0.96052631578" <!-- your aspect ratio -->
    <!-- other attributes -->

Or in Java:

mSimpleDraweeView.setAspectRatio(0.96052631578f); // or whatever your aspect ratio is

See also http://frescolib.org/docs/using-drawees-xml.html at the very bottom.

Answer 2

For dp to px and px to dp on all devices, use the following formula:

Convert dp to pixel:

public int dpToPx(int dp) {
DisplayMetrics displayMetrics = getContext().getResources().getDisplayMetrics();
int px = Math.round(dp * (displayMetrics.xdpi / DisplayMetrics.DENSITY_DEFAULT));       
return px;
}

Convert pixel to dp:

public int pxToDp(int px) {
DisplayMetrics displayMetrics = getContext().getResources().getDisplayMetrics();
int dp = Math.round(px / (displayMetrics.xdpi / DisplayMetrics.DENSITY_DEFAULT));
return dp;
}

SimpleDraweeView does not directly allow wrap_content as dimension. The work around is to extend the class as the answer above clearly indicates.

Use the formula to correctly find your needed metric and set the Layout parameters for your draweeview programmatically.